Time For The Cobra To Get A New Engine - The 347 Build

[94cobra69ss396]

The smog ref didn't say anything about it so I guess it depends on who does it. If mine had passed the tail pipe with just the two cats I would have been good.

[94cobra69ss396]

I installed the new Magnaflow catted X-pipe this weekend and took the car this afternoon to be smogged. It passed! :dancenana:

[BADDASSC6]

Congrats.

[94cobra69ss396]

Thanks.

[Vettezuki]

Yeah!! May the smog gods smile fortune upon my Aveo, which is presently about as clean as an uncatted 70s Camaro. . .

[94cobra69ss396]

I ordered a Mallory Hyfire 6A from Summit today.

[Shaolin Crane]

I ordered a Mallory Hyfire 6A from Summit today.

Finally, no more May Suddenly Die products. I'm hoping mine lasts a bit under that passenger seat.

[94cobra69ss396]

Yep, I had good luck with the one that on the Chevelle. It lasted around 13 years before it died.

[94cobra69ss396]

Installed the ignition box last night. It's so nice to be able to give the car full throttle again.

[94cobra69ss396]

My front brakes have been squeaking the passed couple weeks when I back up so I pulled all the wheels yesterday to check the pads. The rears were about 50% but the fronts were about 90% worn so I picked up some new front pads. While I had all the wheels off I decided it would be a good time to mount my M/T ET Streets to see if they would hook. With the 302 I would hold the rpms up to about 4000 and when I dropped the clutch the tire would spin about 20ft but would still move me forward at a quick pace. After beading in the pads I tried tried just taking off from idle and gave it full throttle at about 15 mph. The tires spun all the way through first but the car still pulled hard so I grabbed second and it spun all through second as well. One day I'm going to have to take it to the track and see how much quicker it is than my best with the 302 of 11.69 @ 119.

[94cobra69ss396]

Here's the progress I've made on the heads. I only have a couple pictures of how they were stock because I had already done a little porting to the intake side.

Stock form from AFR.
http://www.motorgen.com/pic/data/500/2012-07-10_21_27_50.jpg
http://www.motorgen.com/pic/data/500/2012-07-10_21_28_27.jpg

First cut.
http://motorgen.com/pic/data/500/20141109_130233.jpg

After some blending.
http://motorgen.com/pic/data/500/20141109_130302.jpg

Short turn. These I did by hand with coarse emery cloth.
http://motorgen.com/pic/data/500/20141109_152849.jpg

Finished.
http://motorgen.com/pic/data/500/20141109_152909.jpg
http://motorgen.com/pic/data/500/20141109_152825.jpg
http://motorgen.com/pic/data/500/20141109_152821.jpg

I have the intakes on one head finished and I'm about half way finished with them on the other. I'm not sure if I'm going to touch the exhaust since that's what I spent most of my time on the last time I ported them. I'll decide after I clean them and the combustion chambers.

[Shaolin Crane]

Did you hit the pocket under the valve seat? Smoothing that out is what gives the greatest improvements, but, if you hit the seat, guess who'll need a valve job.

[94cobra69ss396]

Did you hit the pocket under the valve seat? Smoothing that out is what gives the greatest improvements, but, if you hit the seat, guess who'll need a valve job.

I did but just to the bottom of the seat and not the seat itself so there's no bump transitioning from the port to the seat.

[94cobra69ss396]

I got a little off track from porting the cylinder heads when it dawned on me that I can do all this work to the heads but if the intake manifold doesn't support it what's the point. So I took a look at the intake and runners 1, 4 and 5 have a pretty big dog leg where they pinch down quite a bit. Runner 1 started out at .859 in the smallest pinch and is now 1.030. The only issue is I broke through the wall and will need to have it welded. I just started on the other ports so once I have them all finished I'll take the intake to someone to have it spot welded where I break through.

