You must be VERY VERY careful with the thrust bearings on 1500s. The 1500s
and 1296s are notorious for pushing con rods through the block. The thrust
bearings wear and actually fall out so the crank has so much play that somethin
g gives. The 1500 only has half circle thrust washers ( the A series for
example has full circle bearings) so they will wear faster than the full circle
ones. this is confounded by the cooling capasity of this motor unit. The
A' series motor can be tuned to over 140 hp, the 1500 can too but at high revs
it generates local hot spots and destroys itself. Essentially the cooling
system and oil circulation system is not as good as it could be and the
engine suffers. One of its weak links is the thrust bearing.
The solutions are:
1) Have your machinist fit a full circle thrust bearing with minimal tolerance
You can call Mark Sayer at performance engineering who wrote a fact sheet on
this. I have not seen this sheet but I know it was published in a motoring
mag. Shouls be not more than $130.
2) Have the engine balanced. About $75-110
3) Fit an oil cooler. 1500s badly need one. About $80 for a 16 row cooler,
stainless steel braided hoses and a thermostatically contriolled adaptor.
Several other cautions if you are doing this engine yourself:
a) Make sure the screw holes in the small alloy bar located at the front of
the engine by the front main bearing cap are all in good shape. Sometimes the
threads get stripped.
b) Be economical with silicon gasket behind the front engine plate. Typically
this is fitted one day, then the timming plate another day. However the
screws and bolts which hold the timming cover on also hold the front plate on
and make sure it is squeezed against the front of the engine. If the silicon
stuff is applied too thick it will set without being squeezed into the joint
by the timming cover bolts. The result is a very hard to fix oil leak.
Another result is that the cam locking plate can bend when you tightening down
if there is excess dried silicon under the front plate in that area.
You can do yourself several other favours: counter sink the head stud holes in
the block and use grade 8 bolts instead of the head studs and all the other
studs and critical bolts for that matter.
Get hold of a dremlel tool and smooth off all sharp edges in the combustion
chambers to prevent hot spots which can lead to ping.
Cheers Dennis
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