Started happening maybe a week ago... on cold startups my engine will idle very rough for about 30sec-1min until it starts to warm up. Blows a decent amount of blue smoke but its not terrible. Smells more like fuel than oil so I'm not sure if the carb. needs an adjustment. After it warms up and I start driving, it runs and idles as it always has - nice and smooth. It hasn't really gotten worse since it started.

Its a CC-Qjet 305 I recently rebuilt (maybe 3k miles on it now) with new gaskets all around, new valve stem seals, all new piston rings, lifters, pushrods, bearings. Has a High Energy CompCam 12-205-2. I've drilled out the tamper plugs, and taken the cap of the idle air bleed valve(?) but have not made any adjustments.

Have replaced all vacuum hoses and checked for leaks, and am all good there. But, could always go back again.
I dunno if I left out any info.....

Since I'm smelling gas, could it be that the carb. is dumping in fuel for some reason?

 

Blue smoke is oil, On mine I had blue smoke and it fowled out 3 plugs so it was pushing out the raw fuel so that may be what you smell. But that is extreme and I changed out the heads and intake manifold to fix it. Something you can check would be the intake and make sure it's not leaking, a vacumn leak will cause a ruff idle and in extreme cases can cause oil to leak into the cubustion chambers.The intake could seal up when the engine warms up stoping the smoke and hard idle.

 

Thanks for the reply. I don't get out of class 'til 10pm today, but I'll definitely spray for leaks again when I can and see what I can find.

Appreciate the help.

 

You can spray but the before you do take a wrench and just see if they are loose first that only takes a few seconds. Besides you said it seems to run fine after it warms up so if you drive it home or were ever you are going to do it it have warmed up and the leak may not show. Thats something to do when the engine is cold thats when the problem happens.
But warm or cold, a quick check of the bolts can't hurt.

 

You may want to check this also. When you first start your engine the choke is closed. as soon as you start the motor vac. pulls the choke open alittle so the engine can get enough air to run.on the top/side of the carb there should be a vac.operated valve that pulls the choke open. if this is bad the car will run rich which is why you smell gas and you could also see blue/black smoke till the engine warm up.This will also make it idle rough until it get's warm also. You can check it by pulling the vac. line and put a vac. pump on the valve to see if it moves.It should hold vac. if it doesn't or it moves back out before you release the vac. it should be replaced. hope this helps it worked for me.

 

Had to leave for work early this morning but, Rob, I took my air filter off so I could watch the choke. When I start up the choke does open to allow air in, so I think I can rule that out.

kd5icr - I didn't have the time this morning to re-check the bolts/spray, but I will definitely get to it early saturday.

We have been starting to get some cold nights here on the island, maybe the engine is just starting out much colder than it was during the summer days?

 

I dont think you need to worry about it getting cooler at nite,that wont cause blue smoke on start up or cause a ruff idle untill it warms up, just check the things I had pointed out, and we can go from there.

 

Sorry I havn't updated on whats going on been pretty busy... kd5icr, I re checked the intake manifold bolts and they are all snug. I did spot something i hadnt noticed before.
this is a picture of the front of the intake manifold... it looks like the gasket just popped right the hell out.

 

It does look like it popped out, but that one will only cause an oil leak. It won't make the engine burn oil.