Street demon 625

[George Rodriguez]

Hello everyone! I am new to the forum just wanted to share some information that may help some of you decide whether to buy the street demon 625 carburetor. I recently bought the 1900 model aluminum non composite model. My build is a mild 1976 318-3 motor from a d100 on my 1971 Dodge Dart Swinger
BUILD:
,mopar purple shaft Purple shaft :430/450 lift @.50 221/228
duration 260/268 , 110 lobe separation smog heads, Hooker headers 360 cast iron spread bore intake manifold,2.5 exhausts dumped at the rear end 8.75 sure grip with 3.23 gears
transmission is an a833 OD gutted into an iron case.After having many issues with my 340 thermoquad (leaks ,bogging after rebuild and many adjustments) I decided to buy the street demon .I did my research and seeing that the keeping is similar to tune to that of a thermoquad I bought it. The carburetor came jetted a bit rich from the factory for my application with primary jets being a size 80 and 60/52 metering rods with an 8 hg spring. Changed it over to 76 primary jets with 62/54 metering rods and a yellow spring 4hg much lighter spring .I did try the 64/56 metering rods but was having lean surges at 65 to 70 miles per hour at steady state cruising. I went back to the 62/54 and that solved the issue. The result has been night and day I can roll on at about 20 miles per hour and floor it and the tires break loose!(3.09 first gear from the overdrive). The acceleration is smooth through out the rpm range due to the 1and 3/8 primaries, I have no flat spots still making power to about 5800 6000 rpm. I did have to adjust the secondary air valve by Tightening.This due to it opening a bit to soon and bogging at WOT,no more issues after the adjustment.Gas mileage improved to 19 miles to the gallon over a 75 mile mixed city and highway commute to work .The driving was mostly highway,driving 65 to 70 miles per hour think .I should have 20, 21 with no problem on longer trips (this is my daily driver). The carburetor started right up from instal with no issues I did need to buy a 1 inch spacer to clear the secondaries from hitting against the manifold. I have yet to see what on max manifold vacuum is and I timed it by ear. If any one is thinking about this purchase it ,it is one of the best investments I have made to drivability and power to my car. I did have to pay 81 extra dollars for the tuning kit with jets, metering rods and springs. Total spent was 394 with shipping but well worth it!
Got my self a Weiand intake manifold and some 302 heads that I need to do some home port work. Will update to see what are the final results for my build

 

[DFX 340 Duster]

Welcome to FABO and thanks for the information on the carb. I have been considering buying one of them for my 340 and doing a comparison with two of my ThermoQuads (1971 and 1972).

 

[1994redram]

Have the same carb on my 360 magnum. I'm pretty happy with it but planning on switching to something larger just to see if I can pick up some power. Driveability is great around town and such so I'm hesitant to get rid of it.

 

[George Rodriguez]

Welcome to FABO and thanks for the information on the carb. I have been considering buying one of them for my 340 and doing a comparison with two of my ThermoQuads (1971 and 1972).

Its great street carb and once the secondary's open up you really feel the power!, Similar to thermoquads as far as design and tuning. IF you require a larger one believe they make a 750 cfm version as well!

 

[sireland67]

I have had one for years on the 360 in my truck, dependable carb, did not have to touch it except adjust the idle screw 1/8 turn.
Starts first crank when around zero degrees outside, or 90.
Replaced a hot soak 3310 Holley that was giving me heat fits.

 

[Mattax]

Hello everyone! I am new to the forum just wanted to share some information that may help some of you decide whether to buy the street demon 625 carburetor. I recently bought the 1900 model aluminum non composite model. My build is a mild 1976 318-3 motor from a d100 on my 1971 Dodge Dart Swinger
BUILD:
,mopar purple shaft Purple shaft :430/450 lift @.50 221/228
duration 260/268 , 110 lobe separation smog heads, Hooker headers 360 cast iron spread bore intake manifold,2.5 exhausts dumped at the rear end 8.75 sure grip with 3.23 gears
transmission is an a833 OD gutted into an iron case.After having many issues with my 340 thermoquad (leaks ,bogging after rebuild and many adjustments) I decided to buy the street demon .I did my research and seeing that the keeping is similar to tune to that of a thermoquad I bought it. The carburetor came jetted a bit rich from the factory for my application with primary jets being a size 80 and 60/52 metering rods with an 8 hg spring. Changed it over to 76 primary jets with 62/54 metering rods and a yellow spring 4hg much lighter spring .I did try the 64/56 metering rods but was having lean surges at 65 to 70 miles per hour at steady state cruising. I went back to the 62/54 and that solved the issue. The result has been night and day I can roll on at about 20 miles per hour and floor it and the tires break loose!(3.09 first gear from the overdrive). The acceleration is smooth through out the rpm range due to the 1and 3/8 primaries, I have no flat spots still making power to about 5800 6000 rpm. I did have to adjust the secondary air valve by Tightening.This due to it opening a bit to soon and bogging at WOT,no more issues after the adjustment.Gas mileage improved to 19 miles to the gallon over a 75 mile mixed city and highway commute to work .The driving was mostly highway,driving 65 to 70 miles per hour think .I should have 20, 21 with no problem on longer trips (this is my daily driver). The carburetor started right up from instal with no issues I did need to buy a 1 inch spacer to clear the secondaries from hitting against the manifold. I have yet to see what on max manifold vacuum is and I timed it by ear. If any one is thinking about this purchase it ,it is one of the best investments I have made to drivability and power to my car. I did have to pay 81 extra dollars for the tuning kit with jets, metering rods and springs. Total spent was 394 with shipping but well worth it!
Got my self a Weiand intake manifold and some 302 heads that I need to do some home port work. Will update to see what are the final results for my build

Keep in mind the Weiend is probably taller than the factory intake. Check hood clearance with some clay before slamming it shut. You're probably OK - but some clay or crumple aluminum foil will same is a good final check. If there's room, a 1/2" phenolic or wood spacer will be useful to reduce heat transfer from the aluminum intake.

 

[b5cuda]

Thanks George for sharing the details of your experience! I was having similar problem with my 340 - lean surges and inconsistent air-fuel ratio - until I went to the next size smaller (thus larger flow) metering rod. Without an AFR gauge I'm not sure I would have known I was running lean.

 

[George Rodriguez]

Keep in mind the Weiend is probably taller than the factory intake. Check hood clearance with some clay before slamming it shut. You're probably OK - but some clay or crumple aluminum foil will same is a good final check. If there's room, a 1/2" phenolic or wood spacer will be useful to reduce heat transfer from the aluminum intake.

Thanks for advice!I did think about clearance issues just have not had a chance to install, I hope it does clear! It does look at least an inch or two taller compared to my cast Iron 350 manifold. I will try to put a spacer on since I have heard of a few people on this forum boiling fuel in the their carbs!