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Discussion Starter #1
My 307 seems to run ok but has no power and is sluggish.the dwell is set at 30deg.it appears to be getting plenty of gas but, it does backfire sometimes.what could it be?
 

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could be bad spark plugs, bad plug wires or the timing could be off

I would check the spark plugs first though.
 

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307 issue...

My 307 seems to run ok but has no power and is sluggish.the dwell is set at 30deg.it appears to be getting plenty of gas but, it does backfire sometimes.what could it be?
Is your back fire a "pop" thru the carb..??? if all the normal tune-up issues are verified....next thing to check is compression and valve train. You could have a burnt valve, cam lobe that is starting to go or collapsed lifter....compression check is pretty simple and you can pull the valve covers and look at the rockers/pushrods in action.....if one is not moving up and down as much as the others....you need to go further inside. How amny miles on the engine..??? has it been rebuilt...??? let us know what you find.

wilma
 

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Discussion Starter #4
the backfiring is a pop through the carb.there is what sounds like a valvetrwin noise in the engine(ticking).the engine is all original with 46000 miles.it sat up for 5 years before I bought it.it has new points,condenser,rotor,cap,plugs.the wires looked brand new.what could it be?it does smoke some(grey).
 

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backfire...

Sounds like a lifter/cam issue for sure....try to isolate which side of the engine the noise comes from. A wooden broom handle makes a good stethascope.....remove that valve cover, start the motor and locate the problem valve(s). You could have a stuck or collapsed lifter or cam problem, either way the intake has to come off to see the problem. I suppose you could have a broken rocker arm or bad adj. nut...but, it sounds like a deeper problem...especially since it sat for so long and the engine smokes. Let us know what you find...

wilma
 

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hmm

as i remember , the dwell was suppose to be 31 for those. I'd check the advance in the distributor and make sure it moves free. I had a 70 chevelle with a 307 that ate a cam at 71,000 miles with good oil change intervals. I think i read on here that some 307's had bad cam cores and they had wear issues early
 

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307...

Would I be better off to put in a new engine?
I wouldn't rush to buy a new motor until you see what's up with this one....if you are unsure about the diagnosis...why not take it to a reputable shop and get it looked at ??....the 307's were a durable and good running motor, but they did occasionally have cam issues. I worked on a lot of them in the early 70's at the neighborhood gas station.

wilma
 

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Discussion Starter #10
I can diagnose the problem.I just have a mild 350 on the stand and thought that would be easier than replacing cam,lifters,etc.what do you think?
 

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307

Well, that's a different movie....I thought you were talking about buying another motor. Since the 307 most likely has cam issues....and if the 350 is good to go...seems like an easy fix. A few of your pals and a case of beer and a weekend...and there you have it.

:yes:
 

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I can diagnose the problem.I just have a mild 350 on the stand and thought that would be easier than replacing cam,lifters,etc.what do you think?
Ditch that boat anchor 307:yes:
 
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