Positive Throttle Stop For QuickFuel SS-650

[mcwho]

Just got my new QF carb, looking thru the box the first thing I see is it says I need to have a Positive Throttle stop. I am using a clip and a throttle cable that came with the complete Kit MK4. Also using the Breeze throttle pedal.

Will the Moroso Throttle stop work for me. (65042)

The is no diagram as to how it fits so I don't know, it says it works with Holley 4150 type carbs.

http://www.jegs.com/i/Moroso/710/65042/10002/-1

[NAZ]

Looks like it should work. Simply mounts to the carb mounting studs and uses a manual adjustment to set the stop.

[boat737]

I built a stop for the actual pedal. I took some 1/8 inch stainless plate and bolted it to the existing structure. I have mechanical throttle linkage, but with either a cable or mechanical setup, there is less stress on the carb end of the cable/linkage.

[CraigS]

It will work but boat37's idea is better.

[edwardb]

I have to admit chuckling to myself a little with these throttle stop threads. Yes, but all means make sure there's a positive stop and the proper return springs. But unless you're tracking the car, don't overthink it. In seven driving seasons of street driving, I could easily count on one hand the number of times I've felt the throttle against the stop. And then it was only very briefly touching it. Never even a thought of leaving it there or trying to mash down even harder. Given the power, traction (or lack of), and how fast things happen with these cars, you're not going to be spending a lot of time there. If you even find it. Trust me. On a side note, if you have a rev limiter, chances are that's going to kick in before the throttle stop. At least in the lower gears.

[mcwho]

Thanks for the responses, I like Boat737 solution, Will use the moroso part and put the pedal stop solution on my list of things to do. Yes, I do have a rev limiter but I thought the throttle stop was more to protect the carb internals from getting squished outta shape.

[edwardb]

Thanks for the responses, I like Boat737 solution, Will use the moroso part and put the pedal stop solution on my list of things to do. Yes, I do have a rev limiter but I thought the throttle stop was more to protect the carb internals from getting squished outta shape.

Correct. The throttle stop protects the internal carb (e.g. not pulling the throttle plate and related once it's all the way open) plus the cable/linkage. I agree it needs to be there. My point was only don't overthink it. Between the rev limiter and what happens when you get that deep into the throttle, I'm saying you're not going to be hanging around down there for long periods of time. :rolleyes:

[johnnybgoode]

While I was mocking up my new QF carb I took the opportunity to test and fine tune the linkage, cable, pedal and throttle stop before I connected the carb to the fuel system. That way you can pump away and ensure smooth operation without having to worry about dumping a bunch of gas into the motor. You can test the location of the ball stud in the different holes on the throttle arm to get you the best compromise of full throttle opening but to still be progressive. You can also make sure there is no binding and ensure you have solid throttle return (make sure you have 2 springs). When I started my testing I found that the RT throttle pedal jammed against the trans tunnel and would hang the carb wide open, not good. I added spacers to the pedal and aligned the linkage and once I was finally confident that I was completely happy with the install I made the final fuel system connections and fired up the car. I have had no further issues over the 8 years I've owned the car and the carb/linkage work like they are an extension of my body. Just my 2 cents for what it is worth. Scott

ps. I really like these AED or similar brackets.

65922

[Avalanche325]

Do a stop at the pedal. Here is why. What you don't want, is the carb all the way open and you are still putting pressure on the cable or linkage. Doing that can wear the housing where the primary throttle rod goes through. Then you get a little vacuum leak and slightly sloppy primary butterflies, and you will never figure it out. The stop at the carb doesn't do anything for this.

The bracket that is there for the FFR pedal is not strong enough. Don't just put a bolt through it. Put a piece of 1/4" steel under it and thread your stop bolt in. I bent mine on my first autocross run without the steel. Solid as a rock now. I autocross a lot. I use my pedal stop.

PS> Look at "elevator bolts".

[boat737]

Do a stop at the pedal. Here is why. What you don't want, is the carb all the way open and you are still putting pressure on the cable or linkage. Doing that can wear the housing where the primary throttle rod goes through. Then you get a little vacuum leak and slightly sloppy primary butterflies, and you will never figure it out. The stop at the carb doesn't do anything for this.

The bracket that is there for the FFR pedal is not strong enough. Don't just put a bolt through it. Put a piece of 1/4" steel under it and thread your stop bolt in. I bent mine on my first autocross run without the steel. Solid as a rock now. I autocross a lot. I use my pedal stop.

PS> Look at "elevator bolts".

Same idea, but I just welded a nut to the back side of my 1/8" plate. (Can't see it in the pic above, but it's there on the forward facing side. Lock nut is on the aft side.) Very sturdy, I think the throttle pedal/arm will break off before that mount moves.