861 Ford pops through carb 1000-2300rpm

dvines · Jul 6, 2015

861 Ford pops back through carb beginning at about 1000rpm through 2300rpm. Have done complete tuneup(cap,rotor,wires,points,condenser,plugs), carb rebuild, compression 140psi, valve job(new valves,springs,guides,surface). Pull #1 plug wire pop stops and resumes when put back in place and does not pop on 2,3 or 4. Distributor cam lobes are not worn, new distributor bushing. Adjusted valves loose and tight, set hot @.015. Timing-4 degrees @ 450rpm, 26 degrees advance @ 2000rpm. Cam gear and crank gear timing marks correct. Camshaft lobes measure the same(mesuring from retainer to top of head) as cylinders 2,3 and 4. Intake has no leaks or cracks and surface is flat(tried copper silicone to seal). Has Zenith carb tag 13875A. Air cleaner has been cleaned. Have tried with and without the fuel tank. Engine runs no different than when started. Idles great and runs good up 1000rpm and then starts to pop. Any ideas?? A friend bought the thing running like this so do not about how it ran before. Thanks for any help.

old · Jul 6, 2015

Carbon build up and or a burnt valve will cause that

sotxbill · Jul 7, 2015

as old said... check valve adjustments and check for no advance on the distribitor and bad timing...

souNdguy · Jul 7, 2015

any bend to your intake pushrod on the popping cyl? don't take much bend to make them bow under pressure.

souNdguy · Jul 7, 2015

forgot to say to check for weak springs on #1 intake as well.

unstyled rider · Jul 7, 2015

sounds like a coil going bad to me.

Anonymous-0 · Jul 7, 2015

(quoted from post at 02:16:48 07/08/15) sounds like a coil going bad to me.

nybody can guess!! How about a diagnostic suggestion?

861 Ford pops through carb 1000-2300rpm

dvines

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old

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sotxbill

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souNdguy

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souNdguy

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unstyled rider

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Anonymous-0

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