mechanical & vacuum secondaries

[rockingchair69]

I was wondering if anybody could exlpain what mechanical & vacuum secondaries

 

[rockingchair69]

I also had another question how do you know if you have a standard or reverse rotation water pump and whats's the difference

 

[HISSIN50]

Very simply stated, mech secondaries are mechanically actuated when the throttle is depressed a certain degree.

A vac secondary checks for a certain vac threshold across the venturis to actuate.

Standard water pumps are normally used with V-belts. If one has a serp belt and the back of the belt spins the pump, a reverse unit is generally used.

Good luck.

 

[rockingchair69]

thanks for the help. I was also wondering how can you tell the difference between mechanical & vacuum secondaries adwell as engine vacuum. I was hoping someone could give me an explanation on the concept of engine vacuum, like what is it and why is it necessary. thanks again

 

[86bluecobra]

a carb that has mechanicall secondary's does not have a vacuum canister on the side (vacuum diaphram) that opens and a spring that closes them. the mecanical just has a linkage. You need to make vacuum in a n engine so that things like power assisted brakes work.