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Discussion Starter · #1 ·
I have a sbc 406 with a platekit nos big shot , i lifted a ring land on #7 cyclnder bought another piston ball home cyclinder filed to fit new ring pack istalled piston. went to the track made motor pass ,changed plugs every thing look good , made a hit on a pass , pulled plugs ,#7 a little wet and black with oil on threads all other plugs looked good . swap #7 plug in #3, made another hit pass same thing on #7. My tune up is 82 square @5.25 fp what do u guys think?:confused: forgot to ad we check the head with fluid in #7 runner and no leakage.
 

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"Darkness"
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I ran 82 square at 5 psi and it was mint. Maybe you already hurt that cylinder again. Did you make changes to avoid this problem or just put it back together and run it?

Do a compression check. It could tell you something.
 

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i wouldve started at like 7-7 1/2 lbs of fuel pressure and backed it off a little at a time ..where was your timing ?

i run mine a little backwars from the sqare jetting ..i was running 65 fuel @ 7.25 lbs flowing with a 73 nos jet and on the 82 nos jet
with a 73 in the fuel @7.5 flowing seemed to put me right where i wanted to be on the af ..
my carb was jetted for 12.5 af on the motor ..i just never felt comfortable with the lower fuel pressures in the plate ..


6 vs 1/2 dozen
 

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Discussion Starter · #6 ·
I ran 82 square at 5 psi and it was mint. Maybe you already hurt that cylinder again. Did you make changes to avoid this problem or just put it back together and run it?

Do a compression check. It could tell you something.
the reason for lifted ring land was bad regulator and 14pounds of fuel,that was replaced before tear down. we flowed after each pass this go around . have not touch the car, will do compression check mon nite.and tear down left side.
 

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Discussion Starter · #8 ·
my engine builder help me put the motor back together and hes kinda stumped as to why . im leaning towards ring failare but not for shure:smt102
 

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"Im learning as I go here fellas but if I am not mistaken a lifted ring land suggests its too rich of a tune up....:smile:"

it could also be ring gap allowing fuel to get under it
 

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Discussion Starter · #10 ·
"Im learning as I go here fellas but if I am not mistaken a lifted ring land suggests its too rich of a tune up....:smile:"

it could also be ring gap allowing fuel to get under it
But all other plugs read good and clean after puting motor backtogether just #7 oiled. I have had other nitrous sbc,s and burnt pistons and put back together no problem.
 

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I would think it isn't lean but fat, 82 squared is alot of fuel even with 4 psi. First I would put a plate on the block and get honed Right, with that kind of pistion failure the cylinder is no longer round. Are you useing low tension oil rings? If so this is an big problem for a wet sump type engine. Back up on your tune-up no MATTER what YOU HEAR you have to look at the plugs. go in small steps. I hope this helps Gerald Dyer
 

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Discussion Starter · #14 ·
I would think it isn't lean but fat, 82 squared is alot of fuel even with 4 psi. First I would put a plate on the block and get honed Right, with that kind of pistion failure the cylinder is no longer round. Are you useing low tension oil rings? If so this is an big problem for a wet sump type engine. Back up on your tune-up no MATTER what YOU HEAR you have to look at the plugs. go in small steps. I hope this helps Gerald Dyer
yes they are hell fire low tension rings but we put a ringpack from je in it, that was my question to was the cylinder out round. thanks for all yours guys replys ,im pulling the motor this weekend and taking it to the shop
 
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