In a message dated 10/3/2005 5:24:20 AM Eastern Standard Time,
Richard.Gosling@atkinsglobal.com writes:
> Darrell,
>
> Hmm, I'm not sure about this, I haven't heard about it before but I guess
> it's theoretically possible. What you are suggesting is that there is
> increased pressure in the crankcase from blowby, then during the induction
>stroke the
> pressure above the piston will be lower than that in the crankcase, so some
> of the oily air will be sucked past the piston rings into the combustion
> chamber and will burn (probably not very completely) along with the petrol.
>
Richard,
Thanks for your thoughts. I have altered the 250's crankcase ventilation and
most likely restricted it from stock. The troublesome symptom is gray/black
smoke blowing out the tail pipe under heavy engine load like running the tach
to
the redline in first and second with oil consumption resulting. Under normal
driving conditions, ( who drive these cars normal) no smoking at all and no
oil consumption. I thought there may be something to this since I have noticed
an oil coating on the dipstick side on the block.
Generally the 250 runs great and has about 20,000 miles on the rebuilt motor
with the 40 over pistons, shaved head and mildly profiled cam. I could never
get her to idle right with the stock emission set up using that stupid PVC
valve on top of the intake manifold. My guess is that the motor was just
developing too much vacuum and air was being sucked in thru the valve. TR250
intake
manifolds were notoriously bad leakers! Last year I blocked all that stuff off
and cut a small hole in one of the pipes to ventilate the crankcase. Not sure
if this is enough and I am not getting much oil build up in the vicinity of
the hole.
Now Just call me,
Smoking TR250Driver,
Darrell
=== This list supported in part by The Vintage Triumph Register
=== http://www.vtr.org
|