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Dave, your cam is big which will bleed some compression, I am assuming you run flat top pistons? Flat Tops with 64cc should be close to 10:1 in a 350, I would expect 160 to 175 compression but even at 150 all cylinders is good and the sign of a good engine.
A leakdown may show you are leaking past the rings in all 8 but that would surprise me.
You bought the tool, might as well play with it.
We have given ideas for checking the manifold seal and finally valve stem seals, after leak down I would go that way. Since compression is the same a leak down test will probably back you up and say all 8 are healthy.
All the cylinders were in the yellow or just barely into the green. This is on a cold engine however, there is no way to do this hot without removing the headers.....then the engine would be cold again. What say you?
Your initial post said you use a 1-2 quarts of oil in 100 miles of driving. From what I see on your gauges, I don't believe there is the cause of your oil usage.
1-2 quarts of oil in a 100 miles would make that engine smoke like it was burning oily rags instead of gasoline. You KNOW you're burning oil because you're fouling the plugs.
I SUSPECT you have badly worn guides and damaged valve seals and the high volume oil pump pumping oil up there would just add to the oil going down the guides.
I think somewhere, you indicated this has become a recent problem, not just shortly after engine assembly. If that's the case, I'd scratch the leaky intake as the cause of your problem.
Whatever it is, I'd get the ring seal off the table.
[QUOTE=MikeM;1589008490]Your initial post said you use a 1-2 quarts of oil in 100 miles of driving. From what I see on your gauges, I don't believe there is the cause of your oil usage.
1-2 quarts of oil in a 100 miles would make that engine smoke like it was burning oily rags instead of gasoline. You KNOW you're burning oil because you're fouling the plugs.
I SUSPECT you have badly worn guides and damaged valve seals and the high volume oil pump pumping oil up there would just add to the oil going down the guides.
I think somewhere, you indicated this has become a recent problem, not just shortly after engine assembly. If that's the case, I'd scratch the leaky intake as the cause of your problem.
Whatever it is, I'd get the ring seal off the table.[/QUOT
Thanks Mike, but I thought the leak down test would reveal this if there was any air leakage. I heard none thru the carb, exhaust, oil dipstick or radiator. I will recheck the guide seals and put in a regular oil pump.
Your initial post said you use a 1-2 quarts of oil in 100 miles of driving. From what I see on your gauges, I don't believe there is the cause of your oil usage.
1-2 quarts of oil in a 100 miles would make that engine smoke like it was burning oily rags instead of gasoline. You KNOW you're burning oil because you're fouling the plugs.
I SUSPECT you have badly worn guides and damaged valve seals and the high volume oil pump pumping oil up there would just add to the oil going down the guides.
I think somewhere, you indicated this has become a recent problem, not just shortly after engine assembly. If that's the case, I'd scratch the leaky intake as the cause of your problem.
Whatever it is, I'd get the ring seal off the table.
Seems like you have several mods to the engine. Are you using the stock oil dip stick and tube? If you overfill the engine it will want burn off the excess pretty quick.
Your initial post said you use a 1-2 quarts of oil in 100 miles of driving. From what I see on your gauges, I don't believe there is the cause of your oil usage.
1-2 quarts of oil in a 100 miles would make that engine smoke like it was burning oily rags instead of gasoline. You KNOW you're burning oil because you're fouling the plugs.
I SUSPECT you have badly worn guides and damaged valve seals and the high volume oil pump pumping oil up there would just add to the oil going down the guides.
I think somewhere, you indicated this has become a recent problem, not just shortly after engine assembly. If that's the case, I'd scratch the leaky intake as the cause of your problem.
Whatever it is, I'd get the ring seal off the table.[/QUOT
Thanks Mike, but I thought the leak down test would reveal this if there was any air leakage. I heard none thru the carb, exhaust, oil dipstick or radiator. I will recheck the guide seals and put in a regular oil pump.
Even if the compression rings hold, that doesn't mean the oil rings are doing their job. But, I don't think your oil rings are your problem either.
Just pulled the carb to look for oil laying in there, and while it initially looked like a light coating of oil, I could not get anything on a paper towel.
Seems like you have several mods to the engine. Are you using the stock oil dip stick and tube? If you overfill the engine it will want burn off the excess pretty quick.
Tom
Understand bro. I am not using a stocker, it is an aftermarket chrome for a SBC. I filled with 7 quarts, (7 qt Moroso) ran it a bit and put a mark on the dipstick. Even if it doesn't show on the dipstick, I figure I still got at least 5 quarts in the pan.
Even if the compression rings hold, that doesn't mean the oil rings are doing their job. But, I don't think your oil rings are your problem either.
I've had the leak down tester on #1 for 30 minutes (cold engine) to blow any residual oil into the pan and I still show about at a steady 5%. Don't know how to check oil rings.
I'm gonna block off the PCV at the carb and install a breather in the valve cover. I'll check after a drive to see if the HV oil pump might be filling the upper cylinder heads and getting past the baffle and into the PCV. I suppose a dripping breather would be a sign of that.
I'm gonna block off the PCV at the carb and install a breather in the valve cover. I'll check after a drive to see if the HV oil pump might be filling the upper cylinder heads and getting past the baffle and into the PCV. I suppose a dripping breather would be a sign of that.
Yes and with the carb off remember the intake gets a lot of heat ,so you may not see wet oil.
A leak down of 2-5% would be considered great. Your compression was even in all cyl's so you are good.
