And yet another T120...

Fast Eddie · Oct 14, 2017

Inlet cam now advanced by one tooth. Lobe centre timings are now inlet @ 99.5 and exhaust @ 100.5, which is pretty close to cock on by my reckoning.

It wasn't absolutely 'wrong' previously, it had been aligned to 6T markings as apposed to T120 markings.

The 6T is the more docile of the two of course, so it will be interesting to see what the difference is like on the road.

I'm assuming there'll be a bit more poke higher up the rev range and a narrower powerband, which the 5 speed box should compliment nicely.

In theory...

Triton Thrasher · Oct 14, 2017

Tightening the head bolts bulges the part of the bore nearest the threaded hole.

A pre-unit Triumph barrel at +60 thou is likely to show these symptoms, so it's worthwhile using bolts/plate to induce the bulges during boring. Unit 9 stud barrels have more metal between the threaded holes and the bores, so it may not matter much.

But then, a big bore kit thins the metal out a bit again, so who knows!

Triton Thrasher · Oct 14, 2017

Advancing the inlet cam improves low and mid rpm power. If it's been a tooth retarded, you will notice an improvement.

Fast Eddie · Oct 16, 2017

Well, against the odds, I managed to make a bit of workshop time and, I think, made some progress...
Burton Bike Bits belt drive, I've normally used Hayward, but (Andy) B-Bogus recommended this one, and as I was buying something else from them anyway, I thought I'd give it a shot. Seems well made and was very reasonably priced.

acotrel · Oct 16, 2017

From memory, moving the cam timing on a Triumph engine by one tooth changes it by 15 degrees. - Probably too much unless it was previously out by one tooth. Your engine should have 3 keyway cam wheels and the cam timing set by dial mike and degree disc. Then strobe the ignition.

Fast Eddie · Oct 16, 2017

acotrel said:
From memory, moving the cam timing on a Triumph engine by one tooth changes it by 15 degrees. - Probably too much unless it was previously out by one tooth. Your engine should have 3 keyway cam wheels and the cam timing set by dial mike and degree disc. Then strobe the ignition.

If I might suggest reading post #81 at the op of the page....

acotrel · Oct 16, 2017

Are you aware that many unit Bonnevilles had an E3275 Tiger 110 profile cam on the exhaust while the inlet cam was E3134 ? I think the Thruxton Bonneville had both cams E3134, but the exhaust cam had a different number because of the extension for the ignition system. We actually imported the E3134 profile exhaust cam and fitted it to a 1963 Bonneville. It became a very fast bike. You need to be careful that you get the timing right when setting up. Over the years, we have tried many different profile cams in 650 motors - the E3134 seems to be the best, but you need the 'R-type' followers.

grandpaul · Oct 17, 2017

I believe E3134 is the core cam blank, with the number CAST into it. The final grinding is denoted by a number STAMPED into it. Is this not the case?

Fast Eddie · Oct 17, 2017

E3134 is the Triumph designation designation for a cam form. Not a camshaft part number. According to Stan Shenton “Triumph Tuning” no less than 14 different camshaft part numbers had the E3134 form on them.

acotrel · Oct 17, 2017

The only E3134 cams I have ever seen have had the number STAMPED on them, often in addition to the cast-in number. The E3134 cam for the exhaust of the unit-construction Bonneville has a different number because of the extension for the points. I don't know what it is, but it makes a big difference to performance. When you are using the degree disc, if you don't have E3134 profile - you should know, because you won't achieve the timings. I usually do my setting-up with nil tappet clearance and correct for the error.
If you use 2 and 4 thou running clearances with the ramp cams from the late 50s preunit 6T, you can also get good performance with a bit more tractability. But you would not have the points extension on the exhaust cam you need for the unit motor.

Triton Thrasher · Oct 17, 2017

E3134 was the part number at one time, in pre-Unit days.

Triton Thrasher · Oct 17, 2017

acotrel said:
Are you aware that many unit Bonnevilles had an E3275 Tiger 110 profile cam on the exhaust while the inlet cam was E3134 ? I think the Thruxton Bonneville had both cams E3134, but the exhaust cam had a different number because of the extension for the ignition system. We actually imported the E3134 profile exhaust cam and fitted it to a 1963 Bonneville. It became a very fast bike. You need to be careful that you get the timing right when setting up. Over the years, we have tried many different profile cams in 650 motors - the E3134 seems to be the best, but you need the 'R-type' followers.

1963-65 Unit Bonnevilles had E3325 exhaust cam profile. That's the T110 cam profile. 1963-65 Unit Bonnevilles had E3134 inlet cams.

1966-on ordinary roadgoing Bonneville 650s had E3134 profile cams on inlet and exhaust.

E3275 was the Thunderbird ramp cam.

Fast Eddie · Oct 18, 2017

acotrel said:
Are you aware that many unit Bonnevilles had an E3275 Tiger 110 profile cam on the exhaust while the inlet cam was E3134 ? I think the Thruxton Bonneville had both cams E3134, but the exhaust cam had a different number because of the extension for the ignition system. We actually imported the E3134 profile exhaust cam and fitted it to a 1963 Bonneville. It became a very fast bike. You need to be careful that you get the timing right when setting up. Over the years, we have tried many different profile cams in 650 motors - the E3134 seems to be the best, but you need the 'R-type' followers.

I thought the Thruxton had E4220 cams, and ran with the very large radius followers. This set up gave the same cam operation as the later Spitfire profile with R followers.

