THIS IS A COMPLETELY RBLT FRESH 396 THAT WAS BORED,NEW RINGS (I BELIVE SPEED PRO),SPEED PRO FORGED PISTONS,heads completely rblt as was complete motor for $4k by a reputable shop thats been in buisness for 35+ yrs.

Motor runs & sounds great but i did notice when i would rev it up to approx 3k-3500 and let it would smoke some with only 1 hr on the motor. My machinest told me the rings were made of very hard material and that they take some time to breakin.

Again the car idles and run great on the road and i dont suspect any problems with the stock cast intake, gaskets,etc. Heads were completely rblt as was complete motor and the gasket surafaces were clean and straight on the intake/heads. The machinest said he only had to remove a very small amount (1/2 the material he would normally remove on a block this age 1969) of material on the block/heads to get them flat that thyat the felpro gaskets were thich enough and of good quality to have no problem sealing which seems to be the case,there are no signs the gaskets are a problems.

I checked down the carb and saw oil in the intake so i removed the carb to clean out he oil from the intake as best i could. The stock intake has ribs in it that were partially filled with the motor oil on both the upper and lower planes of the intake. I noticed that the thin metal heat shield under the carb had oil on it too as i was removing the carb which i think came from the pcv that attaches the the lower front of the stock Q-JET.

Since i only have approx 50 miles on the motor so far could there be enough oil still getting by the rings in the form of blowby through the pcv to get into my intake?
I am running stock chrome valve covers so there are baffles for the pcv and there is no oil going directly into the pcv system.
I also plugged the pcv and ran the motor and there was still some oil getting into the intake which is why i thought the next item i will list below could be playing a role in this problem too.

Also,since i am running a perf cam (222/226 @ .05,.525/.525 lift & 112 deg L/C) there is enough duration (according to the spec sheet) that the intake valve opens just before the pistons hit TDC so could some oil be pushed/forced up from the cylinders into the intake durring this reversion time adding to the oil blowby mist/smoke already being pulled in from the pcv?
The blowby is not what i would consider horrible but it's definately there and the motor only has cam break in time and 50 miles on it so far.

Again ,the motor runs/sound great with good oil pressure and feels strong on my fisrt outing of approx 50 miles where the smoke did clear up just a tiny bit after that ride. Could the oil in the intake be caused from just the senario i mentioned above with the pvc pulling in oil mist/gases into the intake along with oil reversion into the intake all due to the rings not broken in yet.?

How many miles would be normal for these hard material rings to break in before i bother to do a cylinder leakdown test? The machinest made it a point to tell me sevral times these rings are a very hard material and atke their time breaking in but are very durable and resistant to detination if you accidetially get some which is why he uses them on mst bb chevy rblds.

Thanks for your help.... Scott

If oil is in the plenum area of your intake, it must be getting there through the carb. It almost HAS to be related to the PCV. Are you sure it's the right PCV valve? Do you have a breather on the other valve cover for the system to pull through?

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Mike Newby

69 Chevelle 355/TH200-4R
97 Grand Prix GTP
64 Chevy C10 Pickup
79 Suzuki GS550

Mike's right. It's a problem with the PCV system, and hopefully not a blowby problem. Follow his advice about the correct valve and inlet filter.

MIKE,THANKS FOR THE REPLY.

Yes i do have a breather on the other valve cover and the pcv is a GM service replacement for my 396 which looks,fits,and seem to act corect.

Just like you said I also think the oil in the plenum area of the intake has to be coming from the pcv and or a combination of the pcv and the intake reversion my longer duration cam has when the intake valves open a little before the pistons hit TDC. This could push oil back up into the intake if the rings are not seated yet which i hope will happen in the next few hundred miles. I dont want to even think about if the rings were not going to seat at all which would be a real scary thought. I dont even want to go there after all the hard work and 4k i have put into this project.
I have owned the car for 23 yrs now and it's very solid 2 if not between 2 and almost 1 class show car. In 23 yrs it's had 1 paint job and i just rblt the motor for the 1st time,all the exterior body trim,chrome etc is original along with the interior,wheels,motor,rear,trany,starter,alt,water pump,brake system. I did rbld the suspection last yr (springs were weak),had it panted the original dusk blue,and this yr i rblt the motor,but for the prior 21+ yrs i just drove it on nice weekends only for local shows and it's been garaged for all the yrs i have owned it. I bought it from the original owners daughter back in 1978 and i recently found 1/2 of the build sheet under the back seat with the place of purchess,motor,trani,and special oreder 12 bolt rear info (3:07 economy gear yuk).

