I replaced my weber dgv's on my 71 240 with completely rebuilt SU's with SM needles....based on some posts I read on this forum, i decided to use marvel mystery oil for my dampening fluid.....my problem: the car is initially way too responsive-it's almost impossible to drive the car smoothly without jerking myself and the passenger back and forth everytime i shift gears. The acceleration when i lay into the accelerator is fine, but I don't want to pull wheels during regular driving-....could the thin weight of marvel mystery oil be the problem....or could the dampeners themselves be worn....any insight is greatly appreciated.
SU throttle response
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Do you mean it jerks when you hold the gas steady? That probably means your carbs are out of adjustment. It used to happen to mine until I figured out how to get them set up properly. Ztherapy's video helped tremendously.
As for the oil and dampeners.. the best way to find out is to push the piston inside the carbs up with your finger. They should rise easily but with some resistance and fall down with a slight clunk. If one is catching on the way down or one falls quicker than the other that could be the source of your problem.
As for the oil and dampeners.. the best way to find out is to push the piston inside the carbs up with your finger. They should rise easily but with some resistance and fall down with a slight clunk. If one is catching on the way down or one falls quicker than the other that could be the source of your problem.
Not used to all that instant power, are ya? 
This *could* be related to the throttle lever linkage at the firewall. There is a technical article about it at www.zhome.com. I don't have direct experience with this problem or the fix so you'll have to look at it and judge for yourself. You can always try some ATF, 20W motorcycle fork oil or even 10W40. Easy enough to dump out if it doesn't work. (I use MMO BTW)
Let us know what works.
This *could* be related to the throttle lever linkage at the firewall. There is a technical article about it at www.zhome.com. I don't have direct experience with this problem or the fix so you'll have to look at it and judge for yourself. You can always try some ATF, 20W motorcycle fork oil or even 10W40. Easy enough to dump out if it doesn't work. (I use MMO BTW)Let us know what works.
Hi uvazeeman------------Yes, the early Z cars have that "hair trigger " throttle response. 71240L28 is right on with his analysis, IMO. There's a good article that he mentions at www.zhome.com on this subject. Go to Documents, Index of technical articles on the left side menu, and then scroll down the right side to the Engine section, and then down to Intake. The article is titled "improving the throttle linkage or getting rid of the jerk". This will help you, I think. Also, I found this to be a problem that is diminished with time and experience driving the car.
Roadman
Roadman
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If you didnt install the heat shield and proper springs, it could cause that. Springs that are too tight, or at the wrong angle will cause that problem.
Roadman is exactly right. My 240 has the hair trigger throttle, and I remember my dad's old 240 (when it was new) had a mod done to the linkage, but I couldn't remember exactly what was done... but I know it made a big difference. I'm going to check out the Zhome and see if it is the same mod.. probably is.
In the meantime, the way I always have driven 240's to avoid snapping my neck when just puttering around is to place the outside of my foot kind of anchored to the transmission tunnel... then just kind of roll my foot to open the throttle slightly... it works for me....
In the meantime, the way I always have driven 240's to avoid snapping my neck when just puttering around is to place the outside of my foot kind of anchored to the transmission tunnel... then just kind of roll my foot to open the throttle slightly... it works for me....
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