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SU dome springs?

karls59tr

Obi Wan
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There seem to be different dome springs in the various SU H6's I have taken apart. Were there changes over the years? Is there a set uncompressed length that is correct? Do the big 3 and the independent carb rebuilders all have the same spring or does it really make a lot of difference in the functioning of an SU if the springs are slightly different?
 
It does make a difference; and different springs were used in different applications. I don't have my SU application chart handy, but ISTR the spring was the same across the TR3/A/B line and early TR4 (although different for TR2).

Sorry, no idea if everyone is supplying the right spring.
 
You'll find some useful information at the following site on the Internet:

The Wonderful World of SU Carburetors, by Hitachi
 
The spring used on all the TR2-4a with SU carbs is the red 4.5 oz.one. (although the color marking is probably missing. It should measure 2.635" when loaded to 4.5 oz. Heavier yellow 8oz. springs are used on the SU hs6 conversion for TR6s. The heavier spring will enrichen the mixture, slightly.
Berry
 
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