[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:


Main after:


Crank before:



Crank after:




And I can't forget my helper, Kylie.


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.

[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]

Originally Posted by 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.

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?

[BRUTAL64]

Originally Posted by 94cobra69ss396

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?

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.


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.


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.














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

[94cobra69ss396]

Rods.

[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.


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-

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.

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.

[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]

Originally Posted by 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.

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?