Big Block head gaskets to lower compression....?
#936829
02/24/11 11:38 PM
02/24/11 11:38 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
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Posts: 18,493
Granite Bay CA
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I'm looking to reduce the squeeze in my 440/493 and I was thinking of using a gasket THICKER than the Fel Pro .039 #1009 gasket. I have seen .051 gaskets on the 440 Source site, but has anyone used these? I am using aluminum heads with a compression ratio of 10.8 with the standard .039 gasket. A .051 will drop it to 10.5. Not a big drop but it may reduce chances of detonation in 100 degree summer driving. The .051 would help, and a .060 might be the limit as anything thicker may need longer pushrods, cause intake port misalignment, etc. I know that the easiest way to find this out is to call Mancini, but my west coast work hours make that difficult. Can anyone help?
Last edited by Frankenduster; 02/25/11 11:33 PM.
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Re: Big Block head gaskets to lower compression....?
[Re: Kern Dog]
#936831
02/24/11 11:44 PM
02/24/11 11:44 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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You want thicker? I think the Felpro 8519 (+ 2 #'s I forget which) (the std FP blue BB ones) are iirc .054". what is your quench?
live every 24 hour block of time like it's your last day on earth
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Re: Big Block head gaskets to lower compression....?
[Re: Stanton]
#936833
02/25/11 12:34 AM
02/25/11 12:34 AM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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If you have any cam at all in, you shouldnt need to reduce the compression. Your bascially at 9.3-9.8 to 1 with iron heads.
Plenty of guys run 10 plus with iron heads on pump fuel with no problems. Im at 10.6 with iron heads, no quench, etc. Timing at 34 total I have no problems. I do put a few gallons of 100 in it at the track.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Big Block head gaskets to lower compression....?
[Re: Kern Dog]
#936836
02/25/11 10:30 AM
02/25/11 10:30 AM
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Joined: Jan 2004
Posts: 27,347 Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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What is your piston to head clearance? If your running a .039 gasket & your pistons are .011 in the hole your at the very edge of effective quench.. Increasing gasket thickness could actually be worse... It may sound wrong but a thinning gasket could be your best answer if the piston is in the hole .011-.020... Beyond that & your not gonna help it with a thinner gasket.....
As mentioned tuning & water injection could also help..
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Big Block head gaskets to lower compression....?
[Re: BSB67]
#936837
02/25/11 10:33 AM
02/25/11 10:33 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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OP
Striving for excellence
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Granite Bay CA
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Sorry guys, I should have included more info. I am running the '509 MP cam and have Edelbrock aluminum heads. It couldnt tolerate much more than 31 degrees of advance even when using Californias dog water 91 octane "Super" unleaded 15% ethanol gas. I used to run the distributor w/o the vacuum advance, but after reading articles in Mopar Action and from other sources, I ran a line to it and will keep it that way. The pistons are actually at .017 in the hole, and with the .039 gasket, I'm probably already at the edge of losing quench anyway, right? .039 + .017 = .056. I ran the Cometic MLS gaskets a few years back and the car ran great. I believe they were custom made and .060 thick. I was able to increase the spark lead to 34 degrees and the motor felt crisp and responsive. I ended up pulling the heads when I found stem wear on some of the valves, and I couldnt afford to buy the Cometics at the time of reassembly. I had a set of Fel Pro 1009 gaskets so I used them instead. A thread on the Race forum asked of the percentage of power gained/lost with compression changes. The consensus in the past was that each point is worth 4 % of power, EXAMPLE: An engine that makes 400 HP with 10 to one should make 416 with 11 to one. This of course assumes ideal cam conditions and zero detonation. The thread had many opinions and even some actual real world research showing the tested results to be lower than that, often in the 2 % range. I would gladly give up 2% of 500 horsepower to gain more streetability and to avoid having to pull the motor apart every few years! The 440 Source website listed a no name .051 gasket for $15. I was a little suspect of its quality, partly due to the Wal Mart price and the lack of a brand name. Thanks for the help.
