[FOR TRADE] Trade Street Demon 750 carb for 625 carb or other

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johnson1550

johnson1550

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I think I purchased too big of a carb for my car. Carb is a 1904 Street Demon. I have been combatting an off idle stumble and have tried several squirter sizes to compensate. Called Holley and they say the carb may be too big for a stock 340. Anyone buy a 625 Street Demon they feel is too small for their application? I live in the Northeast and would be willing to trade as long as your carb is in new condition like mine is. Thanks
 
did you try to tighten the spring loaded secondary air door? This could cause your problem...

Michael
 
To my understanding, I thought if you had a stumble from the transition from primary to secondaries than the air door could be a culprit. I have a stumble off of idle. Thanks for the tip, I will try this adjustment ASAP.
 
I really don't think the carb is too big, by guess is you have other issues with the engine, timing etc.
I think you just need to double check everything on your engine, something is not correct.

I do have a 625 street demon on a stock 318, its been on there a few years and it a real nice carb, all I had to adjust OTB was the idle. Would not get rid of it for any other carb.
 
I have a nice Edelbrock 600 electric choke.
 
RustyRatRod said:
I have a nice Edelbrock 600 electric choke.
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Rusty, I'm glad you chimed in. I really want to use my stock TQ carb and only purchased this one in case the rebuild it needed did not go well. Unfortunately the TQ carb floods now after the rebuild. I made sure I replaced the "o" rings at the bottom of the fuel wells and replaced the floats with the brass style. Checked the float setting numerous times and is at 1" off of the gasket surface. The one thing that I did not like about the rebuild was the gaskets under the seats were really stuck on there and I used as small flat tip screw driver to scrape the gasket off. I may have damaged the surface where the gaskets sits. Do you think this gasket surface would provide enough leakage around the threads of the new seats to cause this flooding? I would be willing to trade this new carb for a good running TQ carb for a 4 speed 340 car. Thanks
 
sireland67 said:
I really don't think the carb is too big, by guess is you have other issues with the engine, timing etc.
I think you just need to double check everything on your engine, something is not correct.

I do have a 625 street demon on a stock 318, its been on there a few years and it a real nice carb, all I had to adjust OTB was the idle. Would not get rid of it for any other carb.
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I didn't notice any trouble before I chose to rebuild my TQ carb but that doesn't mean anything. You may be right. I have the initial timing set at 12 degrees BTDC but do not know what the total advance or when it comes in.
 
i have the 750 street demon on my stock 340 and it runs great , i did have to do a little tuning (springs and rods) but after that it runs awesome, and pulls better than my themo did, although i could tune the thermo to make it better but knowing that any repair on the jet wells is not anything that will last i decided to stay with the street demon - maybe more timing would take care of the stumble , i am running 20 int and 36 total 55 when vac advance comes in
 
charger 2 said:
i have the 750 street demon on my stock 340 and it runs great , i did have to do a little tuning (springs and rods) but after that it runs awesome, and pulls better than my themo did, although i could tune the thermo to make it better but knowing that any repair on the jet wells is not anything that will last i decided to stay with the street demon - maybe more timing would take care of the stumble , i am running 20 int and 36 total 55 when vac advance comes in
Click to expand...
What springs and rods did you find worked the best? Thanks
 
johnson1550 said:
Rusty, I'm glad you chimed in. I really want to use my stock TQ carb and only purchased this one in case the rebuild it needed did not go well. Unfortunately the TQ carb floods now after the rebuild. I made sure I replaced the "o" rings at the bottom of the fuel wells and replaced the floats with the brass style. Checked the float setting numerous times and is at 1" off of the gasket surface. The one thing that I did not like about the rebuild was the gaskets under the seats were really stuck on there and I used as small flat tip screw driver to scrape the gasket off. I may have damaged the surface where the gaskets sits. Do you think this gasket surface would provide enough leakage around the threads of the new seats to cause this flooding? I would be willing to trade this new carb for a good running TQ carb for a 4 speed 340 car. Thanks
Click to expand...

Hard to say without seeing it.
 
johnson1550 said:
What springs and rods did you find worked the best? Thanks
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when i get home tonight i will get my notes out and let you know about how i have it set up ---
---the carb has 89 primary jets,86 sec jets -i changed the rods from 5640 to 5844 still has the #40 squirter - i had to remove the lower plate on the acc pump housing (the demon uses a rubber valve ) this was torn from the factory ,remove it and install the brass one with metal check ball from a themo (fits perfectly) and install the silver metering rod springs (removing the green springs ) the green ones open at 6 hg and the silvers open at 8 hg , (if you motor is stock you should have around 17 -18 hg at idle so the 8 will be fine) then adjust the linkage rod for the acc pump as you would on the thermo -i did all this and couldnt be happier . From a dead stop at idle i can floor it and both wheels spin untill i let of with 3.23 gears and 295 /50/15 tires and drive in traffic with no hesitations or dead spots , i have not checked mileage since i did all this but i was getting 15 before the mods and the rods leaned it up ,plugs look great , hope this helps
 
charger 2 said:
when i get home tonight i will get my notes out and let you know about how i have it set up ---
---the carb has 89 primary jets,86 sec jets -i changed the rods from 5640 to 5844 still has the #40 squirter - i had to remove the lower plate on the acc pump housing (the demon uses a rubber valve ) this was torn from the factory ,remove it and install the brass one with metal check ball from a themo (fits perfectly) and install the silver metering rod springs (removing the green springs ) the green ones open at 6 hg and the silvers open at 8 hg , (if you motor is stock you should have around 17 -18 hg at idle so the 8 will be fine) then adjust the linkage rod for the acc pump as you would on the thermo -i did all this and couldnt be happier . From a dead stop at idle i can floor it and both wheels spin untill i let of with 3.23 gears and 295 /50/15 tires and drive in traffic with no hesitations or dead spots , i have not checked mileage since i did all this but i was getting 15 before the mods and the rods leaned it up ,plugs look great , hope this helps
Click to expand...
Thank you very much for the info.
 
charger 2 said:
when i get home tonight i will get my notes out and let you know about how i have it set up ---
---the carb has 89 primary jets,86 sec jets -i changed the rods from 5640 to 5844 still has the #40 squirter - i had to remove the lower plate on the acc pump housing (the demon uses a rubber valve ) this was torn from the factory ,remove it and install the brass one with metal check ball from a themo (fits perfectly) and install the silver metering rod springs (removing the green springs ) the green ones open at 6 hg and the silvers open at 8 hg , (if you motor is stock you should have around 17 -18 hg at idle so the 8 will be fine) then adjust the linkage rod for the acc pump as you would on the thermo -i did all this and couldnt be happier . From a dead stop at idle i can floor it and both wheels spin untill i let of with 3.23 gears and 295 /50/15 tires and drive in traffic with no hesitations or dead spots , i have not checked mileage since i did all this but i was getting 15 before the mods and the rods leaned it up ,plugs look great , hope this helps
Click to expand...
Are the jets the ones that came with the carb? I don't see those jets listed on the Demon website for the street demon carb.
 
yes they are the factory installed jets , there are others in the kit but i wanted to change rods first ,
 
charger 2 said:
yes they are the factory installed jets , there are others in the kit but i wanted to change rods first ,
Click to expand...

I installed the rods and springs mentioned as well as put the original .040 pump squrter back in. Also adjusted the acc. pump arm to try to get it to squirt as soon as the linkage moves. Couldn't for the life of me get the acc, pump to squirt until the linkage was just about half way down on it's stroke. This can't be correct.
 
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