How much lift can the stock heads handle if I get the right valve springs? Would it even be worth messing with. I'm on a broke college student budget.

 

You can probably get away with using the ZZ4's cam. You should only have to change the springs and related hardware. You might even be able reuse the hardware if you get the right springs (I think K-Motion makes spring kit that will let you reuse the hardware??).

I did a ZZ4 cam/spring upgrade on my trucks stock heads. But I had them put screw-in studs in for safety.

 

Yes and no.. A high lift cam really won't help all that much on stock heads..because they would reach their maximum flow rate with pretty low lift. You could put something in their to give you more power, but it definitely would work better with aftermarket/ported heads.

 

Hold on a sec, my friend has a radical cam in his car and did some porting of the heads. He put headers and an exhaust and his car will beat a new SS. I will have him write to you as soon aspossible to get you the specs on his stuff.

 

I got the specs of his cam...
230/230 .480 lift@.050" w/108 LSA
As I said he ported the heads and he has what he did on that. He ported them alot and is runnintg 10.1:1 compression. He still runs 92 octane. He will write you on what else he did porting wise I don't know. He is TOM84L69. I will try to get him to write asap. Hope this helps you start

 

Wow...thanks for the repsonses. Does your friend run a carb or EFI? I think 108*LSA would be too little for my TBI system to handle even after some PROM tuning.

 

i have a carb and no computer with my mods. i milled the heads for 10:1 compression. I ported the heads a bit and the intake
(just port matching and general smoothing out. the cam is as stated in my sig and i also run headers. There is no cat, dynomax pipe with flowmaster exhaust. I also have better valvesprings and stronger pushrods.

these mods are pretty extreme for a computer controlled car, but damn they make the car run well!

 

Do you have any dyno or quarter mile times on that motor? What did the motor come out of, what kind of intake carb, stock botom end, any other mods? I was just curious because if it beats a new ss it has some go.

Thanks

Ben

 

well it has beaten SSs before, I also have been beaten by new LS1s, a lot depends on the driver. It's probably a mid 13 second car, though i've never raced it legally.

The engine is my original L69 305, it has original ported and milled heads and original ported intake. I swapped the Computer controlled carb for a non cc quadrajet, and run a replacement HEI. The botoom end is totally stock, even the original 80000 mile pistons! I sized the rods but they were within spec. I chamfered the crank oil holes and polished it on my buddy's lathe. The bearings are Michigan 77 and the rings are some generic replacement.

I cannot remember the valvespring specs but they are much stiffer than stock. I really paid great attention to detail with this car, even to the point of grinding the exhaust pipes at their joints.

Paying attention to detail when porting heads and anything else that has to do with airflow pays good dividends. My dad and I are used to working with very little to begin with, our 1.1 liter Spitfire has the record at Waterford Hills raceway only .8 second behind the fastest ITE Corvette.

This motor pulls to 6000 rpms no problem but I fear running it past there because of the stock bottom end.

Hope this helps!

 

That is a valid point, but you have to consider the entire cam lobe profile in your presumptions. Yes, the limits of flow are going to be reached at fairly low lifts with stock, unported heads. However, the lobe profile of an aftermarket cam with greater lift is going to cause the valve to reach that point of lift sooner, and remain open above that point of lift later, so the effective duration at maximum flow for the heads would be increased for every combustion cycle.

Given that, I would bet that an aftermarket performance cam in otherwise stock heads would cause an increase in overall flow and thus, power potential.

Of course, the definition of "stock heads" can be very broad. I presumed Astro meant stock heads as cast, not ported. I have some ported OEM heads that I would put up against a lot of aftermarket heads on the flowbench, and would feel safe about wagering on their flow. They are still "stock" heads by some definition, but not at all in stock trim. If you port the OEM casting and/or increase the valve face and bowl sizes, the equation has just changed, and even more flow could be expected if the work is done correctly.

Comp Cams has several cams available that are designed to maximize flow with stock heads, so shop carefully and do your homework.