Hi,
I have one or two data points on this.
First of all, my experience has been that I cannot find specs on the
original TR6 "federal" version cam. There are specs on the net for the FI
cam, and I believe that cam to have more lift than stock.
I measured two cams, one from a '69 TR6 with HE engine number and another
cam that I have that has been regound to slightly more lift than stock.
The regrind cam has KCTH2 stamped on one end. I think it is/was an S2 cam.
At any rate, the cam lift for stock TR6 federal cam is .210. That
translates to .315 less rocker clearance of .010 to: .305 lift at the valve.
So, an Isky regrind giving .400 at the valve is roughly 25% more valve
opening.
The regrind cam that I have has cam lobe lifts at around .252. That
translates to .368 at the valve... quite a lot less than the Isky
grind... This one has been reground though, so it is probably a candidate
for a radical regrind with a bizzare profile. I could have some material
welded onto the lobes and then grind it for 290 degrees of duration like
the TT83 grind - power band is 4000 - 6800 and more than 190 HP. WoW!
This one won't idle - period.
Wait, I just found the stock TR6 cam profile. Check out the following
URL: http://home.sn.no/home/egilk/t_tune.html#camshaft. The first entry
there is for a stock Triumph 2500 cam. Again, this is presumably a little
higher lift than the "federal" version, so my numbers are probably okay.
However, it lists the lift at the valve as .330, so the european 2.5L engine.
All of the above assumes that you are using stock ratio rocker arms which
are something like 1.5:1. The URL above implies the stock rocker ratio is
only 1.42:1.
Note: another way to change your valve lift is by increasing the rocker
ration to 1.6:1. This is the easiest way to increased valve lift.
Now, given that the Isky cam is only changing the lift, this grind would
perfectly fine for street drivng and it'll idle fine. When you start
playing with the cam "duration", that's when the idle starts getting
"lumpy" or worse and your motor won't idle - period.
The Isky grind should be fine for the street.
regards,
rml
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Quote: How many Triumphs do you own??? Several. Does an engine count as .20?
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