SU Dashpot Springs (HIF)
Turbo Mini Forums

Hi All,

just a quick little question, what are the driving changes you will notice with a too soft or too weak SU dashpot spring, I know it slows down or inscreases the speed at which the dashpot will rise under acceleration but what would you feel when driving it it were too weak or too strong.

thanks

Grant

179hp on 12psi 1293cc of pure A series
14.0et @101 mph

If I have my SU carb theory correct the spring affects how far it rises more than the rate, If thats true then with a given needle it would affect the mixture, i.e stronger spring, piston rides lower, lighter spring piston rides higher.The correct spring is the one that allows the piston to fully raise to the top at WOT. What I have not worked out is how you can find out if it rises to the top at WOT... esp on a turbo The rate of rise is determined by the oil-- thicker oil slower rise, more enrichment


But thats where I come unstuck, if the piston is lower the needle profile would be on a thicker part of the needle making it leaner but the higher airflow caused by the restriction of the lower piston would suck up more fuel..richer. I guess it just depends on the profile change of the needle.

This is on my todo list when I get back on the road, I want to fit different springs and see what happens.


.

Terry

PS how goes the intercooler??

website:- http://www.terryhunt.co.uk