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this is the second time in less than 25 laps that it has knocked out the bearings on 3/4 the first time it looked like it broke a pick up but now i think it was caused when the rods came out. it never broke a rod just takes out 3/4 bearing. we have had problems sealing the heads do the machine shop champering the top of the cylinders to much they did all machine work to this block ??? could they have left out a galley plug or got something behind the cam bearing. i have checked every thing i know two check and cleaned all oil passages with air and brake cleaner. so what am i missing.or did they mess something up with the block. thank for any help
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The answer to your question is going to be very difficult given the information you provided. What engine is this and little about your combination like type of rods and crank you're running........compression ratio/fuel used and things like that.Off the cuff, I have seen these type problems many times, way too many. The majority of the time there is a mechanical problem like cheeks of rods pointing the wrong way, not using narrowed bearings on big radius cranks, oil pickup too close to bottom of pan, engine running too hot, too tight running clearances, junk oil filters, pistons hitting head or valves, detonation, big oil leak internal from block plug under rear main cap or other block plugs leaking or forgotten, etc etc etc.Pictures would help also.Also. The fact you're having trouble sealing heads seems like a detonation problem to me. Bad ignition timing, carburetor, rotor phasing, too low octane fuel for compression.............etc.Last edited by let-r-eat; 03-10-2013, 04:42 AM.BUCKLE UP NOW, YA HEAR?
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4.165 bore had a 4.180 bore gasket on it. the compression ring crushes into the top of the bore went to a 4.200 gasket this time. will see how that looks in a bit. it is a 3.330 Bryant lentze rod with JE pistons nothing is hitting any thing timing at 33 . 12-1 compression. i have checked plug under pump and all in upper rails and are restricting lifter rail. car ran at 80 cold and 60 hot in shop and never dropped below 60 on track. all other bearing are good just taking out 3/4 and this time it was on a different set of rod on 3/4. the only thing i can think of is the machine shop did not get the rails clean and there is something blocking the main hole under cam bearing. but that hole has been clean and aired out unless it is to big to come out i would think it is clean. the story on this block it was 30 over had them just hone it when i got it home ant took the bag off it the hone never hit the top of the bores so i had them take it out to 40 over they had to take cam bearing back out to do that so they said. was not there so i don't know if they tanked the block after or just sprayed it off with cleaner an put bearing back in. i cleaned every thing out and off with brake cleaner like i always do before i built it.dont know what more to look for.Comment
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Whaat block are you using ????????????????????Comment
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You ran this block before no problems and just put it back together bored .040 with new pistons and no other changes?I gotcha on the fire ring in the bore. Maintaining pressure and burning up bearings means restriction to me somewhere if everything mechanical is right.... CNC knows a ton about blocks etc. Perhaps he has an idea.BUCKLE UP NOW, YA HEAR?
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Whats the bearing clearance at? Was the crank repaired after the first failure? Was the engine completly torn down for cleaning?Josh K.Comment
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rod 2.5 yes it was repaired they had to straiten it and turn rods 10 every thing was cleaned before put together. think first failure was pick up second was crank. have used the place that fixed the crank before with no problems.Originally posted by fast_crew View PostComment
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Reusing parts of an engine that has blown up before not once but twice....there is more damage to everything else than what you think!Comment
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What the material of the crank and what bearings were used?Comment
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4340 king H BEARINGS talked to hendrens he thinks that when the shop we had straiten the crank they heated it with a torch that is was doomed. going back with new crank this week.Originally posted by CNC BLOCKS View PostComment
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That would cause some issues heating the crank with a torch !!! HMMMMOriginally posted by twisterf5 View PostComment
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