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Author Topic:   Burnt Block and head between #3 & #5
posted June 13, 2004 04:45 PM
what are you running for compression and fueland also what did the plugs look like?

posted June 13, 2004 08:12 PM
not sure if this was the cause but we had the same thing happen to us last year, same cylinders and everything. When we pulled it appart we found that the rocker studs were pulling out. The car also overheated. Greg

posted June 14, 2004 08:19 PM
I have had the same problem on both motors you had. The first was a 355 on gas got a tad hot combined with to much timing and it burnt the hole in the head and block. I also had the same block with diff heads burn up the #5 piston....after the block had been fixed with lots of races after. The 377 was the last one and it burnt up the #3 and #5 pistons....I really wanted to know what i was doing to cause this to happen......wich was over about 6 years time. After talking to a few good engine builders and haveing them look at the damage i came to the conclusion that from excessive heat it would cause a detonation wich would cause more heat resulting in the burt up stuff.....i also would run the timing up to 38....and all the times i have had this the car was flat moving and i was in the throttle real hard....probally more than normal. I think i have a handle on it now water to the back of the intake for better cooling and i keep the timing at 34....and i watch the temp a bit closer....not sure if any of this will help just thought i would toss it out there....also i have gone with a locked dist...wich i didnt have before.. Hope you can use some of this to avoid the problem in the future. Craig Moore

posted June 15, 2004 05:55 PM
As an FYI to NJantz... You mighyt consider using a differnt brand of spark plug. My buddy works at a Polaris dealer, and told me once that Polaris doesnt use NGK plugs any more because they are to inconsistent with the heat ranges. Same # plug might be cold, the next hot. Kinda looks like you are having the same deal.

maniac motors
posted June 16, 2004 07:03 PM
distributor needs to be checked on a distributor machine.i have mine checked every 2 years maximum and prefer every year if i can. its cheap insurance and 9 times outta 10 its gonna save MAGSARUS i dont have the number off the top of my head but ed is a great guy to talk to he is in ny state near albany

posted June 17, 2004 08:10 AM
I bought a 383 out of Cal. and 3&5 have lower compression pistons.The motor is a real strong runner. We run 34 to 35 deg.

posted June 18, 2004 11:34 AM
if this where a detination problem you would have top of pistion visible problem, along with rod
and main bearing damage, and possible crank
and main cap damage. #3 and #5 spark plug would also have electrode damage.

where it's burnt lies between the exhaust
valves of the #3 and #5. both of thoses
spark plus where black. that indicates
a rich condition. what did the head gasket look like and what about the exhaust valves of the #3 and #5?

posted June 19, 2004 06:21 AM
A burn between cylinders is usually due to head gasket failure, not a problem with the way the cylinders were running. Are you using good gaskets? Was the deck and the heads cheecked for warpage and a perfectly smooth surface? Were the head bolt hole threads tapped and cleaned well? Was the gasket retorqued? What often happens is the gasket will start leaking from cylinder to cylinder without leaking to the water jacket and the heat and cylinder pressure and fire will slowly burn thru the gasket then the block and the head.

posted June 27, 2004 07:49 PM
i agree with MAVRIK we had the same prob years ago changed to a diffrent brand gasket (quit using the cheap ones) and problem gone

posted June 28, 2004 06:16 AM
Had same thing happen to me. Distributor broke one week before and burned the #3 piston and took out head gasket on the second night. I also have the same plugs. The distributor breaking caused some detonation and damaged the piston. Try running a little less timing I was told by a reputable engine builder not to run more than 34 with alcohol. I would also change plugs I'am. A little thing like a distributor can cause a lot of damage. My car never runs over 200

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