The Thruxton cam is essentially a high lift version of an E3134 and is basically what Norman Hyde sells as his half race cam to be used with stock R followers.

I’m pretty sure mine has E3134s in the inlet and exhaust which should be fine for my intended purposes.

If I was to change them for anything, I’d probably go with Hyde’s half race, they get generally good feedback from users.

Fast Eddie · Oct 18, 2017

This damned gearbox has been a fight...

I followed the book to the letter and got the camplate quadrant indexed right first time. I could shift the quadrant with screwdriver and get all 5 gears up and down.

Then I assembled it all and ... terrible shifting.

Disassembled to check, everything looked good, checked the shifting of the quadrant with a screwdriver again, all good.

Assembled it all again... terrible shifting.

Long story short: the gearchange quadrant (a new and genuine 5 speed part) wasn’t allowing enough movement, I don’t know if the quadrant or outer cover were at fault, but I filed down the quadrant, a little at a time, trial fitting several times, until the shift felt good.

Assembl d it all again ... nice shifting !

It fired up first kick and a test ride showed the cam timing change has made a significant improvement and the 5 speed box has a very nice feel to it.

So... we got there in the end!

daveh · Oct 18, 2017

Fast Eddie said:
This damned gearbox has been a fight...

I followed the book to the letter and got the camplate quadrant indexed right first time. I could shift the quadrant with screwdriver and get all 5 gears up and down.

Then I assembled it all and ... terrible shifting.

Disassembled to check, everything looked good, checked the shifting of the quadrant with a screwdriver again, all good.

Assembled it all again... terrible shifting.

Long story short: the gearchange quadrant (a new and genuine 5 speed part) wasn’t allowing enough movement, I don’t know if the quadrant or outer cover were at fault, but I filed down the quadrant, a little at a time, trial fitting several times, until the shift felt good.

Assembl d it all again ... nice shifting !

It fired up first kick and a test ride showed the cam timing change has made a significant improvement and the 5 speed box has a very nice feel to it.

So... we got there in the end!

Well, Fast Eddie, you have been very busy! I missed a lot of posts because for some reason I no longer get email notification. Well done on identifying the quadrant problem. This was a problem on some of the 4 speed boxes and Triumph issued a Service Bulletin about it, and recommended as you did, to file down the quadrant, rather than the cover, until gears can be fully selected.

acotrel · Oct 18, 2017

The E3325 profile cams were fitted to my 1958 Thunderbird which had the wheel symbol stamped on the crankcases, denoting ramp cams. E3275 cams were fitted to my 1954 Tiger 110. You might be correct in your claim because that 1958 Thunderbird had much more go than I would have expected. I bought it from a cop, but somebody had been killed on it. I've never used the Spitfire profile cams, but my friend has in his road-race Triton and went back to E3134s. If you have a look at the timings of the two-valve speedway Jawa engines, they are pretty much E3134 and a lot of other fast bikes have similar. e.g. the SFC Laverda cam. Whatever cams you use, you will need to match the cam timings to the exhaust system to make the bike ride-able and fast. A restrictive exhaust system will kill the benefit to be derived from a race cam, that is when it might be more effective to advance the exhaust cam. I would not use open megaphones on separate pipes with a race cam - silly stuff.

Fast Eddie · Oct 19, 2017

I intend to keep with the 3134s acotrel and hope that Triumph did their homework on pipes, stock silencers are actually straight through anyway.

I have used spitfire cams and I liked them, certainly not as peaky and un usable as expected, it would still tick over and pull cleanly low down etc. but having said all of that, it was best between 5000 and 7000 rpm which is not where I want to be spending all of my time with the T120.

Fast Eddie · Oct 19, 2017

daveh said:
Well, Fast Eddie, you have been very busy! I missed a lot of posts because for some reason I no longer get email notification. Well done on identifying the quadrant problem. This was a problem on some of the 4 speed boxes and Triumph issued a Service Bulletin about it, and recommended as you did, to file down the quadrant, rather than the cover, until gears can be fully selected.

Did the service bulletin explain what was actually at fault, quadrant or cover?

Mine shifted fine with the 4 speed cluster in it. It would therefore make sense if it was the cover that was at fault, and someone previously filed down the 4 speed quadrant, so when I fitted a new one, I reinstated the problem!

Dave Degens used to set gearboxes up in an old case that he’d cut away. He then ensured the quadrant was indexing the cam plate perfectly before transplanting the cluster and covers into their cases. Cut away cases would have been handy to have on hand these last few days!

acotrel · Oct 19, 2017

I think the E3134 cams were first used with the 1953 Tiger 100 race kit - the one that included the frame with provision for rear sets and the skinny exhausts with megaphones. The exhaust pipe dimensions and inlet lengths used to be well-known and they actually did work well. From memory, I think the recommended exhaust pipe length was 38 inches for the straight pipe.

acotrel · Oct 19, 2017

I'm not one of those people who hate Triumphs. I think a unit construction Bonneville was one of the best handling bikes ever made and certainly had plenty of go. They are much faster if both cams are E3134. But when you race one, it is very difficult to get around that big piston crown poking up into the combustion chamber. My 500cc short stroker used 12 to 1 650 pistons - meant I only had 10 to 1 effective comp. ratio plus the high crown as well as the higher piston weight. The short stroke made some of that a bit better - but not much. It would rev easily to 10,500 RPM, but to my mind it was very wrong in the top end. The cams were very slow lift rate and very long duration - all silly stuff. Made it too difficult to ride well.

And yet another T120...

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