damac

I am trying to decide what carb to put on my 406 I am putting in my 65 4-speed coupe. I am currenlty running a 670 Holley street avenger on my 327 and I am very pleased with it. I need more flow for the 406, so I am thinking of going with a 770 holley. A couple of people have told me that the best carbs around are Demon carbs. I am not sure which way to go.
Does anyone have any info or opinions on the Demon carbs?

Thanks,

Mike

je68

The Demon is better then the old Holley but the new HP holleys look like they felt some heat from demon. So the new holley Hp might be as good but I dont think it has the CNC machining that the demon has on the metering plates.

gearheadz

IMHO, the quality and engiineering of the Demons exceed the Holleys by far. According to published tests (CHP) they outperform the Holleys in head to head HP tests as well.

Mark

Brutal64

I have a couple of friends (Blkblt and MileHigh66) that replace their Holleys with Demons. Both had 8-10% gains in H.P, throttle response and driveability also were improved. The Demons are beautiful well engineered pieces of equipment. I will be replacing my Holley with one as soon as money will allow.

Sigforty

If you use a Demon be careful of over carbing. I have had alot of friends recently purchase Demon carbs at the same cfm as the holley they use to run, and have problems with running to rich. I think the Demon design is so good you should almost run a 100 cfm less on a demon carb than the typical holley.

Mark B.

Alwyn678

I must agree with you on that POINT

damac

Thanks for the advice,

I e-mailed Demon all of the specs on my 406 (Sportsman II heads, 225 lunati cam, 1 3/4 headers, RPM intake, 3.73 gears, etc). They told me to go with a 750. I think that this should be about right, as most 406's I see are running at least 750 carbs.

As far as I can tell the only downside to the Demon is $$. Summit just sent me a cupon for 10% off my next order, so I guess I have no excuses.

Mike

Paul 75 L82

i love my 650 Speed Demon. Check out my motor spec's in my sig. The 650 is just right for me. Too big of carb will have slower response time.

damac

Thanks for the advice,

After getting advice from Lars and Demon, I decided to go with the 750 Demon. Summit says it will be at my door on tues. I can't wait. All I need now is a 400 block.

Mike

Clink69

I have to make this decision also. What is the difference in price? :flag

jamiejamison

After having multiple Holley and Demons on my vette and much talking with other experienced drag racers this is my observations. First I believe it all depends on other factors about the car. I run an 80 vette with a ZZ4 (355hp) 700r4 tranny, 2800 stall converter, 3.73 rear, BFG drag radials 275x60x15, hooker headers, 3 in pipes, high flow converters, dynomax mufflers. First ran a 750 holley mech secondaries, had slight blog off line at WOT from idle. Next a Demon 750 mech, bog off line at WOT from idle, good from 1500 rpm. Went to a demon 650 vac, terrible off line. back to factory twice, tried on other cars, peice of junk. Next was a 650 mech holley, still a little bog. Now I run a 750 Holley vac and it's a beautiful thing. Picked up my short times 3 tenths, I run 1.68/1.69 short times all day. The Demons are smoother and better fuel economy than a holley. If you want to drag race, get a holley. Also, if you do a lot of jet changes, as you will in different seasons (tempertures) when racing, the rear float bowl allen bolts are a pain in the
can. By the way, the holley vac was the cheapests.

redc3vette1

I LIKE THE DEMON CARBS BUT HOLLEY IS GETTING BETTER

QuickVet

i would go demon. they just look so cool :cool: