Lucas Oil Modified 355 Build

[94cobra69ss396]

This will be the build thread for my engine that will be powering a Lucas Oil Modified race car. I started yesterday and spent about 4 hours deburring the block. Today I radiused and polished the oil supply on the rear main bearing, deburred the crank and then washed it all. I also painted the block black.

Next up is to have the current pistons pressed off the rods so that I can polish the sides.

Main before:
http://www.motorgen.com/pic/data/500/2011-06-19_13_00_34.jpg

Main after:
http://www.motorgen.com/pic/data/500/2011-06-19_13_56_44.jpg

Crank before:
http://www.motorgen.com/pic/data/500/2011-06-19_13_00_48.jpg
http://www.motorgen.com/pic/data/500/2011-06-19_13_00_57.jpg

Crank after:
http://www.motorgen.com/pic/data/500/2011-06-19_14_20_10.jpg
http://www.motorgen.com/pic/data/500/2011-06-19_14_20_25.jpg
http://www.motorgen.com/pic/data/500/2011-06-19_14_20_56.jpg

And I can't forget my helper, Kylie.
http://www.motorgen.com/pic/data/500/2011-06-19_15_09_38.jpg

Hopefully Glen reads this. Glen, this is the first time I've deburred/stress relieved a crank. Should I have removed the excess metal from the area that I outlined in the picture? All I did was removed the sharp edges from it and then rounded it down.

http://www.motorgen.com/pic/data/500/2011-06-19_13_00_571.jpg

[BRUTAL64]

You have the right idea. ANY sharp edge can be smoothed/rounded to keep cracks from starting.

Don't worry about the highlighted area---the crank will break at #1 journal long before anything else will break.

What is the casting number of the crank you are using??

The oil feed oil on the rear main cap still needes some work. Try to make the entrance into the hole more rounded --- like two troughs going into the hole.


Noticed you are using a CAST crank. What kind of power/rpm are going to be putting out.

A GOOD cast crank can handle SOME power but rpm can be a bigger problem.


Are you going to deburr/ stress releive the block?

What is the casting number and year of your block?

In the timing chain area what 010 or 020 numbers (how many) are there cast into the block?

It's a four bolt- give me the the numbers cast onto the top of the three center main caps.

Can you give me a picture of the lifter valley from lifters (lifters hole bosses also) to top edge of block?

Also a picture of the front and rear cam hole castings.

All these questions do have a GOOD reason.

[94cobra69ss396]

You have the right idea. ANY sharp edge can be smoothed/rounded to keep cracks from starting.

Don't worry about the highlighted area---the crank will break at #1 journal long before anything else will break.

What is the casting number of the crank you are using??


The oil feed oil on the rear main cap still needes some work. Try to make the entrance into the hole more rounded --- like two troughs going into the hole.


Noticed you are using a CAST crank. What kind of power/rpm are going to be putting out.

A GOOD cast crank can handle SOME power but rpm can be a bigger problem.


Are you going to deburr/ stress releive the block?

What is the casting number and year of your block?

In the timing chain area what 010 or 020 numbers (how many) are there cast into the block?

It's a four bolt- give me the the numbers cast onto the top of the three center main caps.

Can you give me a picture of the lifter valley from lifters (lifters hole bosses also) to top edge of block?

Also a picture of the front and rear cam hole castings.

All these questions do have a GOOD reason.


I'll get you some pictures later along with pictures of the casting numbers. I did deburr the block. I'm estimating peak horsepower to be somewhere between 6500-6800 so the cast crank should be fine. We plan to gear the car so that we hit the rpm where peak horsepower occurs just past the halfway mark on the straights.

I assume what you are saying on the oil main is to smooth out the area that I circled so that it is not as sharp of a turn entering the hole?
http://www.motorgen.com/pic/data/500/2011-06-19_13_56_441.jpg

[BRUTAL64]

I'll get you some pictures later along with pictures of the casting numbers. I did deburr the block. I'm estimating peak horsepower to be somewhere between 6500-6800 so the cast crank should be fine. We plan to gear the car so that we hit the rpm where peak horsepower occurs just past the halfway mark on the straights.

I assume what you are saying on the oil main is to smooth out the area that I circled so that it is not as sharp of a turn entering the hole?
http://www.motorgen.com/pic/data/500/2011-06-19_13_56_441.jpg

Yes, that is the area I was talking about. Just blend that deeper into the entrance.

If that is the "442" crank then there is an issue of strength. If you are going to use the CAST crank in this application it may not hold up for any lenght of time. The weakness is at the #1 journal.
Though I have seen these crank stay together when used in the wrong application-Way over horsepowered.
Do you know O'leary's law?
It is;
Murphy was an optimist.:drink:


Scat sells a really good cast crank for around $200. It is stronger than the factory cast.

I'm just letting you know my thoughts on this. I know you know motors.
What ever way you want to build this I'll be there to help.:thumbs_up:


Oh, one more thing---the rods. If you can give me some pictures of the big end--side and cap.

I'm just trying to make sure you don't have anything that is not up to the job. There are some Chevy rods that are pure crap. They were cast/forged in Mexico. I know these rods just by the look of them and the markings.

[94cobra69ss396]

Here are all the pictures. Let me know if I forgot anything or if you need a better picture.

http://www.motorgen.com/pic/data/500/2011-06-20_19_36_58.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_37_09.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_37_16.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_38_26.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_38_16.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_40_421.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_39_27.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_37_35.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_42_16.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_42_33.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_42_41.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_19_41_07.jpg

It looks like I'll be replacing the crank then.

[94cobra69ss396]

Rods.

http://www.motorgen.com/pic/data/500/2011-06-20_21_50_37.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_21_52_08.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_21_51_13.jpg
http://www.motorgen.com/pic/data/500/2011-06-20_21_50_55.jpg

[94cobra69ss396]

By the way I appreciate all your input. I know enough to build some decent power but I don't know the strength of factory parts and such like you do. Thanks for any suggestions. I want to keep this build as cheap as possible so I want to use anything I can but I don't want to have something break. We'll be spinning this engine somewhere in the 6500-6800 maybe even 7000 on 1/2 and 3/8 mile tracks with some races being as much as 100 laps.

[BRUTAL64]

OK, here we go.:motorsmile:


First the block.
How did you find this block? That is one of the best blocks that Chevy produced. It's got higher Nickel and Tin. It's got the the Heavy Duty main caps -yes there is a difference. The block has very little core shift. This kind of block was only used for LT1s/L82 and Heavy duty trucks apps and is very RARE in the mid seventies. I've been known to keep blocks like these for 25 years for myself. I have one std bore right here. You're really lucky or very good-:hail:

Second the rods.
Yes, those are the good "X rods". Good strong rod for Hi-per street use. Those and the "B" rods were used to make "PINK" rods. You can work them with heat treating (you can do that at home)-I know how. Also, with good rod bolts and the heat treating (side polish not included) these will be a "PINK" rod just like the factory--that is the way they did it with hand picked rods.
OR--
Use the Scat 5.7 or 6 inch CHEVY FORGED 4340 I-BEAM With ARP 8740 7/16" CAP SCREWS. This is the rod in my 400. I got the 6 inch (best way to go- only pistons cost a little more for the 6 inch rod).
I believe they are only 314.00 for a set of 8. You can NEVER get the stock rod as strong (no matter how much work you put in the stock rods) as these are at this low price. Being a "cap screw" they make a great stroker rod for the SBC cause they clear the cam.
2-ICR5700-7/16 25700716 BUSHED 5.700" 2.100" .927" .940" 590
2-ICR6000-7/16 26000716 BUSHED 6.000" 2.100' .927" .940" 605
They do come in press pin--not the best way to go.
These rods were so "pretty" I hated to put them in the engine.:lmfao:

Third the crank.
Ok I know you don't want to hear this but I recommend a good forged Scat crank. At their price (I think about 400.00) it's a steal and really strong. If, you don't want to go that way then Scat's "better" cast crank at (if I remember correctly) 249.00.


Yes, I am a Scat fan. For their pricing you can not do better. I have talked to guys that have had "issues" with Eagel stuff. Scat has had no such "issues". The 400 ( 430 hp with over 500 ft lbs of torque) I'm doing right now is getting Scat rods and an Eagle crank ( I know it's not Scat but I'm trying to change his mind).

The thing that has me concerned is the 100 lap races. The stock crank and rods MAY not hold up under hard "load" on and off for the duration.

What cam and heads are you thinking about??

Any way you want to build this I'll be there to help.:bigthumbsup:

[94cobra69ss396]

My dad had the block. I think he pulled it from a customer's truck whenhe installed a new GM crate engine back when he had his shop and just kept it to rebuild one day for the Jimmy he had then. I'm sure he didn't know what casting it was either.

