1978 Datsun 280z No Acceleration Above 4000 RPMs

[A to Z]

Update, please.

[Kad77]

Sorry for no updates for awhile. 

 

I dug into the carbs and figured out that my float levels were completely off. One was set very rich and the other was set very lean. 

 

After properly setting the float levels, the car accelerates much smoother and does not feel like it is going to rattle itself apart above 4500 rpms. 

 

It will rev up to the yellow line now, and has better power above 4500 now, and it is smooth revs.

 

It still feels like it is missing some power above 4000rpms, but it is way better than before. 

 

I believe the issue is that my carbs are still running lean. No matter what adjustments I make, they run lean. 

 

I do have a very small air leak at the butterfly valve shafts. Not much I can do about that right now. Z therapy carbs are out of the budget at the moment. 

 

I have not yet purchased SM needles, I will do this soon, and i am hoping that they will help get the carbs to run a little more rich.

 

Thanks for all the help! Any further advice is appreciated!

[A to Z]

"SM" needles.  They are made specifically for this issue.  I had the same problem as you, changed to these, and no more problems.  They give you more fuel up there.    here is a link to some I quickly found on eBay for you.  when installing the needle height, you want to use a straightedge to make sure the level is correct and not too far "in" before tightening.

 

Datsun 240z SU Carburetor "SM" Race Needles Triumph TR3 .100 | eBay

 

  Butterfly shaft leak, you may be able to smear a thin coat of grease around the shafts. to stop the Leak, if you take your time, it won't even be noticeable to the naked eye.

 

Let me know how it goes. Please.

[Kad77]

Thanks for the help! I just ordered those needles you gave the link for. Once they show up, I'll install them and give an update on the results. 

 

Thanks again!!