Push or pull throttle control?

I'm having a hard time staging and leaving in a friend's A/FC that is set up to "push" the throttle open (against the return spring). My own car is set up to "pull" the throttle open. I swear that the cable feels like it is slightly binding when you bring the R's up and it is making it very difficult. I keep harping that Morse cables are ment to "pull" under tension and not push. They pull out a photo from ND that showed Manzo's throttle set up to push the cable and just say "if it's good enough for Manzo, it's good enough for you...deal with it!" I don't have problems keeping the launch rpm consistant with my own car set up differently. Any feedback?
Joe Percoco

 

Dude not having been able to drive but helping set up both you have to make the choice as the driver to do what feels right for you. The guys may push but if in the end you are not comfortlable with the system it will show on the slip, so in the end the work will be worth it.jdd

 

Dude not having been able to drive but helping set up both you have to make the choice as the driver to do what feels right for you. The guys may push but if in the end you are not comfortable with the system it will show on the slip, so in the end the work will be worth it.jdd

 

We run a TAD so it may or may not be different, but we have always had our cars set up to pull the throttle open. We've run TAD's for many years starting back way before I was born and have never had any trouble with this. We have talked some of the local TAFC's to switch over to the "pull" setup because they have asked what they can to fix an uncomfortable situation like that, and it truly, I believe works easier when pulling the throttle.

[ September 09, 2003, 11:48 PM: Message edited by: Nathan Sitko - 625 TAD ]

 

Push or pull should work. Make sure the lever angle where the cable connects is correct otherwise the throttle will try to pop open as you step on the gas. I've seen this on cars where people have had problems holding rpm at stage. A good rule of thumb is to have the lever on the injector parallel to the cable bracket at 1/2 throttle. At idle, the lever might be 45 degrees and at wide open throttle it should be abour 135 degrees.

 

I agree With Randy, Maybe you are trying to overcome an "Over-Center" angle of some type in the early portion of your pedal position???
... just a thought, It ALL goes back to "Geometry Class".
Remember, KEEP IT SIMPLE... it always helps in everything I've ever done because it's VERY easy to over-think a situation.
GOOD LUCK IN THE ALKY CLASSES

 

ALWAYS REMEMBER!!!

IT'S NOT GOING TO THE MOON, IT'S JUST GOING A 1/4 mi.

...per the ever wise fuel "guru" Ralph Gorr.

It's always worked for me, So give it a shot.

Good luck in the ALKY Class!!!

 

Thanks for the reply guys. I will take a close look at the linkage angles and see what we can figure out. We are planning on going to Dallas so maybe we can get down the track and get in the show with some luck.

 

How about the fuel pressure?

 

Joe; I'm old, so I've seen a lot of dumb stuff !
Tension or compression is the proper question. This sport has seen lots of races lost by a hundreth. Watch the cable housing flex and then think about it.
I've taken a 17 year break from F/C's, but have done a few blown altereds and a bunch of front motor cars lately, so I've looked at both ways, and the best bet is to mount a small bellcrank about six inches ahead of the pedal with a short pushrod to the bellcrank (actually a near straight piece with 3/16" holes at each end at 4" centers, and a 1/4" pivot hole, centered) this will put the cable low in the car and an easy slow bend up to the throttle arm. BTW, I use a figure of 5.25" from pedal pivot to linkage mount ball or tab. This will still let you control a good burnout without killing the springs while still being able to cut .005 lights. Boy... have I got lots of stories about those wizards that heard **#^ from the guy who's uncle, who's brother lived six doors down Grumpy Jenkins!!

Bob

 

Bob, Thanks for the reply. I actually have two cars of my own and one is set up as you say-with a bell crank. The other was recently purchased as a backup and is at a fabricators now being re-tinned and having a few changes made. One item we are looking at is changing the throttle to be similar to my other car- that is with a bell crank arrangement. I need to look closer at mine and study the dimensions and where the bell crank is located in relation to the pivot. Am I correct in thinking that if you want to shorten the throw (travel) it should be done by altering the length of one arm vs the other on the bell crank? As far as this other car I am driving for my friend, I'm afraid all this would fall on deaf ears.

 

To shorten the throw, the dimension from the centerline of the bellcrank to the cable attachment should be increased and/or the dimension from the centerline of the butterfly shaft to the cable attachment on the injector should be decreased.

[ September 14, 2003, 04:14 AM: Message edited by: Randy G. ]

 

Ok well here you go. Cables are meant to apply tension not compression...When was the last time you were able to push something with a rope. A cable is the same thing only with the sheething around it it allows it in this case to push the throttle.

 

Better go tell Manzo.