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

Crazyhorse

I see you missed this thread :) http://forums.corvetteforum.com/zerothread?id=170591

Blkblt

Damac:

Indeed...check the thread Crazyhorse references. I will never put another Holley on my '66 BB. If I ever sell it, the 750 VS Demon will remain on and the "correct" Holley will go with it in a box - where it belongs. :yesnod:

"Milehigh66"...427/390, put one on soon after I did, and also ran the numbers with LARS...He came out 10% better!

If you go the Demon route (check the Summit catalog), you will need to set up an inline filter. LARS fabricated the one on mine, and put out a tech paper on it in the Forum.

***********

********************
Jeff
Ô66. Modified L72
ÒThe Silver BeastÓ
Keep on :seeya :seeya :flag

58Mike

The thread Crazyhorse references was about an installation of the Demon and at the time, I considered asking how Lars thought it might compare to the Street Avenger. But I didn't and it was never mentioned. I bring this up because the Holley Street Avenger is a new design, and like the Demon, we can't assume it's like the Holleys we're used to. I have the Street Avenger 670 on my 350, but it's only been run without the body on my car, so I have no useful input to offer.

- Mike

d1_bradley

I have a Demon vac secondary on my 396 and have one small "issue". Seems that when I flog it hard, the rear throttle plates won't return all the way to idle. I can either "kick" it down or grab the linkage and twist it closed. The idle stays up about 300 RPM when this happens. And I've had it apart MANY times, new manifold, and its flat, torqued the mounting nuts, you name it I've done it and the problem is still there. With the hood up, I can take a phillips screwdriver and turn the throttle shaft closed and the idle will decrease and all is fine until the secondaries open again. I've even taken the base plate off and checked alignment of the plates, all looks perfect and free. Small but annoying issue.

damac

Thanks for all the input.

I just ordered a 750 Demon. Lars is sending my his fuel line article (Lars is a god) and my carb should be on my 406 soon. I will let everyone know how it turns out when I get it all together and dyno my motor.

Mike

Colevette

You won't be dissappointed
Cole :flag :D

MassVette

Demons are a premium carburetor- Holleys are not.
:chevy :chevy :chevy

Milehigh66

You will not be disappointed with the demon. Huge difference over the holley. the numbers don't lie, but what they don't say is how much different the car feels and responds. hope you enjoy your new demon.

Kurt

Blkblt

Damac:

Since you have made the jump, post your opinion for us if you would after you are up and running! What REALLY would be interesting would be dyno numbers with the Holley followed by the Demon...wadaya think??!! :yesnod: :yesnod: :bb

IMHO, you will like the difference. :cool:

:cheers:
***********
Jeff
'66. Demonized L72
"The Silver Beast"
Keep on :seeya :seeya :flag

damac

I will definitley post some dyno #'s with my demon, but I already sold my holley, so I won't have it around to do a head to head comparo. If I don't spend too much $$ on christmas, I should have my 406 up and running in dec/jan. I have definitely done my part to revive the economy by spending lots of $$ at Summit Racing.

Mike

427Hotrod

This will be interesting. I see several folks here lately have had great luck with the Demon. Maybe something has changed at Barry Grant, but for along time there was nothing but frustration coming out of everyone that bought one. They didn't run right, and customer service was terrible. I mean there was a major thrust going on some other forums in the more hardcore racing groups that were all going back to Holleys or stepping up to the HP series Holleys and were loving them. Demons had a BAD rep.going for a long time. In fact there are some C-3 guys that say the same thing here.

I've looked at them and they do seem to be a quality piece. I also believe that many of the issues with them (but folks won't admit it) is that since they are so "tuneable" as compared to a stock Holley, that people would mess with them and get them so far out of the correct window they would have a mess on their hands. Then they blame the carb.

Keep us up to date.


Jim

Blkblt

Jim:

Interesting observations. I, for one, have been a big promoter of the BGs since I have had such great luck with them. I am one of those folks who generalize in thinking ALL telephone tech rep situations (for anything!) will be a bust. However, I was most impressed with the BG tech rep folks when I contacted them three times on various questions....quick response, friendly, knowledgeable answers. They may well have changed their modus operandi after some bad raps; who knows.

