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i have a 73 350 all set up with a 871 b&m blower when i crank on it about 5500 rpms or so i blow oil all in my engine compartment not pretty looks like im building crank pressure i have it breathing gd would it be my exhaust its only 2 1/4 o.d. tried lots of stuff anybody have any sug. thks kipster
sounds like to me your blower boost is by-passing your rings and going into the pan, and blowing the oil out of the motor. i believe your rings are shot. :CRY: need to do a leak down test. :eek:
Bingo. :CRY:Quote:
Originally Posted by lt1s10
i did a compression check and all cyl. have 100 psi would that still show ring problems
dont know much bout blower motors but i'd say that 100 psi is a problem:confused: . i'd like to build 1 someday and maybe i should read on this be4 i reply**)Quote:
Originally Posted by kipster40
what valve covers do you have are they baffled you say it is vented good what type of breathers ? and how about the oil pan dose it have a scraper windage tray ? all this will add up to alot of oil on the top of the engine if any of this stuff is not rigth or not their and the blower will add to it i think any breather system has to be much better than you may think that is good i have see this with big engines and blower cars and the piston rings may be on up side down
At 100 PSI compression, I would think the puffers doing a fine job of boosting the crankcase. With the compression being that consistant, I'd say it's a ring problem.Quote:
Originally Posted by kipster40
Art
100 lbs is not enough, sounds like to me the motor has gotten hot one time to many and collapsed the rings.:eek:Quote:
Originally Posted by kipster40
Isn't the pressure you'll read a function of the compression ratio you're running as well as cam timing? Assuming the rings are good, what pressure would be expected on a 7:1 blower motor with a healthy cam?
Regards, Mark
yes this was what i was thinking to he did not give us much on the build 100 psi may be a bit low but who knows what cr he hase or what cam lsa is . 100 psi may be all it hase?Quote:
Originally Posted by MAW
the ? is not how much comp. the motor has, its how much comp. will the rings hold, you do a leak down test and you rings want hold 100 lbs. of air then you dont have much. he has boost getting in the pan and the only way its gonna get there is its by-passing something. :eek:Quote:
Originally Posted by pat mccarthy
ok yes but did he do a leak down test and are you sure what is he got going on this ? bad ring ok may be but? at this point oil on the top of the engine could be from many thing and yes ring s to
:LOL: yep no need to do a leak down test if you can turn it over with a open end 5/8 wench with the plugs in
so whats the easiest way to find my problem leak test, pull the heads to look at the rings,this was a running motor before i put it in my 40.so sittin for a year or so cause this?were should i go to have a leak test done any sugg?
if u can see the rings when u pulled the heads u have bigger problems. my suggestion is re-ring it. and another thing i'd try after re-ringing it is evac tubes from your header collector but u need 2 baffeled tappet covers this will help pull crank case pressure.
Kipster
Your best bet if you don't have the equipment is to take it into a shop that can perform a cylinder leakdown test for you. I can't imagine it being more than 1-2 hours labor with an open engine compartment. Better to know for sure before ripping a motor apart.
To satisfy my own curiosity I'll do a compression test on our boat motor this week and see what a 7:1 motor yields. My assumption is that a 10:1 motor would give around 147lbs when tested and a 7:1 motor would see only 103lbs. These numbers being nothing more than normal atmospheric pressure multiplied by the calculated compression ratio.
Cheers, Mark
i have try this on two car with ex 3 inch and 4 it did not work for me but was geat to shoot out oil and the dip stick out :eek:Quote:
Originally Posted by 383 chev