Back to motor talk,have ever heard of motors with fairly long duration pushing oil up into the intake until the rings seat due to intake reversion ?

Also,would you have any idea how long/miles it should take for these rings(speedpro)with upper comp moly faced ring & chrome for the oil rings to seat? I only have cam breakin time and 45-50 road miles on the motor thus far.

Thanks....Scott

Give your mill a little time. If you've got high cylinder pressure from a high compression ratio that will excacerbate the problem. Get some break-in miles on that engine. When it gets up to operating tempurature ONLY THEN will your rings begin to seat. Cycle through numerous acceleration / coast cycles. This forces the rings against the walls under acceleration; the coasting part will help quench it and draw oil onto the walls to help prevent galling (galling is bad as it will actually tear tiny chunks off the cylinder walls). It is also best to begin seating the rings soon as you can because if you just drive it easy and at a constant speed, the rings will just sort of scuff along and potentially put vertical grooves in your walls, and that will adversely affect your oil consumption and cylinder sealing.
Some rings take thousands of miles to break-in (not the kind they use on production engines). Talk to your builder and press them for specifics on how long they expect it to take. I am also assuming that blowby is higher during the time that your rings aren't seated; combine that with possible PCV issues and you have the makings of the oil control problems you are experiencing. No, I am not an engine builder so take it where it comes from. I don't want to be an alarmist. I know it sounds theoretical but I broke in my little twin can 4 cylinder that way and it still doesn't use oil at 350,000 kms. (about 218k miles) and I do scream it sometimes (it was made to, plus it's not like I have a choice with only 100 lbs./ft. @4800 rpm!)

Scott,
The Speed-Pro rings should be broken in within a few minutes, especially if you can drive the car and put a slight load on the engine. Either way, there should not be that much oil in the cylinders that "reversion" would pull it into the intake.
I have seen intake manifolds crack. That would be the first thing I would be looking into. Sounds like you are using a stock cast iron manifold and I have seen at least three of them cracked bad enough to suck oil.
I am betting on that, or the pcv system. Just because you cannot see any oil in the hose, does not mean its not getting sucked in there. Make certain you are using the correct AC DELCO pcv valve. I have seen aftermarket ones cause oil problems.
Hope this helps, let us know what ends up fixing it !

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

This is just a little different thought, is your car an automatic. The modulator valve might be leaking a little and letting fluid get passed it and it's getting sucked into the motor. I know that trans fluid is red and oil is light brown when everything is clean but..... it's a thought.

I think BillK's suggestion of a cracked intake is interesting. A few weeks ago, someone posted a picture here in one of the forums showing a factory low-riser cast iron intake for a big block, and sure enough, it was cracked right in the plenum area. Apparently, this is fairly common.

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Mike Newby

69 Chevelle 355/TH200-4R
97 Grand Prix GTP
64 Chevy C10 Pickup
79 Suzuki GS550

Billk (and others),thanks for your feedback thus far. I will recap below what iv'e done and what i think i need to do next so please feel free to add to it or tell me if i am straying off target with my oil in the intake problem,it's much appreciated.

* The pcv valve is the correct GM part which is connected to the lower front of the stock q-jet on the stock cast iron intake.

* I am running the stock chrome GM valve covers with baffles for pcv and breather on the opposite side of motor valve cover.