Last edited by Frankenduster; 02/25/11 10:38 AM.
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Re: Big Block head gaskets to lower compression....?
[Re: Kern Dog]
#936838
02/25/11 10:39 AM
02/25/11 10:39 AM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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where did you run the vacuum advance line too?? Ported or manifold vacuum?
Cometic MLS gaskets can generally be cleaned and reused.
Last edited by Dodgem; 02/25/11 10:42 AM.
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Re: Big Block head gaskets to lower compression....?
[Re: 1_WILD_RT]
#936840
02/25/11 11:31 AM
02/25/11 11:31 AM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Have you had a AFR meter hooked up to know your air/fuel ratio?
Something doesnt sound right to me. I had the .509 in a 10.5 to 1 iron headed motor. I never had ANY detonation with that motor. Open chamber heads, so no quench at all.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Big Block head gaskets to lower compression....?
[Re: BSB67]
#936842
02/25/11 11:33 AM
02/25/11 11:33 AM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
Do you know what your current cranking cylinder pressure is?
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Big Block head gaskets to lower compression....?
[Re: 1_WILD_RT]
#936844
02/25/11 11:43 AM
02/25/11 11:43 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
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Striving for excellence
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Granite Bay CA
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I ran ported vacuum. This was during the last 100 miles before I pulled the motor for the teardown, so I didnt get much seat time to determine any fuel savings or driveability improvements. I am collecting the parts for reassembly now. I yanked the motor because of an oil burning condition. I have run the gamut with bad cams, a broken rocker shaft, valve stem wear and who knows what else. When I tore down the motor, I didnt find a smoking gun as to why it burned oil, but the machinist did. The rings were bad, and the cylinders were smoother than they should have been for a motor with less than 3000 miles on it. I had the cylinders deglazed, cleaned the pistons and I'm cleaning eveything for the re-rebuild. The rings and bearings just came in yesterday, and by midweek I hope to be ready to set the heads. NOW is the time to decide on head gaskets. I could simply default to the Fel Pro #1009s since I already have a pair.....
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Re: Big Block head gaskets to lower compression....?
[Re: Kern Dog]
#936846
02/25/11 11:52 AM
02/25/11 11:52 AM
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Joined: Feb 2005
Posts: 4,318 Prospect, PA
BSB67
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Quote:
I ran ported vacuum. This was during the last 100 miles before I pulled the motor for the teardown, so I didnt get much seat time to determine any fuel savings or driveability improvements. I am collecting the parts for reassembly now. I yanked the motor because of an oil burning condition. I have run the gamut with bad cams, a broken rocker shaft, valve stem wear and who knows what else. When I tore down the motor, I didnt find a smoking gun as to why it burned oil, but the machinist did. The rings were bad, and the cylinders were smoother than they should have been for a motor with less than 3000 miles on it. I had the cylinders deglazed, cleaned the pistons and I'm cleaning eveything for the re-rebuild. The rings and bearings just came in yesterday, and by midweek I hope to be ready to set the heads. NOW is the time to decide on head gaskets. I could simply default to the Fel Pro #1009s since I already have a pair.....
Sounds like there were a lot of things not right before. I would be cautious in solving the detonation problem when apparently there were other things going on with the motor.
This alone.... Quote:
"I yanked the motor because of an oil burning condition."
.....could be the cause of your detonation problem.
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Re: Big Block head gaskets to lower compression....?
[Re: BSB67]
#936848
02/25/11 01:25 PM
02/25/11 01:25 PM
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Joined: Jan 2003
Posts: 75,070 U.S.S.A.
JohnRR
I Win
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I Win
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Quote:
This alone.... Quote:
"I yanked the motor because of an oil burning condition."
.....could be the cause of your detonation problem.
This and this
Quote:
Little late but I would have had the block decked to zero the pistons....
Not to late ,sounds like the engine is still apart, maybe not zero but I would get them closer to zero .
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