Piston to head clearance ?

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Piston to head clearance ?

Post  whitefield on June 3rd 2016, 12:28 pm

What is the minimum piston to head clearance with a Scatt I beam Rod and J&E flat top piston ? Plan on turning this thing about 7000 rpm may see 7200 . Scatt crank no NOS. Thanks Whitey Cool
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Re: Piston to head clearance ?

Post  gt350hr on June 3rd 2016, 1:23 pm

On a steel rod with a JE ( I was there 14 years) I consider .035 the minimum and I prefer .040. .050 on an aluminum rod unless the block is aluminum too.
I should add "however you get it" . Thanks to Cometic there are various thickness gasket available in case the piston is "out" of the block . Saves cutting piston decks , etc.


Last edited by gt350hr on June 3rd 2016, 4:38 pm; edited 1 time in total

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Re: Piston to head clearance ?

Post  away on June 3rd 2016, 3:16 pm

And your head gasket is .040 anyway at least so deck that boitch and get on with it! lol
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Re: Piston to head clearance ?

Post  IDT-572 on June 3rd 2016, 5:16 pm

Standard Felpro gasket is .041 thick compressed.
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Re: Piston to head clearance ?

Post  whitefield on June 3rd 2016, 10:49 pm

.020 out of the hole !


Last edited by whitefield on June 5th 2016, 1:15 am; edited 1 time in total
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Re: Piston to head clearance ?

Post  rmcomprandy on June 4th 2016, 12:13 am

whitefield wrote:What is the minimum piston to head clearance with a Scatt I beam Rod and J&E flat top piston ? Plan on turning this thing about 7000 rpm may see 7200 . Scatt crank no NOS.  Thanks Whitey Cool

To be honest ... the closest you can get it without making actual contact is best ... every bore size and piston skirt combination will however, be different.

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Re: Piston to head clearance ?

Post  whitefield on June 5th 2016, 1:24 am

rmcomprandy wrote:
whitefield wrote:What is the minimum piston to head clearance with a Scatt I beam Rod and J&E flat top piston ? Plan on turning this thing about 7000 rpm may see 7200 . Scatt crank no NOS.  Thanks Whitey Cool

To be honest ... the closest you can get it without making actual contact is best ... every bore size and piston skirt combination will however, be different.

Randy What do you think about running a .062 thick gasket versus the .041 ? The .062 would get me to what the specs for a steel connecting rods. (.040) Also what are your thoughts on COMETIC head gaskets are ? Thanks Whitey
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Re: Piston to head clearance ?

Post  rmcomprandy on June 5th 2016, 10:48 am

whitefield wrote:
rmcomprandy wrote:
whitefield wrote:What is the minimum piston to head clearance with a Scatt I beam Rod and J&E flat top piston ? Plan on turning this thing about 7000 rpm may see 7200 . Scatt crank no NOS.  Thanks Whitey Cool

To be honest ... the closest you can get it without making actual contact is best ... every bore size and piston skirt combination will however, be different.

Randy What do you think about running a .062 thick gasket versus the .041 ?  The .062 would get me to what the specs for a steel connecting rods. (.040) Also what are your thoughts on COMETIC head gaskets are ? Thanks Whitey

With race fuel, a wide quench clearance won't make much difference at all.
With octane limited fuel, anything more than about .065" to .070" quench clearance will diminish most of the quench effectiveness.
Quench clearance doesn't really matter how you get it if the head gasket is strong enough to absorb the extra thickness.

For a big block Ford, Victor Reinz offers a big bore head gasket .051" thick, p/n 5973SC.

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Re: Piston to head clearance ?

Post  gt350hr on June 6th 2016, 11:25 am

Cometics are awesome. .062 is fine on an iron head . Aluminum heads don't seem to care as much about quench.

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Re: Piston to head clearance ?

Post  whitefield on June 6th 2016, 12:12 pm

gt350hr wrote:         Cometics are awesome. .062 is fine on an iron head . Aluminum heads don't seem to care as much about quench.

Iron block Aluminum heads is what I have. Thanks I am thinking about ordering a set .
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