305 with a quadrajet from a 350 -- main jet change required? what size?

[eric559]

just got a 89 alpha one with a 305 -- previous owner had started rebuild and I basically bought a pile of parts, now it is together and running well but boggs at WOT and loses power if given full throttle right off idle... it will ramp up slowly and run fine up to about 3/4 throttle, so my instincts tell me that the main jet is too big -- especially since the carb came off a running 350.
so, my question is:

What main jet size should I have in a 305 qadrajet?

unfortunately the original carb was completely corroded and was junked so I have no point of reference, I realize that I may still need to make adjustments but I am looking for a good starting point.
Unless anyone has any other suggestions -- should a 350 carb swap right onto a 305? could there be another problem?

any suggestions would be appreciated.
Thanks

 

[Bondo]

Re: 305 with a quadrajet from a 350 -- main jet change required? what size?

Unless anyone has any other suggestions -- should a 350 carb swap right onto a 305? could there be another problem?

Ayuh,.... Welcome Aboard,... Are ya Feedin' the carb good clean fuel, at good flow, 'n pressure,..??

I'd sooner think the carb just needs a good Rebuild, rather than different jettin'...

 

[eric559]

Re: 305 with a quadrajet from a 350 -- main jet change required? what size?

Ayuh,.... Welcome Aboard,... Are ya Feedin' the carb good clean fuel, at good flow, 'n pressure,..??

I'd sooner think the carb just needs a good Rebuild, rather than different jettin'...

I just pumped out the gas tank and put in fresh fuel, so my next trip to the lake will answer whether or not the gas was too old... although I dumped it into my truck and it runs fine in there. if it was a delivery problem wouldn't it take off for just a second and then crap out as the bowl empties? if i just punch it (like if I were trying to pull a skier) it just drops and sputters...

I'll get back to you on the gas situation, I have an electric fuel pump I can sub in temporarily to rule out the mechanical pump...

thanks