max valve lift with stock pistons & Vortec 1.94 valves?

[NJSERRANO]

Anybody have an idea about max valve lift on a set of stock pistons with Vortec heads?

My new heads are at the machine shop. I kept the stock sized valves. I'm not trying to "go big or go home" on the cam, just looking for parameters. I'm mainly interested in the Comp 415 & 430 cams.

Thanks for any input!

 

[dgoodhue]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

You will different valve springs. I used a custom cam and would recommend one. If I had to use an off the shelf cam, I would use a 415 over 430. The 430 is a NA cam. It's lobe seperation 110 is too small for its 224 duration for a street driven FI motor.

 

[NJSERRANO]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

Valve train is all upgraded to support upgraded cam.

 

[dgoodhue]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

You will be fine. I have vortecs with 2.00/1.60 valves and .531 lift cam on balance shaft shortbblock. The balance shaft pistons should have less clearance than stock pistons.

 

[NJSERRANO]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

Great! Thanks for the info. I'm thinking 415 cam just because of the BINs that have already been used. I figured it would be easier to tune.

As far as lobe separation goes, I was researching this issue as it relates to turbo cars (not necessarily F.I.). Longer lobe separation was preferred because of inefficient turbos that would almost force exhaust back into the chamber due to back pressure.

Today's turbos are more efficient and this effect is less common, giving way to tighter lobe separation. There were several references to Kenny Duttweiler.

 

[Don W.]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

I'm running a "custom" Comp cam with .502 at the intake and .484 at the ex. Separation is 114. No issues. I rather doubt this cam would smog if that's an issue. LMK if you want more info.

SRP dished pistons. I'd have to track down a pic. I believe they have reliefs.

 

[TeeTopZ]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

As far as lobe separation goes, I was researching this issue as it relates to turbo cars (not necessarily F.I.)
.

Turbo cars are FI (forced induction)

 

[Quickstop [UK]]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

It depends on the context but I always took FI to mean fuel injection.

 

[dgoodhue]

Re: max valve lift with stock pistons & Vortec 1.94 valves?

I should have written turbo instead of FI (My intent was forced induction) because superchargers don't have the exhaust back pressure in the manifolds that would exceed the intake pressure. I still think that a streetable turbo for our trucks is going to a measurable amount of pressure between the difference of exhaust and intake.

I have never put a pressure gauge on my exhaust manifold, so I am only going by what I have read.