I'm going to run the rods I have but I'll buy another crank. If I can find a cheap used forged crank I go that route but if not I'll go with the Scat 9000. I'm running an Eagle cast crank in the Chevelle and it's stood up to 5 years of 6500 shifts so I may look at the Eagle cranks too.

[BRUTAL64]

My dad had the block. I think he pulled it from a customer's truck whenhe installed a new GM crate engine back when he had his shop and just kept it to rebuild one day for the Jimmy he had then. I'm sure he didn't know what casting it was either.

I'm going to run the rods I have but I'll buy another crank. If I can find a cheap used forged crank I go that route but if not I'll go with the Scat 9000. I'm running an Eagle cast crank in the Chevelle and it's stood up to 5 years of 6500 shifts so I may look at the Eagle cranks too.

Have the rods been resized and worked yet?
You can heat treat them at home if you want.


Eagle cast cranks are on sale at Jegs right now--149.00 for their stock replacement.

Talking to other shops and builders some mention that Eagle's specs were not always right on.


What rod bolts are you going to run?


Got a cam picked out yet?

[94cobra69ss396]

I have some time before I need to get a crank as we've had to put this on hold.

As far as I know the rods are stock. They are out of an engine that my dad had in his boat as is everything else except this block. I haven't looked for rod bolts yet but will most likely be ARP.

I'm going to run the Comp cam that was in it as well which is a hydraulic flat tappet. It's the Magnum series and has 253 @ .050 with a. 525 lift. He originally bought it with the K kit which comes with the lifters, springs, timing set, etc. He had the Sportsman heads set up with those parts back when he first put the old engine together. It was powering his jet drive boat but never saw over 5000 rpms because of the low compression and mismatched impeller.

Here's the measurements for the small and big end.

http://www.motorgen.com/pic/data/500/2011-06-21_20_08_29.jpg

http://www.motorgen.com/pic/data/500/2011-06-21_20_09_42.jpg

[BRUTAL64]

I have some time before I need to get a crank as we've had to put this on hold.

As far as I know the rods are stock. I haven't looked for rod bolts yet but will most likely be ARP. They are out of an engine that my dad had in his boat as is everything else except this block. I'm going to run the Comp cam that was in it as well which is a hydraulic flat tappet. It's the Magnum series and gas 253 @ .050 with a. 525 lift. he originally bought it with the K kit which comes with the lifters, springs, timing set, etc. He had the Sportsman heads set up with those parts back when he first put the old engine together. It was powering his jet drive boat but never saw over 5000 rpms because of the low compression and mismatched impeller.

Ok, then. Heat treat the rods (after polishing the rod's I beam) BEFORE you resize the big end and add the new rod bolts. You probably already knew this, but I'd thought I remind you.:p

[94cobra69ss396]

How do you heat treat the rods? I'm going to have the old pistons pressed off so I can polish the beams. Once I'm done I'll heat treat them your way. After we're back on I'll get the new pistons and a crank then have the rods reconditioned, the new bolts installed, pistons pressed on and then have everything balanced.

[BRUTAL64]

How do you heat treat the rods? I'm going to have the old pistons pressed off so I can polish the beams. Once I'm done I'll heat treat them your way. After we're back on I'll get the new pistons and a crank then have the rods reconditioned, the new bolts installed, pistons pressed on and then have everything balanced.

Your wife is going to love this; Pre heat your oven to 450 degrees and cook the rods for 8 hours. That's it.:D

First heard of this in 1969--it started with having to heat treat the rear end gears in a Chevy 12 bolt. Doing the heat treating allowed the gears to last a whole season instead of 4 or 5 runs.
Same idea with rods---it works.

BTW; Some guys think 16 hours is better-- not sure I agree.


BTW2: do you want me to look over the heads and see what porting you can do? The "old" Sportmans had a very bad exhaust port.

[BRUTAL64]

I have some time before I need to get a crank as we've had to put this on hold.

As far as I know the rods are stock. They are out of an engine that my dad had in his boat as is everything else except this block. I haven't looked for rod bolts yet but will most likely be ARP.

I'm going to run the Comp cam that was in it as well which is a hydraulic flat tappet. It's the Magnum series and has 253 @ .050 with a. 525 lift. He originally bought it with the K kit which comes with the lifters, springs, timing set, etc. He had the Sportsman heads set up with those parts back when he first put the old engine together. It was powering his jet drive boat but never saw over 5000 rpms because of the low compression and mismatched impeller.