Runner 1 after a little work.
http://motorgen.com/pic/data/500/20141118_165751.jpg

Where I broke through.
http://motorgen.com/pic/data/500/20141118_172014.jpg

Still runner 1.
http://motorgen.com/pic/data/500/20141119_070933.jpg

Runner 2.
http://motorgen.com/pic/data/500/20141119_070957.jpg

Runner 3.
http://motorgen.com/pic/data/500/20141119_071007.jpg

Runner 4.
http://motorgen.com/pic/data/500/20141119_071037.jpg

[Vettezuki]

Aren't there any gnarly off the shelf intakes for the Cobra that aren't so expensive? I understand the thrill of DIY and and saving a little dough when possible, but sometimes an off the shelf is a good way to go.

[94cobra69ss396]

Mine is actually pretty good except for the lower. If I could afford it I'd buy a Holley lower which matches up to my Saleen/Vortech upper but I can't afford one at almost $400. I can however port the lower I have to what the Holley is out of the box. Guy told me that they're all over for sale on Corral but I only saw one lower by itself for $120 that was already sold. All the others are upper and lowers together for $400-$500.

[Shaolin Crane]

Aren't there any gnarly off the shelf intakes for the Cobra that aren't so expensive? I understand the thrill of DIY and and saving a little dough when possible, but sometimes an off the shelf is a good way to go.

The Vortech intake is essentially the same as a Holley Systemax. You're absolutely right too, all the porting in the world on a truck lower still wont flow what an off the shelf systemax will, and when you port one of those, holy fuck do they flow.

[Shaolin Crane]

Mine is actually pretty good except for the lower. If I could afford it I'd buy a Holley lower which matches up to my Saleen/Vortech upper but I can't afford one at almost $400. I can however port the lower I have to what the Holley is out of the box. Guy told me that they're all over for sale on Corral but I only saw one lower by itself for $120 that was already sold. All the others are upper and lowers together for $400-$500.

When I looked I saw four, now I can't find them. I'll keep looking, it's not really a holy grail piece.

[94cobra69ss396]

I got about 80% done and then took the manifold to be welded. I picked it up today and will take some pictures of how it looks now before I finish it up. I ended up going through ports 1 and 5. I also ordered all my parts to put it back together today. I still need to finish the last 20% and then finish porting the heads so that I can install the new valve seals.

[94cobra69ss396]

Here's how the welds came out.

Port 1
http://motorgen.com/pic/data/500/20141217_112447.jpg

http://motorgen.com/pic/data/500/20141217_112704.jpg

Port 5
http://motorgen.com/pic/data/500/20141217_112615.jpg

http://motorgen.com/pic/data/500/20141217_112735.jpg

[Shaolin Crane]

Are you going to smooth out the welded spots?

[94cobra69ss396]

If you mean on the inside of the port then yes. If you mean on the outside then no. I still have some more work to do on all the ports and I should be able to work on it this weekend. I also got everything to put it back together and I have 2 weeks of vacation starting next week so I should have it running next week.

[Shaolin Crane]

Yes, inside of the port.

[94cobra69ss396]

I've been working on the intake and heads the past few days and have the intake done and the heads mostly done. I took a couple of the ports I had fixed on the intake but don't have time to upload them today because I have two basketball games tonight. I'll try to take some tomorrow if I can and post them. With shopping for Christmas still to do I probably won't be able to get back to them until after Christmas but we'll see how that goes.

[94cobra69ss396]

I didn't have time to work on the heads today because I had to find a vibration in the front of the Explorer that I got after going wheeling a week ago. I ended up having to replace the passenger side axle U-joint and the drivers side hub assembly. I did take some pictures of the finished intake manifold and a few of the heads.

Here are the few pictures I took of the two ports I had fixed as I was cleaning them up.

http://motorgen.com/pic/data/500/20141220_113658.jpg

http://motorgen.com/pic/data/500/20141220_114419.jpg

http://motorgen.com/pic/data/500/20141220_113737.jpg

http://motorgen.com/pic/data/500/20141220_120145.jpg


Here are the finished ports.