Note: I had to use 2 gaskets under the valvecovers for more neight to clear the comp roller tipped magnum rockers becasue they would not clear the v/covers as the comp people said they would when i called them. I checked and raising the v/covers a tad where the pcv is did not seen to bring it close to where more oil would be avaialble to be sucked in from the rockers etc. There is no oil film or dripping oil at all in the baffle where the pcv goes.
I did find a liitle oil on the carb gasket mostly starting from the halfway point between the primaries & secondaries and then to the rear of the carb,not hardly any was on the area from the 1/2 way point forward to the primaries. I would have thought that if the pcv was the problem the front portion of the carb gasket that's positioned by the pcv inlet to the carb wouild have been soaked with oil but it wasn't which may be a good indicator that the pcv is not the issue.

* I cleaned the intake as best i could with the carb off and then reinstalled the carb,plugged the pcv and then ran the motor to see if the oil would re-appear which it did.

* The car is running very good,smooth etc so I dont feel it's gasket related esp since the oil is in the plenum area above the gaskets which limits it's point of origin.

* The motor was bored .030 over from stock with speedpro forged pistons and rings by a reputable machinest thats been in the area for many so i doubt it's a rings not seating issue. The motor has some blowby when hot but it does not look excessive for the short amount of time (cam breakin 30 mins/miles are 45-50) the motor has on it.

CONCLUSION: It seems like there are only 3 possibilities,a cracked intake,leaking gaskes,or pcv is sucking in oil. Aagain, i blocked off the pcv,cleaned the oil out of the intake,ran the motor and the oil returned into the plenum,a little less but it was still there. I may have run the motor a little less time for the test which could account for less oil in the intake after the test.

It seems to me the only choice i have at this point is to replace the intake to see if this eliminates this problem once and for all,what do you think? Am i jumping too quick to correct this problem or do you think i am justified in replacing the intake at this point?

pls get back to me.

Thanks a lot.....Scott

Scott,
Your machine shop should be able to magnaflux the intake to see if it is cracked. If you remove it, take the heat shield off the bottom, the cracks that we have seen were easily visible by eye.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

WHOA

Don't remove the intake manifold quite yet.

If the intake manifold is cracked along the bottom (Heat crossover)(and yes this is common), this will NOT allow oil into the plenum. It will only allow oil into the heat crossover, which is NOT connected to the intake runners. A crack in the underside of the intake manifold that would allow oil to get into the intake runners would be very very rare and highly unlikely. I've never seen one do this.

I'm sure BillK wasn't thinking when he mentioned taking the shield off the bottom of the intake manifold. An original 1969 396 intake manifold does not have one !

After reading all of the posts here, I'm leaning towards a different scenario.
(Of course this is ignoring the usual obvious PCV sucking oil because the valve cover baffle/s are not there or not sufficient.)

1. Did the machine shop surface the block ?
2. Did the machine shop surface the heads ?
3. Are you using the rubber end rail gaskets supplied in the gasket set for the intake manifold ?
If so, the combination of decking the block and milling the head surfaces brings the intake manifold closer to the block.
Two problems can arise from all this resurfacing.
1. The angles may have changed, which makes it difficult to seal the intake to the heads.
2. The rubber end rail strips may be holding the intake manifold up too high, thus not allowing the head-to-intake gaskets to seal. This would allow oil to be sucked into the intake.
If the heads and/or block were surfaced, then you should not be using the end rail gaskets supplied in the gasket set. You should be putting a bead of black RTV along the rail.
Now here's a trick.....when using the RTV on the end rails, set the intake manifold down onto the heads/bock and just start all the bolts. DO NOT tighten them. Wait 1-2 days. This allows the RTV to take a set. Then you will tighten and torque the manifold bolts. This gives the RTV some crush ! A "squish" factor, if you will.
Otherwise if you tighten the intake right away, you'll just push the RTV out either side.
IF you decide to remove the intake manifold, go about it slowly and look for signs of intake-to-head gasket leaks. Sealing around the ports should be obvious and dry.
You should also run a flat file along the intake manifold-to-head sealing surfaces to make sure there are no "high spots" from being handled roughly. One good dink and it sits too high !

Lastly, I have known some engine builders to use 3 different RTV sealers for the intake manifold. Blue RTV for water and intake ports, black RTV for the end rails, and red RTV(high temp) for the heat crossover.

Keep us posted and let us know what you find.

