With all these posts of 'my boost is bigger than your's' does anybody know the amount of boost pressure that will depress the boost compensator diaphragm to it's maximum?
I realise that this pressure is related to the return spring rate and the star wheel position. Once this boost pressure is reached then any extra will only serve to weaken the mixture as the pump will then be at its maximum output.
It should be possible to measure the force needed to depress the diapragm to its full extent ,using weights, and then a simple 'Force/Diaphragm Free Area' calculation will give the approximate equivalent boost pressure. This will not be an accurate figure as the diaphragm does not act as a true piston as it is restrained at the edges but it should give a good idea. Has anybody tried to do this?
Max Boost?
Moderator: RichardW
Haven't tried mate, but at 20psi it's still pretty smokey, so badly over fuelling. I haven't had a chance to back off the max fuel screw yet, but it's on my list of 'to do's' for the weekend.[;)]
What effect does the boost compensator have, and how do you know when you have it set at the optimum.
I turned mine 180 degrees counter clockwise, but i'm not sure if I wound this back up when I re-tightened the 14mm nut.
Any info you have on this adjustment would be greatly appreciated.[:)]
What effect does the boost compensator have, and how do you know when you have it set at the optimum.
I turned mine 180 degrees counter clockwise, but i'm not sure if I wound this back up when I re-tightened the 14mm nut.
Any info you have on this adjustment would be greatly appreciated.[:)]
As I understand it the boost compensator has 3 variables:-
1) The torx screw on top of the unit, under the tamper proof cap, bears down on the top of the eccentric cone. Screwing this clockwise increases fuelling before the bost pressure moves the diaphragm. Counter clockwise decreases fuelling.
2) The diaphragm attached to the cone can be rotated ,as the cone is eccentric, to adjust the rate the fuelling. As the cone decends due to the boost pressure the pin is allowed to protude more thus allowing more fuel.
3) The star wheel beneath the spring (under the diaphagm) can be wound up or down. Winding down will reduce the spring pressure so that the cone will move at a lower boost pressure.
As I do not have all the dimesions and of the cone, diaphragm, camber and the spring rate it is difficult to determine how these values interact hence my first post. Rotating the diaphragm to face more 'slope'to the fuelling pin will increase fuelling at low boost, but by how much?
1) The torx screw on top of the unit, under the tamper proof cap, bears down on the top of the eccentric cone. Screwing this clockwise increases fuelling before the bost pressure moves the diaphragm. Counter clockwise decreases fuelling.
2) The diaphragm attached to the cone can be rotated ,as the cone is eccentric, to adjust the rate the fuelling. As the cone decends due to the boost pressure the pin is allowed to protude more thus allowing more fuel.
3) The star wheel beneath the spring (under the diaphagm) can be wound up or down. Winding down will reduce the spring pressure so that the cone will move at a lower boost pressure.
As I do not have all the dimesions and of the cone, diaphragm, camber and the spring rate it is difficult to determine how these values interact hence my first post. Rotating the diaphragm to face more 'slope'to the fuelling pin will increase fuelling at low boost, but by how much?