Guys, just got done driving home and car started puffing blue smoke out between shifts. Car runs good, lots of power, but got worse as I got near home and puffs after you let it sit for a while then start it. No other problems before this. Heads are L98 vette alloy heads, bought used, rebuilt about a year ago but did not know the status of the guides. Haven't done any other troubleshooting. Any ideas
Mike

 

Mike,

My guess and a good place to start is the valve stem seals. They could have dried up before you got the heads since you said that you purchased them used. They are not too bad to change with the proper tools and much cheaper then pulling the heads and taking themto a machine ship. Most of the new heads have parts that last a lot linger then the stuff from the 60 & 70.

 

I checked if the seals were even there before I put the heads on (they weren't) so I put new ones on and valve seals also.
Thanks

 

compression test

 

From a very general perspective.

Smoke at startup means leaky valve seals. Whan you are driving, let off the gas for a bit (high vaccum), then get back on the gas and see smoke in your mirror... that means leaky rings.

Other things can cause smoke... keep an eye on your coolant. It could also be a developing head gasket leak. But I wouldn't suspect this yet from your description.

 

No blow by out the oil cap, and it did not smoke on start up. The inside of the plenum (Stealth Ram) behind the throttle body butterflies is soaked with what looks like oil. Shiny black paint looking stuff. Maybe a intake gasket. Car runs too good for it to be rings.
Mike

 

Comp checks anywhere from 195 to 210 on all cylinders. Thinking it is a bad intake gasket. HSR's are known for them

Mike

 

It is pretty common for the intake to get a little oil'd up where the PCV and other vacuum lines connect. There is always a little bit of fluid that gets through and into the intake. If it is a lot of oily goop, check those vaccum related lines and make sure they are ok. Might want to change the PCV valve.

It is common on the V6 engines (which I am more familiar with) to get a black build up right behind the butterfly. That doesn't mean it is a good thing I'm just saying if it is not excessive then just clean it up and put it all back together. Changing gaskets is always a good idea.

 

My Iroc had 191k miles on it. It smoked pretty good when I laid into it, but it ran like a raped ape. Now that I have the shortblock on an engine stand, I can assure you that the rings are worn out.