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Re: [Roadsters] High Speed Hesitation / Potential Fix?

To: divehatteras@aol.com, wattaj@yahoo.com
Subject: Re: [Roadsters] High Speed Hesitation / Potential Fix?
From: Keith0alan--- via Datsun-roadsters <datsun-roadsters@autox.team.net>
Date: Sat, 2 May 2015 20:17:39 -0400
Cc: datsun-roadsters@autox.team.net
Delivered-to: mharc@autox.team.net
Delivered-to: datsun-roadsters@autox.team.net
Full-name: Keith0alan
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Try heavier oil in the dashpot. If it cruises fine then the mixture is  
good. Stumbling on acceleration is a sign of not being enriched enough on  
acceleration. Thicker oil will enrichen more on acceleration. Try some 30 wt  
engine oil and see if it gets better.
 
 
In a message dated 5/2/2015 2:46:55 P.M. Pacific Daylight Time,  
datsun-roadsters@autox.team.net writes:

Potential worn throttle shafts.  Adding choke to enriched mixture  makes up 
for unmetered air that is coming from someplace.  


Check the play in throttle shafts and then look for other areas that  might 
do same. 


Also how's the float bowl fuel level?  Adding choke also drops  nozzle to 
level of lower fuel bowl. But if it runs well otherwise and always  idles 
decent then neither may apply. 


All just wags without being there. 

Dave Sommers  
Dive Hatteras
703-517-3724
703-818-1850


On May 2, 2015, at 16:55, wattaj via Datsun-roadsters 
<_datsun-roadsters@autox.team.net_ (mailto:datsun-roadsters@autox.team.net) >  
wrote:




 
Update:  Reassembled and  plugged the lifter piston hole, and no 
improvement.


Things I have done:
    1.  Verified the timing and vacuum  advance are set and working 
correctly.
    2.  Adjusted the valves to correct  clearance.
    3.  Changed the dashpot oil to ATF.
    4.  Disassembled the Domes, Pistons,  Needles and cleaned.
    5.  Reset the needles to correct depth  according the Z-Therapy video 
method.
    6.  Checked to make sure SU pistons are  moving at the same pace within 
the domes.
    7.  Checked for a kinked fuel lines  from the float chambers to the 
nozzles.
    8.  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@autox.team.net_ 
(mailto:datsun-roadsters@autox.team.net) >
To: "_datsun-roadsters@autox.team.net_ 
(mailto:datsun-roadsters@autox.team.net) "  <_datsun-roadsters@autox.team.net_ 
(mailto:datsun-roadsters@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




 
 









