Anyone run a Street Avenger?

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71Duster

71Duster

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I'm not a huge carb guy and have not had much luck in the past. I do try to learn though.

I currently run a 650 Speed Demon mechanical secondaries in my 340 Duster 3.55 gears automatic trans with 2800 stall. It runs a Hughes cam #heh2328al

111deg lobe seperation/installed centerline 108deg
intake lift .506/ exhaust .524
[email protected] Intake223deg/ Exhaust 228deg

Stock Heads 2.02 intake 1.60 exhaust

This being said the Demon does run ok but its constant fideling to keep it that way. It doesn't run a choke and for a street driver that was a mistake. With the crossover block its very cold natured untill it DRIVES not runs but drives about 5 minutes. 5minutes of idle will not make it happy.

I always wonder if this is just too much high end carb for a simple set up and if vacuum secondaries might make it more street mannered.

I know a Holley style set up the best so was thinking about staying in the neighborhood IF I change.

Any input?
 
You have two problematic issues for street driving: Blocked heat, and mechanical secondaries with a tight converter. Either one will work, but as you have noticed, street manners will take a hit.

Your carb is certainly not too big. The stock Thermoquad on your 71 was 750+ CFM. For mostly street I'd suggest a 750 Edelbrock AFB or AVS. Street/strip and I'd run an old school Holley 3310.

I would be concerned with the "constant fiddling" however. It should be repeatable once warm with the setup you have. You should not have to monkey with it once set. You will probably be able to make it run well when warm, run OK cold or get decent gas mileage. I doubt you'll get all three with that setup. BUT once set, it should not change by itself!!

If you tune up is always changing, look beyond the carb. An old saying is "99% of carb problems are in the distributor". My experience says this saying holds true, and in many cases so long as you have a good timely spark any carb which is fairly close will run pretty darn good.

What is your ignition setup? Intake/exhaust?
 
My main fideling issue is idle speed whih I know is my heat problem, too slow when cold too fast when hot.

Its an edelbrock rpm intake and TTI Headders 2.5" exhaust with x pipe. I have an FBO ignition box

The distributor was curved to match the engine by the shop that built it.

My main question I guess is are some of the cold issues just the nature of the beast or will a choke help that much?

Also I see a lot of debate about just when you should run mechanical secondaries.

When discussing carbs with the engine shop he also recomended the Edelbrock AVS Thunder over a street avenger but I never asked why, also he claims it will have better manners but will loose some performance again no reason to why.

I've thought about a thermoquad and been to Demon Sizzler's site and read the great love it or hate it debate but didn;t want to run an adapter on my square bore intake.
 
If you want consistent idle, open the heat crossover. Just that simple. In Canada, a choke would be perfectly reasonable as well.

As for performance any 750 CFM carb providing the correct mixture will provide the same power as any other 750 CFM carb providing the same mixture. The AFB/AVS advantage on the street is you can richen/lean the power and cruise curves independently. On a Holley pattern carb you transpose the power/cruise curves paralell and together via a main jet change. That is, more power circuit fuel = less mileage when you increase main jet size. You can increase the bias distance between the two curves, but this involves drilling PVCR channels and is neither a simple nor reversible task.

Your combo is not too far removed from stock, and certainly within the realm of an off-the-shelf carb. Personally, I'd run an AVS (Chrysler did).

Really though, open the crossover eh. And see if that helps.
 
I just went through some very similar issues with a 750 Demon with mechanical secondaries. My setup is a bit more removed from stock than yours is, but not too much. A 360 with magnum heads, performer air gap, .525 int and exhaust (231/237 @.050) and 3000 stall.

Could not for the life of me get to the demon to keep a tune. Finally put a fuel pressure gauge on it and figured out that my fuel pressure was not high enough. Fixed all of the fuel delivery issues (High volume mechanical pump, larger lines and heat protection (the lines run a bit close to heat sources in some points) and so far it's been freakin fantastic (Don't know that larger lines were required, but they're in there now.

Tuned it when it was warmed up, and it still had a bad attitude when cold, so I added the demon choke kit. It helped A LOT! Still not the best when cold, but world's better than it was. not sure if yours has the ability to add a choke kit or not. Mine had the choke tower but did not come with a choke. Cost me something like $40 for the choke kit, and it doesn't take much to install it. I've now got almost 1000 miles on it and am loving it!


- Don
 
The fuel system is pretty overkill on the car, sumped tank with AN lines -Yeah someone saw me coming-

Anyways I bought a choke kit and got i on.. wow All of Barry Grant's instructions suck, least thats consistant.

I haven't got the choke set up yet, my Dad will be in the city this weekend and he learned the trade in the 70's where as I have never set a choke or been taught.

C130Cheif I am still thinking about a carb swap though but is there decent instructions anywhere a guy can read on the way an edelbrock is set up with metering rods as opposed to a jet change?
 