Here's the measurements for the small and big end.

http://www.motorgen.com/pic/data/500/2011-06-21_20_08_29.jpg

http://www.motorgen.com/pic/data/500/2011-06-21_20_09_42.jpg

After heat treat and adding the new rod bolts you will need the resize the big end. Are you going to bush the small end for floating pins---I suggest this.

[BRUTAL64]

One more thing---The rods you have are the same that I used in my 400 I build as a test engine in 88. I FINALLY broke 4 pistons five years ago.


I took that engine to over 7,000 rpm all the time--but, that is not the same as doing 100 laps with heavy load on and off load. That's what breaks stock rods loading on and off contuinlessly.

Just letting you know I have used the same rods. I went to Scat rods so I wouldn't have to worry about breakage.


I hope the info I am giving you is helping.

[94cobra69ss396]

BTW2: do you want me to look over the heads and see what porting you can do? The "old" Sportmans had a very bad exhaust port.

Sure. I looked at them and they can definately be improved but I'd love to get your opinion. My dad bought these back around '97-'98 I think and why he went with the 72cc combustion chambers is beyond me.


After heat treat and adding the new rod bolts you will need the resize the big end. Are you going to bush the small end for floating pins---I suggest this.

Bushing the small end depends on cost and what I can afford to do when I'm ready. I'll have the machine shop install the new the new rod bolt and resize the big ends as well as do the balancing when I'm ready to start assembling it.

Another question, should I do the heat treating with the old bearings still in the rods or remove them? I didn't know if having them in would help with anything.

[BRUTAL64]

Sure. I looked at them and they can definately be improved but I'd love to get your opinion. My dad bought these back around '97-'98 I think and why he went with the 72cc combustion chambers is beyond me.




Bushing the small end depends on cost and what I can afford to do when I'm ready. I'll have the machine shop install the new the new rod bolt and resize the big ends as well as do the balancing when I'm ready to start assembling it.

Another question, should I do the heat treating with the old bearings still in the rods or remove them? I didn't know if having them in would help with anything.


I actually found a set of stock rods bushed and resized ready to go for $119.:nuts:
Floating pins are much easier to assemble. Plus, there is no impact on the pistons if you don't get the pressed pins in just right. If you don't get the pin correct (while the rod is hot and the pin is still cold) the very first seconds- then they'll need to be pressed on with a (I used a 12 ton) press and that can be hard on a piston if not done correctly.
Now one more thing on the rods---Once you get all the pricing together to redo your "X" rods how much more would it be to get a set of Scat rods???

They do have a set of Pro Stock 3/8 cap screw rods (8) for 233.00- maybe less. I got a set of these for the 400 I'm building.

Make sure the rods are super clean and no bearings in them. Clean is important, cause of the smell while you cook them.:sm_laughing:

The 72cc chambers are pretty good-cause they can unshroud the valves better than a 64cc. I'll need to see them.

So when do I do a head porting class???:judge:


Can get you a set of Alum heads to your door for 685.00. :)

Aren't I great at spending OTHER people's money.:rolling:

[enkeivette]

Lurk

[BRUTAL64]

Lurk

:inout:

[BRUTAL64]

Here's some light reading on rods.



They connect the reciprocal motion of the pistons to the rotational motion of the crank. The weight of the rods is important because it affects the reciprocating forces inside the engine. Lighter is usually better because less weight means faster throttle response and acceleration. But strength is even more important. Connecting rods have to be stout enough to handle all the horsepower the engine can make, and be strong enough to withstand the tension forces that try to pull the rod apart when the piston hits top dead center on the exhaust stroke. If a rod is going to break, more often than not it will fail at TDC on the exhaust stroke than at any other point in its travels. Consequently, piston weight and maximum engine rpm are more important factors to consider than how much power the engine will make when selecting a set of rods.

Basically, you want a set of rods that are as light as possible, but are also capable of handling all the forces the engine can generate (rpm and horsepower).

If you are building an engine for a sprint car that is constantly on and off the throttle, an ultra light crankshaft with the lightest possible rods and pistons will deliver the kind of performance that works best in this application. But if you are building a large displacement, relatively low rpm, high load drag motor, truck pulling motor or a marine engine, you need the reliability of a heavier crank and the strongest possible rods.

The best advice when selecting a particular set of rods is to talk to your parts suppliers and ask them what they would recommend. Every rod supplier we interviewed for this article said rod selection depends on a number of things. First and foremost is the application. In other words, what kind of engine are you building and how will it be used? The rods that work best in an all-out drag motor probably wouldn't be the best choice for a street performance engine. Nor would rods designed for a circle track sprint car be the best choice for a NASCAR engine or a marine endurance engine.

