View Full Version : Carb selection help

Jimmy Sean
11-02-2005, 10:39 AM
I need to select a carb for my pontiac 350, was hoping for some recomendations. I have a 750 Speed Demon new in the box, 650dp needs rebuilt and a new base plate. I also have two quadrajets that need rebuilding. One is from a 77 454 gmc truck and the other is a unkown application.

I plan on turbo charging it in the future if that would be a consideration.

The motor has 9.0 - 9.5 compression.
Cam spec are, adv duration - 280/288, 0.050 inch - 223/231, lift - .463/.485, Lobe centerline is 104/116.
Max rpm would be 5500.
Edelbrock Rpm intake.
Headers, T-56, 4:10 gears.
Expect 290-340 hp, with nearly 400 lb-ft of torque.

Do you think I could get away with running the demon 750?


11-02-2005, 03:54 PM
Probably. It's a little bigger than you need. You also didn't state whether it was a DP or Vac. Sec. (VE) series. I'd prefer the vacuum if you're going with a bigger than necessary carb.

I think the Q-jet with it's smaller primaries would be a little more forgiving.

Jimmy Sean
11-02-2005, 06:02 PM
The speed demon and the holly are both mech secondaries.

I was hoping to get by for a while with the demon being that it is new. I am really limited on the budget to get this car going. After I get it going and sell my other car I could send a Quadrajet off and have it rebuilt. Really didn't want to spend any money on getting a carb rebuilt before I sell my other car unless absolutely necessary.


11-02-2005, 06:23 PM
In that case, just throw it on and see how she runs. Sounds like the only down side to just trying it, is the carb will no longer be new in the box.

If it runs like, junk you'll need a new game plan. Either that or sell the Demon (new in box), and use the money to rebuild the Q-jet. If you want someone to set it up for you, the Pontiac guys swear by Cliff Ruggles for Q-jet work.

I haven't used him myself as I typically run Holleys. But that's because I grew up using them, so I'm more comfortable working with them.

20579 Berry Rd.
Mount Vernon, OH 43050
(740) 397-2921

11-04-2005, 10:55 PM
I have a custom Qjet by Cliff and after 28 chassis dyno runs I verified the carb was perfect as delivered. Going richer or leaner lost power. My Poncho 455 made 435 rwhp and 495 rwtq (SAE) or about 500/570 at the crank. Throttle response is excellent. Highly recommended.

11-05-2005, 12:13 AM
Go Q-jet. But dont be a wussy, Re build it yourself and learn how to tune the damn thing your self. I enjoy building them my self.

A holley DP or Deman DP cant top the responce and drivability of a Q-jet on the street. Mine has NO BOG and at a "dead punch start" just roasts the tires.

Get a rebuild kit for about 20 bux then get an edelbrock accelerator pump and high flow needle and seat.
And feel free to ask questions.

12-10-2005, 10:57 PM
Hey mo67cam, would you be intrested in a trade? I have a zinc coated holley 750 with vaccum secondaries. Ive driven it on my 383 for about 100 miles. I just think a mechanical secondary would be more like what i want. Let me know.