Allis Chalmers B

[Holmanc]

I have a 47 allis b I did a top end rebuild on over the winter, it had badly worn valves and seats. I cut new seats and replaced the valves, springs, keepers, etc. It starts up great when it is cold but once it has been running for a while it develops a miss that comes and goes and if I shut it off its difficult at best to nearly impossible to get started again until it cools off. It will puff some smoke and fire once but that"s about it. Seems to be getting good spark as well. Any suggestions on where to go from here would be much appreciated!

 

[Janicholson]

Feel the ignition coil when it is beginning to misfire. If it is nasty hot, it could be going bad. A bad coil will be unable to make good starting spark, because the battery voltage when cranking is much lower. Make sure your battery cables are 0 gauge and clean at the connections. 0 gauge is slightly smaller than 3/8 inch. (conductor size, not including insulation. Jim

 

[old]

That is one of the problem with fixing the top end and leaving the bottom as it was. What are the compression numbers?? Good chance there low due to the rings etc. being old and sleeve and rings and piston need to be done

 

[rustred]

my bet is on the coil. so let us know what cures it. with a redone head it sure will not make it harder to start than before if you are sealing the compression better. old wives tale i think,... or old timers tale, as they say doing the valves make the engine burn oil. i sure never found that.

 

[Holmanc]

I haven't done a compression test on it since I redid the head but in my opinion the cylinder walls looked like they were in excellent condition. Been meaning to do the test though just to see where I'm at now

 

[Holmanc]

Thanks, I think that's where I will start. I haven't found that it burns any oil at all, before or after the top end rebuild so I guess it remains an old wives tail...

 

[Holmanc]

Thanks, I will give that a try next time I have it out. The cables and connections are good, I do know that

 

[Steve@Advance]

Did you reset the lifters after retorqing the head bolts?

Magneto or battery ignition?

Either one, check the point gap and condition.

If battery, check the distributor shaft for side play. Any wear and the points will not stay set, they can do strange things. Do check the coil temperature. Is this 6 volt or converted to 12? If 12, be sure to get the correct coil or coil resistor combination.

 

[old]

I learned years ago rebuild the top and blow the bottom out or rebuilt the bottom and not the the top and blow the top out. Do both or neither

 

[Gary Reif]

First thing I would do is check the valve clearances.

 

[Holmanc]

I did reset the clearances on the valve train after retorqueing the head but I'd like to check it again since I have probably 10 hours on it now. The previous owner put a new rebuilt magneto on just a couple months before I bought it from him, I'd like to think it's all in good working order still.

 

[Holmanc]

That's on my radar for possible causes, I will give the valve clearances a check

 

[RalphWD45]

Gary your name intrigs me! do you know where East Pike High school was?

 

[Holmanc]

An update on the b... I checked the valve clearances this afternoon and found they were all very close to spec and I only had to adjust 2 of them, that very well could have been error on my part from last time I adjusted them to be honest, they were very close to the others. I also tried tweaking the timing a bit but that didnt seem to make any difference so my money is on the coil for now. Headed into town in a couple days and I will pick a new one up

 

[Gary Reif]

Have no idea, I live in central Ks.