[TR] Camshaft selections - TRactor Engines

[TeriAnn J. Wakeman]

On 6/26/11 10:45 PM, Randall wrote:
> However, even the stock camshaft should pull OK out beyond 5000 rpm.  The
> factory redline was not because the engine ran out of cam, but because they
> weren't sure it would hold together for the entire warranty period if turned
> faster than that.

Which makes the standard cam good for for a stock engine and maybe a 
mild 260 cam might have a bit more pull approaching 5000 RPM.  Bigger 
cams, like a 280 degree cam pulls strong into the 6000 RPM area  but 
that is not an area where stock engines should be playing.


  if memory serves, the reason for the 5000 RPM red line is that there 
is a real nasty harmonic around 5200 - 5400 RPM that breaks the crank at 
the base of the flywheel mounting flange if you spend much time in the 
low 5000 RPM range.

The whole purpose of the common harmonic dampener kit is to tame that 
harmonic.

I don't remember exactly where it is but I believe the next major 
harmonic is in the low to mid 6000 RPM range and it tends to break 
cranks in the middle and beat up the middle main bearing.  Spend much 
time in that range and it probably would not hurt to drop the pan and 
inspect main bearings every once and a while.

That said, fully prepped race engines often run at 6500 with a nitrided 
stock crank.

My TR3 has the harmonic dampener kit and a nitrided crank.  I usually 
shift at 6000 RPM when I'm on it and the engine has held together well.  
I have a 280 degree cam that pulls strongly to about 6000 RPM and has a 
wide peak.  But with a totally stock engine I would shift at 5000 RPM 
just because I worry about major harmonics.

Getting back to cams, compression affects how well they work.  If you 
have a TR4 head & 87mm pistons the 260 degree cam might be best.  But if 
you have the TR3 head with less squish area you might see added benefit 
with a 280 degree cam and a harmonic dampener kit.  You need to go to an 
electric pusher fan if you go to the harmonic dampener kit.

There have been soft lifters offered for sale over the years. Either buy 
new lifters that have already been individually hardness tested or have 
them tested before installing. Each should be Rockwell  hardness or 56 
or above.

And be sure to use an oil with adequate ZDDP.

Teriann