Firstly, let me say that I seldom post a thread, but I do extensively read on this site and have gained great information over the many years. Thanks everyone!
Now, subject at hand....I am very frustrated and pissed. I'm having an oil issue with a 383 to 451 build. Only 300 miles on this engine and its using a quart of oil on the last 100 miles driven. Oil loss is progressing with usage. Plugs looked great first 100+ miles. Plugs are now oil fouled. I have the blue smoke puff when first cranked after sitting several days, but goes away relatively quickly. I did a cylinder pressure check and all is good, mostly 192 to 198 (#8 had 212). #6 and #8 seem to have the heaviest oil fouling, but all except #2 have enough to be of concern. Heads are Edelbrock RPM 84cc, came assembled. Running XE274H and Comp Cam roller tip rocker assembles. I foresee having to change out all the valve stem seals in the near future. However, I did read a post (somewhere on the net) that said Edelbrock heads tend to pass oil initially until they "fully break in". Is this wishful thinking on my part? I'm putting in new plugs and will be monitoring more, but is there a chance this is going to clear up, and if so...how many more miles? Anyone been down this road? I'm sure these heads came with the 9725 positive-stop seals. I understand Edelbrock also has 9758 umbrella seals for the RPM head. Are the 9758 seals better at controlling valve seal leaks?

Also, something I have never seen before, looking at the spark plug tip on the majority of 8 plugs, one side is clean (though wet) and the other side is black/gunked up. really weird.

Looking forward to your comments.

Scott

Make sure you are getting a good seal between the intake and the heads. Sometimes they will suck oil there. Any oil on the valley pan?

I can't think of an issue that causes oil to leak into the combustion chamber from the heads that will stop once it "breaks in".

Bad seals won't start sealing and if it's excessive guide clearance, I suppose it could coke up enough to stabilize, but I doubt it.

Based on your comments regarding #8 cylinder fouling badly and has the highest compression reading I gotta wonder how carboned up the combustion chamber is.

If you do pull the old seals inspect them carefully for evidence of failure and check the valve to guide clearance, just see how much the valve stem wiggles ought to be enough.

Sometimes I've used no oil seals at all, I would double check the intake. Can you take the carb off and see in the ports?

I have never seen a problem with the seals that come on RPM heads....... for any brand of engine.
And I’ve sold and prepped piles of them.

Never say never, but that would be way way down on my list or probable causes for excessive oil use.

However, as has been mentioned, sucking oil between the valley pan gasket and the head is pretty common.
That’s where I’d look.
An inspection camera/bore scope should point you in the right direction.

bet it's an intake leak.

Yep. Likely intake leak.

If an adjacent pair of cylinders appear worse, like #6 & #8 , this is another indication it's the intake seal.

Great suggestion

Thanks, guys! Fast 68, appreciate the confidence in the Edelbrock heads. I have access to a borescope, and will pop the carb off this weekend to peek inside. Have the RPM dual plane. If oil is pooled on the valve back, it could be from either the valve seal or the intake seal, right? So, I guess if oil is coming from the intake I would expect to see oil at the intake/head runner interface?

If leaking, would you put a gasket between the valley pan and intake, or only use sealant between surfaces.

Had 0.012" taken off block deck surface. Rebuilt this block back in the 80's, but can't remember if the deck with milled then.

No oil pooled on the valley pan.

Went thru this on my 383/432 the past three summers since I rebuilt it

Edelbrock 75cc E Street Heads

Confirmation of intake gaskets or valley pan , was oil on spark plug gaskets or washers , and on wide open throttle and then letting off the gas pedal instant , blue smoke out tail pipes on highest engine vacuum

Pulling the carb and then intake it was obvious

No gaskets - Gaskets on head side - Gaskets on both sides of tin valley pan - What type of sealant if any - Used versus new intake manifolds and alignment variations - Block decking - Blah Blah Blah - Highly debated in thousands of threads


Had my block decking or surface cleaned up only just like yours

Had intake manifold off twice



All fixed to perfection this past spring , and honestly was pretty easy once I measured and dry fitted the intake manifold , then finding a better gasket then those supplied with the Fel Pro tin valley pan

No sealant on intake ports

Not one quart of oil this whole year so far

Yes, bee1971. There was oil at the plug washers on almost all plugs when removed, some much heavier than others. Can't comment about smoke when letting off......haven't noticed it, but I haven't really dropped the hammer yet.
Can you walk me through how to measure the intake fit and is the fix then to face mill the intake surface? Heads are usually face milled for this, right? But I don't want to yank the heads off if I can get it sealed otherwise.

Yikes , thats a lot of oil , holy smokes , no pun

You shouldn’t have to cut the intake manifold if your block and heads where not cut

Did you use any gaskets with your tin valley pan , or install dry only ?



First with that RPM intake - Did you dry fit it on the heads with no tin valley pan in place and make sure it’s sitting completely flush with head surfaces

That’s where I measure with alignment of bolt holes , use your thinnest feeler gauge on the top and bottom of intake in all four corners using different spots between the intake mating surface and heads to see if any areas the feeler gauge will slide in - It shouldn’t - I had a .008 and .006 feeler gauge



Then resting dry on top with the tin valley pan and hold down bars in place , make sure the intake isn’t resting or hitting the corners of the hold down bars

A lot of guys had fitment issues with the intake manifold hitting on the corners of the valley pan hold down bars and had to grind the corners of the intake manifold

Start there first

Yeah, and that one is actually a rather clean one!! The engine builder put the intake on, so I can't say for certain if he used any sealer....no other gasket though. You mentioned a "better" valley pan tin....where did you get it, part #??
Thanks for the tips on measuring. The block was milled a small amount. I doubt the heads were cut on. Engine shop didn't mention it. The engine is sealed externally really well...to my surprise....no oil leaks on the valve covers, valley pan outside, front or back of engine.

So, you had the same problem....what exactly was the "fix" in your case? Just extremely careful alignment and a better valley tin?

to think edelbrock intakes always fit is folly. of the seven i've had four required machine work; and i mean required! anything from wrong angles, being too wide, to the mounting flanges being tapered. i used to think this was only a mopar edelbrock problem but i've found these problems to be true on chevy's also. i take nothing for granted anymore. look at everything! when it comes to aftermarket parts i've become the eternal skeptic.

How are your valve covers set up with the PCV unit? If you are running one without any baffling, thats a big source of vacuum to pull oil through. On some aftermarket covers, the valve is right over a rocker arm. Need to be diligent on the baffling, even on cast covers. The cast covers sometimes provide a baffle plate but it can be improved upon. Stamped steel or aluminum a/m units generally have no baffling. I found that out on my Duster when I put chrome Moroso covers on years ago. No baffling and the valve was right over a rocker.

On the tin pans I always glue paper gaskets on each side. (x4)

I had to do the same with my old TM-6 single plane.

Good point about the PCV valve and no baffles.
That situation can result in some serious oil consumption.

As wet as those plugs are...... that’s not a seal issue.
They wouldn’t be that wet even if no seals were used.