Weber jet size question.

[JoeJoe44]

Ok. So I have a 1968 mustang that I am rebuilding and adding a little horse power to it in the process. I have decided to go with the trip weber set up. On this forum i have seen different people talk about the different jet sizes they put in their set up and i was wondering why the change? Will stock jet size work or are they to small? I have a performance cam, 1.6 lifters, a cylinder head that came off a '78 (i believe) mustang for the intake and exhaust valve sizes, a DUI distributor, and im going to put headers on her. Any info would be great.
Thanx.

 

[Asa]

the more power you make, the more fuel you need
the more fuel you need, the bigger your jets need to be

if you want to make the most power, you eventually have to rejet your carb

also, at different altitudes you have to rejet, air is less dense up in Colorado than it is in Florida because you're higher up

 

[JoeJoe44]

So with my set up do i need to think about going with a larger jet size?

 

[64falconsix]

yes, the stock weber jetting is too lean to run. especialy with other performance upgrades. a correctley jetted engine will run leaner and sometimes require a jet change when headers are added due to the scavenging effect or after a performance cam is added. i changed both the idle and the main jets in my carbs. there is a weber jetting chart for the tri power setup on this site I cant remember where ,try to do a search. i get my jets from http://www.webercarbsdirect.com