knockbill

if it was assembled by the machine shop, and is warranted, i would expect them to make it right...

Dan Hampton

In the final analysis, my bet is that the problem lies with the piston rings--either wrong ones, type, or improper installation. Just my guess.

BTW, what is the advertised compression ratio of this engine?

65tripleblack

In any case, too much pressure in the crankcase, or not, the rear main seal inner lip is supposed to respond to pressure by pressing against the crank even tighter for a stronger seal.................the more pressure, the tighter the seal.

As far as the pan bolts go, the holes are blind on a Chevy block. Are they not blind on a World block?

Comp Cam 1

9.5 to 1

66BlkBB

I had a friend with a 64 Impala 327 that had the same problem. He was getting blow by just like you and couldn't figure out where it was coming from. He installed PCV system and still couldn't get it to stop. He pulled the engine down and we found that the rings were misaligned. The gaps were basically all lined up on the pistons and allowed the pressure to go into the pan area. Once he corrected the ring gap spacing the engine had no blow by at all. Not saying this is your problem but I (like the others) would look at a leak down test first to see if the rings are allowing the compression to escape into the pan area.

vettsplit 63

Just out of curiousity, what weight oil are you using? The reason I ask is that I remember reading in Car Craft I think, that Quaker State had been doing some testing and some of the thinner oils were actually vaporizing as they reached the top ring land on the pistons and causing a massive blow by condition. Another thing to consider- have you had any instances of a water leak of any consequence into the oil system? That can certainly cause a blow by condition.

But all those who have recommended doing a leak down test are right on target. Once you determine where the leakage is you can correct it.

paulywannafly

Well I guess a leak down test is in order , Just will confirm what we already know whatever it is the motor will have to come out . It can not be fixed in the car .

vetrod62

[QUOTE=65tripleblack;1580455763]In any case, too much pressure in the crankcase, or not, the rear main seal inner lip is supposed to respond to pressure by pressing against the crank even tighter for a stronger seal.................the more pressure, the tighter the seal.

As far as the pan bolts go, the holes are blind on a Chevy block. Are they not blind on a World block?[/QUOTE]

I would think so, but I have a 434 sbc World/Motown engine from a fellow racer I have re-worked , because as a crate engine, it was a POS. Not built by World. That engine leaked lots of oil from each pan bolt hole located third from the rear along with many other problems.

World/Motown has had a very bad reputation in the past for bad parts, engines and correcting customer problems.

A leak down test is easy to do and will tell you if it is one cylinder or many.

You should find a well known circle track engine builder and have them go through the engine. Not cheap and get it fixed correctly.

Every crate engine I have witnessed, has been a POS. I guess they figure, if you cannot build your own, You will not know the difference between a 500HP claimed engine and one that actually makes 350HP.

I am sure that there are some quality crate builders out there, But how do you tell?? I would only buy a GM or Dart crate engine, If I did not build my own engines.

Westlotorn

If this is a full round late model seal pressure pushes them right out of the block.

MikeM

A stock production PCV system should maintain 1-2" of vacuum on the crankcase. No positive pressure.

The OP won't have any negative pressure as he is running an open vent in the valve cover. This isn't what's causing the problem though.

65tripleblack

Nope. Read posts 4 and 5.

Of course the crankcase should have (mostly) negative pressure with a functioning PCV system under most, but not all conditions. Positive pressure results during backfire, and near zero vacuum results initially during WOT.

The talk has been about a pressurized crankcase and I responded to a worst case scenario.

Yes, the OP certainly seems to have problems, and they will be found with the leak down test.

OP says he sees no oil in the exhaust. If he's not using/losing oil either, then it could very well be exhaust gases getting into the crankcase via a cracked head or leaky head gasket. Could be a crack at the exhaust seat(s).

Jamis

Like a few guys have sugested a leak down test would be the best way to go. 10% or less is want you want to see. You may find one worse then another and that could be your problem cyl. Commen problems are incorrrect ring for application, wrong cyl wall finish or compression ring installed upside down (this wont show on leak down test but it will cause blow by when running). No matter what you find you will probebly have to tear it down to fix.
How many miles you have on the motor?

