Update on Rough Running

Mike in NRN IN

Mike in NRN IN

Senior Member
Okay,

I think I resolved the Rough Running issues...

I removed the manifold, and found that the manifold gasket had blown on #4.

This created a vacuum and exhaust leak.

So, I had the manifold sanded and checked for alignment (these were both replaced when I put in a rebuilt engine.)

I also checked the float level and indeed it was sitting too high.

The fuel line into the carb was fine (slightly less than 1/8" beyond the ferrule.)

I also found that the tailpipe/muffler was bent back about 5 degrees too far and I could not get a good mate to the exhaust manifold. I clamped the tailpipe in a pipe vise and slowly reshaped the tailpipe.

This allowed for a nearly perfect mate to the exhaust manifold and a few taps of my tack hammer, I was able to reshape the flange to form a good clean mating.

I checked the timing again, and it's spot on.

My daughter helped me get everything back together tonight and we took the car out for a run around the area. It's running much quieter and is smooth. Good acceleration and easy cruising at 45 mph. No hesitation and no backfiring.

Thanks to everybody for the feedback and suggestions.

YAY!
 
Theres no better feeling than to run down the run and find out it was all worth it, way to go mike happy motoring
 
Great summary, and potentially useful information for me, as my B is running rough as well.

Thanks!
Mike
 
qzjrd5,

Are you using a Model A distributor on your B engine? If so you may have a Model B front timing cover also. The B timing cover sets the static timing at 19 degrees advanced. Way to much, this gives 60 degrees advance with lever fully advanced! Engine will buck and run rough.

How to tell if B timing cover? Look at the timing cover and the timing pin. To the left of the pin there is a bolt at about 9 o'clock and an other bolt about 10 o'clock. If timing pin is closer to the 10 o'clock position then you have B cover. If it is near 9 o'clock it is an A cover.

If you have a B cover you can get around the problem by following the standard timing with one exception. Normally the spark lever is put all the way to the top of the quadrant. To compensate for the B cover just set the lever at 1/2 the quadrant and time as usual. When you return the lever to the top to start the engine the timing will be correct for your setup.

Hope this helps.
 
Hey, Mike,

Thanks for the great trouble-shooting summary! Congratulations on the successful outcome! The manifold gasket and alignment was most likely the biggest part of the problem. And that's one of the things most often overlooked when suggestions for fixing engine running problems are posted.

When I had my engine rebuilt by Schwalms a few years back, I now recall that being one of the "routine" things Ora did - He bolted the intake and exhaust manifolds together and planes them down to one perfectly aligned and flat surface. Same on the block's mating surface if it shows the slightest unevenness, roughness, corrosion, etc. Then extreme care in the torquing value and sequence when bolting the manifolds into place.

You've made me more aware for future issues I may have.

Earle
'31 Deluxe Roadster
 
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