And, I must agree with you regarding people "over-tuning" these carbs (or anything for than matter)...twist those ***** and turn those screws - maybe it'll go faster....yeah, right. :rolleyes:

***********
Jeff
'66. Modified L72
"The Silver Beast"
Keep on :seeya :seeya :flag

gkull

This is my Demon and all AN pumbing. I wasn't thinking and got the glass AN fuel filter. I have since replaced it with the blue anodized from Summit. The only thing that I would do do differently would be to get the quick disconnect for the bowls to make jetting that much faster.

This is my 383 just before stuffing it in. Target horse power was 579

gkull

This is a better side shot. Out of the box I had to drill two .125 holes in the throttle blades to get the idle lean enough I also increased the squirter hole diameter from stock. this is a 750 demon double pumper mech seconds without a choke. Chokes were not even an option.





[Modified by gkull, 1:04 PM 11/26/2001]

damac

Gkull,

579 HP out of 383 cubes? Is it blown or on the bottle?
What CR are you running and are you burning alcohol or race fuel?

Mike

Curtis

Now that is a screaming small block. You can't beat them. I would imagine you will be putting many BB's in their place. :lol: I remember my built 350 in my '55 Chevy and I used to dust BB's all the time. I remember one guy with his 454 built up that made me lift my hood to prove to him it was a SB. :cool: I did, and he about fell over. My '55 was really a drag car that I drove on the street. I was in my early 20's. How fun. Fiberglass front, and two fours. It was rather fast. Low 11's and that was when 11's were fast on the street. No slicks by the way, just street tires. I will have to scan a picture sometime and post it. What a ride. I like vettes better though.

Enjoy,
Curt

L79vette

What do you all think about Demon vs. the Holley 4150HP? I bought the
650CFM 4150HP instead of the Demon for a more stock look. Of course the game is up when you remove the air cleaner and see no choke horn and the beautifully smoothed throttle body.

Anyway, the 4150HP has worked well on my 327 and I'm wondering if anyone has compared versus the Demon.

Blkblt

Hey...L79vette:

Greets to another Coloradoan! You should hook up with LARS sometime. He is reasonably close, a great guy, drinks decent brew, restores muscle cars, builds engines, and knows a little bit about Vettes. A worthy contact in your vicinity.... :yesnod:

Don't let the snows get you. :D

********************

********************
Jeff
Ô66, Modified L72
ÒThe Silver BeastÓ
Keep on :seeya :seeya :flag

gkull

Damac - No blower or bottle. I do from time to time run 20-25 % methanol to get the octane up to @ 100 if I'm going to go blow ithe carbon out. I have the twin 125 hp Team - G NO2 port injection manifold for 800+ hp. but it just sits on the shelf. I like the other good time Vettes I have problems with everything behind the motor. So I have a 850 hp 3000 stall 3 clutch lockup 9.5 inch converter 700R4 tranny and all Tom's IRS rear system.


I work around sprint cars and it's no problem to make broad torque curve motors with 358 ci making 650 - 690 hp. So a daily driver with mid 500 hp and more c.i. is not a problem. All you need is light super duty internal parts and heads that flow 300+ cfm at .600 and the ability to hit the 7600 rev limiter. So I have just under 11-1 flat tops with the lastest in Thermal barrier coatings of the entire chambers, pistons, and exhaust valves. The intakes are titanium and also the retainers. Final valve size is 2.08/1.625 with .635/.644 lift from a custom solid roller cam.

I like Demon carbs and if you look close at the picture I have a 1/2 inch wood spacer to keep it cooler. The 750 was from my blown up 355 ci motor and I have since switched to a 825 cfm Race Demon. I put @ 9000 mile on the 383 this summer. I also believe that solid rollers are the only way to go.


Lots of HP can be made in just careful motor assembly and attention to details.





[Modified by gkull, 9:27 AM 11/28/2001]