Join Date: Oct 2004
Location: Abbotsford, B.C.
Feedback Score: 0 reviews
Re: 855 cummins top stop injectors and valve timing on the BIG CAM
If you're wanting to check "injector timing" , you'll have to locate and use one of the traditional dual dial indicator tools unique to Cummins PT fuel systems. Your manual will no doubt show you this, but one dial registers via a long stem through a removed injector hole the piston position relative to crankshaft rotation, while another registers the push rod travel. Different thicknesses of rocker box gaskets are available to move the low mounted rocker rollers in or out of contact with the cam lobe. One gasket choice has to provide a satisfactory average for two cylinders. If you disturb an old engine to change these, you must pull the housing end plugs to renew the "O" rings. Otherwise leakage is pretty much guaranteed once its all back together again.
If all you want to do is a valve, injector set, then just follow the instructions in your manual. In a nutshell that might be:
a)Remove valve covers and Jake housings(keep in order)
b)Clean gaskets, throw an overhaul kit into Jake housings if high
c)Loosen all rockers, and remove the top rocker housings(for
replacement of rocker shaft "O" rings, same as lower housings.)
Reinstall, torque housings.
d)Follow the valve set info applicable to your engine, but yours
is probably A 1/6, B 2/5, C 3/4 as visible on the accessory
drive pulley. 11 and 23 thou was pretty standard for intake/ ex.
e)Injector values for top stops were something like 6 inch pounds,
but if you can rotate the small link which sits into the top
stop collar with your fingers, your close. The set point is part
of the above pulley points, and the chart will clarify that.
f)Torque Jake heads, you'll have to check adjustment value in your
book (I think it was 18 thou)
If you set your injectors too tight they can fail, too loose and the tips will carbon up.
1990 F250 with 325oookm - ATS (non wasteGated kit ) on since 0km's / ZF / Single Cab Conversion to 6 seater keeps the family involved / Getting on, but running strong