MikeM

I don't know what you mean by "nope" In the first place, the OP doesn't have a PCV system, he has a CV system and he'll NEVER see negative pressure with that setup.

The rear main seal lips seal from OIL pressure pushing the lip seal against the crankshaft. NOT crankcase pressure!

65tripleblack

Read post #5.
Paulywannafly says he installed a PCV system, not old fashioned vent system.

The rear seal lip is supposed to seal with oil pressure. Any (unwelcome and abnormal) positive crankcase pressure would serve to aid the lip in sealing, not hinder it. Again........only responding to a possible worst case scenario.

All moot now. It seems that the OP will abandon this engine and install a truck motor.

paulywannafly

Well Mike just would you do to stop this motor from pushing oil out of every possible place including oil pan bolts? they are not blind holes bty tried pipe dope teflon and you name it , I have installed a one piece pan gasket still leaks and as someone else said I have a functioning pcv system just like a modern car so in your expert opinion just what would you do? Oh and dont bother calling Motown they recommended a rear main seal that was wrong for this engine it was undersized and leaked like a stuck pig my own engine builder got me one that didnt leak as bad . I have been playing with chevy small blocks for thirty years and was never unable to plug a sieve like this thing

Westlotorn

I have yet to see if you actually have pressure in the crankcase, any chance you did verify this is the cause?
I have seen sealing problems with pan gaskets that turned out to be pan bolts a couple threads too long that bottomed before torquing. These issues seem very simple once identified but hard to find. All 400 small blocks I have seen are 2 piece rear main seals, is that the case on this World block? Fel Pro does make an oversize 400 SBC rear main seal.
Did World include oil drainback holes large enough to allow this block to vent?
I can't imagine that this engine can't be salvaged.

NOM61

If you are going to pull this engine anyway to swap it with a crate motor, why not just pull it now and tear it down BEFORE you spend another big chunk on a crate engine? If the problem is something simple like aligned ring gaps (which gets my vote as the most likely on a new build with this much blowby), you'd hate yourself for throwing that money away! If you do the tear down and the source of the problem isn't glaringly obvious, then you'll feel somewhat better about spending that crate money. Its only a few hours extra labor after all you've already gone through.

DT

MiguelsC2

The diagnosis needs to be made regardless. Even if money was no object. I would HAVE to know why?

A crate motor may have issues of it's own.

MikeM

By the time I opened this thread, someone had already suggested doing a leakdown test. No sense being an echo box.

Your quote:
"Yes he does I installed it PCV on one VC and a breather on other".

A "modern" PCV system uses manifold vacuum on one side of the crankcase and air inlet flow on the other along with a sealed crankcase. This setup creates a small vacuum (negative pressure) in the crankcase and is called a closed system.

The fact that you have an open breather on one valve cover means you will never draw a vacuum on the crankcase as your system is open. You have just a plain old crankcase vent no more effective than a road draft tube.

If you're really getting that much blowby past the rings that it pushes oil out the pan gaskets and past the rear main seal, that should be readily obvious by simply pulling the breather cap off and look for puffs of oil vapor (indicating 1 or a few cylinders) or a steady stream of vapor indicating all the cylinders are blowing by.

If you don't see the vapor coming out of the breather hole in the valve cover, try laying a flat piece of paper over the breather hole and see if your pcv vavle will pull the paper against the valve cover which would indicate little or no blowby. You have to have a sealed crankcase, including the dipstick for this to work.

I would do this last bit before I went to the trouble of doing a leakdown test because it's quick and easy.

Are you pushing oil out the valve cover gaskets or just on the lower end? Without seeing the engine, that's all I can come up with.

paulywannafly

Mike you mentioned other leaks as well . Yes it has spit the bead of silicone out of the galley and intake once , VC gaskets and even the timing cover . My friend Mark the owner has had problems with this motor from the day it was installed 5 years ago I am the second guy who has been working on it . The first guy who installed it gave up on it long ago. Mark is a guy who will not tolerate bs very long he has the means to toss this motor with no regrets although I agree this motor can be fixed just not in the car