Are any of you guys running a SpeedDemon 750 on a stout smallblock?

I just ordered a Speed Demon 750, but I got mixed messages while doing some research. I was told by one of the Demon techs that it would NOT be the right carb for my motor, he said my block was a little too racey and needed a RaceDemon 750.... all for the low low price of $675. He gave reasons such as my intake, heads, big cam, etc. He didn't even want to talk about the Speed Demon, even though it is advertised for motors from 350HP up to 500HP.

My motor:
406 SB
RPM style intake
AFR 195CC heads
Comp Cams CS 292H-10 244 degrees at 0.050"
10.9:1 Compression
TH400 3000 RPM stall, 3.73 rear.
(it's a very stout 406, but hardly a radical motor)

Second opinion: I called Summit's tech line and I actually talked to a guy that has 4 different Demon carbs. He didn't agree with what the Demon tech had told me. He said for ultimate tunability, yes indeed the Race Demon was the way to go, but for a car that will spend 95% of it's life on the street a SpeedDemon would be fine. He asked if I was really hellbent on buying a $675 street carb, and the obvious answer was no. As I suspected, he said getting the right size is half the battle, and choosing that properly will minimize the tuning necessary to get it running properly.

So... I went with my gut feel and my own homework and ordered a SpeedDemon 750. Even though the Demon techie didn't agree, I think I may be close. I guess I'll find out when I bolt it up. Are any of you guys running one on a 450-500 HP small block? or have an opinion on the matter?

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Shawn Peterson
1969 Z28, 406SB
http://www.geocities.com/corsican69

I've got the same carb on my 72. It's a 406, 11-1, Dart Iron Eagle 215's, Victor Jr., 284XE Comp cam, MSD dist., etc. It runs fine but from what I have been told by some good tuners, there's more to get but it will take some time on a chassis dyno.

Jody

I've got the Speed demon 750DP on mine, but i can't really comment on performance other than its alot better than the 625 Carter i put on there just for diagnosis purposes. I need to play with the accelerator pump cams/squirters to get it to perform better. I put one off of an old holley and it helped a little, but it still backfires every once in a while from a stop. Not nearly as bad as it did before. Anyway, i think its a great carb, and the Race Demon seems a little to pricey and really a waste for a street motor.


67 Camaro
383, Performer RPM heads, cam and Intake. Speed Demon 750dp.

[This message has been edited by Ryan67 (edited 08-07-2000).]

Shawn, you must have talked to the same guy I did when I asked what I should get for my 427 11:1 rectangle port motor. He too specified a Race Demon 750 and no way a Speed Demon. There must have been a "push the Race Demon" sales meeting.

Like you I'm hesitant to spend $675 for a carb - especially when the $400 unit looks viable.

My experience is that they're good carbs - I love my Road Demon.

Shawn,

I push almost 600HP with a BB 396 and a SPEED DEMON 750 DP carb. The rep you talked to was F.O.S.!!!!

The Speed Demon did NOT increase my HP over a HOLLEY 750 BUT it is much more responsive. Secondly, the Speed Demon does not have a problem BLOWING power valves or leaking like the Holley's do.

Now at this point in time, I expect a HOLLEY rep. to respond with what leaks???? We ALL know better, RIGHT???

WOW! Talk about conflicting stories from Demon. I had submitted my application notes via e-mail a few days ago... Check out the response this time around. I'm so glad all the techs there are in clear agreement.

"The 750 Speed Demon should be a good choice for your combination. You may
need to advance the initial timing a couple of degrees to keep it clean at
idle. The carbs do not come with chokes but part # 421440 is a complete
choke kit for this carb.
Thank you"


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Shawn Peterson
1969 Z28, 406SB
http://www.geocities.com/corsican69

Not a speed demon, but a holley 750 vs is what i run on my 406,modified some,850 base,secondary jet plate, choke milled, ect.and no problems. (400est.hp)

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My68Camaro (http://hometown.aol.com/Dougs68Camaro/index.html)
Doug G.
68 Camaro
406 ci.