Triumph Rat Motorcycle Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
1,825 Posts
Discussion Starter #1
The parts manual for my "68" T-120 shows two 'O' rings listed for the tappet guide blocks, one for the intake and one for the exhaust. The guide blocks that I took out of the cylinder have a groove cut deep enough for an 'o'ring in the intake but not in the exhaust block. There is a very shallow groove but if an 'o'ring was fitted I'm sure it would be cut when installing the guide block in the cylinder. I'm thinking the exhaust must be from an earlier year that wasn't machined for the 'o'ring. If I use it, is it going to seep oil? Any feed back/recommendations greatly appreciated.
 

·
Registered
Joined
·
101 Posts
Each tappet guide has an o-ring groove cut right below the flange. The exhaust tappet guide has an additional groove cut about .375" below the o-ring groove with a hole in it. This is to provide oil flow to the exhaust tappets which in turn have a cut out and oil hole in them. They must be assembled correctly or the exhaust cam lobes will become starved for oil with increased wear taking place.

IMHO, you should use the correct bits for your engine.
 

·
Registered
Joined
·
1,825 Posts
Discussion Starter #3
The 'o'ring groove below the flange in the intake guide block is deep enough to hold an 'o'ring. The groove in the exhaust guide block is maybe a 64th of an inch deep if that, not nearly deep enough to hold an 'o'ring. I'm sure if one was installed there it would be destroyed when the guide block was seated in the cylinder. I'm going to run it without one for now. I still can't imagine designing a guide block that has a pressured oil feed without some sort of seal and then putting a seal ("O"ring) on the non pressure fed intake side but then the sludge trap oil filter system is pretty strange to me too.
 

·
Registered
Joined
·
101 Posts
Tappet guide block o-rings

According to my parts books, the first year for tappet guide block o-rings is 1967, when there was an o-ring on each tappet guide block. Prior to that, '66 and earlier, there were no o-rings on either tappet guide block. There is now an uprated o-ring for this application.

Hmmm, I wonder why Triumph changed their design. Nah, it couldn't be an improvement. :p
 

·
Registered
Joined
·
482 Posts
Can't say I've ever had a tappet block leak with or without the o ring mod, just a thin smear of hylomar and they are fine.
 
1 - 5 of 5 Posts
Top