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I have an '84 Spider which I've owned since '87. Current mileage is about 66k. It's always run great. Idles smoothly. Maintenance this year included rotor, cap, wires, plugs, replaced fuel filters, checked in tank pump. Replaced all air/vacuum hoses. Fuel pressure is about 37 as I recall, vacuum about 17 at idle. Ever since I've owned it the car accelerates smoothly to about 2700 rpm then climbs rapidly after that with noticeable increase in torque. As a result I always choose my gear to try to keep rpms above that point. I always assumed I was hitting a peak in the torque curve but I wanted to know if that was normal behavior, and if not, what possible causes could be. I did notice that after all my maintenance this year the acceleration seemed to be more linear for a little while, but it has since gone back to the 2700 rpm jump and that made me wonder.
 

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Perhaps the VVT (variable valve timing) is being activated at about that rpm?

Click on the link in my signature (first you have to click 'show full signature') for a page of info about the L-jet system in our cars. That page has info about the VVT & checking/adjusting the activating solenoid. (The earlier models - '82 to '84 or '85 - have a centrifugally activated VVT.)
 

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So do you mean it runs well and accelerates well up to 2700 and then just gets a lot stronger above that? Are you sure you're not just feeling the power curve of the engine? All cars make more power at higher RPMs (a LOT more power). My car runs well and accelerates smoothly with low revs - but if I really want it to go I need well over 3000 RPM.
 

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Perhaps the VVT (variable valve timing) is being activated at about that rpm?

Click on the link in my signature (first you have to click 'show full signature') for a page of info about the L-jet system in our cars. That page has info about the VVT & checking/adjusting the activating solenoid. (The earlier models - '82 to '84 or '85 - have a centrifugally activated VVT.)
Mine does have centrifugal activated VVT. I've never fooled with it.
 

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So do you mean it runs well and accelerates well up to 2700 and then just gets a lot stronger above that? Are you sure you're not just feeling the power curve of the engine? All cars make more power at higher RPMs (a LOT more power). My car runs well and accelerates smoothly with low revs - but if I really want it to go I need well over 3000 RPM.
That's what I've always thought was going on. The change is just so abrupt and predictable that I didn't know if it was normal. I've never experienced it in another car.
 

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certainly no "abrubt" change in my engine at 2700
My car accelerates smooth thru the range.
After 4500+ rpm does it feel more free, but then it is chipped.

the centrifugal VVT kicks in about 1650 rpm. It can be tested using compressed air into the little hole on the VVT....cam should advance.
Vin's posts #91 (faulty unit) and #96 (working unit) here:
https://www.alfabb.com/threads/another-cam-timing-question.296641/page-5
 

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Mine does have centrifugal activated VVT.
Of course it does. I quickly read your post where you said you'd owned it since '87 and my addled brain focused in on that date.

I can feel the VVT come on at about 1800 rpm if I accelerate slowly through that speed. (are you sure your tach is accurate?)
 
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