Scarlett-73

I'm slowly but surely trying to undo 20 years of DIY's shortcuts and cheap-outs, and my next task is to put the correct carberator on my 73, 350. I'm considering purchasing a Holley Street Avenger 670cfm. Largely because it has the enough vacuum lines to handle the headlights and the charcoal canister. The existing carb does not and I'm dealing with a raw gas smell from the car in the garage. ( I've capped it but don't like to do that).
Anyway I'm asking if anyone has used this carb before and if they have any suggestions other than buying an old Rochester that needs to be rebuilt.

Thanks,
Mark
P.S. I've traced all my lines and have no other fuel leaks. I just put a new tank in as well.

FlyLS6

If you don't want the pump shot (or gas mileage) of a double pumper, I think the SA is a great way to go.....have a 770 on my 454.

You might have to adjust the choke pull off; you'll just have to see once you get it set up. I had to back the "set screw" out about 2 turns to lean mine out at a cold start. Be SURE to follow the instructions on the hot lead from to make it work. Mine now works fine. Some seem to have had problems.

One neat thing about them is that they come equipped with the quick change vacuum can on the secondaries. Swapping out secondary vacuum springs is about a 2 minute job. If I go on a "long" cruise, I put in the black spring which improves low end torque and improves mileage at bit. If I want to get "sporty", the long yellow seems to work best and allows the secondaries to fully open before 6000 rpm...according to the spec sheet.

The also seem to come pretty well jetted from the factory.

kcarlasc

I am looking at the Ultra Street Avenger for my 76 with a 383.. so lookng at the 770. Currently has an Edelbrock 800 which is too much and want to change for a lot of the same reasons, plus the car sat for a while and the carb needs a rebuild anyways.

Porbably going to order if a few days... I will post here with my impressions if interested.. and if you could do the same.. that would be great!!!

Shark Racer

Quadrajet. . .

lars

The Holley is hardly the "correct carb" for your car. If you want to put the correct carb on the car, you need to locate a Q-Jet and rebuild it. This will give you an outstanding level of performance if done right. If you're looking for "some kind of carb to make the car run," there are several choices, including the Holley SA series. A better choice is the "Ultra" series carbs, which have much better metering block designs for a street driven vehicle running today's pump gas than the SA carbs. These carbs still won't perform like a Q-Jet in the low-to-mid rpm range on a mild street vehicle, and you can't use the correct, original intake manifold with the Holley carbs.

Lars

FlyLS6

Something I've wondered....regarding attachments....throttle cable and vacuum lines, etc, is there any difference between the standard and Ultra models....could one simply swap one for the other? It seems like they would be the same...but one never knows.

Matt Gruber

there is still ONE correct NEW replacement available for a 1970, that is the Holley
4 1 6 5 - 6 2 1 0
about $450 and worth every penny.
see page 2 in my article, in profile sig.

Brcmpbl

I'd Quadrajet that sucker myself...not difficult to rebuild / have rebuilt and reliable. A close to correct one for a 1973 shouldn't be too tough to locate either.

Alan 71

Hi Mark,
While your 73 will have 2 lines that would normally be hooked to the carb (one from the pvc, and one from the vapor, (charcoal), canister), the vacuum supply for the headlights should be from a fitting directly into the intake manifold (often right behind the carb) not from the carb itself.
Sounds like you're getting varied opinions on your new carb choices!
Good Luck!
Regards,
Alan

Scarlett-73

Speaking with A buddy of mine from Don's Speed Shop here in CT he didn't think that the Street Avenger was the right way to go. He recomended a modern quadrajet I can't remember the name,.. but it wasn't a rebuilt Rochester (which I'm not crazy about) and can use the stock intake with no plate.
I was looking for kick down linkage when, I discovered that there is no kick-down linkage on this car but a switch attached to the gas pedal which send a signal to the trans at full throttle. I cant seem to find the switch,.. is it possible my car never had one or the prior owner took it off for one reason or another? Will a th350 not have one?
Thanks for your comments,...Mark

ezobens

Turbo 400s use the kick-down switch at the gas pedal, Turbo 350 use the TV cable up to the carb linkage. Do you KNOW what trans is actually in the car?
Crawl under and take a look- If the oil pan is rectangular, it's a Turbo 350 and needs the TV cable, if it's kinda shaped like the state of Illinois, it's a Turbo 400.

