327 Oil Blow By

[Sicboy]

I just rebuilt the 327 in my '66 C10. Includes a .262 Comp Cam, 462 heads, Edelbrock Performer intake and carb, Speedway Tru-Ram manifolds with 2-1/2" exhaust. I chose to stay with the stock "road draft" crankcase vent system. I did an oil change at 100 miles. The motor now has 300 miles on the rebuild. The motor used 1-1/2 quarts of oil in the last 200 miles. Yesterday I noticed that a hint of blue smoke was coming out of the passenger side exhaust continuosly at idle, yet nothing at throttle. I checked the crankcase vent hose after the inline pcv valve and their is a good deal of oil in the hose. So, I figured that the new pcv valve was bad and allowing blow by, so I replaced it with another new pcv valve. That didn't help. Oil is still being sucked through the tube into the carb. My only guess is, that with the increased hp and vacuum, that the oil canister at the rear of the block beneath the intake manifold that is suppose to trap oil before entering the vent hose, is not doing it's job. Is there something inline (i.e. filter) that I can add to trap the oil before getting to the pcv valve? Has anybody else run into this problem and if so, what did you do to fix it?






Video of 1st startup after rebuild...2 weeks ago.

YouTube- 1966 Chevy 327 Startup & Breakin

G

[cdowns]

cant help with the oil problem //but you might want to change out the rubber fuel line before the fire

[68gmsee]

From the looks of the oil on startup, you may have a valve guide that didn't get checked out real good or a seal that's gone bad. Look at the plugs to see if you can determine which one is acting up.

A mechanic has a trick he uses to check the vavle guides. He uses a large screwdriver to wedge against the valve spring and pushes on it to see if he sees slight movement of the valve stem.

[68gmsee]

forgot to add: since you only have just a few hundre miles on the engine and depending on the rings you used, it may take a lot longer to completetly break it in. Once the rings set it will reduce some of the blow by.

[Ticker]

This is yet another situation where a leak-down test will tell you everything you need to know.

I agree it's likely guides Modern rings seat almost immediately, so I doubt that this is going to get better with time. The exception is "el cheapo" iron rings.

That is a sweet engine; I'm sure you'll get it sorted out.

[dznucks]

where did you get the manifolds? i have ram horns but they dont look like that.

[LONGHAIR]

You may also be causing this problem yourself....
The road draft and PCV valve are different concepts.
The PCV system is intended to create a slight vacuum inside the block with at least one vented valve cover to allow some air-flow.
The road draft system works essentially by siphon, or at bare minimum it is "open" to allow pressure out.

The PCV and road draft together would seem to fight with each other. The PCV would be sucking air back in through the road draft tube, rather than letting it out.

[bamabaxter]

Originally Posted by dznucks

where did you get the manifolds? i have ram horns but they dont look like that.

I'd like to know too....sorry for being a little off topic.

[Sicboy]

Originally Posted by dznucks

where did you get the manifolds? i have ram horns but they dont look like that.

They're Tru-Rams from Speedway.com.

[Sicboy]

Originally Posted by LONGHAIR

You may also be causing this problem yourself....
The road draft and PCV valve are different concepts.
The PCV system is intended to create a slight vacuum inside the block with at least one vented valve cover to allow some air-flow.
The road draft system works essentially by siphon, or at bare minimum it is "open" to allow pressure out.

The PCV and road draft together would seem to fight with each other. The PCV would be sucking air back in through the road draft tube, rather than letting it out.

Actually, the OE road draft system does include an inline ball check pcv valve. The new one did the trick...no more smoking.