H Farmall...........

Goose · Jul 9, 2014

I have an H Farmall that just doesn't run as smooth as you'd expect. I've gone through the carburetor, even boiled and installed a different carb. Adjustments on the carb won't bring it out of it. New spark plugs and distributor cap.

If it's idling and you pull the throttle open, it will smooth out as long as the engine is accelerating, then roughen up again. That would seem to be carburation, but could it be ignition? Wear in the distributor? Intake gasket?

Does anyone have any ideas? I bought it on an auction in January, and it's been that way since I bought it.

mmfan55 · Jul 9, 2014

Weak valve spring can cause a miss. Will smooth out under load or acceleration

Wild Bill · Jul 9, 2014

Did you clean and adjust the points? Distributor? Could be wear in the shaft, or gummed up advance weights.

Mike (WA) · Jul 9, 2014

Smooth during acceleration then roughens up? Check for a vacuum leak (maybe the spacer between the carb and the manifold, a crack in the intake manifold, bad intake gasket, etc.) One way to check is to spray WD 40 or ether around the intake area while its running badly, and if it smooths out, you've got a vacuum leak.

gene bender · Jul 9, 2014

Befor you start throwing money on new parts that probably arent needed do a compression test as all the new parts in the world wont cure bad and weak compression. What do the plugs look like that is another quick test and doesent cost any money. Next would be to check tappets. I bought a B cheap as it sure didnt sound good got home pulled valve cover and guess what two pushrods werent even fastened to the rockers to open valves. Got that fixed and checked compression now the engine starts and runs great took a while to get the two cycls firing good with all the junk that was in them from pushrod not working.

John B. · Jul 9, 2014

1. I would check for a vacum leak by starting it and spraying WD40 around all the intake manifold connections when the engine is cold and running. Starting fluid can be used but it's more dangerous and can cause a fire.

2. You didn't say when it runs rough, at an idle or above an idle.

3. You may need to adjust the governor spring tension.

4. Yes do a compression check. With all the spark plugs removed and the throttle wide open. Crank engine over for 5 compression strokes and see what the gauge reads.

5. Does the engine mis-fire or rev up and down (called hunting). Hunting is a governor issue as I mentioned before.

Super-H-Mike · Jul 9, 2014

Once in a while those manifolds will crack inside where you cant really see it, and that is how it will run. Hard to diagnose, swapping it with a known good one is one way to test ! lol

CenTex Farmall · Jul 9, 2014

Vacuum leak, as others stated, possibly through worn guides if everything else checks out. Also have seen weak valve springs cause similar issue.

H Farmall...........

Goose

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mmfan55

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Wild Bill

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Mike (WA)

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gene bender

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John B.

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Super-H-Mike

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CenTex Farmall

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