[TR] Camshaft selections - TRactor Engines

[spook01@comcast.net]

Remember these are non counterweighted cranks.  They will rev to a max of 6500 with a fully prepped engine..a truly prepped engine.
There is a guy who builds proper counterweighted knife edged cranks - I bought one for my MG TB a while back - but that's overkill for a street car.
Another note: the rods on these cars stretch slightly at high rpm.  Wavelock type rod bolts/studs should be used. If you are using the stock bolts be sure to use a mechanical device to prevent the bolt from moving, such as the little tabs.  Lock tite will fail because heat generated will soften it....remember, you remove locktite with heat!

Sent from my Verizon Wireless Phone

----- Reply message -----
From: "TeriAnn J. Wakeman" <tjwakeman at gmail.com>
To: <triumphs at autox.team.net>
Subject: [TR] Camshaft selections - TRactor Engines
Date: Mon, Jun 27, 2011 08:42


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


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