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Hello everyone!
I have a 69 Cutlass with an Olds 350/Th400 trans.
I purchased a 750 Street Demon carb from Lynn at Mondello way back in the fall and I’ve been having issues getting the throttle cable to work properly.
I used the stock 24” cable at first, tuned the carb, the engine runs great but the gas pedal binds up and can be difficult to push down, it doesn’t operate smoothly.
Lynn suggested I use a 21” G-body cable and while that cable operates smoothly it doesn’t hVe enough travel to engage the kick down switch, it doesn’t even touch it at full throttle.
I could really use some help! I’m about ready to ditch this carb! I know I’m not reinventing the wheel with this set up, but I just can’t get it to work. I’ve tried the Demon bracket extension, I even tried a fancy Holley bracket with dual return spring and had the same results with both.
I will try to attach some pictures. First pictures are the stock 24” cable, pics of the 2 brackets I’ve I used, last is where the 21” cable is at full throttle not hitting the kickdown.
Your issues are with the linkage, not the carb, then?
"Bolt on" parts rarely bolt on. You just need to play with it more.
Disconnect that garbage return spring setup, adjust the cables, then worry about the return
Last edited by fleming442; February 24th, 2022 at 06:20 AM.
Your issues are with the linkage, not the carb, then?
"Bolt on" parts rarely bolt on. You just need to play with it more.
Disconnect that garbage return spring setup, adjust the cables, then worry about the return
X2
That return spring is way too stiff. Find a Dorman spring package or hit the local hardware store to find a spring that is less stiff also.
Guys I’ve tried different springs, no springs, different brackets it’s always the same.
I can have the longer cable installed, not attached to anything other than pinched between my fingers with light tension, have my son work the throttle and the bind is there. It’s the large upsweep then down angle into the bracket that’s the issue, when the cable is out of the bracket and straight, no bind.
The 21” cable operates smoothly, but doesn’t engage the kickdown.
As far as the “mismatch” goes, how so. I am the parts Holley/Demon say fit this application.
It sounds like a bracket issue. If it's too low, where the sheath ends, it will be pulling the throttle too close to the pivot, and bind up.
Now if you're saying it binds, unhooked from the carb, with finger tension on it, I'd say it's kinked.
What happens if you leave the carb hooked up, then pull from the inside?
I'm running this same carb on my '69 442. I think your problem is the lever on the carb that you're trying to mount the cable to. Have you gone to the Demon/Holley website to look for options? When I purchased my carb it came with a good install pamphlet that explained the different available cable set-ups. The older style GM set-up should avoid the problem you're describing. I had to get clever in the way I attached the cable but it worked fine with my factory cable. I bought a reproduction cable bracket that fixes to the rear two studs on the carb mount so the fixed point of my cable end was in the original position. I also played with a few different spring tensions to get the pedal feel I wanted.
I wouldn't even consider ditching the carb over this. In my experience, the street demon is a great street carb. I've been very happy with it. If I were you I'd try to get hold of the Holley installation instructions that should have come with the carb and start from scratch on the linkage. That aftermarket set-up you have on there now looks way too Rube Goldberg.
I did go over the directions again, it only
mentions the Demon 1953 extension for GMs with the rod style linkage which I’m using and had the throttle hooked to with the longer cable and still had the same issue with it binding.
I did have to buy a 1/2” air cleaner spacer to clear that fancy linkage bracket.
I see there are a couple of other cable lengths between the stock 24” and the 21” I have now. Maybe a 22-22.5” is the sweet spot. I’ll keep digging.
The issue may be that there is only 1 attach point on the carb for your cable. You may have to reverse engineer. Have someone sit in the car & floor the gas, then move carb linkage to wide open & approximate where the cable should mount for full opening. You may have to re-drill the cable attach point.
Well I made up and universal cable and it operates smoothly but I’m not hitting the kickdown switch.
Should the resting position of the pedal arm contact on the kickdown switch like the second picture?
The first picture is where the stock Fusick cable rests, quite a bit back from the switch arm.
I could add a hose or a clamp to the switch arm as I have seen a lot of other people say to do but it’d be a big hose or clamp to hit the spot where the contacts close!
I’m spending the time and money on a universal cable I may as well make it right.
Thanks for all the help!
February 24th, 2022, 06:03 AM
