News:

We have implemented a Photo Gallery for hosting images right here on SAACFORUM. Check the How-To in News from HQ

Main Menu

Dash pot purpose and function

Started by Corey Bowcutt, February 21, 2022, 01:26:46 PM

Previous topic - Next topic

Corey Bowcutt

I have a 1968 GT350 4 speed with the Holley carburetor.  I am reinstalling my freshly rebuilt motor and rebuilt carburetor.  This is the first time I have had the correct carb on the car sense I have owned her.  Everything is running really well but I felt the idle was high.  I can manually depress the dashpot and the idle settles right where it should be and stays there.  But when I come off the dash pot it returns to a high idle.  I removed the dash pot and it runs great and idles perfectly.  What is the point of the dashpot and is mine just too stiff?

Thank you for any help/suggestions.

Corey

Bob Gaines

Quote from: Corey Bowcutt on February 21, 2022, 01:26:46 PM
I have a 1968 GT350 4 speed with the Holley carburetor.  I am reinstalling my freshly rebuilt motor and rebuilt carburetor.  This is the first time I have had the correct carb on the car sense I have owned her.  Everything is running really well but I felt the idle was high.  I can manually depress the dashpot and the idle settles right where it should be and stays there.  But when I come off the dash pot it returns to a high idle.  I removed the dash pot and it runs great and idles perfectly.  What is the point of the dashpot and is mine just too stiff?

Thank you for any help/suggestions.

Corey
The purpose of the dashpot is to prevent the engine from decelerating too quickly. There is adjustment .You screw it in or out. Sometimes the dashpot goes bad. too stiff or too soft .   
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

Tired Sheep

#2
Quoteis mine just too stiff?

QuoteYou screw it in or out... too stiff or too soft .

:o


Corey Bowcutt

It is screwed in as far as it will go.  I guess mine is just too stiff.

Bob Gaines

Quote from: Corey Bowcutt on February 21, 2022, 02:29:16 PM
It is screwed in as far as it will go.  I guess mine is just too stiff.
Assuming that your bracket is not bent and assuming that you have the correct dashpot the logical next step would be to try another dashpot.   
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

corbins

Quote from: Corey Bowcutt on February 21, 2022, 02:29:16 PM
It is screwed in as far as it will go.  I guess mine is just too stiff.
You mean all the way out ?? It should screw back away from the throttle, or forward towards it. Make sure the little pin is not sticking . Good luck.

Royce Peterson

Several Cobra Jet cars that I have restored have that same dash pot. It works great when it is working right. A new one from Holley (Jegs or Summit) might be the answer. So far the new ones I have bought looked exactly the same as original ones but they tend to be much smoother. The jam nut position might be off on yours - it needs to be forward of the bracket.
1968 Cougar XR-7 GT-E 427 Side Oiler C6 3.50 Detroit Locker
1968 1/2 Cougar XR-7 428CJ Ram Air C6 3.91 Traction Lock

Corey Bowcutt

The dash pot is screwed all the way into the bracket and the jam nut is on the other side of the bracket. This pushes the dash pot as far away from the throttle as possible. The bracket I actually purchased from Bob about a year ago. It appears to be very correct. I think my dash pot part is just no good. I will try one of the new varieties.

texas swede

Never too old to learn something new, I believed, cars with automatics only, had carbs with dash pots.
Texas Swede

Bob Gaines

Quote from: texas swede on February 21, 2022, 09:48:57 PM
Never too old to learn something new, I believed, cars with automatics only, had carbs with dash pots.
Texas Swede
You believed correctly as it relates to 66 and 67 GT350 715 Holley carbs.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

Royce Peterson

The throttle return spring is also part of the equation. If it is not installed correctly you won't have enough tension to overcome the dash pot. You also need the correct return spring and throttle rod of course. The return spring bracket also needs to be the right one.
1968 Cougar XR-7 GT-E 427 Side Oiler C6 3.50 Detroit Locker
1968 1/2 Cougar XR-7 428CJ Ram Air C6 3.91 Traction Lock

shelbymann1970

Quote from: Royce Peterson on February 22, 2022, 10:38:50 AM
The throttle return spring is also part of the equation. If it is not installed correctly you won't have enough tension to overcome the dash pot. You also need the correct return spring and throttle rod of course. The return spring bracket also needs to be the right one.
Is anyone making the correct 68 return spring now?
Shelby owner since 1984
SAAC member since 1990
1970 GT350 4 speed(owned since 1985).
  MCA gold 2003(not anymore)
1969 Mach1 428SCJ 4 speed R-code (owned since 2013)

Corey Bowcutt

I am trying to post a picture of my setup but keep getting an error message so I guess I can not post pictures at this time.  But to the best of my knowledge my setup is all correct.  I really think my dashpot is just too stiff.

I tried looking for a new dashpot on Summit and Jeggs and the ones they show do not look correct to me.

Corey

gt350bp

NPD lists a dashpot for 428 CJ w/ 735 cfm and automatic. I trust it is different or they would have listed for GT 350 also. Might work in a pinch?

Don
gt350bp

Corey Bowcutt

Does anyone have a picture of what the correct dashpot should look like?