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Engine blow by blowing out all my gaskets

I did the leaks own test and am getting anywhere form 18% to 23%. My engine guy says 10-15% is closer to normal. What do you guys think? The test isn't perfect since I can't warm up the engine so I am not sure how that will factor in to the equation. Thanks.
 
I would think for a custom built engine it would be a lot less, like 5% or so. I forgot to think about trying a different oil (I dumb). Course a little late now, but that could have been a "non invasive" test that may have gave a hint to a ring problem. The leakdown is a little excessive, but it's on a cold engine and I'm sure there is a differ.
 
Stopped by and talked to a mechanic buddy and he said that around 20% would be in the normal range for a cold 302. It will be interesting to find the results. I'm still thinking there is an issue with the plumbiing. Are the upper and lower intake connections both behind the TB blade?
 
I did a little calling as well. I called back total seal and they said some of the numbers were a little high but not terrible like 50% blow by would be. My pcv setup is connected to the stock locations. The lower intake goes directly to the lifter valley and the upper intake is at a port on the bottome of the intake after the throttle body. I am begining to think I have a few problems. I theorize that my high flow oil pump was putting out way to much oil, my dipstick was not firmly sealed, the rings were a little loose causing mosest blowby and the breathers/inlets for the vacuum pump were not baffled at all or enough. I am going to put this engine back together and gap the rings myself so that I know I can eliminate potential questions running through my head. If this doesn't solve the problem I may just yank this blower off and go N/A. The engine guy had me run 20w50 oil but the pressure was 50-70 lbs. I went back to 5w30 and the pressure dropped down to 30-50. I don't know if that has anything to do with it.
 
Thinner oils will blow out quicker that thicker oils. Pressure is created when there is a resistance to flow ie thicker oils are harder to push. I run straight 50 on the track car but the engine was built loose and I still have about 90lbs oil pressure. I was looking over at some of the race forums and what I think the general gist is that most of their crank cases are seeing positive pressures in the 8 to 15 lb range once they start their run. Their conclusions were that the vacuum pumps are not capable of keeping up with the bypassing air under boost. Most are running 15lb and up though. In looking at your drawing "if" the pump is overrun, then the pressure has no place to go and will build up. It's like a closed circuit system air goes in but can't go out. If the ring work doesn't work then I would re-plump the whole system and just use engine vacuum (15hg) and add the guards inside the valve covers. Also I noticed that some of the racers were running a 20lb ring to reduce the blow-by. Something that may be worth checking into if your gonna do the rings. I'm still thinking there needs to be an opening in the system for any positive crankcase pressure to go. This would be like a 12 AN from the valve cover (with a PVC valve) to a catch can then to the intake tube between the throttle body blade and the air filter. Note they will always be a negative static pressue at this location and it will increase (more negative pressure) as the engine rpm increases. Also this location insures that any air that may enter the engine has been filtered. I wouldn't ditch the huffer yet, this problem will be figured out.
 
I agree about the rings. The rings I have are low tension due to the 3 mm oil control ring. IIRC the total seal guy said they wee likely under 10 lbs (6? I can't remember). The new rings have a Hugh tension oil control ring but due to the groove in the piston it is about 12-16. I can't recall the specifics.

The addition of the high tension 3rd ring and the overlapping top ring should help my leak down test numbers. I will do the test one more time when the engine is on the stand before disassembly and then after the new rings get put in. They won't be seated at all but if they make a difference then I would be happy.

Today I was working on a baffling system for
My breathers/pump. The problem is the drivers side since the upper intake hangs over it. It will have to be a very low profile. To top off the problem my valve covers have a 1 1/4" hole drilled in them.
 
I got the engine out this weekend and tore it down last night. Everything looked good other than running a bit rich. I pulled the pistons and checked the gap of the current rings. They came in at .032 on both the 1st and 2nd rings which is wider than the total seals recommend end gap. They recommend .028 on the top ring and .024 on the 2nd ring. I think I will try and find out the proper ring gap for the Mahle rings I was running. I don't think it was too far out but I want to make sure before I do anything else.
 
I couldn't find a tech number for Mahle so I called Probe and asked them what kind of ring gap they recommend. They said 020-024 and mine sounded a little loose. They also suggested I check the piston to bore clearance. I should have .003-.004 there. I will check that tonight.

I think I found the place where the majority of my blowby was coming out, my dip stick hole. I drilled out the hole by had and it was slightly larger than the factory hole since I couldn't keep the 18" bit straight. It allowed oil to sneak by even though I siliconed it in place. I have a new cover that I will put on when it goes back in the car. I also ordered a new set of Trick Flow valve covers so taht I can drill the holes in different spots. I want the vacuum pump from the front of the valve covers. In addition I ordered some trick baffles for the valve covers. I'll post some pics when I get everything in and start trial fitting.
 