Your high pressure, high volume pump may be pushing so much oil through the connecting rods that it is over oiling your cylinder walls. The cylinders are oiled by oil thrown off from the connecting rod rotation. If you have tight rod clearance. .002 or less this would not happen but if you are loose on the rods and have your high flow high pressure pump it could happen. I have seen small block race engines running .003 rod bearing clearance and high volume pumps that never fouled out plugs so I bet you are still looking at a valve train or intake/PCV issue sucking oil out of the upper end down into your cylinders.
You can pull the manifold and rule this out. If the intake ports are dry pull the headers and look at the exhaust ports. The problem will show up.
FYI: A valve stem seal leaking one drop of oil per revolution will burn a quart of oil in 400 miles.
( quote from Sealed Power Piston Ring Engineering team )
Sorry guys, I forgot the new Standard, Include your first Name:
Mark
Last edited by Westlotorn; 02-21-2015 at 01:41 PM.
A leak down of 2-5% would be considered great. Your compression was even in all cyl's so you are good.
Your high pressure, high volume pump may be pushing so much oil through the connecting rods that it is over oiling your cylinder walls. The cylinders are oiled by oil thrown off from the connecting rod rotation. If you have tight rod clearance. .002 or less this would not happen but if you are loose on the rods and have your high flow high pressure pump it could happen. I have seen small block race engines running .003 rod bearing clearance and high volume pumps that never fouled out plugs so I bet you are still looking at a valve train or intake/PCV issue sucking oil out of the upper end down into your cylinders.
You can pull the manifold and rule this out. If the intake ports are dry pull the headers and look at the exhaust ports. The problem will show up.
FYI: A valve stem seal leaking one drop of oil per revolution will burn a quart of oil in 400 miles.
( quote from Sealed Power Piston Ring Engineering team )
Sorry guys, I forgot the new Standard, Include your first Name:
Mark
I have the oil pan off now and have taken out the hi volume pump. I have put in a Melling H55 stock pressure/volume pump. I also was able to pick up a V-158 (Standard) PCV valve. I just had an off the shelf 'Schucks' one. The V-158 is not supposed to suck so much. We'll see. I'll put it back together tomorrow and then pull the valve covers to check for torn valve seals.
All the cylinders were in the yellow or just barely into the green. This is on a cold engine however, there is no way to do this hot without removing the headers.....then the engine would be cold again. What say you?
Dave, that leakdown test is not valid! I mentioned this before u need at least 70psi source pressure (on the gauge with PSI increments). Leak down at 5psi means nothing. Also u must be at TDC on the cyl tested - u have to block the crank at this location so it dosnt move.
If leakdown is high u need to listen for air hissing in the intake manifold, exh pipes (use a cheap stethoscope), or out the vlv cover grommet.
Do the test correctly or dont bother doing it as u cant use the information at only 5psi source press.
Dave, that leakdown test is not valid! I mentioned this before u need at least 70psi source pressure (on the gauge with PSI increments). Leak down at 5psi means nothing. Also u must be at TDC on the cyl tested - u have to block the crank at this location so it dosnt move.
If leakdown is high u need to listen for air hissing in the intake manifold, exh pipes (use a cheap stethoscope), or out the vlv cover grommet.
Do the test correctly or dont bother doing it as u cant use the information at only 5psi source press.
No reason to get testy bro. If I bring the pressure to 70-100 on the PSI gauge there is no way to set the leak down gauge to zero prior to plugging it to the cylinder, it simply goes past zero and pegs up against the pin. Probably messed up the gauge. On Youtube a couple folks indicate that the PSI gauge will not go much past 20 PSI, I don't know why.
OK, I went down and exchanged the new Harbor Freight tester for a new one, seems the original had a stuck gauge. I get in the center of the green, about 20% and it's coming thru the rings. I know because the pan is off and I can hear it. There is still no way to put the leak gauge in the 'set' zone and get anywhere near 70 psi. It is about 20 psi on the psi gauge. 20% on the gauge says low leakage, am I to assume this is acceptable? This is on a cold engine remember. Thanks....
Last edited by MasterDave; 02-22-2015 at 03:41 PM.
Ok Dave u are sorting things out. Sorry 'bout the exclamation mark but the test has to be done correctly to be useful at all. Well if u cant get 70psi on that hobo fake tester then return it - or else u have a very serious blowby problem which i doubt if u can get 150psi cranking press (even cold). Dont know what u mean by the "set zone"? Im guessing u mean the pin after 100% on the gauge that says "cylinder leakage". I dont know why u cant plug the tester into the cyl first then raise press? Or just set the press and then plug in for a reading - if the cyl leakage gauge stays pegged then the internal orifice is way to big for your cyl (if even installed). The tester has an orifice inside that determines which size cylinder to test with and the hobo fake unit could be uncalibrated. I used the cheapest Summit leakdown tester with good results: http://www.summitracing.com/parts/sum-900010/overview/. Sorry but U-tube (can i call it u-twit) has some real innovators but not many real scientists. Im not kidding u need at least 70psi for a good reading.
And another note i had to return a HF fuel press gauge that stuck in mid-range - right where i did my readings. Unless u can calibrate HF stuff i would avoid anything that needs accuracy from them.
Hope this helps and Ok ill try to control my caffeine.
No problem bro, at times I need to be told and I understand. I hate crap tools and should have known better. I will return it tomorrow and get a better one at the local hot rod shop. Yes, the psi gauge at just over 20 psi pins the leak down gauge. Plugging it in and then raising the pressure does the same thing. I raised the psi gauge to 70 psi and heard air at the bottom of the piston. Remember the oil pan is off, but without the leak down gauge coming off the max pin there was no way to tell if leakage was within range or not. Keep at me guys and we will figure this out. Thanks
02-20-2015, 10:11 AM
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We'll see. I'll put it back together tomorrow and then pull the valve covers to check for torn valve seals.
