82Five-O

Can i squeeze .488 on the exhaust lift? I am running 350 TBI heads. Will a Different rocker ratio help?

zipfast

iTrader: (2)

In a word (NO).
At .470 I was just hitting the seals. The stock seals have a spring on
top that I knocked loose .
If your doing a cam swap pull the heads and have the guides cut, and
have a 3 angle valve job done on it.

formula_novice

iTrader: (1)

If you are pulling the heads, replace them with better flowing heads.

Just my 2 cents.

Damon

Stock springs will take .500" lift but.... the retainers will hit the guides well before that (around .470" on most heads). PLUS the springs are not capable of controlling the valves in the upper RPMs when used with even a modest performance cam. In short- no. You have work to do before you can run what you've got in mind.

82Five-O

OK, i wasn't sure, but i wanted to check before proceeding. I am going with a .465/.465 lift cam then just to be safe. I have another question...


What is the power difference in a stock 350, and a 350 with only a .040 overbore and stock type oversize pistons?

How much power am i losing if i don't punch this block?

TPI383Camaro

put a 212/214 .444/.454 110lsa cam in there, that with your TBI heads will make awesome torque low and midrange, 2000rpm will pull strong. if youre going to bore the block out and replace the pistons, you might as well spend a couple extra hundred and put a stroker crank in there and make enormous toruqe

i had that cam in my 92 z28 with a tpi on top and it pulled hella strong from idle up to 4800rpm

RebornFromAshes

The power difference will be minimal. Most of what you would gain would be from increased port flow from feeding a larger bore. At best it would probably just be a few HP. Even then, it is possible that the differences could be near zero if you have a thin cylinder wall that flexes and causes increased blowby.

Overbore the engine the minimum amount to make the cylinder walls straight and round.

You will find a few cams that have right at a 0.465" lift since this is about the most you can run with stock heads and valve train parts. Some people have tried running more lift but the end result is usually a bent pushrod or a broken rocker from mechanical interference at the rocker or the valve guide.

82Five-O

my full cam specs are
SUM-K1104
Hydraulic Flat Tappet
2200-5700
282/282 Duration
465/465 Lift
114 degree lobe separation
I think this will be suitable.

If that's the case, i'm gonna hone this stock bore and run flat tops with this cam, the TBI 350 heads ported and polished, an old edelbrock streetmaster intake i have layin around, and a edelbrock 600 carb. Oughta make for a decent engine.

Kevin91Z

iTrader: (1)

Is this a TBI or TPI engine? Either way, 110 LSA makes for a very choppy idle and extremely hard to tune without being rich. For a TBI you should get something small, like 206/210 duration on 113 or 114 LSA. The TBI computer is really fussy when it comes to camshafts. You'll need to get into chip tuning to make it happier. Or put in an LT1 camshaft with 1.5 rockers and you'll have no problems.

If you use the Manley 22410-16 springs and 23652-16 +.050" retainers you can get up to .510", but you still have to check the valve stem seal clearance to be sure. And replace the valve stem seals so you dont get the blue puff of smoke on startup.

82Five-O

This is going to be a carbureted engine, no computer controls, and my LSA is 114 not 110. I'm going with edelbrock springs and retainers. I'm just using the TBI heads because they are the only 64cc heads i have. I ran these heads on a 400 in my truck and they worked out great.