I used the same rings on my 396 rebuild 25,000+ miles ago and I don't think the rings really seated for several thousand miles. I'd say 6-8,000. But my bores were not fresh either. They had about 50,000 since the previous rebuild. I just did a ring and bearing freshen up.

I agree with everything CAM said too. He's right on the money.


Nate


[This message has been edited by SS3964N8 (edited 09-02-2002).]

I have run into basically what SS3964N8 discussed, but want to add a couple of points.

First, when you pull the intake be as careful as possible to not damage the existing intake gaskets. You will want to take a look at them and see if you are getting any crush on them. The crush will clearly show up on the gasket and will indicate whether there is a spot that might be leaking (intake vacuum sucking in oil splashed up by the lifters.) Problems are likely to be right at the base of the gasket.

Second, a good FelPro embossed gasket should not need any sealer to work. BUT it is also important to be sure the gasket stays in place when setting the intake down on it. What I tend to do is to put a thin bead of weatherstrip adhesive around the bottom of the gasket around the water ports, then lay the gasket down on the heads and pushing the gasket down on the head around the water ports to get a good seal. You will need to go back periodically to realign the gasket while the adhesive seals (about half an hour). When the gasket no longer moves while pushing on it you can be assured it will not move when you put the intake down. Of course it take a little extra effort to clean up the weatherstrip adhesive the next time you want to replace the gasket, but I know a lot of racers do this also and do not even bother to replace the gasket between intake changes. (Personally I do not like to take the chance with a used gasket, but I do not pull the intake very often either.)

Finally, NEVER use the rubber end seals. I always use the Black GE silicone and have never had problems. FelPro should dump the rubber seals and include a little tube of silicone...

SWHEATON,
Something I just thought of.
If you have a gross leak at the intake manifold, but it is from the inside, you can try this test. Of course this may only be effective with a "gap" between the intake and the heads. (bad angle mill job ???)
With the engine idling, hold your hands over the carb and try to choke off all the air coming in through the carb. If you can completely choke off the air supply from the top, or get real close, then it's likely the engine is getting air into the intake runners through the crankcase. This would explain the oil in the intake.

JackV...I agree with all you said. Good points !

Nate

another way to check that is plug your vac hose to pcv valve,then plug the 2 valve cover grommets with your fingers,you should build a small amount of crankcase pressure(enough to feel it puff out if you remove your finger) but if you got vaccum in the valve cover,you got an intake leak

<BLOCKQUOTE>quote:</font><HR>Originally posted by SS3964N8:
SWHEATON,
Something I just thought of.
If you have a gross leak at the intake manifold, but it is from the inside, you can try this test. Of course this may only be effective with a "gap" between the intake and the heads. (bad angle mill job ???)
With the engine idling, hold your hands over the carb and try to choke off all the air coming in through the carb. If you can completely choke off the air supply from the top, or get real close, then it's likely the engine is getting air into the intake runners through the crankcase. This would explain the oil in the intake.

JackV...I agree with all you said. Good points !

Nate

<HR></BLOCKQUOTE>



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1968 Chevelle Conv.
383 cu.in. 4spd

You did check what jayman29 said, I have had a vacuum modulator leak and suck ATF into engine. Todays ATF can look like motor oil.

Hello guy's,I have some followup on my oil in the intake problem.

I did all the above mentioned tests and they all came up neg for a vacuum leak. I have had the car out on the road and it runs great just like it did when i first started the fresh motor but the smoking has calmed down considerably in the few 150 miles i have diven it. I stopped by the machine shop and the machinest said the motor sounds great and he said since all tests i did came up neg for a vac leak that he feels the long duration cam allowed some oil to be pushed back up into the intake due to reversion just as i suspected from the begining.(I hope he is right) He said this was becasue the rings he got me have a very hard surface that is more durable to ward off cracking due to detination but they take longer to break in and do let some oil by esp in the first 500-1000 miles on the road and can take 2-4k miles to fully seat. So I will keep my fingers crossed that the rings will seat fine and my problem will go by by.

Thanks for all your suggestions/help.

Scott