Cylinder Head Questions
 

My car is set up for autocrossing where I stay mainly in 2nd gear and spin around 5500-6200 rpm at the most. Currently i'm running an E cam, stock 87 intake, and stock heads with Trick Flow valve springs. Question is I would like to stay with stock heads and do work to them like porting, screw in studs for hardened pushrods, would this be sufficient for this? And would the 2.02 valve heads be a little much for this and needing the bottom end torque?

I suppose you can do work to the stock heads...but they really arent anything special. Waste of money if you ask me. Might actually make you run out of breath if you have to do rpms that high fairly regularly.

New heads will gain you a LOT of power....maybe you can find a good used set to cut costs, like on ebaymotors... 2.02 intake valves are too big for several reasons I believe... But the main one is they wont work. ;) The 2.02's will hit your stock pistons. And if they don't, they'll come SO close that it's insanity to try to run them. I know...I tried. The thin layer of play-doh on the piston was all ripped up by the valve. 1.94 is about the biggest we can go I believe without aftermarket pistons, or widening the brow on the factory pistons.

Yeah right.....LMAO...........My modified stock E7's are awesome.

Ported, Polished milled, blended bowls, trick flow springs and a 3 angle valve job.

I knocked off 4 tenths of a second in the 1/4 with the heads alone. and picked up 3 mph. Hows that for a waste.

Keep the stock valve size. Putting larger valves in E7's is a bad idea for a # of reasons.

Along with the heads slap an Explorer GT-40P intake on there cause the stock one sucks. Ported heads and the explore intake complement each other nicely.

Sorry for the off topic point, but Dark_5.0, why is it bad to put larger valves in the stock heads? I have a completely stock 5.0 HO I'm going to rebuild probably for my car and was planning putting slightly larger valves in them.

I might not have explained well enough. The 2.02 valves were referring to aftermarket heads. I know that if you go bigger you take away from the bottom end and more for top end, and I rev up to 5500-6200rpm and let off. So I think the stock valves are 1.76 int and 1.54 exhaust maybe, correct me if i'm wrong.

I might be also messing up with the fabbed sheet metal upper but we'll see. While the base is a truck lower.

Well the E7's are more capable than I thought...but I still dont see the point of spending all the cash on a set of heads that are ultimately not the best out there... It's all good if you plan on keeping them....but if you feel the urge to upgrade down the road, then it's not worth it to me ya know? Don't get me wrong, I'm not trying to put you down man. Now if you did the work yourself though, then hey, why not.....wouldn't be that much money if you had the equipment. Just giving my .02.

No you don't need 2.02 intake valves for autocrossing ... thats all bottom end. You'd be better off with some cleaned up stock heads than big valved high flowing low velocity heads. I use to Autocross in a 289 Sunbeam Tiger ... basically stock heads and a stock 4bbl holley .. the car had more horsepower than it could handle on a tight Autocross course. You need most everything on the bottom end and a suspension that will stick like a go-cart

Thanks HotRoddin, thats what I was kinda figuring. Had an autocross Saturday and the car pulled clear to 6000rpm without any hesitation. Now it needs a rev limiter to keep it from going any farther on accident.

Do the 86 Stangs not have the factory 6,250 rpm fuel cut-off as the rev limiter?

The stock heads dont have enough flow potential to take advantage of larger valves. You end up sacrificing air velocity which hurts horsepower and low end torque.

I've done the mass airflow conversion with an A9L computer and it doesnt seem to shut down anywhere up to at least 6300rpm yet. I've heard that the A9L's dont shut off. But I dont know if thats true or not.

I have no idea what computer I have....but I've tached my car clear up to 6500 rpms. ONCE. Funny part is...the motor was stock internals, burning oil like crazy, and filled with sludge....but it sounded like it could do 6500 all day!

If that rpm was by the stock tach, it might be off that much.

Yeah it was the stock tach. Are they really that bad?? The rest of my gauges are basically trashed. Speedo gauge is toasted. Oil pressure gauge never goes past the very bottom 2 lines now. Alt, Fuel, and Engine temp seem to be ok, except the temp has a tendency to stick and then drop suddenly.

They vary but I have seen people report being off more than that.