Weird Cold Starting problem.
 

My truck has a stock Rochester 4B. After it's been sitting a few days ,it blows bluish smoke and rev's up very briefly (2-3 seconds) after being started. Very soon after that, it settles down, idles normally and drives normally.

I don't know if it's related or not but in the cold weather, it started really hard and usually failed to idle down when warmed up.

I also recently disconneted my smog pump because it was causing backfiring and popping.

The smoke/Rev up is my most pressing problem now that we are getting warm weather.

Any ideas??

Thanks, Tom

Re: Weird Cold Starting problem.
 

Has the carb had the plugs epoxied on it? If not it could be leaking gas into the engine when it sits....

LockDoc

Re: Weird Cold Starting problem.
 

Thanks lock doc,

It seems like gas is leaking while it sits and the gas is buring off on start-up.

I am not sure what you mean by having the ports epoxied. All the smog control stuff is still there and connected. I just have the smog pump belt off.

I am kind of wondering if it might be time to rebuild my carb between this problem and the choke problems.

Thanks.

Re: Weird Cold Starting problem.
 

Must be a ND thing Tom. Fired up my 68 the other day and it wouldnt idle at all. Farted with it for a bit and finally came to the conclusion the quadrajet needs a rebuild.

Re: Weird Cold Starting problem.
 

Don't jump on that carb yet!!
Bluish smoke is oil burning. Oil seeps down past the oil seals and guides as your motor sits.
The choke problem is likely a simple rod adjustment or choke coil replacement.
The wells Lockdoc speaks of are in this link.
http://www.crankshaftcoalition.com/w...4MV_carburetor

Re: Weird Cold Starting problem.
 

You might wanna check the intake bolts too see if they are loose and the intake gaskets for a vacuum leak.
it could be sucking oil when the carb is fully choked then then when it opens some not sucking so much oil. Also from the engine warming up everything is expanding and could seal up the internal leak.
your idle might change if it's sucking extra air also this could be why your rpms are not dropping.
Then there is always the suspect choke acting weird.

But the valve seals can have the same symptoms but from what i have seen is usually it will always puff warm or cold from bad valve seals.

Re: Weird Cold Starting problem.
 

Thanks everyone. I think I will try to get my choke working properly and go from there.

Re: Weird Cold Starting problem.
 

Do you have a pic of your choke?
Might be something obvious.