I want to get a Rochester Quadrajet carb to put on my rebuilt 455 Olds engine and was thinking of getting a remanufactured 4MC Rochester Quadrajet from Rock Auto.
Engine is bored +30 thou,9.5 comp ratio,has mild cam,1972 Ga heads (2.072"/1.685" valves with Air bumps removed)1972 cast iron non egr intake and Hooker Headers.
Engine is going into a 1972 Firebird with auto trans.

Which year and model Olds with a 455 in the Rock Auto catalog should I choose a carb from ?
Do you guys think a carb for a 1970 Olds 442 or Cutlass would be a good choice ?
I know whatever carb I get will prob need rejetting at a later date but which carb do you guys think would be the best starting point ?

 

Commercially rebuilt Q-jets generally aren't consididered a very good choice, to one that has been custom built up by a good carb shop that know's what they're doing. Contact Q-Jet guru Lars Grimsrud v8fastcars@msn.com, and he'll send you his Q-Jet tuning papers. The Q-Jet I'm running on my 455, is off a 77' 403 I had since new, set up/jetted for my application, and is very reponisive. Well worth the trouble.

 

Check out he 442.com site for tech information on quadrajets. I know practically nothing about carbs, but that site has been a good education. I also bought Cliff Ruggles book on Quadrajets, and that by Doug Roe, both of which I found very informative. Cliff seems to like the 1976+ M4M carbs as a starting point, note that from 1980 on they had the electronic parts which you do not want. From what I have read so far 76-79 would be a first choice core and tuned for your setup, but I look to the more experienced to confirm that.
People on CO seem to think highly of Sparky's, http://www.sparkyscarbs.com/, and apparently if you tell them your application they will tune the rebuild accordingly.
Let us know what you decide and your experience.
Cheers, Peter

 

Thanks for replies. DeltaPace77 - yes,I still have the factory fitted Quadrajet on the 403 in my 79 TransAm,it still runs great !
I'll email Lars later.

pcard - yes Peter,442.com site has great info,I regularly check out stuff on there. I have Doug Roes book too.

My reasoning for maybe getting a Quadrajet from Rock Auto for a 455Olds for a 1970 442 or Cutlass as a starting point was that out of the box I thought it might be a bit more performance orientated and a closer match to my engine modifications than say a carb from mid to late 70's.
Cheers

 

As Delta says - you may be disappointed with the product right out of the box from a generic auto store. The ones dedicated to carbs would be best. Call one of them and explain what you have and they will work with you. The 70 carb specs may not be the best starting point from what i have read.
Cheers, Peter

 

I've either had nothing but trouble from a q-jet or no trouble at all. If it works it works. When I replace one I use Edelbrock. But if you can find somebody that knows what they are doing to build/rebuild one for you you'll probably never even think about a carb again. Like I said they either work or they don't. I'm sure it's all in knowing what you're doing and I don't. The 442 we just got has one and it works just fine. Step-son calls them quadrajunk like all ford people do and has the wife wanting to replace it. I think I'll just tell her I replaced it. She'll never know. Maybe I'll put an edelbrock sticker on it and call it a day.

 

Ok guys,after hearing what you think re rebuilt Quadrajets and having been in touch with Lars I now wont be getting a rebuilt carb from Rock Auto,Summit etc.
I think i'll just get a brand new Edelbrock 750 cfm carb from Summit shipped over and use that instead

 

Problem with a new carb out of the box(no matter the brand), is it's still gonna need proper tuning/jetting to your specific engine set up, to run right. Really think a well set up Q-Jet is a better choice than an Edelbrock 750(actually Carter AFB). Also, remember the two carbs use different intake manifold patterns.