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73-87 Chevy _ GMC Trucks => Performance => Topic started by: Uno99 on August 10, 2007, 06:21:47 pm

Title: How much carb?
Post by: Uno99 on August 10, 2007, 06:21:47 pm

I need to put a new carb on my truck.  I have an 81 GMC (used to be a 5.7 diesel) with an OLDS 350 yanked out of a 79 Toronado. My Uncle did the conversion about 7 years ago but has passed away so I don't have much info on he internals. My Dad recalls that he put an Olds 442 cam/Lifter/valvetrain in it. Basically stock parts nothing wild. I just picked up an Edelbrock Performer intake for it and it has stock manifolds with 2.5inch true duals that's it. It has a quadrajet on it now and what I have read it may be a 750-850 cfm QJ carb that seem alot for the motor. What do you think would be a good carb. I looking at a holley 4160 600cfm carb right now.  The guys on the Olds boards keep telling be to rebuild the Qjet but I have had nothing but problem with qjets.

Title: Re: How much carb?
Post by: FlatBlack77 on August 10, 2007, 07:47:04 pm

If I was you I would either rebuild that Q-Jet or get a remanufactured one. You've probably heard that befor but that's just what I think.

Title: Re: How much carb?
Post by: 123 pugsy on August 10, 2007, 08:07:26 pm

600 cfm should be more than enough. Over carbing is not good.

Title: Re: How much carb?
Post by: VileZambonie on August 10, 2007, 08:43:31 pm

There's no better carb for your Olds motor IMO either replace the Q-jet or rebuild it as suggested. If it's giving you problems be specific as to exactly what it's doing and we can help you pinpoint your problem

Title: Re: How much carb?
Post by: 75stepside454 on August 13, 2007, 04:23:45 pm

The Q-jet is roughly 800 c.f.m., if it were a square flange carb it would be way to much, but a q-jet uses very small primarys for great off idle response & cruising. Q-jets can be a pain if not properly tuned, but done correctly there hard to beat.
 My first choice would be a q-jet, find someone in your area who knows em well, or contact val Hedworth in macon MO..he knows all to well.
 my second choice , since your using stock manifolds & a performer intake, your staying within 5500 RPMs, really maybe within 5000 RPMs. Id say 600 cfm holley or Edelbrock...I prefer Holley myself. If I recall correctly the Performer intake for 350 Olds only accepts a q-jet, so youd have to use an adapter...Id rather use a q-jet

Title: Re: How much carb?
Post by: Uno99 on August 13, 2007, 07:52:35 pm

What does it run to rebuild a qjet?

Title: Re: How much carb?
Post by: VileZambonie on August 13, 2007, 09:33:05 pm

$25

Title: Re: How much carb?
Post by: FlatBlack77 on August 13, 2007, 10:40:24 pm

I need to do the same where can I get a rebuild kit? advanced auto or auto zone?

Title: Re: How much carb?
Post by: Captkaos on August 14, 2007, 11:01:02 am

Just about anywhere should have a rebuilt kit.  Advanced, Autozone, Napa....

Title: Re: How much carb?
Post by: Uno99 on August 15, 2007, 01:05:15 pm

I went with a holley 4160 adj carb with electric choke. The qjet is in pretty good shape. I'm goona clean it up and either sell it or take a stab at rebuilding it.

Here are a few pics of the new carb and the used performer intake I picked up for $70.  The intake cleaned up ok and I painted the valve covers. cruise control module, and thermostat housing.  I still have a few think to button up but I've got to tell you...this think runs like a whole new truck I am soooo please with the outcome. My qjet was on it last leg.

(http://i25.photobucket.com/albums/c69/Uno99/carb2.jpg)
(http://i25.photobucket.com/albums/c69/Uno99/Carb1.jpg)