Jus got finished rebuild on my 1980 Delta 88 350 motor. Ended up boring it out .30, .475/.480 lift cam, roller rockers, etc. Problem i’m having is excessive blowby smoke out the valve covers. I did overfill the motor hy about 2-2 1/2 quarts, so I emptied and refilled it, and all other fluid levels are correct. Any possible ideas as to whats going on? Took a few carbs to actually get it to idle and run, but haven’t been able to drive it due to it shutting down once in gear. (Assuming vacuum leak SOMEWHERE) attempted to attach a video, doing this from mobile so excuse me if it’s all wonky


edit: i’ll just post a link to the video, i dont think it uploaded.

https://m.imgur.com/gallery/K58F0be

 

Your two issues may be related, as in there may be an intake manifold leak that's sucking oil into an intake runner.

 

Wow, that is bad, never seen one with that bad of blow by. Did they forget the oil rings😳. Yeah, I would look at resealing the intake and look over the carb and spray it down for vacuum leaks as well.

 

If there was a vacuum leak under the intake there wouldn’t be that much blow by coming out of the breather. You have a serious problem with your rings not seating or the ring gap is too large or some of them were cracked during install. You are going to have to pull the motor back out and do some exploratory surgery.

 

Do you mean that you actually swapped carburetors instead of tuning one with a vacuum gauge and tachometer? Did you set your timing with a timing light?

 

No, I put the oil rings in. Staggered my rings as they should’ve been.

 

The one thing I figured but was hoping wasnt the case. Gonna head back to the shop Friday for compression test and come to a decision. Preciate the input

 

My buddy wanted to go with a Quad, and I wanted the Holley. Rebuilt a Holley for it, and put it on for the sake of getting in running and the rings seated. Didnt tune it with a vacuum gauge, but the timing was set by light. Plan on going and looking back into Timing Friday.

 

Got around to doing a compression test on it today. Bear in mind the heads are off a 72 Olds 350, these were the results. Did an oil change and blowby is still super excessive. Any ideas ?

 

How long have you run this engine? You could try a road test performing hard accels and long decels to try to get the rings to seat. It couldn't hurt at this point.
excessive blow by is from combustion pressure getting past the rings and into the crankcase. So go for it. Assuming you have good oil pressure what do you have to lose.

 

How long have you run this engine? You could try a road test performing hard accels and long decels to try to get the rings to seat. It couldn't hurt at this point.
excessive blow by is from combustion pressure getting past the rings and into the crankcase. So go for it. Assuming you have good oil pressure what do you have to lose.

 

been running it the past 3 weeks. Changed the oil last week, and did compression test today. Oddest thing is now my Engine light will illuminate every now and then. No knocks, piston slap, or odd/concerning engine noise; just heavy blow by. Also noticed every 3-4 days, it will be about a quart or two low. ....then again, at the crankcase breather there IS a ton of oil all over it, as well as being pushed out of that grommet. Every time I remove it, theres just a ton of oil.

my valve covers are the aftermarket Mr. Gaskets, part #9822 which i didnt realize weren’t baffled. I found the 9805 and have been wondering if those would work, only downside being they’re 4 bolts instead of ten or my original, 5 per side.

i’m at a loss for whats going on, but i’m going to continue to monitor and drive it. Like everyone else has said, I’m thinking my rings are my problem. Are there any other tests I can run to possibly diag anything else I may be missing? I appreciate the help all.

 

...also, intake leak has now gone away. No leaks currently present, lol.

 

What engine light? You mean the oil pressure idiot light?

 

Where is the smoke coming from on the passenger side? I don't see a breather on that valve cover.

 

I would definitely stick with a 10 bolt valve cover with a baffle. the compression numbers seem to vary quite a bit for a rebuilt motor . were the heads redone when the motor was built?did you do a leak down test ?

 

I’ve been trying with very little luck in the 10 bolt baffled area, but the heads were worked (to my knowledge). At this point, I’m thinking stuck valves...but no leakdown test yet.

 

its mostly out of the driver’s side breather. On the passenger side, if I pull the pcv smoke will come out that grommet, but not as heavy as the driver’s side of the motor.

 

...no, I on the same instrument cluster where my lights are, there is an Engine light. That is the light that illuminates. Right next to my GEN light.