5.7 TBI Questions

[Tom Parker]

K.E. Towle <karljiml at compuserve.com> wrote:

>1. Engine went bad (exhaust valve stems mushroomed, broken lifter) after
>30K miles. What would cause an observed excessive carbon build up on the
>stem side of all the intake valves?

I have quite thick carbon buildup on the stem side of the inlets in my Mini. I
am guessing that it is due to a high overlap cam being run at low engine
speeds. Poor combustion going into the inlet on overlap leads to carbon
deposites, which don't go away. The exhuasts were virtually clean, I guess
becasue the exhaust gases burn it off..

--
Tom Parker - parkert at ihug.co.nz
           - http://www.geocities.com/MotorCity/Track/8381/

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org