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AQ225D blow by

D

dslater

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"I just purchased a 78 Fiberfo

"I just purchased a 78 Fiberform with AQ225D/280. I like these old boats. Engine had a burnt valve so I had the heads rebuilt and installed an Edlebrock Performer intake and carb. Runs like an absolute champ!...but I am getting an inordinate amount of blow by. I know I will need to pull the engine a short block it eventually, but for now, I'm thinking about rerouting the breather tubes from the flame arrestor to the exhaust mainfold and out through the exhaust...so it won't stink up or dirty up the engine compartment. Anyone ever done this?...and if so, where would you connect to the exhaust to carry it away?"
 
The breather tubes are connect

The breather tubes are connected to the flame arrestor because the carb pulls a vacuum. The exhaust manifolds will be under pressure (from combustion) and will not evacuate gases from the crankcase. I do not advise your suggestion.

What's the compression on the engine?
 
"On an interim basis, you may

"On an interim basis, you may want to consider using a thicker oil (SAE20W-50 or straight 40 for example) and/or adding some additive to the oil to try to improve compression/cut blow-by. However, I suggest you keep the vents going to the flame arrestor and run the blower on a continuous basis if there is still too much blow-by."
 
"The engine is running 135-145

"The engine is running 135-145 compression on all cylinders except #5: 85lbs. I'm thinking rebuilding the heads probably increased the compression from what it was and number 5 just isn't holding it...bad rings in that one cylinder. I wasn't aware that engine oil weight would have any affect on blowby. If I use an additive, what would be suggested?...Like I said, a short block rebuild is in the future."
 
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