Midget 1500 [Triumph] 1975 US Model

[datsun_medic]

Sorry, this is a double post from the Spridget forum, but it pertains more to the Triumph I suppose.

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I just checked the cam timing on my 1500. From what scarce info I've found online it's suppose to be 18:58, 58:18. Of course I don't know what those numbers are referenced to so it does me no good.

I've measured at the lifter 12:19, 54:29 @ 0.050. The intake centerline measures where the calculations put it but the exhaust centerline is off about 20 degrees (I could have made an error measuring with it being 3:30AM).

Is the exhause lobe assymetrical on these engines to compensate for the crappy exhause port?

If I base the centerlines off the calculations then my cam is advanced 4 degrees, which might be better with these numbers on the low-rpm torquey 1500.

The wear on the cam seems negligible and I'm getting 0.243 lift off the intake lobe. I haven't checked the exhause lobe yet. Next day off though.

Does anyone know the cam timings @ 0.050 on the lifter? Or does anyone know what lift the 18:58, 58:18 value is measured at?

 

[datsun_medic]

Ok. I realized trying to get the cam to lift significantly at 18 BTDC was futile because my centerlines were not at an even split if I did it that way. So I redegreed the cam using the centerline angle method and here are the new readings:

All taken at the cam...

0.010 16:59, 58:20
0.020 6:49, 47:7
0.030 1:43, 42:0
0.040 -3:39, 38:-5
0.050 -7:36, 35:-10

Centerline angles are ~112 for both intake and exhaust. Lobe separation at 110. Definitely a torque cam.

This gives a nice even split. So either factory cam patterns are established at 0.010 cam lift or it's a little worn, but even. I can live with that for the time being. I appreciate the ideas and support.