260 with round tops touchy throttle

[Guest 260Shinyuu]

Early 260z from november of 73' with SU 4-screw round tops. I can't even touch the pedal without RPMs picking up to maybe 2k or above. I need to check the linkage to see if its mis-matched 240 and 260, but need a baseline. Anyone have any pictures of the correct linkage from the firewall to the round tops?

[Challenger]

Its called raw, brute power!!

[Guest 260Shinyuu]

Its a little ridiculous, you have to let out the clutch and hope the car takes it, cause if you put your foot on the accelerator you'll borderline holeshot.

[jeffer949]

do you have a good throttle return spring on it? i found when i had a lite spring on it or i forgot to put one on it was to easy to push the throttle and made it really touchy. but then i put a stiffer spring on and it went away.

[Guest 260Shinyuu]

plenty of return and there's no pedal travel. Lay the weight of your foot on the accelerator, you'd be at 2k.

[gira]

Shinyuu,

I have had the same issue with one of many Z's I've had. Actually it's still on one of my 240 race cars. I call it the cam effect, meaning likage geometry, not actual engine cam. It's almost impossible to apply a little bit of throttle to this car. I attibute this to two things. We don't run any oil in the carb tops to dampen the carb piston movement. Also the geometry of the linkage. You can mess around with both of these. Try a little heavier weight oil in the dashpot of the SU. Make sure all the linkage is lubed up good. Our race engines are hardley ever at part throttle so it's only real noticeable around the pits.

 

Greg Ira