here we go again .. new guy needing help

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newmodelaguy

Junior Member
ok so 1930 tudor every thing orignal ( no modern up grades) .. runs good up to about 45mph then starts cutting out and back firing through the carb. acts like the points are closing but not the case just a reference to the way it is cutting out. is time for a carb. rebuild ?
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Since you already checked the points, (and the timing?) I'd look at the fuel supply. Trash in the bowl, partially clogged line etc. Good Luck!
 
Here is something to consider: Do you have the "Spark Lever" fully advanced - level to the bottom?

A couple of years ago I was having an issue with my 1930 Canadian Roadster where it was cutting out when I got to 40-50 mph. This was happened for quite a while. I started some experimenting and eventually moved the spark lever up slightly, less spark advance, and the motor smoothed right out with no cutting out.

Two years ago I was doing some test runs down our local small drag strip when we were testing the lights. I was able to achieve 48.4 mph and 26.5 seconds in the 1/4 mile with the ignition cutting out. Later that summer was when I had moved the spark lever up slightly and the ignition smoothed right our and no cutting out. Hey if I had done that when testing the car on our drag strip, I probably could have achieved 50 mph in the 1/4 mile. My reaction time for the lights on the Tree was 0.96 seconds, another good number. I only took a couple of runs down the strip - but it was interesting to see what the car could so
 
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Could weak valve springs cause the problem? Intake valve not closing or closing slow cause the back firing through the carburetor? I would put this at the bottom of your list, check out what others have said, do the easy stuff first!
 
ok like i said runs good till around 40 to 45 when it starts cutting out and backfires through the carb. you can turn the gav 4 or 5 rounds open and it dont change a thing.. the only change with the gav is when you close it all the way..
 
I seriously doubt it is a carb issue, though it may be a fuel delivery problem. I would check the basic electricals first, including your spark lever position at that speed.
 
newmodelaguy said:
ok like i said runs good till around 40 to 45 when it starts cutting out and backfires through the carb. you can turn the gav 4 or 5 rounds open and it dont change a thing.. the only change with the gav is when you close it all the way..
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If it'll run all day at your 40-45, cuts out above that and will resume running good when slowed back down to the 40-45, then it seems to me there is a fuel delivery issue.
The easiest thing to do is loosen the fuel cap and see what happens. Aftermarket fuel caps are famous for plugging the vent with rust [ which can usually be blown clean] .
Removing the fuel line at the carburetor and checking for a good long running supply of fuel [ at least a gallon] should check condition of fuel supply system.
These are at least easy to check.
 
ok sounds crazy but here it goes ,
the flange on the carb. where it bolts to the intake had warped and was sucking to much air,, sanded the flange back to a flat surface and a new gasket and running great at 54mph
 
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