Blow-by

[waterlife]

on a 1970 M code, to me there is excessive blow-by. The PVC seems to be working fine. Engine hadnt run in few years, I soaked it with marvel mystery oil for 2 days and she fired up in only a few cranks. Smoked like a factory for about 30 minutes then went away. To me there seems to be more pressure on the right side of the engine. Have not driven it yet, maybe rings ?Nothing out of the exhaust tho, opinions?

Al

 

[Don C]

Compression and leakdown tests are the only way to make sure.

 

[Jeff73Mach1]

The Marvel Mystery oil will smoke for a bit. If you had to free it up, then I'd treat it like a fresh engine and break it in for 300 miles before doing much of anything. From there I would start with checking plugs, doing a compression check and checking valve seals.

 

[waterlife]

Didnt have to free up the engine, cranked right over and started on the 3rd go

What about the use of a Zinc additive?

Al

 

[will e]

I use valvoine zr-1 for its higher zinc content. But that won't help any blow by. Best bet is the compresson test and see where you are.

 

[MeZapU]

Guessing you changed the oil, right?

 

[waterlife]

Yes, I changed oil using 20/50

 

[c9zx]

The rings may not be moving freely in the ring grooves (carbon deposits). I've had good results using Marvel Mystery Oil. I know the name sounds silly but I've used the product, with good results, for a long time. Pull the plugs and put about a tablespoon full in each cylinder, let it sit for a day, crank the engine to clear excess from the bores, install plugs and start. It will smoke terribly for several minutes, then clear up. If you don't want the mess from this process, just drain a quart of oil and replace it with a quart of MMO. Drive it normally for a couple hundred miles and see if the problem goes away. Just an idea.

Chuck

 

[waterlife]

Hey Chuck, When I got the car it was not running, more likely for years?? who knows....

The first thing I did prior to trying to start was adding MMO to each cyl. and let it sit for 2 days. The car started right up(3 trys) and it smoked like crazy!! I have been running the engine off a gas can until I flushed out the tank. I overused the MMO in the gas to lubricates the top end of the engine( I even used 2cyl oil few times), I would be suprised if it were engine damage, it runs too good, no noises, idles perfect. I have not driven it yet, waiting for carpet and a corrected title, it only idles in the driveway.

Al

 

[c9zx]

Sorry I missed the part where you tried MMO in the cylinders and you already know about using it in the tank. As to the oil I'd use oil formulated for old flat tappet cams instead of using additives that may not be compatible with the additive package in the oil. Here is a link for some oils to consider. https://www.corvetteforum.com/forums/c3-tech-performance/2484100-list-of-flat-tappet-oils.html

I use Amsoil Z-Rod, Driven (Joe Gibbs), and Maxima. Expensive oil is very cheap insurance.  Chuck

 

[waterlife]

Normally I use basic SAE 30, I had the 20/50 on the shelf

 

[c9zx]

I'm not too concerned about the the viscosity rating of the oil being used. I'm concerned about the anti-wear package in the oil being used. The newer oil formulations do not have sufficient levels of ZDDP to prevent cam and lifter wear. http://www.amsoil.com/newsstand/classic-and-vintage/articles/flat-tappet-cams-in-classic-cars/

Chuck