Can't find a carb!

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Can't find a carb!

Postby Monzadude » Wed Feb 27, 2008 9:05 pm

I've got a 231 with a 4 barrel intake and was told to get a 390 cfm carb. A Q-jet was recomended by a few people so that's what I'm looking for. I've looked around for one but can't find one. I don't know much about carbs so I'm sure there's places buy them that I don't know about. Any idea?

The intake had a Q-jet on it years ago but it wasn't very good. Someone had rebuilt it and did a very poor job. I was told by a few people at the time to get it re-done but didn't have the cash so I swaped it back to the 2 barrel intake and carb I already had. When I sold the car I kept the intake but the carb went with the car. I wish I'd kept it now.

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Postby mldeolde » Wed Feb 27, 2008 9:21 pm

check e-bay you might find one there but be aware quadrajets are notorious leakers and need to be rebuilt by only someone who is familiar with ther idiosyncrocys and is willing to do what it takes to make them right . when done right they are a good carb just not the ultimate performer but quite good enough for a lot of applications...
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Postby bugdewde » Wed Feb 27, 2008 10:10 pm

My 215 V8 sports an Edelbrock 500 carb (also known as a Weber and/or Carter) that has been de-tuned with smaller primary jets and rods by D&D fabrications. It's a dead bolt on and works great.

The jets used are 0.080" (original 500 uses: 0.086)
rods: 0.062 x 0.052 (original 500 uses: 0.065 x 0.052)

throttle response is great with the little 215. I assume it would be just as good on a larger 231.
RPI Engineering did a comparison of these two carbs (de-tuned Edelbrock 500 and Holley 390) on a 215 powered MG here..... http://www.v8engines.com/old-pages/Test/carbs-1.htm

Here's pages of info on the comparison between the two carbs:
http://www.google.com/search?hl=en&q=rp ... 0+390+carb

Brand new with manual choke was like $200. They are on ebay all the time. Any parts store would have them available, too..... Advance, AutoZone, etc......

Of course, you'd have to pay a little extra for the new jets and rods to swap in :? Just an idea.
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Postby mldeolde » Wed Feb 27, 2008 10:39 pm

i like the Edelbrocks for mid performence builds also. when i had to detune the 355 in my Nova to make it pass emissions requirements i put on a new 600 cfm ,electric choke, emissions certified carb. after changing the cam ,lifters,intake ,water pump, and the afore mentioned carb ,all aplicable emissions equipement the engine fired right up and idled like a Lexas. i was duely impressed. equipement with that carb..........
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Postby Astre-mutt » Thu Feb 28, 2008 12:02 am

I replaced my Quadrajet with a Holley spread bore. I've had it for years so I can't tell you right now what model it is. It's one of the newer styles that has a removable top instead of individual float bowls. You can change the jets in under 5 minutes with out spilling a any gas. Really easy carb to tune.
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Postby Sirshredalot » Fri Feb 29, 2008 12:37 am

ive got a spare 390cfm holley....it needs a few parts...actually a rebuild and a throttle arm....but its 93% complete...lol.

lemme know if you are interested.

God bless
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Postby Sirshredalot » Fri Feb 29, 2008 12:38 am

ive got a spare 390cfm holley....it needs a few parts...actually a rebuild and a throttle arm....but its 93% complete...lol.

lemme know if you are interested.

God bless
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Postby Monzadude » Fri Feb 29, 2008 5:49 pm

Thanks for the offer Shred but I'm not sure if I should get a used one. I don't know enough about carbs to do the work my self so I'd have to get someone to do it for me. Also how hard would it be to get parts?
Not knowing much about them I was thinking it might be better if I get something I can just bolt on and go.
Of coarse I don't have a clue what's involved in a rebuild or what it would cost. If it's not too expencive then maybe I'll go that way but i'll have to fine someone around here that can do it.

I've looked on e-bay but if it doesn't say what size it is then I have no idea what I'm looking at. There's a used Q-jet on e-bay right now that looks small but it doesn't say what size and it's used the condition unknown.
Wish I knew more about these things. It would make my life easier. Oh well, live and learn!
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Postby HAULIN' IT » Fri Feb 29, 2008 9:46 pm

Bill, There is only two cfm sizes of Q-jet's. A 750 cfm & 800cfm. This is the advertized maximum cfm they flow. From the outside, they are the same size. The nice thing about the Q-jet is the small primarys & the vacuum controled air valve that only lets the engine "see" the amount of air/fuel mixture it needs. This is how GM got away with using them on everything from V6's to 500ci Caddys. Lorne
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Postby Monzadude » Fri Feb 29, 2008 10:28 pm

If a 390 cfm carb is recommended then what would I do with a Q-jet? I know I had one on a 231 V6 before so can they be set up with little effort? 750 & 800 sounds really big for this engine isn't it?

I'm looking for something that will be decent for a daily driver( not too hard on gas) but still have some kick when I want it. That's why I was told to go with the Q-jet. Is that right?
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Postby spyder_xlch » Fri Feb 29, 2008 11:05 pm

I recently read on speed talk that there were more than 2 sizes of Q-jets made. Turbo Buicks used a smaller Q-jet. Not sure on the size.
EDIT: found the link, also says mercruisers used a smaller Q-jet

http://speedtalk.com/forum/viewtopic.ph ... light=qjet
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Postby HAULIN' IT » Fri Feb 29, 2008 11:29 pm

Matt, My goal is not to argue & please don't misunderstand, I'm NO Q-jet or any carb expert! Go back & re-read the post on Speed Talk. What it says is the secondary air door was severly limited, this was done on many of the smaller engines (v6, 260,267,305,ect) & this is how they got the new cfm flow rating. Not from a "smaller"bore carb. Are we in agreement on this one? I feel this is a good plan for Bill, just limit the amount the secondaries/air door open. Lorne
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Postby spyder_xlch » Fri Feb 29, 2008 11:56 pm

Opps, I didn't see that part. I always thought there were only 2 sizes until I read that on speedtalk. Guess I didn't read everything.
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Postby Monzadude » Sat Mar 01, 2008 10:46 am

Would the carb work off an early Regal t-type? I've found a few listings for them. They seem quite expencive but if they work. Rock auto has a listing but it's almost $500. I'd be willing to pay that as long as it's the right part for the job.

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Postby SunbirdMan » Sat Mar 01, 2008 11:23 am

I'm not sure about Regal T-Type but off the top of my head, I'd think that they are computer controlled carbs (at least in US) and probably pricier because of the application( turbo?). You don't want a computer carb. If I were you I'd check with some local carb shops and see what they sell rebuilds for. I don't know the layout of you 6 cylinder intake, but you may want to determine if you need a q-jet with the front fuel inlet or the side fuel inlet. The q-jet is a variable cfm carb.
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