Well after spending the past month or so focused on body work and cosmetics, I have finally had a little time to dump into working on my carb. I have a 79 camaro with a 305. It has what appears to be a 350 iron intake and a 750 quadrajet.I assume this much carb would be way to much for my engine and plan to buy one smaller. (prolly a 600?) Could too much carb be the reason for secondaries not opening under full throttle on the road? When I first bought the car I tried to do a little burnout just to see what it had and when I punched it with the brake down the carb choked and the engine died. I guess im not exactly sure how vacuum secondaries work. Any info on vacuum secondaries or advice would be greatly appreciated! Thanks!

 

Too much carb would not keep the secondaries from opening. When you say the carb "choked", do you mean it flooded the engine or did the engine backfire. If the engine was flooded, your problem is more than just the secondary fuel circuit. If the engine back-fired (lean mix condition), your secondaries could have a couple of issues. There is a dashpot on the rear passenger side of the carb the slows the opening of the secondaries, this part may not be functioning correctly and is allowing the butterfly to open to quick. Also, it is possible the gas feeder holes to the secondary metering wells could be plugged, this would stop gas from getting to the secondary circuit entirely.

Another thing, if the butterfly is stuck, the engine would get too much fuel when the secondaries open.

 

There is also linkage on the passenger side of the carb that prevents the secondaries from opening if the choke isn't opened fully. Make sure your choke opens all the way, and that the lingage then drops out of the way.

 

thanks for the input...your advice seems to be pointing me toward buying a new carb...the one I have now isnt even worth rebuilding as it is missing parts and linkages on the passenger side...and it would be nice to have an electric choke for those cold starts...do you guys think a 600 would be alright or should I go for somethin smaller?

 

Also, by "choked" i mean it sputtered and died. Iremember it didnt backfire so i would lean toward it flooding. To be honest it was such a long time ago i dont exactly remember...I may have to try it out again to see what it does...

 

So i checked it out and its definately flooding. I put it in the drive way and revved it up in park and the secondaries opened great and it ran perfect. I put it in drive and gassed it with brake on and it flooded and died as the secondaries tried to slightly open...

 

So after checking it out some more and doin a little research ive decided that the vacuum advance it shot. I disconnected the advance and ran the engine in park and in drive and recieved the exact same results as when it was connected. How do I go about repairing this problem? thanks

 

Sounds like you may need to just take it off and do a re-build if its been on there a long time.
Theres been some talk about the ethanol gas "eating" at gas tanks, fuel lines, etc. and small pieces of debris clogging the fuel systems and pick up filtersof tank sending unitsin older cars. If you are thinking about a new carb, Summit or Jegs are good places to look. Itook a 750 performer Edelbrock off my 350 ZZ4 and replaced it w/a thunder 650 AVS endurashine. Havent had to touch it since I put it on, well over a year ago. If you are strapped for cash, I still have the 750.

http://store.summitracing.com/egnsea...400065&Ntk

 

Yeah I am trying to do this as cost effectively as possible. But I was lookin for something smaller than a 750. I actually would love to get a 500 for my 305 but it seems like they are impossible to find used for a descent price. But to fix the rest of my problems I debating just buyinga new gm distributor. I found I guy who sells them on ebay for like 60 bucks. I also figured I may as well swap the intake as well if im gonna have the carb and distributor out. I thinkin this would be the best long term solution to make my engine more reliable.

 

go with a Holley 600 with vaccum secondaries and an electric choke and you won't be disappointed.

the Rochester Quadrabog were horrible carbs and they aren't to friendly to tuning. they sucked back in the day and they suck now.