I need a drawing of ET84, exhaust nut

[Monkeypants]

The belt drive is 40 mm with a 7 plate clutch, thinned plates. Top ends are from the last batch Terry made up (unless there is a penultimate last batch) 92 MM heads and cylinders.
The crank is 102 MM stroke with oversize mainshafts.
The cases are machined for same, fortunately Molnar cases have just enough metal for the 72 mm mainbearing size. Original cases don't.
I dont know what to use for a starter, Was advised that the Grosset starter wont be up to the job.



Glen

 

[Bill Thomas]

Hello Glen, They look a lot like the Tom Sommerton Cams from many years ago, I have a set in my Special, But my followers look like standard ones with the lumps welded on, I like them, When you turn the engine over it is a lot less clacky !! Cheers Bill.

 

[johnmead]

No, they are relieved on the top.

 

[johnmead]

My crank has 30mm main shafts and I am using a pair of Timken tapered bearings on the drive side. It was a bitch to get the ET77 replacement spacer to the correct thickness so the rods were centered in the cases. I also had to shim the oil pump gear to make sure it was centered on the pump shaft so I didn't get any extra friction and wear on it.

I have had the topend kit from Terry for 3 years so it may be from the penultimate batch.

I contacted Herve on the starter kit and a 92x92 engine and he said that as long as the initial advance was low enough it should work ok. With the dual plug heads, I am going to be running full advance at 28BTDC so initial would be in the range that he likes.

When starting the engine I plan on holding the BT-H kill button down until the starter is spinning over, then releasing it.

John

 

[Monkeypants]

Ive heard that with Sommerton cams in an otherwise stock bike you will never be late for the movie. Must have been a very good profile.
Glen
l

 

[Monkeypants]

Herve is making a starter of his own that is supposed to be stronger than the Grosset. It is being tested on a 1360 hi comp motor at this time.

Glen

 

[Bill Thomas]

Hello Glen, From memory they were a bit more square than Terry's, But I have not been in there since 1980 !!, I was always worried that the welded bit would fly off !! Good Luck, Bill.

 

[Howard]

Hello Glen, From memory they were a bit more square than Terry's, But I have not been in there since 1980 !!, I was always worried that the welded bit would fly off !! Good Luck, Bill.

I had some Somerton cams in something (my memories gone too) not a Vin, and I remember thinking they were like a speedway track - 2 180 bends and 2 straights.

H

 

[Monkeypants]

Just read an old MPH technical article on Vincent cams, written by Norman Walker. He compares the special Picador type cam to MK2s but also notes that he has been informed by Prof Higgins that the Picador cams he measures are actually Somerton copies of the Picador setup. Apparently some Picadors got MK2s, others got this more radical cam which uses curved followers. These are the cams that Somerton copied. So the curved follower on a Vincent engine is a very old idea.

Norman Walker mentions that he transformed the performance of his standard displacement Vincent by installing Somerton cams. It suddenly became capable of 135 mph at the end of a standing start 1/2 mile.

He also discusses a flaw in the profile of the MK2 Vincent cam. This same basic flaw is also present in the Series A cams as noted from data provided by John Lumley.

Glen

 

[Howard]

http://www.voc.uk.com/net/docs/3.5c/3.5-595-25.pdf

I'm having a slow work day.

H