I finally found some specs for the Mahle rings I had. They had ring gaps recommendations of .024 for blown applications. It looks like my rings were out of spec and too loose at .032. Do you guys think that that is enough to cause me the blowby problems I was experiencing?
 
Yes, too much gap in the rings.
I was chatting with a fellow that runs Sc on his cars. I asked if they have stepped rings avail or what does he do?
He said when he is building an older eng for forced ind, He angle gaps his rings at approx 30*and not a blunt end gap style.
This will keep the blowby from the forced induction from popping the gaskets out when he is at the track and cranks up the psi.
:shrug. It may be worth a try.
 
Thanks for confirming my suspicions. I hope to have some time this evening to get started putting the engine back together. I got my new baffle for the valve cover today. It is a Jeg's brand and looks like it should work well.
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Having good baffles is important. I was running the BBK SSI intake, and it has a poor design for the pcv baffle. I was going through oil like there was no tomorrow. I even put on a oil separator, and I was having to empty it about every fill up. I'm surprised my fastback didn't smoke everytime I took a corner, oil was pooling in the upper at every flat spot. I swapped over to the Holley SystemMax II intake. That solved my oil problem. The oil level is constant, and I haven't had to add any since the previous oil change.
 
:thu, Goodlooking baffle. I want 2.
Did a quick google search and found stepped piston rings at Grover Corp.
Try checking for rings your size to stop the blow by from the forced ind.
 
I started gapping my new Total Seal piston rings last night. Very nice I must say. The top ring is actually two seperate rings. The top side is L shapes and the second slides in behind to fill in the void of the L. Gaps are set 180 degrees apart so you get a "total seal". I did have a problem with a second ring. One had a brocken section where the scraper was missing about 1". I called them today and they are sending me another one today. I will have it tomorrow. They have given me fantastic service. I hope the rings work as well as the service they provide. I hope to have the engine together by the end of the weekend and running by the 15th.
 
I have the engine back together now. Flywheels is on but I have run into a problem. I was about to install the clutch and noticed a problem. I am using a Fidanza 3.2 clutch that has a Kevlar disc. I noticed an unusial small groove on the pressure plate and investigated a bit furher. it appears that the disc is shot. My disc has a rivet that is barely touching. I have noticed a little bit of slipping recently and now I know why. I don't think I had the clutch adjusted correctly and was running a bit much preload. I now have to try to find another clutch disc. I will call Fidanza tomorrow to see about getting another . If they can't supply me a new one do you know if I can use a disc from another mfg? I assume I can. I don't want to replace the entire clutch since the engine guy I used balanced the assembly with the current pressure plate. He actually welded on it to get the engine balanced. I would have changed that now if I could go back. Thanks for the help.
 
I just ordered a new disc and it should be here tomorrow. That is my $100 lesson on how not to adjust a clutch. At least I noticed it before it went back in the car.


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I am a little annoyed with Fidanza. I paid for overnight shipping and they sent the wrong part. They sent me a resurfacing kit for their flywheel instead of a clutch disc. It is too bad the workers don't know the difference in the products they sell. Being on the west coast they were already closed before I could call.


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I had an adventure today in locating a disc that would work. I called Fidanza again and they said that the clutch was made by Zoon otherwise known as Prfection Clutch. I called them up and they referred me over to American Powertrain in order to "remove the middle man". I then called up American Powertrain and spoke with Gray Fredrick. He is a very knowledgeable mand and extremely helpful. I told him my dilemma and he is setting me up with a new ceramic disc that should work better then the Kevlar disc I am taking out. It will handle more power, last longer and give me good street manners. I can't wait to get it tomorrow.

I will pass on this bit of information though. NEVER let the machine shop use your pressure plate to balance the engine. If I were not able to locate a disc that would work I would then have to replace the entire clutch. By doing so I would have to rebalance the engine. Again don't use a consumable to balance the permanent part of the engine. Why would someone recommend doing that and say it is a better way to balance the engine? Less holes and plugs to put in the crank or something like that? :shrug
 
The more parts that are balanced together, the smoother the engine turns......thus a happier customer.....until the consumable parts need replacing. Then they can say it is not their work that is out of balance, it is the replacement parts.
 
"68EFIvert" said:
I will pass on this bit of information though. NEVER let the machine shop use your pressure plate to balance the engine. If I were not able to locate a disc that would work I would then have to replace the entire clutch. By doing so I would have to rebalance the engine. Again don't use a consumable to balance the permanent part of the engine. Why would someone recommend doing that and say it is a better way to balance the engine? Less holes and plugs to put in the crank or something like that? :shrug
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When I saw that comment earlier I was going to ask if they really did do that, or if they balanced the engine's internals first and then did a secondary balance to insure the PP and disk assembly where matched to it.

The shop that did mine sprayed some paint on the assembly and told me to match it back up upon re-assembly, but I don't beleive that they relied on the PP balance to get the engine in balance. Perhaps your shop did it the same way. It might be worth a call back to them to verify.
 
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