74 power wagon dream truck...

j par

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I don't think I've had the RPMs up over 4000 and really probably only up to 3,000. It's built and balanced to do way more than that but it's just kind of a fun driver truck I have my duster for all the insanity...
 

j par

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I just think you mis-used the 8553. Be thankful you close to home. 1008's will serve you better but will push the compression up just a tad more.
Yes my intention was to have dish pistons and domed heads.. keep the compression low and use cheap pump gas and drive the hell out of it with the AC ah blowin...:D...
 

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Yes my intention was to have dish pistons and domed heads.. keep the compression low and use cheap pump gas and drive the hell out of it with the AC ah blowin...:D...
Did you have the heads resurfaced before assembly ? (not reading 52 pages for that info lol) Just sayin', if they were raised in the center even .005 that wouldn't help the 8553's out at all either
 

j par

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Did you have the heads resurfaced before assembly ? (not reading 52 pages for that info lol) Just sayin', if they were raised in the center even .005 that wouldn't help the 8553's out at all either
There were the heads that came off of my duster when I put the speedmaster aluminum heads on my duster. They had been previously machined...
They probably had less than a couple thousand miles on them on the duster. They were completely rebuilt by the machine shop when I originally did the stroker for the duster. K-line valve guides Crower springs chromoly retainers 202 valves... The works and always perform flawless in the duster with 1008 head gaskets LOL...
I really didn't think much of it when I put the 8553s in there...
 

j par

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Actually the 8553's I was thinking that they would be a little thicker and lower the compression...
It certainly wasn't thinking they would be a weak link...
 

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Actually the 8553's I was thinking that they would be a little thicker and lower the compression...
It certainly wasn't thinking they would be a weak link...
You are correct, they would help lower the compression a little. I've never lost a 8553 head gasket, but I like them on stuff under 180 psi cyl pressure. I have them on half my small blocks now, but most my stuff is nowhere near even 180 psi
 

4spdragtop

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Sucks with the head gasket, but like you said no collateral damage, which is rare!
Glad yer back on the road to getting it running. That seems like awfully high compression lol.
Truck looks great, nice work!
 

TT5.9mag

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A forged piston not likely...
Again there's no signs of detonation...
A44DCB34-250B-47B7-AE09-9A79356D05A9.png

J par, THAT ^^^^ is about the biggest sign of detonation I’ve ever seen.
 

TT5.9mag

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That’s a lot of cranking compression. What fuel are you using? What’s the timing CURVE look like? And how do the plugs look?


I was using 91 non ethanol but have been backing that off just to 87 as that's what I built it for at about 9.3:1 compression.…
As I recall I was at about 16 initial and 34 all in with no vacuum advance.
The plugs were looking great until this happened..
Again everything was working running and operating absolutely perfect until this happened..
The tops of the Pistons in the spark plugs weren't showing any signs of detonation....
16 initial and 34 total is not the curve. Those are just numbers. How fast is the curve and what rpm is you total all in at?
 

AJ/FormS

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I've lost 8553s in the same manner at less pressure, without detonation, using alloy heads.
The Static Compression Ratio is nearly useless in regards to avoiding detonation.
It's all in the measured cranking cylinder pressure, and the expansion ratio and time.
I cannot see running over 200psi at WOT, with a 4bbl carb, and with iron heads and pumpgas. Not with any gasket. Not with any decent timing. This is my opinion.
Your engine will produce peak torque somewhere between 3000 and 4000 rpm. Wherever it peaks, is the same rpm where your engine will be most efficient and thus producing the maximum amount of RUNNING WOT cylinder pressure, which is typically 5 or more times it's CCP. Five times 210 is 1050psi. I don't think the 8553 gaskets can handle that, no matter how well the decks are prepared. Not to mention detonation.

To get 200psi in a 360 with a typical Ica of say 60 degrees will require a static compression ratio of [email protected] elevation..... so I'd be looking for a new compression tester, lol.
With a true Scr of 9.2 and the same 60*Ica, and 200ft, the pressure should be closer to 152psi.....and 5 x 152=760 which is well within the 8553's capability, so long as detonation doesn't drive the pressure much higher.
The sound of detonation, is caused by the sudden rise in cylinder pressure, of colliding flame-fronts inside the combustion chamber, hammering the piston/rod assembly back down onto the crank, and slamming the piston skirts into the cylinder walls.Plus the chamber rings like a bell.
I don't believe your failure is detonation, because of where it failed, the same place mine did, into the valley. When mine did that, I checked the rod-bearing in that location and it was fine....... but I have the hi-volume pump and oiling mods, so that might have had an effect. However, after I installed the 1008s, I ran the same timing curve, for another season.

