I got a '90 350 vette motor, and I think i'm gonna convert it over to a carb setup, with upgraded vortec heads that allow .575" of lift, rpm airgap, and a big cam....I'm wondering if I can do all of this without modifing the bottom end, like pistons, rods, crank, etc...will this all hold up to the power of the heads and cam?

 

Yes, the bottom end can handle 400HP.

I see the Vortec heads being a minor problem, however. They have 64cc chambers where the original aluminum 'Vette heads were 58cc- that's going to lower your compression by at least 1/2 point. The Vette motor originally had about 9.5:1 compression.

If you use a relatively thin GMPP .028" compressed thickness composite head gasket you will keep compression around 9.1:1. A really thin steel shim head gasket (.018") would keep you about even at 9.5:1, but they don't seal up real well unless you have a VERY flat block deck and heads, so I wouldn't generally recommend using them (although there are new-era steel shim gaskets available aftermarket that have better sealing properties).

If by a "big" cam you mean something over about 230* duration I wouldn't go that big with only ~9:1 compression. Low compression and big cams don't play nice together.

 

okay, what do you suggest on a replacement for those heads that are around the same price as those heads? FYI, the heads+airgap intake+all seals and bolts comes to like 940 for the whole package...so i'm assuming the heads around around 6-700...I want something around that price, nto much more...I'm not too farmiliar with all the new applications out there, so i need help on picking out a combo...whenever i ask for help, everybody just says SEARCH, and I usually have trouble finding stuff still...so help would be greatly appreciated..

 

those aluminum vette heads are pretty awesome, i would put my money into those

 

you think so??? that's what my first idea was, and everybody was like no no no, even if you do get work done to those, they still won't be really good....so thats basically what steered me in the direction of aftermarket heads....we have a race motor builder in my area, that is well known becuase alot of the muscle car guys get a lot of work done by him, so i could prolly just take them there.....what all should be done?? port job, new springs, i dunno what else, help me out guys?

 

That's not really a problem. They reduced the chamber size to up the compression (closer to 10:1) so the aluminum heads would be at about the same power level as the L98 iron head version was. Aluminum allows more heat to pass through it, and since heat = power, you have to make up for it. The typical approach is to use higher compression with aluminum heads. The heat loss also means detonation is not a problem even with the higher compression - again, equivalent to the iron headed version.

 

well, if you do go with an aftermarket head, i am interested in your factory aluminum ones for my 305.

 

You seen the timing tables on those vettes too? Lots of spark.

I'm voting for the 113 heads too. Go with those, upgrade the springs. Lingenfelter got those heads to flow damn good with porting. You allready own 'em, so why not spend a little money on 'em?

As far as the engine, Tim (traxion) was prolly closer to 500hp on a stock l98 bottom end

-- Joe

 

alright, i'll do that...i'll take my heads in, get them redone, ported, new springs, the whole works...then i'll get that airgap intake and a 650 carb, then a good sized cam to match the whole setup....400+ HP is a reasonable goal for this right???

 

how much horsepower am i gonna need to run low 12's, or maybe high 11's? i'm gonna run 295 tires on the back, 3.73 gears and a 6 speed tranny...with all the suspension components to keep it too the ground, panhard rod, control arms, etc etc....do you guys think this could be obtained by the combo listed? I got a kid in my school with a SRT-4...pretty much a neon with a turbo, and he's running his mouth about how fast his car is, and I said that his car was slow as hell today, and he said don't talk trash about my car being slow untill you get one faster....well i think my car is already faster, but never got to race him cause he was scared...but now he wants to buy stage 2 and stage 3 performance that mopar sells for his car, and it puts him at about 12.5 secs in the quarter mile....so if he gets that crap, I wanna still be able to wax that kid....he's driving me up to the wall, and somebody has to shut him up...what do you guys think?

 

You can port for days upon days and the Vette heads will not flow on the intake like a stock Vortec head. Vortec's are better. I used to woop on ZZ4's all the time when I had my Vortec heads. I could also beat a Stage 3 mopar SRT-4 from a stop in the 1/4. Watch out though, they keep up better than Z06's do from a roll. BTW I ran a best of 12.30 @ 113.5 all motor. My motor only put down 330 hp at the wheels with the Old Vortec heads but it put down 360 torque all the way across the chart from 2500 up. It is torque that moves weight. I also only have 3.42 gears. PM if you want to know more-Ross

 

Yes it can....

 

Doesn't work that way. ET is about tracktion, gearing, and torque line from launch to shift.

HP generally contributes to a high MPH.. For example, I can run any ET from a low 12 to a mid 14 on my old setup, but
it always traps 119mph. Just depends on how hard I hit it out of the box and how much the tires spun down the track. IN reality, I coulda prolly ran around mid 11s with some slicks.

I'd talk to a few vette owners with ported 113's and get there HP, MPH before I listen to the guys running the vortecs. I keep hearing of guys running "super fast' with vortecs, but I've yet to see any real MPHs.

I like my vortecs in my 1/2 ton truck, it pulls my boat nicely. But i'd never run an oddball iron head in a race car.

-- Joe