T140 conundrum

Fast Eddie · Mar 27, 2022

IIRC Triumphs original spec was 100.5 for in and ex?

I read that having the ex at 105, or even more, is supposed to support a better mid range at the expense of some higher rpm ‘go’.

It would be interesting to try back to back and see if that’s true and what it feels like.

My T120 has E3134s and I got them as close to 100.5 as I could, can’t recall off hand what I ended up with. But mine has the light crank and that combined with the cams and timing sure makes for a revvy motor, which I love !

acadian · Mar 27, 2022

Thanks, standard T140 intake cam is 107 LC

Just checked valve/piston clearance and I have more than enough with the intake timed to 101, will see how it goes.

Pics!

Fast Eddie · Mar 27, 2022

You drilled drain holes in that front chamber right ?

acadian · Mar 27, 2022

Fast Eddie said:
You drilled drain holes in that front chamber right ?

Yes, and in the correct location too (i.e. bottom left corners)

Funnily enough, a spare primary stator wire boss makes for an ideal vent spigot

acadian · Apr 4, 2022

Got her all buttoned up and out for a break-in run, started first kick, took off right away and wow! She's quite a bit more lively now. A fiddly oil leak here and there but overall a positive return on attention to detail

Fast Eddie · Apr 4, 2022

Just recapping here…

So you still have the T140 inlet, timed at 101.

And a new 3134 exhaust, timed at 105.

Correct?

Do you know what CR you have ended up at?

And…

Did you get to the bottom of the oil pressure loss ?

acadian · Apr 4, 2022

Fast Eddie said:
Just recapping here…

So you still have the T140 inlet, timed at 101.

And a new 3134 exhaust, timed at 105.

Correct?

Do you know what CR you have ended up at?

And…

Did you get to the bottom of the oil pressure loss ?

Correct, inlet @ 101 and exhaust @ 105, using a standard copper head gasket, a base gasket, and with my crush figures I'm guesstimating a CR around 9:1.

Oil pressure issue not concretely identified, but the big ends were out of round by about .005, so maybe something there. I replaced them with new Harris rods. Also note the new PRV from Harris blows off at 60 psi as opposed to the 80 psi of the SRM valve I had in there previously. I still have the option of blocking off (or restricting) the tappet oil feed in the new barrels (if that is indeed a contributor to the oil pressure issue)

Onder · Apr 5, 2022

Once heated what sort of pressure do you see? Lower blow off is probably good as when cold you are better off and once hot I bet you don't see 80 pounds anyway. At least that has been my experience.

L.A.B. · Apr 5, 2022

acadian said:
Also note the new PRV from Harris blows off at 60 psi as opposed to the 80 psi of the SRM valve I had in there previously.

60 psi would be normal for a twin. A triple is 75-85/90 psi.

kommando · Apr 10, 2022

If your exhaust cam is nitrided then you can drop the cam follower oil feed, a T140 inlet will be nitrided but the inlets did not suffer as badly as the exhaust cam.

T140 conundrum

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