If you choose a set of rods based strictly on a catalog or Web site description, or you choose a set based solely on length, weight or price, you may not be making the best choice. That's why a few minutes spent on the phone with your rod supplier can be so valuable. They may recommend a particular type of rod you hadn't considered, or they may have some new product offerings that have not yet been added to their catalog or Web site. Catalogs get out of date very quickly, and many Web site are not updated as frequently as they should be.

ROD DESIGN
The engineers who design connecting rods know how to analyze the forces that act on rods. Years ago, the design process involves a lot of trial-and-error testing. An engineer would design a rod configuration, test it until it broke, then try to beef up the areas of the rod he felt were weak. Today, most of the development work is done with computers and sophisticated software. Engineers nowadays use finite element analysis (FEA) to analyze the compression and tension forces on a rod. The software creates 3-D images with color coding that indicates the areas of highest and lowest stress. This allows the engineer to visualize what's actually happening to a rod at various loads and speeds. He can then tweak the design on his computer screen to add metal where extra strength is needed, and to remove metal from lightly loaded areas where it isn't needed. By repeating the FEA process over and over with each design change, he can optimize the rod to deliver the best possible combination of weight, strength and reliability -- in theory anyway. It still takes real world testing to validate the design. But with today's design and analysis software, most of the work is done before a prototype part is manufactured.

One rod supplier said using FEA on their current rods allowed them to increase strength 12 to 15 percent with less than a 2 percent increase in overall rod weight.

Computer controlled numeric (CNC) machining also allows manufacturers to machine billets and forgings in ways that were previously too difficult, too time-consuming or too expensive. This allows manufacturers to offer a wider variety of rods in terms of rod length and beam construction. It also allows them to produce custom made-to-order rods very quickly. In fact, some rod suppliers say the majority of the rods they sell today are custom order rods rather than standard dimension rods from off the shelf stock.

Rods essentially come in two basic types: I-Beam and H-Beam. Some rod suppliers only make I-Beams, others only make H-Beams, and some offer both types. I-Beam rods are the most common and are used for most stock connecting rods as well as performance rods. I-Beam rods have a large flat area that is perpendicular (90 degrees) to the side beams. The side beams of the rod are parallel to the holes in the ends for the piston pin and crank journal, and provide a good combination of light weight, and tensile and compressive strength. I-Beam rods can handle high rpm tension forces well, but the rod may bend and fail if the compressive forces are too great. So to handle higher horsepower loads, the I-Beam can be made thicker, wider and/or machined in special ways to improve strength.

Rod suppliers produce a number of variants on the basic I-Beam design. The center area may be machined to create a scalloped effect between the beams, leaving a rounded area next to both beams that increases strength and rigidity much like the filets on a crankshaft journal. These kind of rods may be marketed as having an "oval-beam", "radial-beam" or "parabolic beam" design.

H-Beam rods, by comparison, are typically designed for engines that produce a lot of low rpm torque. This type of rod has two large, flat side beams that are perpendicular to the piston pin and crankshaft journal bores. The center area that connects the two sides of the "H" together provides lateral (sideways) stiffness. This type of design can provide higher compressive strength with less weight than a comparable I-Beam, according to the suppliers who make H-Beam rods. That's why H-Beam connecting rods are often recommended for high torque motors that produce a lot of power at low rpm (under 6,000 rpm). Of course, an I-Beam rod can also be strengthened to handle almost any load but it usually involves increasing the thickness and weight of the rod and/or using a stronger alloy.

STOCK CONNECTING RODS
Over 60 percent of late model connecting rods are powder metal I-beam rods. Powder metal (PM) rods are made by compressing powered steel in a mold and then heating the mold to a temperature where the powder melts and fuses into a solid part. This method of manufacturing allows parts to be cast to very close tolerances. This reduces the amount of machining needed to finish the rod, which lowers its cost. Powder metal casting also allows the ingredients in the steel alloy to be combined in ways that are impossible with conventional metal casting techniques, and the finished parts have less internal stress as a result of the fusing process. PM rods can also be up to 20 percent lighter than a comparable rod made of forged steel. Only one aftermarket rod supplier (Howards Cams) currently offers performance rods made of powder metal.

The special alloys that are used to make powder metal rods allows the rod caps to be "cracked" (separated) from the rod rather than cut. Score marks are cast into the part along the rod parting line, and the cap is then sheared off in a large press. The cracking process leaves a slightly irregular surface along the parting line between the cap and the rod that is like a jigsaw puzzle and only goes together one way. The result is better cap alignment and a stronger rod when the cap is bolted to the rod.

