[Roadsters] High Speed Hesitation / Potential Fix?

[Roy Haslett]

Check for air leak at the intake manifold gaskets/blocks.  With car running carefully spray carb cleaner around gasket areas.  If car revs go up then you have a leak.  Watch out you don't spray on the exhaust.

      From: wattaj via Datsun-roadsters <datsun-roadsters at autox.team.net>
 To: "datsun-roadsters at autox.team.net" <datsun-roadsters at autox.team.net> 
 Sent: Saturday, May 2, 2015 1:55 PM
 Subject: Re: [Roadsters] High Speed Hesitation / Potential Fix?
   
Update:  Reassembled and plugged the lifter piston hole, and no improvement.
Things I have done:   
   - Verified the timing and vacuum advance are set and working correctly.   

   - Adjusted the valves to correct clearance.   

   - Changed the dashpot oil to ATF.   

   - Disassembled the Domes, Pistons, Needles and cleaned.   

   - Reset the needles to correct depth according the Z-Therapy video method.   

   - Checked to make sure SU pistons are moving at the same pace within the domes.   

   - Checked for a kinked fuel lines from the float chambers to the nozzles.   

   - Set/Tuned the carbs according the write-up by Keith Williams.

The only thing that seems to get the car running smoothly and able to accelerate once at speed is to pull the choke out or set the mixture to very rich.
I would maybe suspect the distributor is worn out, but if that were the case I wouldn't think pulling the choke out would make any difference.
Thanks,Alan


   

   From: wattaj via Datsun-roadsters <datsun-roadsters at autox.team.net>
 To: "datsun-roadsters at autox.team.net" <datsun-roadsters at autox.team.net> 
 Sent: Saturday, May 2, 2015 10:49 AM
 Subject: [Roadsters] High Speed Hesitation / Potential Fix?
   
I have been chasing this issue for a while and I am hoping I may have found something but would like your feedback.  (Thanks in advance!)
When cruising around 3000 to 3200 RPM, if I press on the accelerator, the motor wants to hesitate or cough, it will eventually get beyond this, but is annoying.  I have done my best to tune things and the only thing that helps is making the front carb run very rich.
Today, when dissembling the carbs, I noticed the front carb was missing the Lifter Piston (part # 16324-10400) that you can use to test the lean/rich mixture from the bottom of the carb without having to put your finger into the throat of the carb.  
Could that be creating a vacuum leak and cause of my issue?
Thanks,Alan
67-1600 (with a 67.5 engine)Portland, OR


   
________________________________________

datsun-roadsters at autox.team.net

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe: http://autox.team.net/mailman/options/datsun-roadsters/wattaj@yahoo.com




   
________________________________________

datsun-roadsters at autox.team.net

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe: http://autox.team.net/mailman/options/datsun-roadsters/hrhaslett@yahoo.com




  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/datsun-roadsters/attachments/20150504/cbf10917/attachment.html>