Q: How often should I change my belt?
A: For V8 drag race applications, we
recommend changing the belt after about 250 passes. For any
type of oval track or endurance applications, the belt
should be changed when the engine gets freshened. If you
experience any engine failure that may have even temporarily
locked up the rotating assembly, change the belt, its cheap
Q: Is it OK to clean belt?
A: The belt can be cleaned with mild soap
and water detergents. Never use harsh chemicals such as
lacquer thinner, brake clean or mineral spirits. If the belt
gets saturated with engine oil, we recommend replacing it.
Q: Should I cover my belt
A: If you are running your engine on an
abrasive surface such as a dirt track, it is highly
recommended to shield the front of the drive to keep dirt
and debris from damaging the belt and pulley surfaces.
Q: How much camshaft endplay
A: On belt drives with adjustable thrust
plates, we recommend running approximately .010” camshaft
endplay. Excessive amounts of endplay can cause premature
lifter failure while not enough will limit the amount of oil
reaching the thrust surfaces. We have cam adapters available
for certain models which utilize a needle bearing thrust
assembly instead of bronze thrust washers. The needle
bearing assemblies can be run down to as little as .001”
worth of camshaft endplay.
Q: How much belt backlash is acceptable?
A: Due to the round tooth profile inherent
with the Gates HTD® timing belt, belt backlash between 2°
and 4° degrees is acceptable and normal under a fully
assembled valvetrain. If you experience backlash greater
than 4°, it may be necessary to use an undersized belt or
oversized upper pulley. JESEL stocks undersized and
oversized belts for all applications.
Q: Should I oil the crank seal
before installing the lower pulley?
A: The seals used in our belt drives are
Teflon® coated and should be installed dry for proper
break-in. You should not oil the seal area on the lower
pulley or the cam adapter.
Q: Will my cover fit without
modifying the block?
A: We try to make our belt drive covers as
universal as possible and have it bolt on to several
applications, but due to the vast number of aftermarket
blocks that are modified from OEM prints, it may be
necessary to machine the block for additional clearance. We
highly recommend test fitting the components before any
final assembly work is completed.
Q: My block has been aligned
bored. Can I still use a belt drive?
A: The belt drive cover plate locates off
the OEM dowel pins and is set to the factory cam to crank
centers. The material used in the seals can adapt to a cam
to crank center that varies by as much as ±.015”. If your
block has been aligned bored more than .015”, you will need
to remove the dowel pins and allow the cover to center
itself off the installed lower pulley.
Q: Will I have to use a degree
wheel to set cam timing?
A: It is highly recommended to degree in
the cam using a high quality degree wheel. The alignment
dots on the upper and lower pulley are for general reference
only. We have seen too many discrepancies in the placement
of dowel pins and keyways in aftermarket camshafts and
Q: How do I adjust cam timing?
A: All JESEL belt drive feature externally
adjustable cam timing, a feature which greatly simplifies
engine tuning on the dyno and track. Adjust the cam timing
by first loosening the four nuts on the spider and rotating
the crankshaft clockwise to retard – counterclockwise to
advance. Torque the 4 upper pulley nuts to 25 lbs/ft when