Street Rat

Stick with a Quadrajet carb. Send it to Lars and let him rebuild it for you.

iokepakai

There is a new Street Demon 625 cfm Carb that just hit the streets this year.Looks like a modern Qjet.
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There are some you tube video's about this carb.If I didn't purchase a new carb earlier I would've liked to try this one for sure.It's available in a polymer bowl which helps to keep the fuel cooler.I was having problems here in Hawaii with fuel boiling with the Holley carb.Another nice street carb that runs great and only cost around 290.00 is Summit's brand carburetor.I have the 600 cfm vac sec,it uses mostly Holley parts is ez to tune.It utilizes annular booster for better fuel atomization.My fuel mileage has been steady at around 20mpg hiway with my ROD trans. Summit carb bolted on my motor:
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Tim H

If you want to drive the car anytime soon and not have to frig with it for months buy a new Holley.

gdh

Lars, have have you had a chance to work with the new Street Demon that was pictured above. Many of us would be very interested in your impressions of it and comparison with the Qjet.

Shark Racer

The street demon is a slight upgrade to the Chrysler Thermoquad design. It does use a mechanical air-valve secondary like a Quadrajet. Don't know a whole lot about it beyond that...

Between Lars and Cliff Ruggles there's a whole wealth of information on QJets that is very easily accessible. Lars' papers are great.

lars

As Shark stated, the "new" Demon carb is a re-pop of the old Carter AVS Thermoquad, used by Chrysler for a few years. It has no commonality with a Q-Jet, but shares all design features of the old Carter. Demon has changed the plastic bowl to a nice aluminum casting, and claims to have made other improvements and refinements over the original design. I have not yet run one on the dyno to make any comparisons, but neither Cliff nor I have seen good performance results from the Carter AFB re-pops (aka Edelbrock Performer) or the Edelbrock AVS re-pop designs: They tend to be a good, cheap alternative to get a car running if it doesn't have a carb and if you don't know much about carb setups and tuning (this is not a criticism - just a factual observation that many people do not have the experience needed to properly set up a carb).

I do find it interesting that all these "new" carbs are just re-pops of old, obsolete carbs that were never regarded as "performance" carbs when they were new. The Edelbrock "Performer" is just an old Carter AFB, which was deemed obsolete by GM after the '66 model year. Nobody with a performance car used these things in the 60's, and threw them in the trash can in favor of a Holley. The Summit carb is nothing more than a 1962 - 1965 Autolite, commonly used on the 352 Galaxie and 390 Thunderbirds. It, again, was never regarded as a performance carb, and was quickly deemed obsolete. Now, we're seeing Edelbrock and Demon releasing the Carter AVS/Thermoquad designs, which were complete failures in terms of reliability and performance when they were new. Amazing what a little marketing and a few years will do to make people forget why these carb designs were abandoned...

If I can get my hands on one for my next dyno session, I'll be glad to wring one out and publish accurate comparison data of this carb versus a Q-Jet: I have a near-stock 463 Pontiac almost ready to test that would be a good test bed. We'll throw a 750 4150 Holley into the test, too, just to get all 3 points of view...

Lars

gdh

As always thank-you very much for your insights Lars, greatly appreciated.

Scarlett-73

At the moment I haven't replaced the carb because I've discovered a few other issues to work on. My oil guage was leaking (from the connection behind the cluster) so I've had to clean that up. As well, thanks to the factory assembly manual I purchased, I've discovered how my vacuum lines are supposed to be hooked up. So the Carb issue has been shelved for the moment. However if anyone can recommend where I can buy a Q-jet already rebuilt and reliable I'm all Ears! Thanks, Mark

gdh

pm or email Lars, if he doesn't have one I am sure he would know where a good candidate for him to re-build one for your needs.