well i have a 305 ,5 speed 470 lift cam,323 in the rear ??? looking to buy a car carb.I have a few to pick from a carter spead bore or go with a vac sec 600cfm holley or holley 650 cfm dp mech sec.I have owned a 650 mech sec and had no prob but that was on a 350.Don't really know

 

go with a 550-600 cfm carb.........and if you have a manual transe try to get a mechanical secondaries carb.......tho ive ran a similar setup yrs ago with a 600 cfm vac secondaries carb with no issues.just had to tune the secondaries by changing the spring

 

Go for the 650 DP.

What Carter spreadbore are you looking at? Carter hasn't made a spreadbore carb since the Thermoquad stopped production in 1985.

 

if you use the 650 you will have to re jet it for the 305.plus you will have to lean it out as well.........why over carb a small engine????????

 

You have to re-jet any carb for any engine to get the most out of it. A 650 isn't such a terrible stretch for a 305.

 

very true but why not start with something that is close to what he needs

 

There aren't many suitable performance DPs that come much smaller than 600-650 CFM. Smaller carbs tend to be VS designs for fuel economy, or DPs for dual carb NA and blower setups.

 

well i found a 650 dp ms for $50.00 i think its a score for the price in pretty good cond ,but i also fount a 600 vs in almost mint for $30.00 what would be the better one i am borrowing a holley 600 vs from some one i know for now but i don't really feel the sec ??? it worked perfect on his motor he says i just don't like the feeling is this the way the work i had all ms in my motor but they were all 350s

 

You shouldn't ever feel the secondaries if a carb is tuned properly. Either of those would work, the DP would be preferred. Expect any used carb to need a rebuild.

 

 

Yea i think im going with the double pumper and just mod the jets in the back so when flooring it im not over carbing it.

 

the 650 is a good choice specially with the price being so low...please go thru the carb and also try these jets 62/70 or 63/71 should be good for what u need

 

Well not to take the conv some where ealse but the reason for switching carb is because my Qjet started acting funny but i think i found the fix ??? Do any of you know if my Qjet shold read the same vac reading as a holly would ? I'm geting 16 from the holly and only 14 1/2 from the Qjet