engine vacuum problems

Making an assumption the valves are set correctly. Get a bottle of mmo and run it down the carb when idling till it almost chokes off. Smoke the garage out. Road Run the crap out it and repeat. I had to do this till my rebuilt motor guides set in. Still do it every spring. It's not going to harm anything if all is well mechanically (valves hitting heads, bad pistons, etc).

Back in the day they had lead in the fuel to lucubrate the top end of a L head motor. But really it could be anything. It's really just a jumping off point. You want to see a steady 19-21 at idle carb set, not flutter. I guess you could use some diesel fuel or drizzle a bit of oil down the carb. But mmo works very well.


Medical creed same as engine creed. Do no harm.
 
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i had my cam grind done at Delta camshafts in Tacoma wash., have to find my paperwork to get grind details but it was a mild grind for street use for flathead they use to say 3/4 cam, I just checked the cam to crank gears to make sure the dots were lined up, thats ok.
 
hmmech said:
i had my cam grind done at Delta camshafts in Tacoma wash., have to find my paperwork to get grind details but it was a mild grind for street use for flathead they use to say 3/4 cam, I just checked the cam to crank gears to make sure the dots were lined up, thats ok.
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There have been several post questioning the timing gears being marked correctly, but I would exhaust all the other possibilities before tackling that issue. It is always a good idea to degree a cam during installation so you know what you have and a baseline to work from.
 
Not sure if there is a difference between a 4" stroke french crankshaft and one from a merc ,I bought mine from so-ca speed shop sacramento
 
Don't let information confuse you. You might go over the entire engine and find there is some sticky valves. You'd know pretty quick if the time gear was off by clocking the dizzy on a 8ba. But you would know that right way on startup. Remember: Popping exhaust, fluttering vacuum.


If you trust your builder, move on.
 
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