I have a 350 tbi in my firebird with a comp cam .470 / .478 lift and 225duration.

heads machined to flow 210 cfm intake and 160 cfm exhaust

10:1 compression ratio

I am going to convert the car over to a carbuerator and would like an idea on what the best brands, models, and cfm rating would be best for my set up

Thanks

oh yea, i already have an edelbrock performer intake manifold

 

The heads and that intake are choking off your top end.

A Holley or Demon 650 would be a good choice. A 750 of either of those wouldn't hurt. A Stealth or RPM manifold would pick up the top end.

You need something other than TBI heads.

 

i believe it has old style heads on it that came with the block (77)
but they had been machines to flow what they do now....

another question.... as far as secondaries, is mechanical the way to go? or is vaccuum just as good?

someone i was talking to told me to make sure to get the mechanical secondary but if its not going to drastic improvement over the vaccuum then i wont bother

 

Smog-era 70's heads or TBI heads, they're bad news. The 70's are probably even worse than TBI swirl-ports, because they have large chambers which decrease compression as well.

Unless you plan on towing with the car, mechanical secondaries (also called double pumper) is the way to go.

 

Thanks alot man.

 

IMHO, if you have an auto tranny, go with vac secondarys.MHO!

 

well it is a very mild street car i'd go with a vac. sec. (750) ........but if your building a very hot street car i'd go with a 650 double pumper

 

The chart on this site is extremely helpful:

http://www.holley.com/HiOctn/TechSer...nfo/P225A.html

A 350 that stalls at 1500 RPMs can handle a 750 double pumper.

I'll admit I'm a recent convert to double pumpers. My early experience "back in the old days" was a 302 with a 600 DP, a cam that had a 2500-6000 powerband, and a Powerglide with 1200 RPM stall (I was a poor serviceman at the time and couldn't afford a higher stall converter). That made me gun-shy for years, and I always followed the auto-VS/stick-DP mantra. But the chart above finally convinced me otherwise this past July. You'll note, though, that my old 302 doesn't even make it on the chart.

If you have a very mild street car, get a smaller CFM double pumper (assuming you're on the chart).

I'm hanging on to my 750 VS because I may need to slow my car down sometime in the future.