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Discussion in 'Engine Topic' started by ddc456, Dec 6, 2011.
Run a 670 street avenger.
no way would I run a vac sec carb on a hot rod stick car
It is certainly a personal pref. I ran a 650 DP on a 460 BBC with an auto in a 5,500 lbs 68 Chevy 3/4 ton. Loved it. Goes against all logic and yet it was fun as hell. It was a factory 3.54 posi. Loved to go sideways in the rain and it was like trying to steer a school bus sideways.
What is your intake vacuum at idle? IF it is over 10" of vacuum (vacuum is measured in inches of water column NOT PSI) then run a vacuum secondary carburetor.
Here's my personal preferences:
Choice #1 carb for a "street" engine: Quadrajet hands down. It is the most economical (mpg) carburetor. Even Hot Rod (who are biased about Holley carbs) had to admit that the best OVERALL performand and economy carb is a Qjet. BUT, IMO, you have to have the correct intake for ANY carb. If you have a "spreadbore" intake than you have to run a Qjet or Holley spreadbore. BTW, you WILL NOT get better MPG or performance with a Holley Spreadbore.
Choice #2: Edelbrock Performer or Carter AFB. IF you have a squarebore intake, then the Qjet is out and the Edelbrock/Carter carburetors are the best choice for a street motor. JD had a Qjet on his '83 S10 with a 350 SBC, Edelbrock Performer cam and was getting 19+ MPG. He HAD TO have a better carb so he put an Edelbrock Performer 1406 carb on it and now get 16 mpg.
Choice #3: anything Holley. I am NOT a big fan of Holley carbs for the street. IMO, a Holley is the best performance carb as all you have to do to it to make it work on a cam'ed up engine (no vacuum at idle) is to install power valve blockoff plugs and upjet it.
These are all my opinions that I've formed from the 45+ years of working on cars.
Do you prefer Skidoo, Polaris, Artic Cat.......It think it's hard for new posters to get answers in these areas because there is just too much opinion which is usually base on experience. I have 2 mechanical Holleys running on a street tunnel ram flawlessly. Not a radical motor and 17" at idle. I have not had good experiences with Edlebrocks and hate Q-jets. What does that mean? Nothing
DP with a manual is the way to go and 650 is more than adequate for your 350. I run a Holley 750 DP on my 383 / TKO 600 and am quite pleased its performance from idle to WOT. This is not your average 383 either.......engine dynoed at 595hp and routinely see 7000+rpm. You wont have any issues or lack of breathing capacity using a 650 DP on a street 355.
People who say they hate Qjets usually have no patience with them nor do they know how to determine what is wrong with them. They are very easy to rebuild and to set up on a motor that has good vacuum at idle.
As for Edelbrock Performer carbs, almost all of the problems with them are related to incorrect float height and drop or vacuum leaks of which we had all three on JD's '83 S10 with a 350 SBC, Weiand Action Plus intake.
BTW, if you have any questions or problems with a Qjet, PM Damon here as he is VERY knowledgable when it comes to Qjets.
Actually, my reason is a pretty stupid one. I hate their looks. Same reason for the lack of love for most Chrysler products of the 60s. Don't care if it has a Hemi or not.....if it looks like ass then what's the point. I know on the other boards guys will argue function over looks but you certainly get both with a Holley. Like the Q-jets, you need to know what you are doing. I go through about 300 Holleys in one way or another each year. I think a lot of guys dislike Q-jets because they have never had a good one to start with. They think "swapping gaskets" is rebuilding one and it doesn't work that way. Like you say.....they need to be correctly setup!
Problems with Qjets: original floats would sink after using dry gas (isopropal alcohol) causing flooding. Welch plugs in the bottom of the main body start leaking causing hard starting when engine is warm and a definate loss in fuel mileage. Carb base to throttle shaft bore gets worn out = vacuum leak = surging engine at idle and difficult to set idle mixture screws. Late 70's "electronic Qjets" a challange to tune for those of us who aren't electronicly adept. Difficult but not impossible to tune for cams that kill intake vacuum at idle.
Almost all of the above can be said about any carburetor BUT because there were literly MILLIONS of Qjets on vehicles from the middle 1960's to the late 1980's, people either embraced them (and made them work) or abandoned them (and "fixed a problem" with a Holley carb.)