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Old 09-11-2011, 09:50 PM
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blow by new 383 stroker AFR heads

My new 383 stroker has about 1500 miles on it and it's running strong but there is a lot of blow by, both sides, wow where do I start? compression test? it does have the heavy duty high out put oil pump, No pvc valve, roller rockers,

Could use some guidance ? Tmouse

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Old 09-11-2011, 10:01 PM
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What finish on the bores and what rings, what oil??

At 1500 miles, there shouldn't be much blowby...
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Old 09-11-2011, 10:20 PM
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Quote:
Originally Posted by bates_k
What finish on the bores and what rings, what oil??

At 1500 miles, there shouldn't be much blowby...



x2 and where the specific tolereances for the pistons and rings followed
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Old 09-11-2011, 11:06 PM
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A good place to start is with a leak down test at TDC and was the block plate honed?? What was used for a hone??
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Old 09-12-2011, 09:11 AM
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Quote:
Originally Posted by Tmouse
My new 383 stroker has about 1500 miles on it and it's running strong but there is a lot of blow by, both sides, wow where do I start? compression test? it does have the heavy duty high out put oil pump, No pvc valve, roller rockers,

Could use some guidance ? Tmouse
What are you using for valve guides and seals? Regardless, you need to determine where the leakage is coming from. Best way to do that is to get a leak down number from each cylinder of a warmed up engine and listen for the sound of escaping air coming from the breather hole or dip stick tube (if rings) or from the carb if it's an intake problem or from the headers if an exhaust valve. Guides will also appear from the valve covers, spray can be used around the valve guide and stem to see if the guides are leaking.

A compression test will show you if there's one really weak cylinder but it's harder to tell if there's a small leak or many small leaks. Telling if it's rings requires you to shoot oil up inside the cylinders to try to seal the rings, but this is a hit or miss affair at best.

I don't know what your idea of a lot of blow by is, but I would advise you to run a PCV system once the problem is found and corrected.
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Old 09-12-2011, 04:46 PM
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You should install a PCV system first and see if that solves your problem. Also make sure your valve covers have baffles in them (a must have). It seems that alot of people just remove the baffles when installing roller rockers because they hit the rockers, bad decision. If need be, install a taller valve cover but make sure they have the baffles. Another thing to consider is the oil pump. You say it is a high output. Is that a high volume or high pressure output pump and did you use any oil restrictors?
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Old 04-27-2012, 09:12 PM
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x2 on the pcv valve
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Old 04-27-2012, 11:55 PM
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I too had this issue with my blown 406. It was also pushing oil out werever it could. I ended up doing a rering job. That was the trick!

Keith
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