Re: Head gasket BORE diameter....
[Re: Kern Dog]
#1533668
11/15/13 11:25 AM
11/15/13 11:25 AM
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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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Yes as you know you wouldn't want the fire ring to overlap the bore. I'd want the gasket to be as reasonably close as possible just for more gasket support area (I aint' sure how critical that is but that is my thinking). yes you lose a slight & I mean very slight amount of CR with a bigger bore gasket. Get on the KB site & plug in some numbers & you'll see. By the way have you computed your actual CR? since people have opinionated that something else is going on with it pinging at your stated CR. I think it's just crap gas & too high of SCR & reportedly left coast gas is the worst & people in the gasoline industry have reported that octane levels vary all over the place & quality control is terrible & ain't nothing like it is touted up to be. Post all you want, it's a free (no limit) site & if people dont like it they can ignore anything that is bothersome & just me I'm OK with it. I say get a conservative cam in there that suits your driving parameters/ drastically lower the CR either with a way thicker custom Cometic gasket OR with chamber and or piston deck material removal then a .017" custome Cometic gasket to maintain your quench . I've got a bet going on with this for what it will take to fix it. EDIT meant to say .023" gasket since you are .017" in the hole
Last edited by RapidRobert; 11/15/13 11:57 AM.
live every 24 hour block of time like it's your last day on earth
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Re: Head gasket BORE diameter....
[Re: JohnRR]
#1533672
11/16/13 02:44 AM
11/16/13 02:44 AM
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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
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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Maybe I was not clear. I ran the engine at 16 initial, 30 total and it detonated at just over half throttle. I retarded the timing while I was on the road testing it. It still knocked. I backed off the timing again. ( Again, just for testing purposes) It was at this third timing setting that the engine did not knock at WOT. At home, I checked the timing with my light and found that it was at 6 initial and 20 total. I had no intention of ever keeping the timing at this setting. I was just trying to see how far back I had to retard the timing to get the detonation to go away. I appreciate your efforts and suggestions though. Thank you.
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Re: Head gasket BORE diameter....
[Re: Kern Dog]
#1533674
11/16/13 10:20 AM
11/16/13 10:20 AM
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Joined: Jan 2003
Posts: 75,098 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,098
A Banana Republic near you.
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Quote:
Maybe I was not clear. I ran the engine at 16 initial, 30 total and it detonated at just over half throttle. I retarded the timing while I was on the road testing it. It still knocked. I backed off the timing again. ( Again, just for testing purposes) It was at this third timing setting that the engine did not knock at WOT. At home, I checked the timing with my light and found that it was at 6 initial and 20 total. I had no intention of ever keeping the timing at this setting. I was just trying to see how far back I had to retard the timing to get the detonation to go away. I appreciate your efforts and suggestions though. Thank you.
I don't remember seeing that you put the timing back to where it should be , but what was that?
The fix is to do something about the pistons and your compression ratio , anything else has been halfassed attempt that is just wasting time and more importantly ... money ... you've had the heads off 3 times now , you could have pulled the engine , gotten a new set of pistons and been done ...
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Re: Head gasket BORE diameter....
[Re: BradH]
#1533675
11/16/13 03:20 PM
11/16/13 03:20 PM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Quote:
What heads?
Fel-Pro 1009 are a tight bore fit at 4.375" w/o any significant chamfer on the top of the bore.
Fel-Pro 8519-PT1 (standard replacement) and 17059 (marine-spec) are both 4.500" bores -- yes, I've measured them -- regardless of what the advertised spec is.
I am using the 8519-PT with some of the early 84cc Stealth heads on the 440 stroked to 505". If you have smaller chamber heads, the Cometic 4.380" works great on my 400 stroked to 500" with the Victor heads.
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Re: Head gasket BORE diameter....
[Re: 451Mopar]
#1533676
11/17/13 02:17 PM
11/17/13 02:17 PM
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Joined: Jan 2003
Posts: 1,607 Western Washington
Sixgun
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,607
Western Washington
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Very interesting comment/fact on the 'crevice volume'. I learn something new everytime I come here. I have gathered over the last year that indeed it is critical to A)not have the gasket fire ring overlap into the chamber as it will erode and eventually fail, and B)now I see it is equally important to have the gasket fit near'perfect'to the block and head combo. One thing I am a little puzzled by is I always thought alloy heads allowed a little more compression ie. better heat dissipation and also 'cushioning' the crank mains a bit lessening the pounding they would take with a more rigid iron head at the same compression (not that those 2 things are related, just sayin'). Not that that would crutch bad gas or other related issues... Could the timing be coming in waaay too early down low and contributing to this?(and/or maybe a part throttle lean out?)If this could not be solved with a conventional dizzy,maybe a programmable timing curve box? I also did not know what Cab said about even minute oil contamination causing detonation, but it makes total sense. Lastly,Franken,your pics to my eye show NO long term det. It would manifest, as others said, as a 'craters on the moon'look.Thank god you stopped before it was too late. Bear
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