#1
http://motorgen.com/pic/data/500/20141226_154434.jpg

#2
http://motorgen.com/pic/data/500/20141226_154445.jpg

#3
http://motorgen.com/pic/data/500/20141226_154455.jpg

#4
http://motorgen.com/pic/data/500/20141226_154509.jpg?728

#5
http://motorgen.com/pic/data/500/20141226_154523.jpg

#6
http://motorgen.com/pic/data/500/20141226_154532.jpg

#7
http://motorgen.com/pic/data/500/20141226_154539.jpg

#8
http://motorgen.com/pic/data/500/20141226_154552.jpg

Here's a couple of the cylinder heads.

Exhaust
http://motorgen.com/pic/data/500/20141226_154806.jpg

http://motorgen.com/pic/data/500/20141226_1548191.jpg

http://motorgen.com/pic/data/500/20141226_154852.jpg

Intake
http://motorgen.com/pic/data/500/20141226_155055.jpg

http://motorgen.com/pic/data/500/20141226_174640.jpg

http://motorgen.com/pic/data/500/20141226_155242.jpg

[Shaolin Crane]

Work looks great, too bad you didn't do that before the valve job though.

[94cobra69ss396]

Why's that? I didn't touch the guides at all and I'm going to lap them after I clean all the carbon off them.

[Shaolin Crane]

Why's that? I didn't touch the guides at all and I'm going to lap them after I clean all the carbon off them.

I know, but you could have gone all out, hit the pockets, seat rims, everything.

[94cobra69ss396]

I finished porting the heads and then cleaned and lapped the valves. After that I cleaned the heads and intake manifold, installed the new valve seals and then assembled the heads. I had a couple of valves that were pitted on the seat and I wasn't sure if they were going to leak so I tested each port after I assembled them. I ended up with one intake and one exhaust that seeped. I lapped those two valves again and was able to get the intake to seal but the exhaust was still seeping so I ordered a new valve. It came in a few days ago and it is now seals.

I started installing the headers onto the heads because it's easier to install the heads with them on than it is to try and install them after but when I went to tighten the header bolts on the driver side head I pulled the threads on three holes. Now I need to drill, tap and install helicoils on it. I did get the passenger side head on and torqued down and tonight I will fix the other head so that tomorrow I can try and have it back together and running.

[Shaolin Crane]

There's a reason why the big dollar race heads are completely helicoiled.

[Vettezuki]

Think I had to use some helicoil to hold in some shocks on the Vette. Great stuff.

[94cobra69ss396]

There's a reason why the big dollar race heads are completely helicoiled.

I really wish AFR would have done that on these because I've also had to switch the heads f ok the sides I normally run them on. The one I use to have on the drivers side has stripped the accessory holes so it is now on the passenger side.

I agree Ben they are great.

[94cobra69ss396]

I finished up the Cobra last night and took it for a test drive. It ran great but when I got home I noticed oil dripping under the car from the back of the engine. After looking it over it looks like it's coming from the rear of the intake manifold. I must not have built the silicone up enough to seal it. Now I have to pull the intake off and fix it. Hopefully I can get it done today.

[Shaolin Crane]

I noticed I usually have to let the silicone dry over night or it leaks.

[94cobra69ss396]

I've never waited for it to dry overnight and never had an issue. I think I got a bad tube because it was still wet when I pulled the intake off this morning. I'm glad that it did leak though because I found that the lower part of the lower intake gaskets are leaking. The bottom of both sides were wet and the intake track on the heads was wet with oil. If that was happening before that might be the cause of the light throttle miss I've had. This time I used silicone on the intake gaskets around all of the intake ports. I normally do that around the water jackets only but this time I did everything. I'm also letting it dry overnight. I did start it after letting it dry for about 3 hours but just so I could move the car.

[94cobra69ss396]

So updates to this thread. This build always burned oil, I'm not sure why but it did. Well after a couple of years it started to get blowby as well so I decided to pull it apart to see why. I couldn't really find a reason for it but I think the intake gaskets have been leaking the entire time. I was just going to re-ring it but I found a couple of cracks in the block so I started all over with another block that I already had.

