302 crank case pressure building up and i cant find where

blueracecar · 09-21-2008

my 1989 mustang race car has been blowing the dipstick up a little and spitting some oil out.i have crankcase evacuators down to the collectors with check valves and they are working fine.i even took the bullet mufflers off and put turn downs to decrease the back pressure even more.i have done two leakdown tests on it and there is less than 5% across all eight cylinders.it only does it during higher rpms (above 5700 rpms). i am thinkin it may be an exhaust valve spring going soft and not shutting the valve soon enough.any ideas?

reds · 09-21-2008

hope you find out because my racecar is doing the same thing. 71 302 block with goodies

blueracecar · 09-22-2008

i have been talking to a lot of people and this is what i think it is.somewhere down the cylinder wall is messed up.the leakdown test i did only checked the top 1.5" or so of the bore.i am going to allow the crank to rotate the piston down on the compression stroke and do the leak down check again.even though i havent checked it again yet i feel pretty strongly that it what it is.it sucks since i only have 150 passes on it.looks like i will be running a 347 next year.goodbye 11.50s hello 10.70s

reds · 09-22-2008

well that is a good point there.damnit!!!

blueracecar · 09-23-2008

it turns out it is a ring problem. i havent pulled the engine yet so i am not sure of the damage.at least i was able to catch it before i did any serious damage

**RLG34750** · 09-23-2008

Quote:

Originally Posted by blueracecar

it turns out it is a ring problem. i havent pulled the engine yet so i am not sure of the damage.at least i was able to catch it before i did any serious damage

sometimes we get lucky

and other times go boom.....

good catch on the problem......