Is it possible for someone to tell me, from the information provided below, if I'm going to have problems with piston/valve clearance issues or will I be in the clear..?
Any input would be appreciated...

The setup:
1988 L98 with stock pistons,
Trick Flow Super 23 heads milled from 62cc to 58cc,
Comp Cams 268XFI HR13

Cam spec:
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 224
Duration at 050 inch Lift: 218 int./224 exh.
Advertised Intake Duration: 268
Advertised Exhaust Duration: 276
Advertised Duration: 268 int./276 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.570 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.565 in.


Thanx
/Per

 

I highly doubt you will. But it's tricky to be sure. Is it assembled yet? If not, grab some play-doh and measure to be sure. Or if it's mostly assembled, bring the piston to TDC on a cylinder, remove a valve spring, and lower the valve until it hits the piston, and measure how far down it had to go. Granted that's at TDC, but it helps give an indication.

 

No, it's not even close to be assembled.
I'm still in the process of gathering parts and just need some advice if these milled heads would work with the XFI268.

/Per

 

I wouldn't bother milling the heads. Why are you planning on doing that?
You should have 9.3:1 right now, which is fine.

 

The heads I'm looking at are already milled, so it's not my choice to make...


/Per

 

oh!! I gotcha.
Do the math to check your CR. With a tight cam like that it'll be pretty high (dynamic). Should be ok, but worth looking at carefully.

P-V clearance is something you really need to mock up to know for sure. If you're buying these sight unseen with no return policy, then it's your call. You can always mill the pistons to fit, but like I said before, I really think you won't have a problem.

 

how much did u have them milled?

 

general spec is .006 per cc. 4 cc's is about .024"

considering pistons are probly down in the hole about .020-.025 depending, and if you use a .015" gasket for proper quench, thats .035-.040" piston to deck height.

For my 383, i am running a 230/245 cam with .603/.613 lift on a zero deck block, flat pistons, and .041" piston to deck clearance with the gaskets. I have well over the recommended .100" piston to valve clearance on the intake, and the exhaust is around .120" which the recommended min is .080"

So you should be fine with your setup as long as the cam is installed right and degreed to verify. Even tho milled .024 inch or so, my cam has .020+ lift and more duration and i clear fine. You also have dished pistons so should have more clearance

 

my heads (same as his) was shaved .030 to clear up them form being hit when my old motor come apart. so they what 57cc now. im using a vortec block with dish in the hole .025 and .039 head gasket. want to run .523 lift will i have any problems?

 

how much duration? i dont think you'll see problems with .523 lift and that gasket/in the hole height.

also .039 gasket and .025 in the hole is abit much for quench height. Thats 064"...kinda on the high side especially since your compression will be up now with those cc heads. I'd get a .015-.028 gasket for better performance/detonation resistance. Still should be fine on PTVC

 

xe274 with 1.6 rr dur is 230/236. cam card has it 490/490 with 1.5. about head gasket didnt want to mess up my heads surface already being mill down .030.