I just installed Holley Sniper EFI, new aluminum intake, and headers on my 440 that has 750 miles on it. Engine fired right up, but when it gets to max temp 185-190, it starts blowing blue smoke from the exhaust. Any thoughts on what would cause this? There also appears to be oil dripping at the header collector flange. When I replaced the headers, I installed a fresh set of plugs and noticed that they had oil on them. I checked the PCV valve and it's good. I'm planning to do a compression check on all of the cylinders next but thought I'd check here the mean time.

Sounds like you have a oil ring not sealing.
How many spark plugs are oily? which ones?

Should be performing a leak down test on it.

Blue smoke from both banks or just one?

it's blowing blue smoke from both sides.

I removed all plugs and each plug shows oil.

Cylinder compression test showed 119-129 between all cylinders.

I'll do a leak down test next.

Intake manifold gasket leak.

Excessive blow bye pushing oil into the intake?

Oil on the outside or on the inside of the the plug?

on a few or all 8

118-129 on compression seem a bit low depending on your combination?

Did you have this issue before? if not I would suspect the intake/ valley pan

I would also see how much blow-by the motor is putting out when hot at idle, and when throttling it
keep us posted

oil was on the inside of the plugs, on all 8

I would remove the intake manifold and intake valley pan and then set the intake on the heads and use a set of feeler gauges to see how much clearance you have on all four corners between intake and the heads at the top and bottom of all four corners, write those clearances down and share them with us.
As already mentioned, you may have an issue with the valley and intake not sealing up tight against the heads allowing oil to be suck into the intake manifold runners from the cam valley and the intake valley pan scope:
I've had that issue more than once with both B and RB as well as 426 Hemi motors: whiney: The good news is it is fixable, and you may learn something new with this problem

BTW, fixing the oiling issue will help your motor make more POWER

Are you running a PCV system?

yes, pcv valve is connected to a port on the carb.

But your reported compression numbers still bother me.

Might also do a kwik blow by check before pulling the intake.

Did the motor have this issue before the swap?

intake gasket !

Bad Intake gasket won't cause compression to be that weak. If anything oil in the cylinders should up the compression some.

With that much oil in every cylinder, where else can it be coming from? Oil dripping from the header collector flange, that is a LOT of oil. Can't be the valve guides. Unless there was some kind of gross assembly error, can't be the oil rings with an engine that only has 750 miles on it. The OP said he checked the PCV and it is functioning, so...... Without knowing what CR and cam the engine has, those compression numbers may not be out of line. Not everyone is running 13.5:1, LOL!

When I installed the headers, I replaced the plugs and there was evidence of oil, but it didn't blow blue smoke like it does now.

I was told the motor was rebuilt to stock specs but the idle seems a bit rough for a stock cam. Another symptom is low vacuum, about 12-13 inhg at idle.

Here are some video links of it idling and a rev that shows some of the blue smoke.

Idle w/carb

Idle w/EFI

Quick Rev

Any chance the rings are installed upside down?
THe vacuum is low, but is the needle steady?

If you have 750 miles on the engine and didn't have the smoking issue to that point and you have it now AFTER you installed a new (different) intake manifold I would agree with those members that say "intake" gasket or something related to the new intake manifold. Can't see how headers would create an oil burning issue being downstream of the combustion chambers. Overly rich condition could foul (wet) the spark plugs but the exhaust would either be black or whiteish smoke not blue like oil smoke. All of the valve stem seals couldn't have gone bad at the same time and that can be checked by running it up in the RPM and quickly backing off and your rear-view mirror will let you know if they are bad. Did you just switch from a break-in oil to a full synthetic oil?

I'm still running the break-in oil.

Why?
Change it now please and let us know what that does for your motor
I change all my newly rebuilt motors oil and filter after 20 to 40 minutes running times depending on the cam and lifter types, if it has a roller cams and lifter I change the oil and filter after 30+minutes, flat tappet type cam and lifters max of 30 minutes before changing both.
I cu the filter cover, outer shell, off so I can inspect the filter element after cutting all of it off the inner canister holder so I can inspect what is in the pleats

I always heard about the 1000 mile rule and followed it.



You are almost there so changing it won't hurt.





So where is the pvc connected to after the EFI And you said the pvc valve works but what about blow by? Take off the pvc valve and see how much "blow by" comes out after you are at operating temp. If it's excessive that's what is blowing oil into the intake.

This, and I also change the oil again at 500 miles. May be overkill, but I sleep better knowing for certain what is going on inside after cutting open the filter.

If you didn't have a problem before you replaced the intake manifold, and you have a problem now, go back to the last change, the intake. I'd replace the intake gaskets/ valley pan, and check the head surfaces on your new intake to be sure they are flat and not gouged or something. Did you reuse the valley pan, or install a new valley pan? Oil fouled plugs would be expected if the intake ports are not sealed off from the valley and is sucking oil into the intake, and low intake vacuum would be expected if the intake isn't sealed to the heads. Both of which would indicate poor gasket seal.

Oil on the headers would tell me your valve cover gaskets are leaking, or the front and/or rear corners of the valley pan are leaking.

You pulled the intake, change the oil after you replace the intake/valley pan gasket, a bit of antifreeze could have gotten into the motor with the intake manifold/gasket change. Change it again in another 500 miles, just in case.

Years ago I bought a rebuilt 440 pretty cheap, it was using a quart of oil every 500 miles. I changed the intake valley pan gasket and solved that problem. It was a great motor. The guy didn't believe me.

New aftermarket valve covers allowing the PCV to suck oil (no baffles)?

Check the inside of the PCV hose. Or the port its plugged into for oil.

If you pull the intake you should see signs of oil being sucked in, but all 8 cylinders, well either you forgot intake gaskets altogether or the intake is seriously mis-machined.

My engine is no longer blowing blue smoke. I've taken it for a few drives now. It has plenty of power. I am really stumped on what the issue was.

Strange? Maybe the lower intake was leaking a sealed itself after a few heat cycles

Must have been assembly or fabrication lube some where.