Head gasket??
Thread Starter
Safety Car
Joined: Sep 2005
Posts: 4,226
Likes: 643
From: Orange County Ca
Head gasket??
69 BB 390hp, basically stock, with '71 low compression oval port heads.
Question--If I replaced the FelPro fiber type head gasket (part # unkown) with a stamped steel head gasket, would the compression ratio increase enough to matter? Any problems associated with the steel gaskets??
Question--If I replaced the FelPro fiber type head gasket (part # unkown) with a stamped steel head gasket, would the compression ratio increase enough to matter? Any problems associated with the steel gaskets??
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
On an 8:1 motor, it will raise CR approx 0.2 - 0.3 ... if you're at 8:1 now ... it'll go up to about 8.2 - 8.3:1.
On a 9:1 motor, it will raise CR approx 0.3 - 0.4 ... if you're at 9:1 now ... it'll go up to about 9.3 - 9.4:1.
On a 10:1 motor, it will raise CR approx 0.4 - 0.5 ... if you're at 10:1 now ... it'll go up to about 10.4 - 10.5:1.
If both head & block surfaces are very true ... the thin steel shim gaskets will be fine ... otherwise, thin steel gaskets don't seal as well as composition gaskets.
On a 9:1 motor, it will raise CR approx 0.3 - 0.4 ... if you're at 9:1 now ... it'll go up to about 9.3 - 9.4:1.
On a 10:1 motor, it will raise CR approx 0.4 - 0.5 ... if you're at 10:1 now ... it'll go up to about 10.4 - 10.5:1.
If both head & block surfaces are very true ... the thin steel shim gaskets will be fine ... otherwise, thin steel gaskets don't seal as well as composition gaskets.
Thread Starter
Safety Car
Joined: Sep 2005
Posts: 4,226
Likes: 643
From: Orange County Ca
Well, the best I've come up with is 9 to 9.5 cr, so now the question is, would I gain anything with a .3 to .5 increase? Alot of work involved. If I ever need to replace the head gaskets, I think I'll give it a go with the thinner ones. Thanks for the info.
Pro
Joined: Jan 2002
Posts: 624
Likes: 0
From: Marietta ga
Originally Posted by jackson
On an 8:1 motor, it will raise CR approx 0.2 - 0.3 ... if you're at 8:1 now ... it'll go up to about 8.2 - 8.3:1.
On a 9:1 motor, it will raise CR approx 0.3 - 0.4 ... if you're at 9:1 now ... it'll go up to about 9.3 - 9.4:1.
On a 10:1 motor, it will raise CR approx 0.4 - 0.5 ... if you're at 10:1 now ... it'll go up to about 10.4 - 10.5:1.
If both head & block surfaces are very true ... the thin steel shim gaskets will be fine ... otherwise, thin steel gaskets don't seal as well as composition gaskets.
On a 9:1 motor, it will raise CR approx 0.3 - 0.4 ... if you're at 9:1 now ... it'll go up to about 9.3 - 9.4:1.
On a 10:1 motor, it will raise CR approx 0.4 - 0.5 ... if you're at 10:1 now ... it'll go up to about 10.4 - 10.5:1.
If both head & block surfaces are very true ... the thin steel shim gaskets will be fine ... otherwise, thin steel gaskets don't seal as well as composition gaskets.
true. I have a friend who is running steel shim gaskets and they leaked. His block was freshly decked and his heads were new out of the box. He took the motor back to the machine shop, and as it turns out the new heads needed to be resurfaced right out of the box. There was nothing wrong with the heads, but since the tolerences are so exact with steel gaskets they leaked.
So, if you plan on having your block out of the car and decked, and your heads resurfaced go for it. If not, stick with the felpro's
Racer
Joined: Apr 2004
Posts: 401
Likes: 0
From: IL
Stamped steel for BB? Who's?
What were you going to use? Fel-pro #1071-1 MLS gasket is .053" compressed, don't have catalog in front of me, but I'm not sure of a thinner one. Though some new stuff is coming out. Reference = Standard FP perf gasket thickness is .039".
Later.
What were you going to use? Fel-pro #1071-1 MLS gasket is .053" compressed, don't have catalog in front of me, but I'm not sure of a thinner one. Though some new stuff is coming out. Reference = Standard FP perf gasket thickness is .039".
Later.
