My 250 does the same thing, it has a time limit on restarting. If I drive 8 - 10 miles and run in to get my celery and come right out, it fires right off first hit. If I set and eat the celery, it cranks for way longer than needed but will fire off eventually. If I let set for a couple hour or so, it hits right off like a new truck.
I'm pretty sure mine is heat soak letting the fuel boil over into the manifold flooding the engine. The short trips to the hardware store is not long enough to really heat up the carbs, but 20 - 30 minutes does. I can see fuel residue running down the side of the block where it seeps out of the rear intake port gasket ( it all runs to the back due to the engine installed angle). I keep it wiped off, but last week it was 100* out and it was terrible to restart. I have insulating plates under both carbs, but it needs a fuel pressure relief return line to let the heated fuel go to the tank instead of the carb bowls. Thats my next project then I get time.
I don't notice any black smoke when it starts, but holding the throttle open while cranking seems to clean it out some. I have tried holding partial open, giving it more fuel, leaving it shut, nothing seems to help much other then just cranking it till it starts. I have a good working HEI and a new battery, 99% sure it over fueled related. I should look at the carbs when it won't start, just too lazy to pull the air cleaner lid.
Mine runs on the lean side, I also have a small catalytic converter that puts a lot more heat into the exhaust and holds it there. But, it runs great when it starts, doesn't smell, the exhaust is clean, it gets great fuel mileage, so I tend to live with it no more than I drive it. 250 inline six, dual Carter W-1 carburetors, HEI ignition, A/C.
Last edited by Joe H; 09/04/2026 1:35 PM.
