> I finished my 60 TR3A restoration a couple of months ago and want
> to do the
> last bit....and engine and OD tranny rebuild.
> I removed the pan and head on the current engine; decarbonised,
> lapped the
> valves, put new rod bearings in and put it back together. It's
> fine when cold,
> but it raps slightly at 3000 rpm as the oil pressure drops to
> 25psi (excess
> clearance?).
The low pressure sounds like excess bearing clearance or possibly a broken
pump (what oil do you use, when was it changed), the rapping could be worn
pistons, wrist pins, main bearings, etc. What was the clearance after you
changed the rod bearings ? Might be the crank journals were worn too ...
> I've got an older spare engine with OD and I want to start the
> rebuild with
> the head and tranny. The tranny seems pretty staightforward...replace the
> seals, the OD solenoid and check for a bad clutch and broken gears, etc.
At an absolute minimum, I would replace the synchro rings and thrust
washers. Unless you know it was working perfectly before, I would suggest
checking all the clearances, etc. Don't forget the seals on the shifter
shafts in the top cover, but be warned that the seals being sold today don't
always fit. You may have to cut spacers to go in behind the seals. Same
problem may apply to the seals on the OD control shaft. The OD that HVDA
rebuilt for me last year was apparently out of spec from the factory, Herman
had to cut some special washers to get the clearances right. Sure works
sweet now !
Unless you know it's bad, it seems odd to me to change the solenoid and
nothing else ... it's not any more particularly prone to wear than other
components ...
> What do I check for in the head? Do I just go ahead and replace
> the valves,
> springs and shaft...is there anything else I should look for?
I'd start by having it magnafluxed, no sense rebuilding if it's cracked.
Also check the bottom surface for flatness, if it's warped by more than
.001-.002" then it should be surfaced. The guides are more likely to be
worn than the valves, and after changing them, the seats should probably be
ground. The old valves may not need to be replaced, check the stem diameter
and the margin between the seating surface and the top of the head. If you
do replace them, you might consider using TR4A exhaust valves, which have a
smaller stem and are less likely to float IMO. There are special guides
available to fit them to the earlier heads.
If the shaft shows any visible signs of wear, chances are good the bushes in
the rocker arms are shot, too. My suggestion is to send the whole shaft
assy off to Rocker Arm Rebuilders unless you're obsessed with doing it
yourself. They did an outstanding job for me, for about $100 + shipping,
which is probably less than the parts would've cost me. (Just the shaft and
bushes come to something like $75.)
Randall
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