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Magoo2 09-14-2020 02:20 PM

Lack of power/rpm

Iím having an issue with my 31 closed cab pickup. It starts and idles fine. I just timed it, thatís ok, removed inline fuel filter, new plugs ,points, condenser. I also did a compression test and got a range of 47-54 psi. When I push the accelerator to the floor the rpms donít seem to increase enough and I think Iím detecting a slight miss. There is very little power in the engine. I read somewhere that if you have a lower compression engine you should run with the spark slightly retarded.
Anyone have any opion on that or some other trick I might try?

100IH 09-14-2020 03:16 PM

Re: Lack of power/rpm

Get an old motor manual for info on compression testing. cylinder leakage test, and shorting out cylinders while running. No way around not having compression. Must find out where, how much and why. then you know how to start a repair. Add to the list a vacuum test to see if exhaust is plugged. Off the used book store or U-Tube.

Patrick L. 09-14-2020 03:59 PM

Re: Lack of power/rpm

I'm not sure what you are expecting. Model As are in no hurry to do anything.

The compression numbers are Ok and if the engine idles and runs smooth it should be ok.

If there is a real problem then maybe its running out of fuel or the timing is late/retarded a little too much.

Timing at start-up should be 0ļ/ TDC. Once running the left lever should be 1/2 - 3/4 down.

Try running with the fuel cap loose and see if that helps. Fuel cap vents are kinda famous for plugging, especially repro's.

Chuck Sea/Tac 09-14-2020 05:09 PM

Re: Lack of power/rpm

Running retarded because of low compression doesn’t make sense. You need the spark at the correct time. Running retarded will cause the symptoms you describe.

Sparky 09-14-2020 06:13 PM

Re: Lack of power/rpm

Is this a sudden problem, or has it always run badly?

I had similar symptoms appear suddenly a few weeks ago. After some investigating it wound up being a loose compensator jet in the carburetor. This resulted in a too-rich mixture when accelerating. Take a look at your plugs and see if they look sooty.

Magoo2 09-14-2020 07:01 PM

Re: Lack of power/rpm

Thanks guys. I knew I would get some good suggestions on this site.

Jacksonlll 09-14-2020 07:15 PM

Re: Lack of power/rpm

Make sure your fuel line is not goin too far into the carb. Ferrule should right at the end.

Purdy Swoft 09-14-2020 07:23 PM

Re: Lack of power/rpm

Too little points gap has a retarding effect . try a gap of .022 and it will have a slight advancing effect . Ford specs called for a gap of eighteen to twenty two thousands. I run the twenty two thousands gap on mine . The wider gap gives better throttle response and more time before the points have to be readjusted .

Jim Brierley 09-15-2020 04:52 PM

Re: Lack of power/rpm

Lower compression engines need more spark advance in comparison to higher compression. The mixture burns slower, in higher compression engines, the fuel molecules are closer together, so burn faster.

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