I am considering replacing the Edelbrock 1406 carb on my stock 1972 Cutlass 350 with a 1901 Street Demon. I have a few questions I was hoping someone could help me with.
1. Do I need an adapter/spacer since I have my stock spread bore manifold?
2. Will the stock throttle cable/bracket work? ( TH350 tranny)
3. Will my stock air cleaner work without needing an adapter?

Thanks in advance!
Will

 

1) The carb comes with everything you need. I think you still use the sealing plate.
2) If it worked with the edelbrock, it'll work with the demon.
3) Yup. Might need to make a new stud at a different length.

 

Thank you. What has your experience been with the Demon carbs? My Edelbrock has been fine except for the issue of hard starting when hot, even with a phenolic spacer.

 

IMHO you should throw the other carbs as far as you can unless your car is for race only. Get a well tuned Q-jet. Your engine will run better all around.

 

For any Demon made before Holley took over I would do this. Take it apart completely and check everything...everything. Their quality control is crap.

 

I love quadrajets, but the Street Demon has some Qjet DNA like primary boosters, and spreadbore. The plastic bowl version reduces temp 20 degrees (advertised). Not a bad choice, hope you have good luck.
https://www.chevyhardcore.com/tech-s...on-carburetor/

 

Hi, I think I can give you some real feedback. I've been running a 750cfm street demon on my slightly modified '69 442 for a few years now. It has the phenolic bowl. The engine (400G) has an aftermarket cam, aluminum heads, Performer intake, headers. I've had no issues with the carb. Adapting my stock throttle cable took a little ingenuity but pretty much anything you need is sold through Holley.
In terms of tuning, idling, running I've had zero issues. It's always performed very well. No complaints.

 

I have been wanting to try this carb, I may go that route instead of completely retuning my Qjet for my 424 project. The Street Demon is heavily based off the Carter Thermoquad except with a bunch of the issues fixed, better choke, all new 3 barrel castings and an Aerospace polymer body vs a Bakelite body. You may need a spacer to clear the iron intakes back holes since the back barrels are one piece.

 

Thanks for the feedback guys. I will post after I get it installed. Since my 350 is stock, will the 625CFM be big enough or should I go with the 750CFM?

 

I ran the 750 on my 450hp 403 for a few months. It was easy to tune and drove really well on the street. I never could get enough gas out the secondary though, even with drilled out jets, so I had to move on.
I would go ahead and get the 750. The air door and small primaries on this carb makes it act like a qjet, so a larger CFM isn't an issue like it can be on a traditional Holley.

 

Interesting, I should be in that range with my 424. It just ran lean? What kind of fuel supply? What carb did you go with?

 

Couldn't get WOT any richer than 13.5:1 or so. Ran great, so if I didn't have the gauge I wouldn't have noticed.
I'm using an in-tank electric pump for an F250.
I spent the next few months trying to get a Brawler 750 to work. No matter what I did, the front accel pump boiled. Ran great, excellent power and good manners, but once that pump starts boiling it stumbled really bad at stop lights. I drilled a vent in the pump body, drilled a vent in the accel feed tube, used an isolator, used and isolator and a plate, etc etc.
So I'm back to the qjet.
And it turned out I had an ignition problem which started all this carb adventure. 90% of carb problems are ignition problems, which apparently I have to re-learn every few years.

 

Thanks. How big did you drill the secondary jets? There are huge jets available, assuming their info on Standard Holley jets fitting the secondary side is correct. I will add O2 bungs and get an AEM air fuel gauge for this motor from Mark. I think it is worth a try, if it doesn't work I can build my 800 cfm Qjet. I also agree the 750 will work but both Street Demons will need leaned out on a stock 350. Buy a tuning kit, the one for the 625 carb might have be closer. Some guys on here, mentioned the rods and jets they used in their Street Demon on a stock Olds 350. Good luck.

 

At the time I didn't have anything other than the two tuning kits. Drilled the secondary jets to 0.106" or so.

 

Good to know, might need some really big jets, I believe 150 are available.

 

Interestingly one guy here dynoed pretty hot sbc350 with 750 Street Demon, and they faced the same problem, it went lean at WOT pulls no matter what they did, and it was 750. Changed to "regular" Holley ( dyno owner had on shelf) and all problems were gone.

 

Looked, do you have a link?

 

I wonder if the channel feeding the secondary jets is too small?

 

Dont have a link now, and Finnish language anyways translates really scrubbishly with translators. Separate words- ok, sentences- not even close, many times translating to whole different meaning.

 

Ok. Was it in the non Olds engine section? I just didn't see it, search brings up nothing.

 

Nope, it was on our national multi-marque ( american cars ) forum.

 

Ah, that would explain it. It must be an orfice issue. The dyno tests with 625 don't seem to have the issue. What is a good WOT AFR, high 12's to low 13's?

 

12.5-12.7, generally, to be safe.

 

I think it is worth trying. I can always use it on my 88 with its 8 to 1 Olds 350. Pretty sure that won't run lean. The Qjet might just need slight tweaking for the 424, idle was a touch rich with the 214/214 cam, 220+ duration cam should idle OK. I do have an early 307 manifold to add an O2 for a wideband to tune the Street Demon on the 350 first.

 

Will,
First, I claim not to be an expert on carbs. My '70 W-31 had a Holly R6497. After an engine rebuild we couldn't quit dail-in the old Holley no matter what jets were installed. I gave up the ghost and went with a 750 Street Demon. Not sure what fuel rod was installed as I bought it from Lynn at Mondello Performace. Out of the box it was a major improvement, it no longer dogged when hitting the pedal. Electric choke and composite bowel nice features. So far, so good.
I did install an Edelbrock 2696 Square Bore Adapter. The only problem with the 3/4" riser is the manifold heat tube doesn't quit reach the snorkel. Also, I had to purchased a valve cover to air cleaner tube from a big block which is longer. Rerouting the fuel line was not a problem as it allowed me to put in an inline filter. I was able to used my original throttle cable bracket.

Good luck,
J.O.

 

Good to know it will work on a stock intake with the plate. What stud did you use to attach the throttle cable?

 

I used the back left stud that came with the kit. See closeup pic'.

Stud location for throttle cable bracket.

 

Cool thanks. I will have see if the factory 2004R bracket will work with the Street Demon.

 

Olds 307/403,

I did buy the 1953 S.D. throttle bracket, but I felt it didn't line up with the cable coming from the firewall as well as the stock one. You might have to bend the stop tab down a little more to keep the bracket at 90 degrees to the carb. If you or anyone can use the Demon bracket you're welcome to it.

 

Interesting on their bracket. Did the throttle cable attachment stud come with the carb? I will also need the TV cable attachment stud for the 2004R. I assume the choke cleared your air cleaner? That looks like an air cleaner to go with the W25 hood on your car.

 

You know, I don't recall if the stud came with the carburetor or the spreadbore adapter. No problem with the air filter pan clearing the choke, but without the adapter the choke sits pretty close to the manifold.