Btw, my engine was running a tic under [email protected](alloy heads). I have since lowered the pressure with a later-closing intake valve and a redesign of the Quench .
 

j par

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View attachment 1715982825
J par, THAT ^^^^ is about the biggest sign of detonation I’ve ever seen.
Sorry I'm not going to let the guru's get in my head... Seen it happen to many times.
Going to clean up the gaskets and already got new ones coming tomorrow... Going to put it all back together and continue on my marry way and try to forget it happened...
I appreciate your concern
 

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Usually with detonation, the spark plug insulator will generally have "metallic" looking specs on it. Detonation will cause the ring to overheat, and it can freeze up in the landing. Piston will show as well. Detonation is like most things, mild to wild. Just want to make sure you don't miss the mild symptom or it can go wild .... LOL
 

TT5.9mag

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Concern is all it is Jpar, not trying to bust your balls. You built a bad *** truck and I’d rather see you enjoy it then have to rebuild it. Thanks for calling me a guru. That puts me in good company. I’ll watch quietly.
 

j par

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Usually with detonation, the spark plug insulator will generally have "metallic" looking specs on it. Detonation will cause the ring to overheat, and it can freeze up in the landing. Piston will show as well. Detonation is like most things, mild to wild. Just want to make sure you don't miss the mild symptom or it can go wild .... LOL
I've seen the signs of detonation on my duster when I took these heads off of it the first time to have the 202 valves put in them. There was kind of a blistering in the carbon on the tops of the Pistons. I have none of that here... And I swear not even my duster with flat top pistons have this much compression but then again I had a much more radical cam in the duster at that time...
I think it's just a lot of cracking compression and not a good performance gasket...
 
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j par

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Concern is all it is Jpar, not trying to bust your balls. You built a bad *** truck and I’d rather see you enjoy it then have to rebuild it. Thanks for calling me a guru. That puts me in good company. I’ll watch quietly.
You're fine I just I'm not going to let it get to me that much I'm going to clean up the mess put it back how it was and see what happens...
I strongly believe it was just a simple miscalculation of too much cranking compression and not enough of a strong gasket... I can't count the amount of small block mopar's s I've had anymore and I've never had this happen.
Now I'm going to chalk it up as bad luck and again clean up the mess put back together and continue forward...
 
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j par

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IMG_20220910_141548362.jpg

I bought some of those little Willie discs from harbor freight to clean up the head and the block. I got the worst part the block mostly cleaned up and of course the mess it made cleaning it up. I rotated the engine once to get the cylinders cleaned out and re-oiled.. I noticed as I rotated it over and the Piston came up on the number five it does come above the block just a hair right there.. probably part of the contribution to the problem...
 

j par

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Well the I told you so'ers should be jumping on this... A few of the Pistons that had some definition on the top of them but I didn't see before.. the distributor I have doesn't have enough adjustment or for that matter any adjustment in the curve... I need too much initial so it must have been running too high all in. I'm just going to order a fully adjustable distributor... Like the duster I'll probably just run 14° of timing and run it 20 initial and 34 All in...
Thing is it ran perfect and they never heard any detonation or rattling... The spark plugs always looked fine.. no speckling or anything with that.
I know the Pistons are coming above deck just a hair so I'm hoping this gasket takes care of that. I know the heads have been counterboard...
 

j par

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The odd part was some of them did some of them didn't so it's leading me to believe I have distributor problems as well..
 

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The odd part was some of them did some of them didn't so it's leading me to believe I have distributor problems as well..

fuel distribution and tolerances can explain cylinder-to-cylinder variance as well. Not all detonation is audible either - knock sensors will pick it up LONG before it becomes audible. I learned it the hard way with a turbo 2.2 many years ago. My top ring came out like dust, I then later cracked a chunk of the piston top out - twice. Never heard a thing until it was blowing oil out every seal and the exhaust...
 

j par

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Just get a FBO limiter plate and recurve the existing one . Check the vacuum can specs as well
I never use the vacuum on the distributor I had in there. I just purchased a new distributor this morning that has full adjustments for the curve the limitation and the vacuum advance which I probably won't use again...
The distributor I have or I should say had a dissected and there's no way of really adjusting things. I just left it apart and ordered a new one..
It was just cheap Chinese junk to begin with so I'm not worried about it and could have been part of my problem...
 
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