that is what happens when the seals go, and they are reeeaaally easy to replace too, all u need is a valve spring compressor and the seals (literaly like $5) and to change them you hook up you compressor to the spark plug holes and pump them up the air pressure will keep the valves in place, compress the spring, pull out the retainer, then the spring, u will find the small seal in 4 or 5 pieces, replace it and put the spring back on slip the retainers back into place and you are done. it is a good idea as well to buy new valve spring retainers, just cheap insurance and for doing the seals it is a goo idea to bring each cyl to TDC while doing each seal so if a valve slips it doesnt drop into the engine, also a good idea to look if the valves are loose in the guides, and try not to use the 305 heads, it will turn the engine into a pinging detonating dog that cant breathe

 

Thanks for the help. That sounds like a job I can do, I just need to find the time. I'm glad that it should be inexpensive.
*****

 

1 more thing is i should tell you how to set the valves after, take the engine to TDC (top dead center) and tighten the rocker arm untill the pushrod is just gettint friction while spinning in its seat, then turn the rocker nut 3/4 of a turn, do #1 cylinder first, then the rest following the firing order with each piston at tdc respectively, also account the $15 bucks for new valve cover gaskets, and check them with a strait edge, SBC valve covers are notorious for getting warped and dont tighten them too tight or they will leak

 

Hi rwillys,

Welcome to the Chevy Forums.

I agree. It sounds like the valve seals just need to be replaced.

 

Thanks for the warm welcome. This is my first Chevy, I come from a Ford family. I have to admit that I really like this car, even tho it is an older one. I know most of the stuff made in the USA in the early 80s leaves alot to be desired but once I get this motor issue figured out, it will be a great car. It rides smooth, lotsa room, the 350 has more than enough power. I will let ya know how the seal replacement goes if I dont have anymore questions before I do the job. *****

 

no prob man hope all goes well for you, let us know the results

 

I finally got started on the valve seals. I removed the spring and only found the O ring seal, no other seal is there. I am going to put on an umbrella seal along with a new O ring. Is it unusual to run without umbrella seals? (might be why it smokes so much, LOL) I will try to post a pic.

 

OK,
I got it all back together and it still smokes, I am going to pull the engine, take the heads off and have them checked at a shop, I will have them either repaired or replaced. I should have gone thru the engine before I dropped it in, now I am paying the price of not doing it right the first time. It's not a very difficult job actually, I just don't like doing things twice.
I wouldn't be surprised if I didn't put everything back together properly, so I think pulling the engine and working on it out of the car is much easier, and I will have the room to do it right, instead of hanging over the fenders trying to do it.

 

We r changing a 305 and a 350 trying to identify numbers on passenger side backside of block c284