Thread: Too much crankcase pressure, novice engine builder

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The only reason I am hesitant to do that is because I don't know what I would change. The rings are gapped where I want them to be. I don't have the money for new pistons and a larger bore. I feel tearing it down and rebuilding it wouldn't accomplish anything. This is why my original question is about additional things I can do to keep crankcase pressure down. I've been doing research extensively, and I've seen people mention such devices but I was hoping to hear from people with opinions on them.

I appreciate the advice, I really do, but I'm confident the engine was built correctly. I'm aware that my combination has additional blow-by from the extra ring gap, but in order to run boost, like I'm planning to, I was instructed by various sources to add that gap.

You never want to use an lube that is designed for bearing/crankshaft on cylinder walls or pistons/rings-it is too slippery and the rings/ cylinder walls will just glase over and be too polished for the rings to seat and seal effectively. there are some ring seating compounds out there for quickly seating the newer type race rings-----

You might want to try the old method of seating some industrial rings by sprinkling BONAMI powder thru the carb while gently revving it up a few hundred rpm--------has always worked wonders and doesnot ever fail to impress some neighbors standing around as the smoking tones down and goes away--------

Since you said novice engine builder--------please explain the gapping method, alighnment, top/bottom side and how you squared the ring to the bore???????????

Gapping method was relatively simple from how I understand it
I watched many guides, but probably followed this one the closest, just with a hand file instead of a specific ring file:
https://www.youtube.com/watch?v=uAguO3EPzcI

in summary, place the ring in the bore, use the piston head to push it down square about an inch, use feeler gauges to measure gap. While doing this, I closely watched the shape of the gap ensuring each end of the ring was square against each other and not tapered. The rings I have denoted the top face of the rings with a small dot. All of which were facing the correct way when installed.

I only say novice engine builder because this is quite literally the first engine I've built. With the exception of the engine this replaced but that was just 15 year old me finding one in a junkyard and throwing that in my car.

As the choice of lube, I was told it would work fine when I asked my local machine shop after taking my block to them. At this point the engine has been running for about a month now. It doesn't smoke once it's warm, so I am assuming ring sealing went okay. Oil has been changed twice now, all the old assembly lube is likely out by now. But I will absolutely take that into consideration for future reference. That's something I didn't know.

How did they hone the cylinders? Was it a Sunnen CK10 type machine or a hand drill with a porta hone??? what grit numbers and hone crosshatch pattern????what rings-stainless, moly surface, chrome, just plain cast????final piston to wall clearance and how was the piston measured???

Unsure of the exact machine model they used, but I can say it was an actual honing machine, not a hand drill. As for the grit numbers, I also don't know. They weren't reported to me and I wasn't aware there were differences. Minimal material was removed since the piston to wall clearance that I had was already considered acceptable. I only rehoned because a few of the cylinders were scored when I bought the block. Crosshatch pattern, again I was not given an exact number, but I assume the 45 degrees it's supposed to be at. Rings are moly coated. Unfortunately, I put the engine together 2 months ago and didn't write down the final piston to wall clearance. I know I checked it and it was within spec from what I could find on the internet. Just trying to go off memory here, I'm pretty sure it was 8 or 9 thou.

was this block a newly over bore at .030 or a used .030 block????Question relates to upper cylinder wear---top ring area especially

since this only happens at a high rpm and you have 10-1 compression ratio-you are probably getting some detonation/spark knock---------there are 2 things to do to try to solve------it all comes around to timing and octane----------

I bought the block used bored 30 over, however the amount of time it was running like that was unknown. Long story short the friend I bought it from bought it from someone else who tried to make a race motor out of it, failed, and then got rid of the motor. The block was checked out by the machine shop I sent it to to do the re hone. I trust their work and he said it was good and would work.

I hadn't thought about detonation being the issue before. I'm currently running 91 octane. The engine sounds perfect at idle. Is there an easy way to check for that other than sound? It's a bit hard for me to hear, and this being my first engine I'm not sure if I could pick that out at high rpm.

However, I am planning on taking this to a tuning shop to have it professionally tuned and dynoed. If you think this issue could be as a result of my sloppy tune, I will be elated lol. I just haven't taken it yet because I was hoping to have this leak problem fixed. But if a proper tune will fix this, I will take it ASAP.

Start putting higher octane fuel in it and run it quite a bit so as to get rid of all the 91octane--one of the biggest mistakes we have seen doing dyno and computer tune ups are the fuel that the owner runs-then brings to dyno with something else and then returns to piss after he leaves-----drain out all the fuel and then replace with best you can get around where you are located----and stay with that------do you know what your timing curve is and/or jetting info of your carb plus the carb model and running fuel pressure

The goal was to run on pump gas. Do you think that is still feasible? Race gas isn't the easiest thing to get a hold of in my area, though a few stations in the city sell 93. I'm familiar with the function of octane and timing. From my understanding, if some timing gets pulled out, lower octane gas will work ok at the expense of some horsepower. Does that sound right?

I'm running a 1411 Edelbrock. I have an AFR gauge and it's set to run a little bit rich right now just because I don't completely know what I'm doing when it comes to power tuning and I know it's better to be rich than lean. I currently have it idling around 13.5 AFR and WOT gets to about 12.0 AFR. I don't know what my timing curve is. I'm using an HEI distributor. Not sure what the exact model is however. It was a piece I was running on the old engine before the rebuild that I bought from Autozone 8 years ago. I have a basic timing light though.

Originally Posted by NegativeZero

I'm familiar with the function of octane and timing. From my understanding, if some timing gets pulled out, lower octane gas will work ok at the expense of some horsepower. Does that sound right?

Yes, once you've got the AFR dialed in. Curious, are you running aluminum heads or iron? Also, is the 91 octane fuel you run an ethanol blend or ethanol free?

Aluminum heads by Trick Flow. The gas is 100% gas, no ethanol.

Originally Posted by NegativeZero

Aluminum heads by Trick Flow. The gas is 100% gas, no ethanol.

With 10:1 compression and Trick Flow heads I believe you'll be just fine with 91 octane, and I prefer non-ethanol fuel personally, for non-computer controlled vehicles or for anything that doesn't get driven a lot (everything I own!). Like Dave & Jerry said, doing the leak down test is a good idea, and if everything is OK there back some timing out and see if it makes a difference. Just my $0.02. There're a lot of smarter guys on here, and decades upon decades of experience!

Originally Posted by NegativeZero

I'm running a 1411 Edelbrock. I have an AFR gauge and it's set to run a little bit rich right now just because I don't completely know what I'm doing when it comes to power tuning and I know it's better to be rich than lean. I currently have it idling around 13.5 AFR and WOT gets to about 12.0 AFR..

JMHO, your AFR numbers above are not rich enough to wash the rings. And, the compression dropping severely is a good indication of there may be more trouble ahead.
Glad you're tearing it down, hope you get it solved.

Originally Posted by 36 sedan

JMHO, your AFR numbers above are not rich enough to wash the rings. And, the compression dropping severely is a good indication of there may be more trouble ahead.
Glad you're tearing it down, hope you get it solved.

Yea once I saw that big a drop in compression, I knew it was time to crack it open. Rings are fairly cheep, so I'm honestly not too bothered by it. Planning on reducing the gap to 24 on the top and 25 on the bottom. I still think that leaves plenty of room for low boost applications and will hopefully reduce blow-by. Also adding a windage tray so hopefully keep crankcase pressure down a little bit more.