Stromberg temp compensators

[alan_thomas]

The last remaining thing to finish off the rebuild of my carbs were the temp compensators, they were stuck closed and ,when freed, opened at different temps.
There are random bits of info on the web but nothing specifically for the Stag. On the Grampian Stags excellent site there is an article reproduced from elsewhere but I suspected that the temps given for the adjustment were wrong, and so it proved.
Burlen Fuel systems have all the original data and are very helpful, they checked original documentation and this is the info they gave me.

The compensators have a letter code stamped into the long leg of the casting. The letter equates to a temp where the valve is just beginning to open.

'O' = 18c 'T' = 27c 'N' = 30c 'U' = 35c

My original units were stamped with 'O' and therefore should just begin to open at 18c . This is significantly lower than the 115F (46C) in the Grampian Stags article

Knowing the underbonnet temp on a stag even after a short run this would suggest that the compensators spend almost all the time fully open when running and are only closed for starting and cold wintertime.

Hope info is useful - Alan

[jbuckl]

O is a worn mark… it’s actually a C

C = 130…..

(or closed)

warning humour

[Goldstar]

I suspect they are more trouble than they are worth and so I just blank/close them off

[Philip Wardle]

I found an article by Steve Sutton which had originally appeared on the Vintage Triumph Register website and was repoduced on the Grampian Stags site, I think this is the one Alan has referred to. This is the pdf:

adjustment.pdf

I had a collection of six compensators which I adjusted and calibrated in a shallow frying pan on a hotplate using an infra red thermometer to monitor temperature. I then did a select on test to get three pairs with the best match in each pair. Open / close set points might vary a bit between engine types but I should imagine having the best match for a given pair has the most infuence on maintaining balance as the engine warms up.

[alan_thomas]

I found an article by Steve Sutton which had originally appeared on the Vintage Triumph Register website and was repoduced on the Grampian Stags site, I think this is the one Alan has referred to. This is the pdf:

adjustment.pdf

I had a collection of six compensators which I adjusted and calibrated in a shallow frying pan on a hotplate using an infra red thermometer to monitor temperature. I then did a select on test to get three pairs with the best match in each pair. Open / close set points might vary a bit between engine types but I should imagine having the best match for a given pair has the most infuence on maintaining balance as the engine warms up.

That’s the article Phillip, informative but wildly wrong with the quoted opening temperatures.

[Philip Wardle]

That's interesting to know Alan, I had assumed Steve Sutton's info (begin opening at 115 F / 46 C, fully open at 140 F / 60 C) were correct (at least for a TR6) as I had seen the same info on the Bullfish Garage TR6 restoration pages, but I guess the info could still be wrong or perhaps the Stag set points are different to a TR6. Not sure now ...

[richardthestag]

while you are at it be sure to source a pair of throttle discs with the horrendously unreliable poppet valve

Seriously though, the instruction on Grampian stags explains it as good as any

http://grampianstags.net/TCs.htm

Personally and on every single occasion I encounter them, I wind them closed and give them another turn so that they will not open. The carb set in good order will easily achieve 3.5%co and run better without them.