GTR1999

Ok,... here are the questions:

ENGINE: 350-WP Sportman heads,64 cc w flat tops about 10-1 CR,RPM intake, headers- 2.5" pipes, Xe268 cam, stock HEI dist.

Have a NIB 670 St avenger vac sec,electric choke.

With all the recent talk on the Speed Demaon Mechanical sec carbs is it worth it to sell the Holley($325) and spend another $150 on the Demon? Will the change be that much different for a street car?
Do the Demons come with a choke?

What do you think? I have a Q-Jet on it now and have to adjust the sec because of a bog @4000 shifts and soem backfiring off idle?

Thanks in advance,

Gary

verskel

From the Summit catalogue it says that Speed Demon's with Mech. secondaries do NOT come with a choke. Choke kit avail. separately. :yesnod:

Other than that, I'm not impressed with 'new' Holleys and I've heard lots of praises for the Demons. :chevy

Fevre

When and where did you buy the street ave? If from summit call and see if they will swap it for ya since you will be spending more $.

OkieVett

I can't say enough about my Demon carb. Personally, I noticed a difference going from an Eldebrock to Demon. Worth the money, my .02 worth

SHAKERATTLEROLL

I would go for the Demon . The Holley is just there way of kinda revamping the old carb where as Demon took the design and ran with it. Demon is a much improved carborator.

SmokedTires

Since I won't be able to install the EFI onto my car this year, I've been looking at carb options. The Demons look like very nice pieces :yesnod: & if I had the $ I'd certainly be considering one. I have a 2 year old Holley 750 vac sec that I just ordered a 4150 conversion kit for (secondary metering block instead of the metering plate). I'm not sure about the vac secondaries on this new engine, but my builder says it'll probably help my traction if we delay the secondaries from immediately opening :D

Corey_68

I'm really fond of my 850DP Demon. :yesnod:

gdh

Have they (BG) fixed the quality control problems that so many ppl had in the past, I just remember reading so many on the forum having problems with the SD. I would love to try one, but have both a Holley 4779 and and Edel 1407, another carb would put me in the dog house for awhile.

djgrelli

I'm running the same street avenger on my78. I've been very happy with it. If you're just running it on the street as I am it'll do just fine. I'm running about 375 hp and the performance is just fine. The choke works great and there's no fine tuning to do. Just bolt it on and go. Of course everyone has there own opinion on the subject. Just my 2 cents worth

JScott

I've got a speed demon on my 65 365hp engine and it runs great. It has vacuum secondaries and an electric choke and I've had no problems with it at all.


[Modified by JScott, 9:23 PM 3/15/2004]

lostpatrolman

You need to watch out for the clear fuel float level sights on the avenger. I have had nothing but problems with them. After a few months the head breaks off, leaving the plastic threads screwed into the float bowl. The only way to get them out is to take the bowl off, drill a hole through the plastic plug that is left and try chipping whatever is left from the threads. This happened to both of my float level sights at the same time.

GTR1999

Interesting comments guys. I heard of the plastic sight plug giving problems too. I think I would use them for setting float level then switching to the brass ones.
I also heard of problems with the QC at BG, but then I heard of the same @ Holley and Edelbrock too? So you just hope whatever you buy is correct. The posting by Lars on the carbs indicates you have to check the throttle plates on either type of carb out of the box.

I didn't buy the carb from Summit or Jegs but a speed shop,so returning it isn't an option. It is only 3 months old and still wrapped up in the box. They sell for between $300 - $325 on ebay in this condition.

Again the question is for street use, shifting between 3k -6k,but mostly under 5k rpm. How much difference would the Mec sec be in this case over the vac for a stick car?

Money is a factor,as always.

Thanks,
Gary

Chris69

I have the Street Avenger and it works great. I don't know about the plug-n-play thing though. I had to make some minor jetting changes, but after getting the right combo dialed in, the carb really does well is and much more responsive than the AED modified DP it replaced.

71roadster

I have a 750 vacuum secondaries w/electric choke speed demon for sale. It is in excellent condition and ready to rock. I ran it for about 1000 miles. I comes in the original box with the original video tape and users manual. $350 includes shipping.

Chris

GTR1999

Thanks Chris, I think that if I go with a Demon it will be a Mech sec one though. I'll let you know if I decide to make a move.
Thanks,
Gary

Ryan77

Hey Gary,
As you know I used to have the Holley 670 on my old motor, and was pleased with it, but for an all out performance motor like my new 383, I choose to go with the Speed Demon 750 mechanical secondaries. This is what Lars recommended to me about 6 months ago when I purchased it. He said he's seen many dyno results were the Demon 750 mechanical was putting out 20hp more than the vacuum. The mechanical has no choke (you can purchase on separately) but the vacuum does come with one. I'm sure you also saw the post from Lars/Signguy last week :cheers:

GTR1999

Hey Ryan,
Yes I did read Lars post and it was great. I really wanted to hear from a few guys,like yourself, who have 1 or the other, maybe both. I think the Holley will be fine once I follow Lars advice and since I would still have to add another $150 it might not be worth it in my case.
I'd like to see your car when you get it on the road. Maybe we can meet up at Marks cruise in Granby this summer?
Gary

Ryan77

Sounds good Gary, I'd definately be willing to meet up at a cruise. I'm almost finished with my new motor install, I'm almost done cleaning and painting the engine bay, and then I'll just be waiting for some more cash for a clutch and accessories. Should be ready to run in May :cheers:

Sigforty

I have not tried a Holle, but I have had two demon carbs. I had a Road demon on the old motor and now I have a Speed demon on the ZZ4. Both are great carbs. I really like the way they look and how they operate. They have all of the trick features one would want in a carb.