One of the drawbacks of powder metal rods is that the caps can't be reground to compensate for bore distortion or stretch. Consequently, if the rod bore is out-of-round or worn, the rod usually has to be replaced unless a replacement bearing with an oversized outside diameter is available.

Stock rods are typically designed for 5,500 to 6,500 rpm, and 300 to 350 horsepower in a V8 engine. In an overhead cam four or six cylinder engine, the rods may be designed to handle up to 7,000 rpm but probably only about 200 to 250 horsepower. As a rule, most stock connecting rods can handle up to 25 to 40 percent more horsepower than an unmodified engine was originally designed to produce. So for a typical budget street performance engine or a Saturday night dirt track racer, the stock rods may work just fine.

Even so, to ensure reliability the rods should always be "Magnafluxed" to check for cracks. Any flashing, burrs, nicks or other defects along the sides of the rods should also be ground off (grind lengthwise, never sideways) to eliminate stress risers that could lead to cracks and rod failure later on. Shot peening is also recommended to improve fatigue resistance. When the shot strikes the surface, it compresses the metal slightly and actually relieves stresses that might lead to cracking and rod failure.

If an engine is being built to turn significantly higher rpms than the stock motor, or to produce significantly more power (more than 40 to 50 percent), the connecting rods will probably have to be upgraded to assure adequate reliability. For a high revving engine, some type of stronger aftermarket I-Beam rods would be a good choice. For a low rpm torquer motor, either H-Beam or heavier I-Beam rods would work well.

ROD MATERIALS & APPLICATIONS
Most aftermarket performance rods are made using 4340 billet or forged steel. This is a chrome moly alloy with high tensile and compressive strength. A word of caution, though, is that all "4340" steel alloys are not necessarily the same. Heat treatments can vary, and this will affect the properties of the steel. Some rod manufacturers also tweak the alloy by adding their own proprietary ingredients to improve strength and fatigue resistance. Several rod suppliers said the 4340 steel that some offshore rod manufacturers use falls short of American Society of Metals quality standards, and is not as good a steel as they claim it is.

There is also a debate over the relative merits of "Made-in-USA" forgings versus foreign forgings that are machined in the USA or rods that are forged and finished overseas. Labor costs are far cheaper in China and other Third World countries, so there are cost advantages for suppliers who source their forgings and rods from offshore manufacturers. Patriotic and international balance-of-payment issues aside, a connecting rod that meets metallurgical quality standards, is heat treated properly, and is accurately machined to specifications is the same no matter where it comes from or who made it. The engine won't know the difference. So as long as the rod supplier stands behind their product with their brand name and reputation, the "foreign versus domestic" rod debate shouldn't matter.

Over the past couple of years, the price of high quality steel as well as many other metals such as copper and titanium has shot up dramatically for a variety of reasons (China's exploding economy being one, the ongoing war in Iraq being another, and changes in the steel industry itself being a third reason). Some rod suppliers are now having to add a steel "surcharge" to their current prices to help offset their higher cost of materials (which doesn't matter where they buy their steel because the higher prices are world-wide and affect everybody). The soaring cost of titanium has almost priced this metal out of the aftermarket. Some rod suppliers have discontinued making rods from titanium. Those who still offer titanium rods say the only people who are buying them today are the high end professional racing teams with deep pockets. One rod supplier said titanium has become "unobtanium" for the average racer.

Connecting rods made of light-weight titanium rods can reduce the reciprocating mass of the engine significantly for faster throttle response and higher rpms, but at a cost of up to $1000 or more per rod, who can really afford them?

Another lightweight material that has long been used for performance connecting rods is aluminum. Many drag racers run aluminum rods because they cost less than titanium and provide a good combination of lightness and strength. Most aluminum rods are fairly stout and typically much thicker than a comparable steel I-Beam rod. The added thickness may require additional crankcase clearance, and it increases windage and drag -- which at really high rpm may cost a few extra horsepower to overcome. The rods also require a dowel pin to keep the bearings from spinning because the bores stretch more than a steel rod. Also, the rod itself can stretch and grow in length at high rpm. This means extra clearance must be built into the engine so the pistons won't smack the heads.

Though aluminum rods are popular for drag racing and other high rpm forms of racing, most of the rod suppliers we spoke with do not recommend aluminum rods for street engines. Why? Because steel rods will hold up much better over the long run than aluminum rods. Aluminum rods are fine for a drag motor that will torn down after 200 runs and freshened up or rebuilt with a set of new or reconditioned rods. But for street applications or engines that have to run at sustained high speeds and loads for long period times, steel rods are usually better.

