compression numbers??
Thread Starter
Pro
Joined: Nov 2004
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From: Nice Lake Ontario
compression numbers??
OK I know there's a few compression ratio experts here 
What kinda ratio number would I end up with if I install a set of oval port, closed chamber, 69 427 heads on a newer (74-80) block 454??
Would I end up with about 9.5-1? At least that would be my guess
What kinda ratio number would I end up with if I install a set of oval port, closed chamber, 69 427 heads on a newer (74-80) block 454??
Would I end up with about 9.5-1? At least that would be my guess
Last edited by sxr6; Aug 23, 2005 at 06:54 AM. Reason: correction
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
To calculate CR we need the following info:
Bore (standard or overbore)
Stroke (running the 454 crank?)
Piston type, dish/dome volume. Valve relief volume.
Deck height (how far is the piston down in the hole)
Cylinder head chamber volume with valves and spark plug installed.
Head gasket thickness and hole diameter.
Bore (standard or overbore)
Stroke (running the 454 crank?)
Piston type, dish/dome volume. Valve relief volume.
Deck height (how far is the piston down in the hole)
Cylinder head chamber volume with valves and spark plug installed.
Head gasket thickness and hole diameter.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
Originally Posted by sxr6
Geeze I donno 
Just was wanting to take a newer 454 car engine (8.5-1) ratio stock & know what kinda ratio I might end up with with those heads??
Shouild be worth the swap!
Just was wanting to take a newer 454 car engine (8.5-1) ratio stock & know what kinda ratio I might end up with with those heads??
Shouild be worth the swap!
My 454 was 8.75:1 with stock 113cc heads. Swapping to Edelbrock 100cc made that about 9.5:1. Maybe that helps? I have no idea what the chambers measured on the old 427 heads, nor what the chambers of the stock 454 heads that made 8.5:1 were.
Thread Starter
Pro
Joined: Nov 2004
Posts: 575
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From: Nice Lake Ontario
Thanks Zwede for trying to help me
Chevmania says these 427 heads are 100cc oval port.
I have an option to buy them & in this area any perf parts are hard to come by! Let alone a 69 dated set!
I am hoping to pick up a BB to install in my 69 which was a BB originally. Not that I'm particular on a high HP engine just want a responsive driver I thought these heads may come in handy later on when I find a BBlock to put in it??
The most common engine I might run into would be a mid 70s 454 or earlier 396-402!
Chevmania shows the most common head I would run into on a latter 454 would be a 118 rectangular port. So I should be going from 118 to 100cc.
Chevmania says these 427 heads are 100cc oval port.
I have an option to buy them & in this area any perf parts are hard to come by! Let alone a 69 dated set!
I am hoping to pick up a BB to install in my 69 which was a BB originally. Not that I'm particular on a high HP engine just want a responsive driver
I thought these heads may come in handy later on when I find a BBlock to put in it??The most common engine I might run into would be a mid 70s 454 or earlier 396-402!
Chevmania shows the most common head I would run into on a latter 454 would be a 118 rectangular port. So I should be going from 118 to 100cc.
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
I think your doing it bass ackwards. Get pistons for the more modern heads, not closed chamber heads for the modern pistons.
Even better live with the low compression-- make it work for you. Pop a charger on it since the compression is fairly low to take advantage of.
Put the money towards super power.
Even better live with the low compression-- make it work for you. Pop a charger on it since the compression is fairly low to take advantage of.
Put the money towards super power.
