LT14LIFE JT

iTrader: (1)

I'm doing a cam swap on my '95 Z28 I just picked up. I'm planning on shaving the heads to pick up a few points of compression. What is the maximum amount of material I can remove and still retain a decent piston to valve clearance with an aftermarket cam? If anyone has any insight, thanks in advance.

Ed Wright

iTrader: (1)

You HAVE to check your valve-to-piston clearance after the cam is installed to know how much the heads can be cut. The iron head LT1 head gaskets are a popular deal which usually puts them to about 11.5-1. Depends on the cam whether you have enough valve-to-piston clearance to use them.

SS RRR

iTrader: (2)

I thought Impala gaskets bumped up the compression to maybe 10.8 on stock block/heads?

bufmatmuslepants

iTrader: (3)

0.026 gaskets put you at 11:1 on unmilled heads, milling 0.010 puts you at 11.8:1.

Ed Wright

iTrader: (1)

I stand corrected. Never measured it myself. Just going by what kids tell me. They probably read it on the Internet. Should not comment when I don't actually know. :-(

SS RRR

iTrader: (2)

I'd rather hear it from you from hearing/reading it than most anyone else, dear sir.

bufmatmuslepants

iTrader: (3)

I'm using 54cc heads, 0.05" stock gasket, 4.030 gasket bore, 4" bore, 3.48" stroke, -7cc pistons, 0.022" in the hole, getting 10.43:1 stock compression ratio. Changing gasket thickness to 0.026 gives 11.09:1. With impala 0.028 gaskets its 11.03:1. Am I doing something wrong or are you just being an old fart? I meant 11.5 not 11.8 if milled 0.010 but yes that was using someone else's calculation I read on the all knowing Internet, that flat milling each 0.006 = 1cc, rounding up to 2 for 0.010, calculates to 11.47:1.

SS RRR

iTrader: (2)

Stock pistons?

bufmatmuslepants

iTrader: (3)

Assuming stock, but I keep seeing anything from 4-7cc for stock pistons and 0.022-0.033 in the hole, either way, with a baseline of 10.4:1 and changing nothing but gasket thickness, you get 11:1 with 0.026 or 0.028 gaskets.

LT14LIFE JT

iTrader: (1)

Thanks for the input guys. I'm trying to get the most out of a cam swap without buying aftermarket heads and wanted make sure shaving the heads was worth the effort/costs. Question #2: Does anyone know what gains I can expect from shaving my heads .010/gaining compression? ETs or dyno #s are appreciated.

RamAir95TA

iTrader: (2)

It is unlikely anyone would have that data. I can tell you it'd be worth a handful of HP, maybe 3 or 4, on a stock engine. A bit more with a cam swap.

cardo0

If u can calculate your cr ratio and cr ratio increase then u can use this D. Vizard chart in this Popular Hot Rodding article to find your percent power gain: http://www.popularhotrodding.com/tec...on_ratio_tech/.

Good luck,
cardo

Ed Wright

iTrader: (1)

Often doesn't work that way in the real world. Too many variables. Vizard is kinda "out there". :-)

LT14LIFE JT

iTrader: (1)

Thanks again guys. I appreciate the info. I'm planning on using a little nitrous and I'm glad to hear that I'll be at least 11.0:1 CR to make the nitrous more optimal. Heads are coming off this weekend and headed to the maching shop for milling. Let the fun begin.

cardo0

I ' d r a t h e r h e a r i t f r o m y o u f r o m h e a r i n g / r e a d i n g i t t h a n m o s t a n y o n e e l s e , d e a r s i r. B u t D . V i z a r d m e n t i o n s h o w i t c a n v a r y i f y o u h a d b o t h e r e d t o r e a d t h e a r c t i c l e.


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