147 original backfiring through exhaust

[SDBOB]

Just went out to fire up 147 after winter in unheated garage. Started up fine. Then, missing, no power on throttle up. Noticed a little black smoke on starting, I choked carb. Backfires loud through exhaust. Took off carb, cleaned, no dirt or corrosion. New Autolite plug, number which I've used for yrs. I'm thinking stuck exhaust valve,or carbon buildup. I've never done head removal before. I've rebuilt many Pontiac V8s, lapping valves,etc. So I have some mechanical skills. I have factory manuals that I bought from advertisers here. Just need some pointers, torque technics, valve lapping, adjusting clearances that manuals may not be clear or mention. Thanks in advance.

[RLause]

The service manual is available from Kohler Engines for free.

[R Bedell]

I am guessing you are running "lean" as fuel/air mix on your Carb.

[Billy-O]

Originally Posted by R Bedell

I am guessing you are running "lean" as fuel/air mix on your Carb.

Yep.......... I concur

[twoton]

Originally Posted by SDBOB

...... I've never done head removal before. I've rebuilt many Pontiac V8s, lapping valves,etc. So I have some mechanical skills. I have factory manuals that I bought from advertisers here. Just need some pointers, torque technics, valve lapping, adjusting clearances that manuals may not be clear or mention. Thanks in advance.

Hey SDBOB, I tried to compile some useful info in one of my threads on de carbon heads and such if it helps;

https://www.onlycubcadets.net/forum/...339#post337339

[SDBOB]

Thanks for the info. Engine ran fine when parked in fall. I thought dirty carb, fuel. I have rod set at 2 -1/2 turns. I tried as suggested to richen, engine, will not start now, some burnt fuel coming out exhaust, nothing. I didn't take time to do compression check yet. I'm thinking no compression. Been busy with other things. I'm going to CC dealer to get head gasket, remove, check all to make sure. My trusty 100 plow tractor, runs and runs and runs. So I'm spoiled. Retiring next week so I'll have more time to fix.

Thanks again.

[ironman]

I think I'd check the points before tearing into all that other stuff.

[dodge trucker]

2-1/2 turns out on the mixture screws sounds like alot
When all is right I usually wind up with it open about 1/2 of that may be a little more though once I get it going and under a load, I tweak the adjustment til it sounds best without hesitation, but once I get to that point I don't run it in and see where it winds up at....
It winds up where it winds up, with the engine running it's best.

On the backfire I have a K341 here off of another brand of machine that popped and backfired when the engine was cold and the weather is cold enough for snow, had a hard time getting it going til it warmed up a bit, especially if I left it outside between plowing sessions.

I found out that the exhaust valve was necked, and very sloppy in the guide, and the Piston top land was worn away enough to see about half of the top ring. And though it didn't smoke while running, both times I had the head off the Piston was soaked with what looked like fresh oil. I tried to band aid it with a new valve and a valve job and it helped a little but definitely didn't fix it
I just wanted to get thru the winter, as I had another engine sitting here for that tractor but didn't want to have it down for the swap when I might need it to plow with.

I have since gotten the other engine in before mowing season and I can tell a big difference.
I'm gonna be rebulding the old one when I get the extra cash for the machine shop bill.

[Mike McKown]

Originally Posted by ironman

I think I'd check the points before tearing into all that other stuff.

[SDBOB]

Ok on points. Went to my C C dealer, Labuda Farm Service in Herminie,PA. John, the owner said, yes it could be carbon, also pull exhaust valve and ck clearances. May need to ream guide. His wife is a computer, tell her what I need, she goes to shelf. Doesn't need a parts book! Thanks guys for ideas to check. Like I said my 100 goes and goes, I'm spoiled.