The build is the same as before just with the custom cam that I had done before instead of the Comp cam I'd been using. Since I was doing it all fresh I let my kids pick the color for the engine and then we did a raffle to see who won. My younger daughter Mya won with VHT Burnt Metalic Copper. So I took my time and cleaned and painted everything. I only have 50 miles on it but it doesn't have that burnt oil smell it used to. I need to pick up a new harmonic balancer for it because the one on it is bad so it's just sitting until I can get that.

http://motorgen.com/pic/data/500/medium/20170506_191401.jpg

http://motorgen.com/pic/data/500/medium/20170522_195859.jpg

http://motorgen.com/pic/data/500/medium/20170602_164808.jpg

http://motorgen.com/pic/data/500/medium/20170618_170147.jpg

http://motorgen.com/pic/data/500/medium/20170618_145257.jpg

http://motorgen.com/pic/data/500/medium/20170715_171928.jpg

http://motorgen.com/pic/data/500/medium/20170823_191031.jpg

[Shaolin Crane]

I'm curious to see what that cam does with the 347, because it made stupid power in mine.

[94cobra69ss396]

Hopefully I find out here in a month or two.

[Vettezuki]

That's tight. Looking to see what you get.

[94cobra69ss396]

I'm not going to synonym it again. It runs good so there's no need. I also hooked up my methanol injection so the next time I take it to the track I should be able to run on 91.

[Leedom]

Maya has some good taste. That color looks awesome!

[94cobra69ss396]

She does. I finally was able to get the harmonic balancer and got it installed this weekend. I just have to take it to be smog gee to complete the registration and I can drive it again.

[94cobra69ss396]

The Cobra passed easily so it is all done. It's so nice being able to drive it again.

[Vettezuki]

The Cobra passed easily so it is all done. It's so nice being able to drive it again.


Know the feeling. It sucked when the Vette was down for a while, before the rebuild. Now it just starts and runs (mostly) like a regular car! :judge:

[94cobra69ss396]

The Cobra runs great! No more burning oil smell and it has a ton of power. I think with this cam it has as much power on the pump gas tune as it did with the race gas tune before.

[Vettezuki]

Wow. That's amazing and passing (ever tighter) smog! Sometimes I think to supercharge the vette. But 400WHP~ and 3,100lbs is enough for the street really.

[94cobra69ss396]

But it's fun when it breaks the tires loose in third gear passing someone at 60mph. You should do it!

[Shaolin Crane]

I know Steve was shocked how much power that cam made in mine, sometimes I wonder how much more power it could make if I had Joey grind in a little more lift but that's a happy valve train setup that doesn't trash the springs and lifters. I was most pleased how much vacuum in made, really made a difference in how it drove.

[Vettezuki]

But it's fun when it breaks the tires loose in third gear passing someone at 60mph. You should do it!

Sounds fun! I'd have to get real tires and almost certainly update the diff. I just have the stock aluminum Dana 44, which has held up to some abuse, but much more power with real tires and it probably gonna go boom.

[94cobra69ss396]

Probably. I've already cracked one stock carrier in the Cobra. Luckily GTR had one laying around that they sold me cheap so I was able to fix it the day after I broke it.

[Vettezuki]

Probably. I've already cracked one stock carrier in the Cobra. Luckily GTR had one laying around that they sold me cheap so I was able to fix it the day after I broke it.

It's tempting though. My now forged pistons and rods with stock balanced crank is supposedly good for 600 WHP all day long if I want.

I think there's a kit for an iron 12 bolt for C3s that should be good for well beyond that much. But I think that alone is in the $1,500 or more range.

So total starts to look like $7k and I'd like to clean it up with paint and interior just to be a nicer place to be before I worry about what is really a lot of power to stupid power. :judge:

Also not sure my T56 would handle it. I only have carbon fibre synchros. I don't remember, but I don't think I have the viper spec output shaft or anything else all that upgraded.