514/635. Speed demon or AED 850

[rated x]

a lot of replys think my cobra 514/635 h.p. should have a 850 holley,BUT which one! Vacuum or mechanical secondaries .There are some out there Barry Grant"speed Demon" AED which one would you choose for street use?

[scootter]

I have the 514/635hp Bracket with the 1050cfm with mechanical secondaries. Ford racing specs that size carb.

[rated x]

I think ford spec"s the 1050 dominator mostly because it is set up for 1/4 mile use and not really for street driveability. seems that carb likes real high rpm and takes a long time to warm up. anybody else agree?

[ItBites]

Get one of the many Holley clones instead of the Holley. Speed Demon is likely OK. The clones are actually improved over the original.

As far as carb size goes: I posted a whole dissertation on manifold pressure as a function of carb restriction in another thread and if I knew how, I'd direct you there, but:

Ford uses a 1050 or so because that is what the motor wants in order to make the best power (they can advertise big numbers that way). Driveability is somewhat sacrificed. Warm-up or whatever you're worried about is not the issue. The issue is signal from the cylinder to the booster venturi that draws fuel from the bowl. with a larger carb, the manifold pressure is closer to atmospheric and therefore the resolution of the signal is not as high fidelity as with a smaller carb. This is only an issue during transition from low to high throttle positions(Throttle response).

On the other side, with a small carb (and 850 is small for a racing engine of that size), the manifold pressure will always be somwhat low, even at full throttle, and resultingly the charge density into the cylinder will also be low, reducing power.

For power, you want a high density charge in the cylinder (more air and fuel = more power). For response you want better manifold vacuum.

Everything is a compromise. I'd go with the 1050 from BG or Speed Demon or someone that builds a good carb and with a light car and big engine, the throttle response issue will be hardly noticeable.

BTW, don't even bother with vac secondaries, that big mill will pull right thru any hole a vacuum sec is designed to fill.

OR do like I did and go injected and forget about vacuum signal required to pull fuel from a bowl - how primitive...

[Tom Wells]

Hello rated x,

I started with an 850 Speed Demon with vacuum secondaries on my 521. It stumbled, stuttered and bogged so much that it was extremely frustrating. That particular carb is NOT recommended. I went to Dahlonega and tried to get help. I let some "experts" fiddle with it. No joy.

Finally, I switched to the MPFI from Holley. It works well - after some sorting, but not near as much as was tried on the Demon.

If you're determined to stick with a carb, you might want to try a 900 or 950 Holley with mechanical secondaries. Edelbrock makes one too.

Yet another $0.02

Tom

[rated x]

alot of different ideas out there !what if I sent out my carb for some fine tuning?blueprinting? would I get better throttle respone at lower rpm??

[djseed]

I am using the the AED on my 501 and it runs like a champ. It may be a tad rich so I am putting on a bigger air cleaner before I monkey with the jets.

[rated x]

Will AED or BIG take my carb 1050 Dominator and fine tune it for my 514/635 h.p. I am looking for better response at lower rpm?

[Perf. Eng. Eric]

I like to use the Mighty Demon series carb from Barry Grant. It is better suited for the cam in the 514. I would go to the 850 size with the downleg boster. This carb actually flows close to what a 1050 Dominator will flow. Hope this helps

[joedeats]

Ive used holleys, edelbrocks (carter) and berry grants (demons) in my cuda I drag race and daily driving rods. Id say the best carb is the demon, it holds a tune and has alot fo really nice features not to mention it looks great. The choice however between which demon is dependent on what your doing, are you street driving, drag racing or road racing? they all need special set ups to be at there best. If you drive on the street with occsional drag racing id take a speed demon, good price lots of features and an 850 should work great.

[Shawn C]

rated x,
I have a Holley 950 HP that has been worked over for AED for sale if you want. I had it on a 460/535HP Ford crate engine. I am switching over to EFI. The carb has less than 500 miles on it since I got it back from AED. I'll also throw in the Edelbrock heatshield, regulator and fuel lines as well as spare gaskets and stuff if you like. It's only sitting on the shelf now. I have over a grand in it make a fair offer and its yours.
Ciao,
Shawn C

[rated x]

Ok it seems that I should get away from 1050 dominator and look at speed demon by grant what do you think 850 or 950?