It's interesting to note that aluminum rods are only available from a few suppliers (GRP is one), and at least one supplier who used to offer aluminum rods (Manley) has discontinued them.

Another material that is used for many high performance rods is 300M, which is a modified 4340 steel with silicon and vanadium added, plus higher amounts of carbon and molybdenum. The 300M alloy is up to 20 percent stronger than common 4340 alloys, and was originally developed for aircraft landing gear. Now it is used for high end connecting rods.

The strength and fatigue resistance of most metals can also be improved by "cryogenic" processing after the rods have been heat treated. Heat treating causes changes in the grain structure of steel that increases strength and hardness, but it can also leave residual stresses that may lead to fatigue failure later on. By freezing parts down to minus 300 degrees below zero in special equipment that uses liquid nitrogen, the residual stresses are relieved. The super cold temperatures also cause additional changes to occur in the metal that help the parts last longer and run cooler. That's why cryogenic freezing is used on everything from engine parts to tool steels, aerospace hardware and even gun barrels.

The cryogenic process is a slow one, taking anywhere from 36 to 72 hours depending on the parts being frozen, and it must be carefully controlled to achieve the desired results. Most rod suppliers have their own cryogenic vendors who treat their rods for them. But you can also have ordinary untreated rods (even stock rods) frozen to achieve the same results.

BY THE NUMBERS
Other factors that affect the selection of rods are rod length and rod ratio. Rod length depends on the stroke of the crankshaft and the deck height of the block. If you are switching to crankshaft with a longer stroke, you are obviously going to need rods that have a shorter overall length. Even so, replacing the pistons with ones that have a higher wrist pin location can allow you to use longer rods.

Racing legend Smokey Yunick used to say that the longer the rods are, the better. His logic was based on the fact that a longer connecting rod for a given stroke allows the piston to dwell longer at TDC before it starts back down on the power stroke. This allows pressure to build longer in the combustion chamber before it starts to shove the piston down. The result is usually a broader, flatter torque curve than the same engine with shorter rods. An engine's horsepower and torque curves depend on a lot of variables other than rod length alone. But if everything else is equal, many engine builders say longer rods produce a broader torque curve. Others disagree, and say it doesn't really matter.

Rod suppliers say the only trend they see in rod lengths today is that there is no trend. Engine builders are buying just as many standard length rods as they are longer rods. This brings us to rod ratio, which is the length of a connecting rod (center to center) divided by the stroke of the crankshaft. The range in engines today may be from 1.5 to 2.1, but most performance engine builders are going with ratios in the 1.57 to 1.67 range. Some say that going with a rod ratio over 1.7 makes engine torque too "peaky." Lower rod ratio numbers are typically associated with lower rpm torque motors (a 383 Chevy street motor with a stroker crank and a rod ratio of 1.52, for example), while higher rod ratio numbers tend to be high revving high horsepower motors (a 302 high revving Chevy with a rod ratio of 1.9).

Another dimension to consider is the pin offset of the rod. On most rods (except Chevy "LS" engines), the pin bores are offset slightly. The change in pin geometry reduces the stress on the piston pin and small end of the rod when the piston reaches TDC and changes direction. It also reduces the rocking motion of the piston as it passes TDC to reduce piston slap and noise.

One new trend in this area is to run rods that do not have bronze bushings in the small end. Several racing teams are running bare rods with specially plated pins to improve durability. Eliminating the bushing, they say, leaves more meat in the small end of the rod for added strength. The only drawbacks are that the fit between the rod and pin has to be much more precise, and the wrist pin has to have a wear-resistant coating to prevent wear and galling. Also, if the pin bore becomes worn or out-of-round, the rod and piston will both have to be machined to accept a slight larger diameter pin.

[Shaolin Crane]

Ron if you still need the pistons pressed out call me friday and i'll use my press, if not we'll go across the street at talk to shawn, probably wont be very expensive. Best talk to him about all the work you need from a machine shop, will be very cheap, Ben has learned this and im sure will be a future customer

[BRUTAL64]

Ron if you still need the pistons pressed out call me friday and i'll use my press, if not we'll go across the street at talk to shawn, probably wont be very expensive. Best talk to him about all the work you need from a machine shop, will be very cheap, Ben has learned this and im sure will be a future customer

Machine shop?? Tel me more.

