Completed Project Superchargered 347 Stroker Build

This isn't for a truck but for my 1994 Cobra. What started this build is when I broke another rocker arm and bent another pushrod. It was the second time that it happened. The first time was about 20,000 miles prior. With 90,000 hard miles I figured the cause was weak valve springs. So I pulled the heads and and while I had them off ported them. I then took them to Pacific Engine and had them machined and a valve job done. While doing so they discovered that AFR had way too much spring pressure and that some of the springs only had .500 lift before going into coil bind. My cam with 1.7 rockers has .530 lift so it's surprising they lasted 90,000 miles.

Here's the broken rocker.

Here are some of the porting work I did on the heads and lower intake manifold.

After.

Intake manifold.

While the heads were being machined I started cleaning the carbon off the tops of the pistons and noticed a nick in one of the cylinder walls. With that discovery I really didn't want to just slap the heads back on so I started looking into the cost difference of rebuilding the 302 compared to buidling a 347. The cost diference was going to be very little so I'm building a 347.

When I pulled the shortblock from the Cobra and disassembled it I discovered what caused the nick. I found that two studs that hold a splash shield on the intake manifold had come out and fell into the pan. They must have been in there for a long time. There were nicks on the bottom of the pistons, cylinder walls, crank, rods and one lobe on the cam. Here are some pictures of the worst piston.

I ordered a short rod stroker kit from Coast High Performance a couple of weeks ago and picked it up on Friday. Over the weekend I clearanced the cylinders and today I dropped the block off at Pacific Engine. Of course I forgot the pistons so I'll be making another trip out there so they can machine the block for .004 piston to wall clearance.

 

[rjcooperss396]

I scheduled my appointment with Steve for next Tuesday the 9th!

 

[rjcooperss396]

Dyno tuning is done but the car isn't. Steve said that I have to install methanol injection because the inlet temps are way too high for the power the engine is making. So what's it making? Let me start by saying that we again had trouble with it spinning the tires in 4th. When the car was cool it put down 476 rwhp and 470 rwtq but that was with the tires spinning. That was on the pump gas tune. After that Steve made the pulls in 5th but then the IAT's were so hot that the car was making less power even though it made more torque. On the final pump gas pull it put down 467 rwhp and 490 rwtq which Steve made after he finished the race tune. This was with a total of 15 degrees of timing.


I then added 5 gallons of race fuel and Steve started on the race tune. For the race tune he just adds timing and trims a little fuel. Total timing ended up at 20 degrees. Again, because of the IAT the race fuel tune didn't pick up that much over the pump gas tune. The final pull on the race fuel was 494 rwhp and 504 rwtq.

I video tape some pulls but I don't know how much I got because one time when I went to start recording the camera said the card was full. I'll go through what I have, edit it and then upload the video. Steve also printed out the last two pulls so I'll post those.

 

[CDW6212R]

Excellent, quick work there.

 

[Turdle]

Those are good numbers-you should be proud. Hard work, you know.

Waiting for the videos. In the meantime-a round of applause!!

 

[rjcooperss396]

Thanks guys. With the old 302 on the race tune it made 471 rwhp and 387 rwtq. The extra 103 lb/ft of torque really make the car feel so much stronger. Especially since it weighs just under 3650 lbs with just me in it. Now I just need to come up with another $500 so I can get the meth injection system I want. Until then it won't be on a track. Steve said I could get away with running the pump gas tune on race fuel like I did before but after all this work I don't want to risk it.

 

[rjcooperss396]

Here's the dyno sheet with the last pump gas and race fuel pulls.

 

[rjcooperss396]

And here's the video.