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LBL 10-07-2012 10:28 PM

Valve Covers
I have a 351 windsor that is rebuilt and has 150 psi compression. I have Edelbrock aluminum valve covers that don't have baffles for the PCV valve or the valve cover breather on the opposite side of the engine that is vented into the bottom of the air breather. The problem I have is I am fnding oil on top of the valve covers after I have driven the car for a while and am wondering if it would be from the lack of baffles in the valve covers or if it may be actual blow by that is pushing oil out on to the valve covers. I do have the rubber grommets in the valve covers with the rubber diaphram in them to act as a baffle but I don't know if it's enough to stop the oil. The other thing I am wondering is , if that is the problem, why do I have oil on my alternator and plug wires on the pass. side if the PCV valve is at the back of the valve cover ?

WDCreech 10-07-2012 11:38 PM

You apparently have too much pressure building in your crank case. Check to see if the PCV valve is clean and working.


LBL 10-08-2012 11:43 AM

That's kinda what I have been thinking, must be pushing some oil out the dipstick tube. It doesn't seem like too much crankcase pressure when it's sitting at idle but I guess once I start increasing the revs to drive it, it must increase the pressure. Looks like I'm pulling the motor out again and getting it bored out over the winter ...

LBL 10-08-2012 01:35 PM

Before I start pulling the engine, is there anything else I should consider other than blowby that might be creating too much crankcase pressure ?

66GMC 10-08-2012 02:55 PM


Originally Posted by LBL (Post 1597216)
Before I start pulling the engine, is there anything else I should consider other than blowby that might be creating too much crankcase pressure ?

Try doing a "wet" compression test first, and compare to the "dry" readings. That should give an indication as to how much is getting by the rings?

Definitely install the correct baffles, and inspect/replace the PCV valve (and filter, if equipped)

How about the "china wall" seal at the front of the intake?
Fords also use an o-ring to seal the distributor ... right?
Any oil leaks from the front of the engine will get blown all over the place by the fan.

LBL 10-08-2012 03:19 PM

I'll Check
Those things but what is a 'china wall' ?

66GMC 10-08-2012 03:26 PM

The "China Wall" is kind of a nickname for the ribbed portion of the engine block, front and rear, that the intake manifold seals to.
Great Wall of China

LBL 10-12-2012 09:49 PM

I did a dry compression test and the cylinders are all between 145 and 160 with most being 150. The 'o' ring is good on the distributor and I put the proper baffles in the valve covers. To do the wet compression test, do I just put a squirt or 2 of oil in each cylinder just before doing the test again ?

LBL 10-13-2012 09:28 PM

Wet Test
I found out how and did the wet test and the compression increased minimally from between 0 to 10 psi , nothing was any more than 10 psi difference. I really don't know that much about V8's but I am thinking that I don't need to pull the motor and rebore it with numbers like this . Am I correct or should I be thinking of boring it out. I haven't driven it since I changed the baffles so I can't say if that helped with the crankcase pressure or not. I'll be able to take it for a spin on Tuesday.

LBL 10-14-2012 03:04 PM

Can anyone help me out here ...Thanks

ssmonty 10-14-2012 03:23 PM

If your talking about the little sheild plate that is screwed into the cover under the PCV port on an Edlelbrock Elite valvecover, don't waste your time. I hate to say it, but its a poor design. You need some different valve covers with stock type baffles IMO.
I'm not familiar with much Ford stuff, but it sounds like your compression is ok, and a little blowby is normal.
As far as the oil on the wires, it could be from a bad valve cover gasket.
Just out of curiosity, where is the pcv vacuum side connected, and are you sure its the correct one for the set-up you have. Does it rattle easily when you shake it up & down?

LBL 10-14-2012 04:03 PM

the PCV valve is new and does rattle when I shake it so I beleive it's okay. I have the hose from it running to the front port of my carb ( Edelbrock). I also have the breather on the opposite valve cover vented into the bottom of the air breather. I am thinking that I am getting some oil pushed out the dipstick tube, but nothing shows up when it's idling , only after I've driven it for a while. Thanks for the reply.

66GMC 10-14-2012 04:20 PM

IMO, 10 psi signifies fairly significant wear, and is probably enough leakage to create positive pressure in the crankcase.

The baffles will likely help a lot. Like SSMonty said, check the PCV valve and make sure that the entire PCV system is set up correctly.

You need filtered air going in on one side of the engine and a PCV valve connected to manifold vacuum (quite often from a carb spacer plate on a Ford)

ssmonty 10-14-2012 04:38 PM

I know it somewhat dangerous, but after the engine is hot you might try chocking the wheels, have someone in the car that can hold the brake HARD while its in drive, and giving it a little throttle. Just for a look see. If dipstick is blowing out, remove the pcv temporaraly and try again. If it doesn't blow out you'll know the pcv set-up may be wrong, or just way too much blowby. Never tried it, but it might point you in the right direction?
If what I saw in your last picture of your engine is what your using now, IMO I would try a different PCV/breather set-up with a regular PCV valve with a larger diameter hose. If you don't have room for the spacer that 66GMC suggested, might try temporaraly using a vacuum port on the manifold(same as brake booster), but don't leave it on the same port as the booster for long, just for troubleshooting.
The pcv should be on the carb circuit for proper A/F ratio.IMO

LBL 10-18-2012 10:55 PM

Seems good
I put the valve covers back on with the baffles in them and replaced the generic PCV valve with one for the 351 Windsor and took the car for a ride on the highway and it seems like it's okay. There is no oil on the valve covers so I am thinking that it will be good. I am putting the car away for winter now but am optomistic that it will be good when I get it out in spring. Thanks for the advice.

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