[Shaolin Crane]

Well im not sure if Ron will need any machine work done but my builder has VERY good rates. He is the one who did the porting on my heads in my build thread. Bill for assembly to oil pan which includes the rebuild on the heads, valve job, porting,bowl work, all the block work required for the 348. Tapping the block to 1/2" threads, machining of the lifter bores, degreeing of the cam, setting lash etc. Basically assembly of the entire engine was only 600. I think he charged me around 65 to assemble the engine since "he'll already be in there" most cant even touch the porting and head work he did for 600.

[94cobra69ss396]

Ron if you still need the pistons pressed out call me friday and i'll use my press, if not we'll go across the street at talk to shawn, probably wont be very expensive. Best talk to him about all the work you need from a machine shop, will be very cheap, Ben has learned this and im sure will be a future customer

No need to press off the old pistons. I'm pretty sure I'm going to be buying these instead of using the stoke rods.

http://www.summitracing.com/parts/SCA-35700/

[Shaolin Crane]

If you talk to my builder he may be able to get you rods on a discounted price

[BRUTAL64]

No need to press off the old pistons. I'm pretty sure I'm going to be buying these instead of using the stoke rods.

http://www.summitracing.com/parts/SCA-35700/

Good choose. I use the ones with the cap screws. Gives better clearnce of the cam with long strokes.:bigthumbsup:

[94cobra69ss396]

Do you mean these?

http://www.summitracing.com/parts/SCA-25700P/

[BRUTAL64]

Do you mean these?

http://www.summitracing.com/parts/SCA-25700P/

Yep, I use those (under 500 hp) and the 7/16 cap screw rods- for over 500hp and over 7,000 rpm. Have the 7/16s in the Vette's 400. They were so pretty.:thumbs_up:

I have alway been a fan for cap screws instead of bolts since I saw my first Ford FE 427 Le Mans rod (still have it hanging on the wall) way back when. It justs has better cap retention =-Better way of doing it.:D

[BRUTAL64]

Well im not sure if Ron will need any machine work done but my builder has VERY good rates. He is the one who did the porting on my heads in my build thread. Bill for assembly to oil pan which includes the rebuild on the heads, valve job, porting,bowl work, all the block work required for the 348. Tapping the block to 1/2" threads, machining of the lifter bores, degreeing of the cam, setting lash etc. Basically assembly of the entire engine was only 600. I think he charged me around 65 to assemble the engine since "he'll already be in there" most cant even touch the porting and head work he did for 600.

I'm sure he is very good at what he does. From what I could see of the heads they look good. Would have to see them inperson to be sure.

I charge $500 flat to assemble a V8- that includes stress reliving the block and oil hole correction for/with bearings.

Head porting is something I've done since 78. --

"It is not what you grind it's what you leave that counts." -Brutal 1979:judge:

[BRUTAL64]

Which is better:

"It is not what you grind it's what you leave that counts." -Brutal 1979:judge:

OR

"It's not what you grind it's what you leave behind."


Just wondering.......:drink:

[94cobra69ss396]

I like your original saying.

[BRUTAL64]

I like your original saying.

Yes, I'm leaning that way.:bigthumbsup:

[Shaolin Crane]

I'm sure he is very good at what he does. From what I could see of the heads they look good. Would have to see them inperson to be sure.

I charge $500 flat to assemble a V8- that includes stress reliving the block and oil hole correction for/with bearings.

Head porting is something I've done since 78. --

"It is not what you grind it's what you leave that counts." -Brutal 1979:judge:
He did a fair amount of work to save the heads, some jackwaggon ported the heads by eye and damn near ruined them.

I know that the amount i was charged is unmatched by any company i've heard of, considering all the work. Being across the street from the shop helps alot too. I'm sure thats all factored into the cost.

They've been in business for about 40 years now and Shawn was an engineer of the ZR-1 corvette back in the 90's. He's kind of an eccentric fellow but most sharp cookies are.

[BRUTAL64]

He did a fair amount of work to save the heads, some jackwaggon ported the heads by eye and damn near ruined them.

I know that the amount i was charged is unmatched by any company i've heard of, considering all the work. Being across the street from the shop helps alot too. I'm sure thats all factored into the cost.

They've been in business for about 40 years now and Shawn was an engineer of the ZR-1 corvette back in the 90's. He's kind of an eccentric fellow but most sharp cookies are.

That is a great price you paid for all that work.:thumbs_up:

[Shaolin Crane]

Yeah, I at least owe them lunch :uh: