I am looking for some guidance on how to properly pick the right carburetor for my engine.Below I have listed what I think are some of the important details that one would need to be taken into account when trying to make this choice.I have had some people recommend the Holley Street Avenger 770 and others recommend the Street Demon 750.I am a true novice in the engine building aspect of auto restoration and would appreciate any feedback, insight, straight-up “schooling” from the seasoned veterans like Cutlassefi and/or Smitty275.Thank you all for your assistance. Also I will be installing this motor in a 67 CS that I will primarily be a street car.

1970 F Block bored 0.40
Mondello hydraulic Cam Shaft (JM 20-22)
Intake Lift=0.496
Exhaust Lift=0.512
Adv Int/Exh Duration=266*/266*
Intake @ 0.050=226*
Exhaust @ 0.050 = 230*
Lobe separation =110*
RPM Range =1400-5800
Mondello Posi Flow Heads (not ported)
Edelbrock Performer Intake
Mondello Forged Aluminum Pistons 0.040 (14.5cc Dish)
MSD Ready to Run Distributor (8529)
Hooker Comp Headers
Pypes 2.5” exhaust

 

Here is a rebuilt 7040251 QJet, affordable

http://www.442.com/class/partsforsale.html

 

Thanks Octania.... So I assume you recommend the Qjet. I had one dealing with BAP and that was an ordeal so I wouldn't be buying from them.


I look forward to hearing from others. Thanks again.


Drew

 

I'm a Quick Fuel guy. I'd do their 830 Electric Choke. Or for max performance an 850. Look at 70cutty's build. That had an 850 on it and pulled over an inch of vacuum at wot. That says the carb wasn't big enough.

 

Thanks Mark. I did some preliminary research and it looks like either the HR or SS series would for my application best. However, I didn't see a 830 cfm in either series. I will continue to research. Thanks again for your input.

Drew

 

Try their Super Street 830. It's a true 830. Their 850 is really 870-880, it uses the same body as their vacuum secondary 880.
But both the HR and SS series offer removable air bleeds etc., that's key in being able to tune it the best way possible.

 

Mark I really appreciate your guidance on this. I will look into this. Thanks again.

 

If you plan no 1/4 mile runs, the Qjet or Street Demon 750, which is an improved, new castings version of the Thermoquad, will provide much better mileage.

 

Hmmm not so sure Christian. A well tuned QF will do well too.
They have changeable low and high speed air bleeds, adjustable linkage on the double pumpers and adjustable vacuum secondaries on those models as well. Plus you can change the power valve circuits too.

I've used a half dozen in the last couple of years. Only had to make minimal changes to any of them.

The Hot Rod series is an HR-850, the 830 Super street is an SS-830.

 

I don't intend on going down the 1/4 mile but I am also not overly concerned about fuel, I mean it's a 455 it's going to slam through the fuel no matter what. I just want something that best fits my application.

 

Cutlassefi:

Just looked at the Quick Fuel site and couldn't find a vacuum secondary 880 listed. Could you point me to it.

Thanks,
Scott Dean

 

For some reason they're not on there but go to Summit, they're on there.
http://www.summitracing.com/parts/qf...0-vs/overview/

 

The carb isn't for sale by BAP it's a private seller in Tucson AZ. He posted the "parts for sale" section from 442.com. The second posting has two 7040251's for sale.

 

I saw the BAP at the top of the page and I just closed the page.

 

Probably true Mark, not like a 455 owner is after max fuel economy as he said. The Quickfuel are very nice, many features for their price.

 

http://www.aedperformance.com/ho-street-strip-carbs


AED HO series 750 & 850 HO carbs are my go to carb for a performance application. Never a problem with them & competitively priced.

 

The Quadrajet works for me. I run a 77 Olds Qjet on my 72 stock 350, with a rebuild kit from Cliff Ruggles. But it takes some diligent tuning to get the most of it. It offers good economy now, and no bogs.

 

Thanks dave and seff. Everyone's input is greatly appreciated.

 

Thanks I appreciate it.

Scott