melted windsor pistons
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melted windsor pistons
i have a 74 351w that i have rebuilt 3 times now. it is bored .30 over, 498 lift comp cam. heavier valve springs, flat top pistons. i have melted 3 pistons on it at different times. wondering if anyone else has had this problem or any ideas of what could be going on???? i have tried a 4 barrel intake and carb and a 2 barrel intake and carb and it happened with both, put 78 jets in it ran great but seemed like it was getting to much fuel, put 76's in it and melted a piston, went back to 78's plugs looked perfect and then melted another piston, help me please, thanks.
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im using the stock, electronic ignition for a 78, i am using autolite 45 plugs, no advanced timing (no vacuum at wide open throttle and thats where its mostly ran) plugs look just a little brown just like they should so its not lean, But i think i might have another idea, ring gap isnt wide enough??? what does everyone else think?
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need a little more info. melting piston is usually lean condition. Or preignition. Is the reason you think its ring gap because its burned on the side. As for info. which pistons, and wheres the melting at on the pistons.
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Assume valve train is correct and not causing the problem, Try this: go to colder plugs. I would go down 2 sizes to start. I say 2 because you went to flat-tops and again because of cam change. If the 43's foul out go to 44's. I would go back to the most fuel you gave it before.
What are u using for rocker arms? Make sure u have the right ratio for your cam.
other reasons: Exhaust valves not closing. causing lean condition.
Make sure you don't have vacuum leak.
What are u using for rocker arms? Make sure u have the right ratio for your cam.
other reasons: Exhaust valves not closing. causing lean condition.
Make sure you don't have vacuum leak.
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From: Conyers
If too small of a ring gap...the rings would have butted, siezing up in the bore ans breaking off the piston skirt and ruining the cylinder wall. I'm willing to put money that he's running lean. maybe a blockage in the intake? Bad carb tune? Not enough fuel pressure?
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okay it cant be lean, its been cylinders 2, 4, and 5. intake has been magnaflux and have used two different intakes and carbs that have both been rebuilt, and new fuel pump each time. pistons are forged, and its a 10to1 compression
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I understand the plugs seem ok. But from everything I see from the post's, this motor is starving for more fuel(lean). The problem may be at WOT (wide open throttle). Try a inline fuel pressure gauge before carb. I would stick with the 4bbl and intake. As for 4bbl is it vacuum secondaries? You might want to check that they are opening when you want.