The Stovebolt Site Forums The Shop Area Engine Shop Idles Rough When Cold

Hi Everyone,
My truck did the same thing last winter too when she's cold trying to warm up, she'll sit there rocking side to side with a miss. :o Also while she's warmin up, she'll blow out this black splatter out the exhaust pipe, with some moisture. Right now there's a area of 2x4 feet on the driveway that's black. it has accummilated over a few weeks.

Valve stem seals? I get a little leakdown in #4 and sometimes get the miss/splatter you describe.

Oil spatter or unburnt gas?

Could it be unburnt gas. Does it seem to smoke just a little when running. put your hand at the exhaust pipe then smell your hand does it smell like oil or gas Has the carb been rebuilt? Had the same thing happen to a f**d that I had. Rebuilt the carb and it ran better than when new

I get black spatter out of mine when it is warming up and it is tuned perfectly. It's just the carbon in the exhaust getting mixed with water and shooting out the tailpipe. You might want to check your valve clearances since a lot of your problems seem to point to them being set too tight- low vacuum, low power when hot, miss. Either that or your ignition is needing some tuning.

Hi Everyone,
I had rebuilt the carb around last september. I'll have to check the moister + black stuff from the exhuast tomorrow. I'll get some pics posted too.

I'm with Josiah , you're describing classic tight valves symptoms . no one likes to do this important job so they al say " oh I checked them , they're fine " ~ every time I offer to bet $5.00 they're tight the story suddenly chages .
Valve adjust , set dewll , set timing and it'll be fine .

Hi Everyone,
I checked the exhaust today, I watched the black splatter for a few minutes while the engine was warming up. As I watched the black splatter come out, it was in little chunks half the size of a BB gun BB. They were flat black when they were coming out, but when they hit the ground they turned into wet black dots. I also put my hand up to the exhaust pipe, and it smelled like fuel maybe a little rich?? I forgot to take a pic of the splatter on the ground, i'll try to get one up tomorrow.
Many thanks,
Chevyboy

My 235 does the same thing, as nate says its probably the valves but as nate also points out its a pain to check. Here's what I do, after it starts I push the choke in about half way, it smooths right out and stops smoking. Maybe mine is a different problem but it works. Just idles a little slower than full at choke but runs great.
Good luck

They are really not too much of a pain to check, just pop off the valve cover and slide a feeler gauge in there. The rocker arms on the valves that are closed should show some clearance, click when rocked by hand even, if they don't you know they are way too tight.