Jeff,
I did much the same, but used a 280 degree cam and took the flywheel down
to 22 pounds. I used my old head, as it was in good shape and I was low on
cash and time. This head has never been shaved, but it is an early head
and does not have the chamfered squish zone, so I pick up some compression
there. I wouldn't want to run much above 9.5:1. BTW - going to 87mm
pistons probably raise your compression ratio to 9:1, just by virtue of the
larger bore. I did switch to the later Diaphragm clutch, but this will
have no bearing on your vibration.
I will pull 6,000 in an AutoX and very occasionally on the street.
Usually, I abide by the 5,000 redline, as there is a harmonic at 5,800 in
these engines which may be harmful over the long term. Check your tach
with a digital tachometer so you know where you really are too. Mechanical
tachometers are notorious for slipping out of calibration.
I removed the fan extension and use a thermostatically controlled fan, but
have no harmonic dampner. My decision was based on feedback from several
racer friends. My engine is very smooth with a small vibration just before
6,000, which must be the above mentioned harmonic.
Your engine - If you suspect the extension was not balanced with the crank,
pull off the extension and fan and have it balanced separately, assuming
the machinist can do this. If the crank and engine components are balanced
adding another balanced piece will not change anything.
Conversely, the fan hub extension has six bolts so you can rotate the
entire assembly in 60° increments. Try rotating it one bolt hole clockwise
at a time and see what happens. If nothing changes it isn't the hub
extension. If the vibration changes it could be the both crank and the hub
extension. I had each piece, flywheel, crank, pressure plate, stub fan
extension, all balanced independently; they were all added one by one to
the assembly, so any piece could be removed and replace by another balanced
piece without affecting the engine's balance. You can do this with the fan
extension and fan. Also, a lightened flywheel will not affect vibration
(much). Lightening, if anything, may make for worse vibration at idle.
Your flywheel weight is not the problem.
Summary - If you trust your feelings about the machinist lack of including
the fan hub/extension, bring it in and have it balanced separately, if he
has the capability to do this piece independantly. A balanced engine
should not have a significant vibration, even at the 5,800 rpm harmonic.
Good luck,
Jack Brooks
Hillsdale, NJ
1960 TR3A
1980 TR8
1974 Norton 850 Commando Roadster
> The crank, rods, pistons, pressure plate and flywheel were all
> balanced. New AE 87mm pistons were used. The crank was turned
> down .010",
> and I had the cam reground by ISKY, and I have the TR 555 grind
> which was
> supposed to be a 'fast road' cam. It has 268 degrees of duration. The
> flywheel was lightened by a few pounds, but it still weighs a
> country ton
> with the old-style ( many little coil springs ) pressure plate.
>
> It runs quite well and pulls like mad from 1800-4200 rpm. I
> have an OD, so
> I'm guessing I have the 4.10 rear end.
>
> In my 20/20 hindsight, I would have done a couple of things
> different, and
> I probably will when it starts raining some time in December. They are:
>
> 1) Shave the head to get the compression higher
> 2) Ditch the '4' flywheel and gone with a 4a flywheel or
> perhaps even an
> aluminum one with a 'modern' diaphragm-type pressure plate
>
> So briefly, that's the drivetrain.
>
> What I'm noticing is that the engine is quite smooth until you
> get up to
> around 4800-5000 RPM when a vibration sets in. I haven't tried
> going past
> 5000. It feels unhealthy.
>
> In that article recently posted
> http://www.speakeasy.org/~mgendron/Kastner_TR4A.html ) by
> someone on the
> list about Kastner doing salt flats racing and drag racing, he
> was pulling
> six grand on his motors.
>
> .....and Terry Ann Wakeman, who is also on the list, has a
> hot-rod TR3
> see her nice web site at:
http://www.cruzers.com/~twakeman/TR/index.html )
and I believe she has a harmonic balancing pulley on her car. I seem to
recall her saying once that she shifts at 5700 on on-ramps.
I'm jealous.
So here are my fears, questions:
When I had the motor balanced, the machine shop guy got a little beady-eyed
when I asked him if he had balanced the crank with the front fan extension
on the crank. I'm wondering now if that's the problem? It's a fair-sized
chunk of cast iron.
Or
Do these motors really need a balancing pulley to rev? Did Kastner have
these?
Or
It it just impossible to make them rev with a 35-40lb flywheel \ pressure
plate combo?
What steps should I take to make 'er rev?
Once again, I'd appreciate any first-hand experience from the racers out
there.
-jeffrey
Jeffrey J. Barteet, System Administrator
National Center for Ecological Analysis and Synthesis
735 State St., Santa Barbara, CA
barteet@nceas.ucsb.edu 805.892.2508
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