427 rat comp. ratio
Thread Starter
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
427 rat comp. ratio
Neighbor has decided to pull the 350 out of his 72 4 wheel drive pickup,
use the block and cranks I sold him to build a .060 over 427 for it.
He wants to use aluminum heads I will probably suggest the edelbrock
oval port 100 or 110 chamber. Edelbrock says with a flat top piston with the smaller 100cc chamber only gives 9.0 comp. is there a .060
over 427 small dome piston that can bring the comp. up more like 10.0.
Did the 427/390hp have a small dome piston to get the comp. it had
with the 101cc oval port heads ?? would that piston work with the
edelbrock chambers??
Nothing is set on parts buying but 9.0 comp,
with aluminum heads sucks, any combo of
oval port alumunum heads with any combo
of pistons and chamber size that would get comp.
north of 9.0 is what i'm after.
use the block and cranks I sold him to build a .060 over 427 for it.
He wants to use aluminum heads I will probably suggest the edelbrock
oval port 100 or 110 chamber. Edelbrock says with a flat top piston with the smaller 100cc chamber only gives 9.0 comp. is there a .060
over 427 small dome piston that can bring the comp. up more like 10.0.
Did the 427/390hp have a small dome piston to get the comp. it had
with the 101cc oval port heads ?? would that piston work with the
edelbrock chambers??
Nothing is set on parts buying but 9.0 comp,
with aluminum heads sucks, any combo of
oval port alumunum heads with any combo
of pistons and chamber size that would get comp.
north of 9.0 is what i'm after.
Last edited by Little Mouse; Dec 31, 2007 at 05:30 PM.
Pro
Joined: Jul 2002
Posts: 723
Likes: 0
From: North Port, FL
SRP has an off the shelf piston that might work for you. It is one of their small dome pistons (part # 212134). Specs are : 4.31 bore, 6.135 rod, 1.765 compression hight, 29 cc dome. With zero deck hight. 0.040 head gasket and 110 cc chamber you will have ~10.7 CR.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Also ......
Sealed Power / Speed Pro forged bbc 427 piston p/n L2300F60
4.310, 1.767" CH, dome height 0.140", dome volume +16.8cc
this marketed as replacement piston for 66-69 427-335HP & 390HP w/ closed chamber heads.
will yield approx 1.1 less scr than +29cc srp piece.
Suggest you recalc scr math for your combo.
Here's handy, rather accurate scr calc from Federal Mogul (aka SP):
http://www.21cgt.com/FMWebCatalog/frmConversion4.aspx
Sealed Power / Speed Pro forged bbc 427 piston p/n L2300F60
4.310, 1.767" CH, dome height 0.140", dome volume +16.8cc
this marketed as replacement piston for 66-69 427-335HP & 390HP w/ closed chamber heads.
will yield approx 1.1 less scr than +29cc srp piece.
Suggest you recalc scr math for your combo.
Here's handy, rather accurate scr calc from Federal Mogul (aka SP):
http://www.21cgt.com/FMWebCatalog/frmConversion4.aspx
