76projectstingray

Title sounds like a comic book!

Ok, on my other thread about what size carb to use it seems that most would use a 750 dp instead of a 670 street avenger.

Now i'm wondering which carb is better, a holley Dp or a BG speed demon. which is made better???

Thanks Jim

Also , I am running a TH400 trans, should I stay with a vac secondary or are you guys using mech sec on your autos?

willem wallace

I am currently shopping for a carb for my ZZ383, auto(turbo 400). Everything I have read to this point indicates these street driven automatics perform better with the vacuum secondary's.

Grumpy 427

Stay away from Demon carbs, too many problems with them and poor customer service. A well tuned holley with a vac secondary will be the best deal for the street, and all around performance. Unless this is a race car only, run a vac secondary carb. They are very tunable with an assortment of secondary opening springs.

ED69ray

if you are looking to get a carb built or tuned, I highly recommend this guy

http://www.chucknuytten.com/carbs.htm

for very excellent work and service. Call and talk to Chuck - he will be glad to help you out. I have his model 750-2003

I did some research before going with a 750DP - my info was a light 4 speed car with good gearing would rock with a mech sec DP - but I'd have gone with a vacuum sec carb on an auto tranny car.

I have gone from vacuum (cv) to mechanical slide carbs on perf bikes and the difference is astounding- but again the light weight, good gearing, and manual tranny rule applies here

Just make sure whatever you buy will fit under the hood.

Good Luck, Ed

miechesa

I have a demon 750, works great, no problems. for auto trans use vac sec.

TheSkunkWorks

I'll echo that vac 2nds are best for any auto, as well as for any heavy car and/or one with tall gearing. And, since you can get a way with a bit of over-carbing with vac 2nds anyway, I'd definitely go bigger than 670cfm, which will become a restriction on top end. 750cfm vac 2nd certainly isn't too much for even a mild performance 350, so I'd save the 670 for 305 builds, IMHO.


TSW

Drunken Peacock

I'm running a 770 Street Avenger and love it. I had the jets downsized by one size and I get tons of smooth power out of it.

vetteguy75

I've been using a 670 Street Avenger for the past 7 years....LOVE IT!!!

dmaaero

I just got a 750HO from http://www.aedperformance.com/index.htm can"t wait to get off this shut down an find out how it works !!!
70 jets in the front 82"s in the rear 31 an 35 shooters air fuel flow is 12.8 front an 13.1 rear. As you can tell it"s been on a flow bench an on a dyno test engine. John dikkey has a very nice facality to say the least!

OldCorvetteKid

with all votes for vacuum secondaries for a street driven car....I have a 660 Street Avenger(about 340-350 h.p.), its very tunable and have not had any problems whatsoever with it. It was very close to optimum right out of the box for my application. The size for you will depend on horsepower and RPM range you have.

tnovot

Ditto. I have a vac secondary 670 CFM Street Avenger on my ZZ4 350 and am very satisfied. Starts well and runs strong. I do not autocross nor do I run it on a dragstrip but I have run it very hard on the street and open road with no problems.
Terry

yellow 72

I have two Speed Demons on a roots blower. Easier carbs to tune than the Holleys I've used in the past..

Reggie Dunlop

The Street Avenger is a super good carb. I have two - a 670 on my daily driver '79 vette (350 cu) and a 770 on a '77 Firebird Formula (400 cu). Both auto trans cars with mild perf cams and headers. Easy install, set pretty close right out of the box, and plenty of vacuum ports to hook up brakes, pcv, dist, etc. I did have to jet the 670 up 3 sizes front and rear. The 770 was dead on. I would buy another. That being said, these 2 carbs are nothing more than the old 1850 - 600 cfm, and the 3310 - 750 cfm with a little different idle circuits and some other gingerbread. If you don't think they are the same, just go to the Holley website's technical section and pull up the carb numerical listing. It has all the spec.s of every Holley carb going back to the '50s. The primary and secondary bores are identical in size to their non-aveanger counterparts as are the throttle bores and booster design. When I called Holley about this I was told "Yeah, they are the same main bodies, we just rate them wet flow instead of dry flow". Great carbs non the less.

gingerbreadman1977

unlike someone else said i have no problem with my demon carbs. i bolted it on straight out of the box and it hammered. i did get a dyno tune a year after installing and it only went down 1 size in 2 jets so it was pretty close to perfect straight out of the box for my motor. also its a mechanical secondaries and i wouldnt have it any other way . its a weekender driver . 355 gears behind a TH350 , 3000 stall . around 400hp.

TheSkunkWorks

gingerbreadman1977, is that a Mighty Demon? Looks very nice, ...but don't see a vacuum hose PB booster filter, FWIW.

gingerbreadman1977

oh geez now you have me worried. i thought thats what the plastic part on the booster itself was. isnt that a check valve or is there meant to be something else?

TheSkunkWorks

OMG, your brakes will fail immediately! JK, couldn't resist making a classic V-Twin style quip.

In line filter is a separate piece from the check valve at the booster. Apparently it keeps fumes/contaminants from damaging the diaphragm over time. Available thru many resources, btw.

But, back to my question, which Demon model did you go with there?

gingerbreadman1977

ill look into that filter. it hasnt had one on for 6 years and all good so far but better later then never. ill have to dig up my old box that the carb came in and cross check the part number. i really cant remember if it was a mighty demon or race demon. i get confused between them all but someone who knows about them prob can spot the difference.