What are you blower guys using for a throttle cable and pedal?I have a 6-71,2 Holley's with the sideways linkage. Also a 700 r4 with tv cable,Lokar throttle cable, s**** pedal.man it is hard to push. It also appears the lokar inner cable runs the aluminum housing at 3/4 throttle.
Lokar stuff is ok, but you need either a heavy cable linkage[like a trans shifter type cable] or mechanical linkage. Opening two carbs takes some strength, and don't forget you need a strong return spring also.
I would use a Morse cable. And pull , don't push. Lippy http://www.appliedracing.com/morse-cables-and-accessories/morse-cables-1.html
I have a vintage MOON foot pedal , bell crank and rod. Mechanical . Works great. I had a cable on but did not like the feel of it, and I have had cables fail in the past.
Check out some boat hardware suppliers, they use Morse type cables and I have even seen hydraulic set ups that need very little pressure.
When I had holleys on my blower, I had a home made linkage, operated by an OEM throttle cable, it worked fine for 25 years. Then when I put the blower on my Chevy II, I went with Carter carbs, and a new aftermarket linkage, which I connected to the OEM pedal and arm. It works fine. From your description, I can't really tell what you have...I can kind of guess...but a few pictures would help us help you figure out what changes you might want to make.
I have always fabricated my own from scratch...., This site is a good starting point .. even if it just for ideas .., http://goodvibesracing.com/Enderle_Linkage_Kits.htm
Oh and yes being a long time drag boat racer Morse cables work really well in auto apps too. They are used for shifter cables in lots of auto trans apps.
Yes, it's definitely not going to work. I had the Morse cables on a jet boat, but didn't think I can get anything that short. I figured it's a pretty common setup,just don't know how people do it. No blower guys around me.
The setup you have could probably be made to work. Be helpful to see the carb end of it, too. The gas pedal cable situation...if you moved the pivot point out off the firewall, and also raised it up a bit, then it would probably be much better. Try to set everything up so it's at a right angle in the middle of it's travel, not at the end of it's travel.
Like Squirrel says: ALL rotating arms 'equidistant', another thing is return springs. Put return springs on the end of the linkage, or in a straight continuous line with linkage. Springs attached to opposite angles of carb arms tend to encourage the throttle shaft (s) to 'saw through' their bushings. ...and the idle setting gets higher...and higher...and hi...
I see some horrible engineering practise there. Big long levers, horrible mechanical advantage, cables pulled at bad angle. I have twin Holleys on a tunnel ram, throttle is finger pressure. It won't be any different with a blower underneath. How far does your foot pedal move to get full throttle? My throttle pedal is home made, pedal moves twice as far as it pulls cable, cable has to be pulled 2" max to wide open throttles.
I can't take credit for engineering the linkage. All I did was duplicate weiand's, and made all the parts myself on a machining center. Running carbs inline would sure be alot easier,but not possible at this time.
Im with Jim it needs to be a straight pull. And a blower will try to **** the ****erfly shut at part throttle IF YOU ARE RUNNING ANY BOOST. Damn I keep thinking race car ****. Lippy
your spring setup looks ok to me, it's pulling on the linkage, not on the bottom of the throttle arm. Take a look at all the angles, I think the pedal is the main issue, but there are some other angles that are hard to see from the pics, that might be causing problems, I can't really tell what the bellcrank that goes from vertical to horizontal movement, looks like. Also the springs don't need to be very stiff, you might try some different ones and see how it affects things. For racing the tech inspectors like to see double springs in case one breaks...using light springs is a necessity when there are 4 of them you're working against.