Having trouble with old Tecumseh L head

[creia]

Hello guys,
I could sure use some help on this one:
1979 Tecumseh 3 HP Horizontal shaft
H30-35311M SER 91078
Diaphragm carb
We did our (usual) full disassembly, cleaning (ultrasonic), carb kit rebuild and new gaskets everywhere.
1. The idle rpm steadily increases as the engine warms up from about 1,400 to 2,000+ rpm
2. Even when fully warmed up, if we shut if off and try a restart we MUST use full choke each time or it will not even fire and run.
Once it starts the engine runs fine and takes throttle very good when opened.
My son and I have done a fair number of old Tecumsehs. This is the first time we have experienced these conditions. Of the 2 conditions, # 1 bothers me the most, but I would bet that they are related.
Does anyone know what could be causing this?
Thank you in advance,
Michael

[lee]

I'm gonna guess lean condition caused by an air leak, maybe around a worn throttle shaft? What happens if you take a propane torch and put it up next to the carb intake (don't light it! lol) and let it suck up a little propane? I bet the propane cures the lean condition and the rpm's drop.

[creia]

Thank you for the reply Lee. I will be checking for air leaks as you recommended at various locations including the throttle shaft this morning. I will report back with my results.
Michael

[creia]

UPDATE:
Checked for air leaks everywhere with propane- NONE.
I then richened the low speed/idle screw about 1/2 turn and it will now start when warmed up w/o choke. The idle speed rpm creeping up seems to have gone away on its own for the most part . It now only increases about 100 rpm from start up (big improvement over 600 rpm!) which I can live with.
Michael

[Arkie]

and make sure the ADJUSTABLE timing is right on the money at .035 BTDC and some of them Tecumseh carb H jet adjustment will have slight effect on the Idle also. 1/8 turn on the H jet will still get a good High speed run and also smooth the idle, working back and forth between the L adjust jet and the H jet. (try adjusting the H jet just little bit while holding the engine at idle then check the high speed for good response if the H jet on the bottom of the bowl has a slight effect on the idle.
Kinda rare instances for the H jet to have a effect on the low idle, but when it does it can really cause starting and warm up issues on the little Tecumsehs. (and some old model Briggs engine had this same issues with the carb adjustments and the carb adjustments will be even more so critical if a full tank of gas and not venting properly or a very slight gas flow restriction, for example using a fuel filter (wrong filter) that is not for a gravity flow system. (white (50 micron) instead of red) (improper fuel delivery flow causes carb adjustments to be more touchy and critical)

[bobodu]

I wonder what percentage of old Tecumseh problems are related to TIMING....not one of anyones favorite jobs to do.

[Arkie]

I wonder what percentage of old Tecumseh problems are related to TIMING....not one of anyones favorite jobs to do.

Right: Just when you think you have the timing all set correctly and you tighten down the coil mounting screws the timing changes AGAIN. Figure out now which way to set the timing so as when you tighten the coil mounting screws it will shift into the correct time.

And on some, think maybe is was the H30's had TWO different timing specs per serial number change per year of manu.