How much to Shave Heads ?

[JEFFTATE]

I've got a brand new sbc GM crate engine pn 10067353.
I bought it for the core value because it was knocking when they cranked it. Someone accidentally dropped a screw down the intake and damaged #6 piston.
These engines only have 8.5:1 compression ratio.( dished pistons )
So I'm gonna' put a set of hypereutectic flat top pistons in it and bring the compression up a little.
I figure the flattops are good for about 9:1 compression.

I'm also gonna' have to have the heads shaved just a little because of some damage to the head surface.(They are 76cc chambers.)
My question is:
How much should I have the heads shaved to achieve 9.5:1 compression.

[Mr.VENGEANCE]

ask her, Jeff..

https://static1.pt-content.com/images/noimg.gif

hahhahah

[JEFFTATE]

You're Funny Amir !

[Damn True]

Does the carpet match the drapes?

[JEFFTATE]

We've seen the carpet ( or lack there of ) . It matches .

Now what about my engine !
Anyone ?..........
Bueller ?..........

[Mr.VENGEANCE]

dammit look what i did, jeff...

[wendell]

Until you have the exact cc of the chamber= head cc+ cc from the gasket+ (or-) cc from deck height + dish (or - dome) you can't determine the CR. Your machinist will know how much to mill/CC, from there you can get to the CR you want. Better to talk to your machinist about this than solicit opinions from strangers on the internet.

[MonzaRacer]

SBC is 1 cc per .010 milled as long as it has standard chamber heads and not the weird "quenched" chamber.
Basicly I would make sure of your piston distance to the deck.
If you have between 015 and 018 from the deck to the pistons then use a steel shim head gasket it really gets the quench tightened up to cause good swirl in the cylinder, dont get radical with the cam and it will be a torque monster.
As for me 9.5 is borderline for pump regular so if you can handle premium go for it.
If you want to use a composition head gasket have decks zero decked so your piston is even with the deck.
Squareinging and honing with torque plate is a must on thinwall blocks.
I used a set of Federal Mogul flat top 2 eyebrow hypertec pistons that could be ran with full floated rods too.
I like to run them both ways and as long as I have 035 from piston to head clearance in the quench area your good to go unless you run aluminum heads.
Some give rediculous clearances on piston to head but if you have good rods and bolts and get a steel rod to stretch 035 you have it seriously rapped out.
The compression ratio I would look for is the 9.0 to 1 .
Mill the heads the same amount each, and cc them and try to getthem within 1 cc or less, Do a minimum square on the block, use a steel shim gasket and choose your cam wisely.
Good luck
Lee Abel
AFTERMARKET PERFORMANCE

[JEFFTATE]

This is an economy build. So I put flat-top four valve relief hypereutectic pistons in it. I had .015" milled off the heads. So at 1cc per .010" I should have got the combustion chambers down to 74.5cc ?

I think these engines have .015" deck height.
I'm using a .026" thick ( compressed ) head gasket.
The valve reliefs in the pistons take up 6.25cc.
So with a 74.5cc chamber ,
I should have around 9 : 1 compression ratio.
I think.
I know this is just a guess without cc'ing the heads and accurately checking the deck height.

[MonzaRacer]

Ok so which brand of head gasket you using I never found any at 026" As for the pistons I gave a $100 for them, new.
A GM block can run anywhere from 018 to 026 and be crooked. Get it squared after mock up and measure your piston depth.
Standard Felpro blue gaskets are 039" thick.
If you want some snap to its lowend bring your deck height to 010-015 in the hole and use either a Felpro or Detroit gasket steel shim.
They are pretty much bullet proof. If you do this you get a "squish" in the quench area that creates mixture motion and bette torque. Use a solid mid sized port (ie the victor intake wont work)or even an older style intake such as the old Edelbrock scorpion (I love mine) and dont over carb it a 780 cfm vac secondary is plenty and remember keep the cam in the decent range, and this combo will love more timing/lift on the exhaust too.
The FM pistons are very inexpensive and tough as nails.
Basicly if I used stock type heads look for a set of 991 truck heads(3/8 exhaust stems), raise the guides port side 5/32 of an inch, then throat the bowls to the same size as the ex valve face inside diameter, have machinse shop give them a back cut and do a good 3 or 5 angle valve job,,,, super flow potential for mild engines as the smaller tougher ports can be massaged slightly and never break through, being a tough head and the large, sodium filled valves keep tons cooler.
Second choice on heads are 487s or 441s, both used in Corvette engines in early mid 70s, decent flow with minimal work (same as above ) teamed with Z springs or the new beehive comp springs and you have killer cheap heads. Or I have a source to bick up Vortec heads modded for up to 550 lift, have them drilled for both bolt patterns and you have a win /win.
Good Luck
Lee Abel
AFTERMARKET PERFORMANCE

[pdq67]

Try here to figure CR!!

http://www.campbellenterprises.com/Race%20math%20calculators.htm

Usually a 350 dished piston is -12 cc's so go from there!

Add a pair of Vortec heads that either measure or are cut to 62 cc's and a pair of Fel-pro, #1094's and you will be right at 9.71 to 1 CR w/ a stock like dith piston of .025"!!

pdq67

PS., or 305HO, bowl-blended -416's at 58 cc's along w/ Mr. Gaskets .020" headgaskets and come up w/ a 10.04 to 1 CR and then bleed some pressure off using a schosh bigger cam and then you will start making some good power, imho..