830 gas misfire

[mopar66701]

i have this 830 problem case. has an intermittent and apparently random misfire at any engine speed cold or hot. mainly indicated by that weathercap flapping clattering around .during the process of rebuilding this thing to put back to use i have installed all new ignition parts, rebuilt carb, the heads were supposedly redone prior to me buying it however everything the prior owners did i have had to go back and redo. they claimed they were checked and reworked blah blah blah. i can say that looking through the sparkplug holes the cylinders have hone marks on them and the valve margins look pretty thick too. checked for combustion gas in cooling system as i was worried they had a poor headgasket installation. has 150 psi compression on all cyl. less than 25% leakage past the rings on all. (measured cold) fires right up at the tap of the key. ignition scope didnt really help narrow this down any at all. im thinking the previous owners may have set the valves too tight or something. or maybe the valve springs are iffy. what do you think. anybody?

 

[Gene Dotson]

Check your distributor for excessive sideplay on the shaft bushings.

Gene

 

[1370rod]

Those intermittent misses can drive you crazy,but start with the basics. You did not mention if it misses under load. Double check cap, rotor, points and condenser. Point gap and timing and ignition wires. Carb and manifold air leaks can cause that condition if engine is not under load when the flutters occur. And there is a difference between a actual miss and just rain cap flutter. The 870 we have fluttered a lot until I repaired the throttle shaft air leak in carb, did a tune-up now it purrs. Dist. shaft play affects gap and timing and what the heck, check tappets. I doubt that will help but you mentioned the previous work has questionable.

 

[mopar66701]

No load condition. I havent yet got it ready to use so ive never had a load on it.

 

[1370rod]

Then it could be anything Gene or I mentioned, good luck, Rod.

 

[jon f mn]

They don't call those rain caps dingers for nothing. Are you sure your not just seeing normal carrying on for a rain cap on a gas? Most gas tractors I've seen the cap carries on up there a bit.

 

[mopar66701]

Its such that it will suck my fingers down a bit when i hold my hand over the muffler.

 

[Adirondack case guy]

Gene,
I'm sideing with you on this one.
Loren

 

[rustyfarmall]

(quoted from post at 18:37:45 03/19/13) Check your distributor for excessive sideplay on the shaft bushings.

Gene

I had the same problems with a Farmall M. Found out the distributor was flat worn out. Installed a GOOD distributor, played with the timing a bit, and she's smooth as silk.

 

[Brokengun]

My D17 allis had a similar problem, the distributor was worn out.

 

[mopar66701]

Ok guys. I feel dumb but i owe you an answer on what it was. The dwell was too short both before and after i replaced the points and other components as well. I dont use that dwell meter much anymore so i guess i read it wrong. Its up about 42* now and just purrs smooth. Getting some sleep, stepping away for awhile, and some input helped me think better. Thanks guys. Btw i read this board daily but rarely have much to add. However i enjoy everyones projects and progress and the history collected here. Have a good one