Early Series 'A' Tappets

[Robert Watson]

Pins from Conways are .500 and after you have put the bushing in and discover that the threads are not tapped as deep as the hole and the pin bottoms out before getting home you then do discover that 1/2 BSF taps are indeed a few thou over .500! Fortunately only one bushing installed so not a big chore to rectify the threads except to grind down a tap to cut the last 2 threads!

Putting A stuff together ain't for the faint of heart..

 

[delboy]

Pins from Conways are .500 and after you have put the bushing in and discover that the threads are not tapped as deep as the hole and the pin bottoms out before getting home you then do discover that 1/2 BSF taps are indeed a few thou over .500! Fortunately only one bushing installed so not a big chore to rectify the threads except to grind down a tap to cut the last 2 threads!

Putting A stuff together ain't for the faint of heart..

Which begs the question,
why aren't Conways making 'em as PEI intended?

I Guess the heads might have been tapped with the 1/2" BSF thread with a guide bushing, before the E67 Rocker pin collar was pressed into the head? Maybe?

Why did nobody tell me they weren't for the faint hearted years ago!
Delboy.

 

[Robert Watson]

So where did you get the .500 in the E67 dimension from. Was it from an original drawing or from measuring things? Conways had no rockers so those came from Australia and were a perfect fit on the .500 pins. The old pin I have came from a Bronze head that came 4th at Daytona in 1938 on TTR110. It has been sitting since the mid 1950's but still that is close to 20 years on a race bike that had who knows what done to it!

 

[delboy]

So where did you get the .500 in the E67 dimension from. Was it from an original drawing or from measuring things? Conways had no rockers so those came from Australia and were a perfect fit on the .500 pins. The old pin I have came from a Bronze head that came 4th at Daytona in 1938 on TTR110. It has been sitting since the mid 1950's but still that is close to 20 years on a race bike that had who knows what done to it!

Roberto,
I never mentioned the diameter of E67? [It just so happens it is 0.500" ID]
Rocker bush E26 is 0.500" ID, From a factory drawing from dear old John Mellor decades ago.
QED, Rocker pin E28 should be 0.499" at it's largest.
It's all very typical PEI dimensioning.
Cheers, Delboy.

 

[Robert Watson]

Thanks, I knew that John supposedly had some of the original drawings. It would be great of they ever came to light. I think that the pins are now made .500 so the E26 and E 67 are both made .501 to accommodate that.

 

[delboy]

Thanks, I knew that John supposedly had some of the original drawings. It would be great of they ever came to light. I think that the pins are now made .500 so the E26 and E 67 are both made .501 to accommodate that.

If I had looked further than the end of my nose, I would have seen that Bob Stafford tells us the rocker bush is 1/2" bore and the rocker pin 0.499". - 0.001". That's in "Vincents ab initio".
So the new rocker pins could be up to 2 Thou oversize!
I don't quite get it, why wouldn't you make them original?
cheers, Delboy.