460 gasser overhaul-still some issues

I've posted quite a few items a week or so ago ref my rebuild. I'm down to the last few items and i'm still not there. Looking for more ideas. I had a mysterious bobble after an overhaul and I thought I found the issue when I found that the oil pump and dist were worn out. replaced both and played with the oil pump positioning and got her in happy middle ground. It made a difference.....but still has a slight miss... I plowed some snow the other night and its not right yet. Still having issues while under a load. It will get to a point where the gov kicks in cause of the load and it will kill the motor unless you throw in the clutch and back the throttle off. My exhaust manifold is not in the best shape so I have ordered a new set of both exhaust and intake manifolds. I did order them off ebay--made in china....not real thrilled but I think they should work. They will come soon. I do have some exhaust leak on one exhaust port but I sprayed wd around all the intakes and carb and it did not change anything. Dont know if it would do anything cause it is slight and does not run rough ..except every now and then it has a bobble and it does not matter if it is high speed or idle it shows up. The bobble is faint and even when its running at full speed the bobble or miss wont hit on at steady rythmic time-just every 3-5 seconds or so sometime longer and sometimes quicker with a longer pause between them . Have set the static timming several times but does not remove this little bobble. While trying to find the source of this I removed the oil cup from the air filter and it has great suction. put it back on and you can hear the bobble all the way back to the air filter. Sounds like a popping sound comming from the oil cup. I can hear this slight bobble/stumble from the exhaust and from the air filter. It does not improve by removing the oil cup or anything I do. While running the motor at all different speeds I walk away and can hear the bobble even better. I guess the only thing I can do now is rebuild the carb and replace the heat riser/exhaust and intake. I have not replaced the coil but could that be the issue as well? Hope the carb rebuild will fix it but right now I'm not super hopefull. I do think the carb might be the issue because I can adjust the air mixture needle all the way in close it down and it is has a slight change. I can also back it all the way out and it only changes when I pull the needle all the way out but it will still run but runs rougher. Any other ideas.

What plugs shoud be in the old girl. I just replaced the old ones with the same ones-autolites.

Thanks for your help.

Havin' trouble remembering your posts, but have you tried re-adjusting those valves yet?

The "popping noise" just smacks of a valve too darned tight.

Bear with me. If you got the engine hot and then re-torqued the head bolts after the overhaul, that in turn is gonna change the valve clearance----as much as .003" tighter out there at the tip of the valve stem.

Allan

I did not go in and re-torque but did set the valves and reset them after I warmed it up but did not re-torque. I have thought along the same lines and I'm wondering If I should have replaced or resurfaced the tappets that ride the valve stems. they were worn but I seem to get good reedings. How far out could I set those?Once I have the cover off again I should back them off far enough to totally rule it out but dont want to go too far

The only way to measure the clearance on a worn rocker arm (where it meets the valve) is to use a dial indicator set to read in alignment with the valve stem. The cup shape of the worn rub point will defeat a feeler gauge every time. The only good thing is it makes them loose which is much better than tight. If it dies out when the throttle opens, the carb is probably partially plugged. The idle adjustment is also an indicator of goop in the passages. A clean carb might make it much better.
Start it and get it so that it does the burbling thing, then run a little propane into the carb inlet (hose off) from a propane torch with the nozzle off (pure propane) if it then smooths out, you know it is carb related! Jim

Retorque reset valves then set the ing timing as per manual at rated rpm as to what it is with out looking at my books i am not going to guess on it and i ain't running back out to the truck as it is pouring .

If the manifolds are really bad, and leaky, all the carb adjusting in the won't make a difference. I am thinking you have what we call in the fuel injected world "unmetered air"; the engine is sucking in air after the carb. Just a guess!

New manifolds and gaskets should really help! Be sure to have the heat regulator flap in the exhaust manifold installed, and the spring on it the right way!

Best of luck! Hope you solve it soon!