I've had good luck with the eddie thunder avs. Not for real performance but a great daily driver.
 
Well after some more learning this weekend at the car show/drags and running the car down the strip for my first time ever I'm starting to learn the Demon more after talking to some people. My major issue with idle consistancy was having the idle speed screws set in too much exposeing the idle transfer slots on both ends making tunign a decent idle nearly impossible.

With no experiance or prep I pulled from the show and shine to the strip on a HOT HOT Alberta day and turned in a 15.2@93mph with pumped up street tires and lots of wheel spin and a slight bog that was the test and tune run from there it was a king of the hill so I figured with no changes I'd put a dial in of 15.2, the only change I made was pushing the car up the stageing lanes and I was told when in the shade of the tower and running to keep reving the car to keep cool fuel in the carb and improved to a 14.8@96mph with the bog from the heat gone.

The shop who built my engine was there looked a my plugs and says its just a little lean yet and a jet change was needed. That being said I think I'll keep on the demon for awhile yet, it wasn't built as a drag car but I'm told it has more in it.
 
I tried a 725 Road Demon and could not get it to run well under 2000 rpm after a summer of fiddeling and went back to the Holley 600 vacuum secondary I had on it. Last year I picked up a Holley 670 Street Avenger carb. This carb is by far the closest thing to a drop on an go universal carb I have ever tried. The idle mixture and accelerator pump were spot on and the mains were as close as I am going to get them without an air/fuel meter. The carb delivers 5 mpg more than the Road Demon and 2.5 more than the 600. By the but dyno it has the same top end as the 725 and just as good low end throttle reponse as the 600.

This is on a 10.6:1 compression 360 with a Comp XE268H cam, Crosswind intake, magnum heads, A833OD and 3.55 gears. This combo is making aprox. 370 HP based on a best 1/4 of 13.7 @ 102 with a very traction limited 2.2 sec 60'.

Don't think you could co wrong with the Street Avenger carb.
 
Well the Demon is still being a Demon and I'd like to try somthing else is for no other reason then just to experiment. I e-mailed Demonsizzler but can't get a reply anyone had better luck?
 
Well, I had 2 Street Avengers....because the first was defective at the acc pump....miserable....

The second was better, but always had an issue with the same (having to feather the car, and hesitation from the pump.......Holley worked with me on it, but never solved the problem)........AND, their electronic choke system is totally undependable in my opinion..........constant adjustments with weather changes..............Never again.

My 2 cents.
 
I've heard a few few people complain but I wanted to try either a TQ or Thunder AVS just to try somthing that I normally dismissed due to others opinions etc
 
Well I ordered an AVS today, cheap enough anyways so I'll see how that goes, new teriotory for me never having had an edelbrock/carter
 
That's what Chrysler installed on these engines but WTF would they know about Mopars? :snakeman:
 
71Duster said:
Well I ordered an AVS today, cheap enough anyways so I'll see how that goes, new teriotory for me never having had an edelbrock/carter
Click to expand...

We put an AVS Thunder 800, on a close to stock 440 (headers, 2.5 inch duals w/ crossover, performer intake, carter fuel pump, chrome ecu, large k&n air filter, made minor adjustments, and haven't touched it since. Its a touring car. Jensen Interceptor w 24k original miles. So, no track time, but reliability throttle response and w.o.t. performance seem excellent. Original TQ and a reman TQ both were a nightmare even with all those other "tune up items", hence the Edelbrock was one of the last things we did. Heat crossover is blocked off, electric choke works nicely. Car weighs 4400 with the driver. Torque converter appears to be possibly hemi converter or other "hi stall" factory mopar. Anyway, the Thunder AVS really kicks butt.
 
71Duster said:
It doesn't run a choke and for a street driver that was a mistake. With the crossover block its very cold natured untill it DRIVES not runs but drives about 5 minutes. 5minutes of idle will not make it happy.

I always wonder if this is just too much high end carb for a simple set up and if vacuum secondaries might make it more street mannered.

I know a Holley style set up the best so was thinking about staying in the neighborhood IF I change.

Any input?
Click to expand...

thats cause you the oil doesn't get to temp like the coolant does in idle.
you have to load the motor to really heat the oil for the most part.

I won't wot mine until the oil heats up enough and the psi drops to where it should.jmo
 
I am running 2 Dusters with 340'ds in them - One my wife shows and races it is a 73 - 10.5-1 - J heads - 30 over - air gap intake - PROFORM 750 on top - car runs 13.57 at 99.80 in the 1/4 - Mine is a 74 with a 60 over 340 - 10.5-1 - 69 X-Heads - Gasket matched - M-1 intake - Mopar Purple Shaft .533" Hydraulic cam - Doug Thorley headers - Runs 12.70 @ 108.67 with a 750 Proform - Both cars have no chole and it does take a little extra to warm them up - but once warmed - you can't beat them -

I have 8 cars between me and customers of mine all running Proform on the street & Track
 
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