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ole_document=20
color=3D#000000 size=3D2 face=3DArial>
<DIV>Try heavier oil in the dashpot. If it cruises fine then the mixture=
 is=20
good. Stumbling on acceleration is a sign of not being enriched enough on=
=20
acceleration. Thicker oil will enrichen more on acceleration. Try some 30=
 wt=20
engine oil and see if it gets better.</DIV>
<DIV>&nbsp;</DIV>
<DIV>
<DIV>In a message dated 5/2/2015 2:46:55 P.M. Pacific Daylight Time,=20
datsun-roadsters@autox.team.net writes:</DIV>
<BLOCKQUOTE=20
style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"=
><FONT=20
  style=3D"BACKGROUND-COLOR: transparent" color=3D#000000 size=3D2 face=3D=
Arial>
  <DIV>Potential worn throttle shafts. &nbsp;Adding choke to enriched mixt=
ure=20
  makes up for unmetered air that is coming from someplace. &nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>Check the play in throttle shafts and then look for other areas tha=
t=20
  might do same.&nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>Also how's the float bowl fuel level? &nbsp;Adding choke also drops=
=20
  nozzle to level of lower fuel bowl. But if it runs well otherwise and al=
ways=20
  idles decent then neither may apply.&nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>All just wags without being there.&nbsp;<BR><BR>Dave Sommers=20
  <DIV>Dive Hatteras</DIV>
  <DIV>703-517-3724</DIV>
  <DIV>703-818-1850</DIV></DIV>
  <DIV><BR>On May 2, 2015, at 16:55, wattaj via Datsun-roadsters &lt;<A=20
  title=3Dmailto:datsun-roadsters@autox.team.net=20
  href=3D"mailto:datsun-roadsters@autox.team.net";>datsun-roadsters@autox.t=
eam.net</A>&gt;=20
  wrote:<BR><BR></DIV>
  <BLOCKQUOTE type=3D"cite">
    <DIV>
    <DIV=20
    style=3D"FONT-SIZE: 16px; FONT-FAMILY: HelveticaNeue, Helvetica Neue,=
 Helvetica, Arial, Lucida Grande, sans-serif; COLOR: #000; BACKGROUND-COLO=
R: #fff">
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492>Update: &nbsp;Reassembled an=
d=20
    plugged the lifter piston hole, and no improvement.</DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492>Things I have done:</DIV>
    <OL id=3Dyui_3_16_0_1_1430599258577_4440 dir=3Dltr>
      <LI id=3Dyui_3_16_0_1_1430599258577_4446>Verified the timing and vac=
uum=20
      advance are set and working correctly.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4445>Adjusted the valves to corr=
ect=20
      clearance.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4444>Changed the dashpot oil to=
 ATF.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4443>Disassembled the Domes, Pis=
tons,=20
      Needles and cleaned.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4442>Reset the needles to correc=
t depth=20
      according the Z-Therapy video method.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4441>Checked to make sure SU pis=
tons are=20
      moving at the same pace within the domes.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4439>Checked for a kinked fuel=
 lines=20
      from the float chambers to the nozzles.<BR>
      <LI id=3Dyui_3_16_0_1_1430599258577_4439>Set/Tuned the carbs accordi=
ng the=20
      write-up by Keith Williams.</LI></OL>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr>The only thing tha=
t seems to=20
    get the car running smoothly and able to accelerate once at speed is=
 to pull=20
    the choke out or set the mixture to very rich.</DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr>I would maybe susp=
ect the=20
    distributor is worn out, but if that were the case I wouldn't think pu=
lling=20
    the choke out would make any difference.</DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr>Thanks,</DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr>Alan</DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492 dir=3Dltr><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3492><BR></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3821=20
    style=3D"FONT-SIZE: 16px; FONT-FAMILY: HelveticaNeue, Helvetica Neue,=
 Helvetica, Arial, Lucida Grande, sans-serif">
    <DIV id=3Dyui_3_16_0_1_1430599258577_3820=20
    style=3D"FONT-SIZE: 16px; FONT-FAMILY: HelveticaNeue, Helvetica Neue,=
 Helvetica, Arial, Lucida Grande, sans-serif">
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    <HR id=3Dyui_3_16_0_1_1430599258577_3867 SIZE=3D1>
    <FONT id=3Dyui_3_16_0_1_1430599258577_3866 size=3D2 face=3DArial><B><S=
PAN=20
    style=3D"FONT-WEIGHT: bold">From:</SPAN></B> wattaj via Datsun-roadste=
rs=20
    &lt;<A title=3Dmailto:datsun-roadsters@autox.team.net=20
    href=3D"mailto:datsun-roadsters@autox.team.net";>datsun-roadsters@autox=
.team.net</A>&gt;<BR><B><SPAN=20
    style=3D"FONT-WEIGHT: bold">To:</SPAN></B> "<A=20
    title=3Dmailto:datsun-roadsters@autox.team.net=20
    href=3D"mailto:datsun-roadsters@autox.team.net";>datsun-roadsters@autox=
.team.net</A>"=20
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    href=3D"mailto:datsun-roadsters@autox.team.net";>datsun-roadsters@autox=
.team.net</A>&gt;=20
    <BR><B><SPAN style=3D"FONT-WEIGHT: bold">Sent:</SPAN></B> Saturday, Ma=
y 2,=20
    2015 10:49 AM<BR><B><SPAN style=3D"FONT-WEIGHT: bold">Subject:</SPAN><=
/B>=20
    [Roadsters] High Speed Hesitation / Potential Fix?<BR></FONT></DIV>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3824 class=3Dy_msg_container><BR>
    <DIV id=3Dyiv2199568988>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3828>
    <DIV id=3Dyui_3_16_0_1_1430599258577_3827=20
    style=3D"FONT-SIZE: 16px; FONT-FAMILY: HelveticaNeue, Helvetica Neue,=
 Helvetica, Arial, Lucida Grande, sans-serif; COLOR: #000; BACKGROUND-COLO=
R: #fff">
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4642>I have been chasing=
 this=20
    issue for a while and I am hoping I may have found something but would=
 like=20
    your feedback. &nbsp;(Thanks in advance!)</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
><BR=20
    clear=3Dnone></SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4643>When cruising around=
 3000 to=20
    3200 RPM, if I press on the accelerator, the motor wants to hesitate=
 or=20
    cough, it will eventually get beyond this, but is annoying. &nbsp;I ha=
ve=20
    done my best to tune things and the only thing that helps is making th=
e=20
    front carb run very rich.</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
><BR=20
    clear=3Dnone></SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4699 class=3Dyiv219956898=
8>Today,=20
    when dissembling the carbs, I noticed the front carb was missing the=
 Lifter=20
    Piston (part #<FONT id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4955=
=20
    size=3D3>&nbsp;</FONT></SPAN><FONT=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4954 size=3D3><SPAN=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4857 class=3Dyiv219956898=
8=20
    style=3D"FONT-FAMILY: Arial, Helvetica">16324-10400)</SPAN>&nbsp;</FON=
T>that=20
    you can use to test the lean/rich mixture from the bottom of the carb=
=20
    without having to put your finger into the throat of the carb. &nbsp;<=
/DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
><BR=20
    clear=3Dnone></SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4806>Could that be creati=
ng a=20
    vacuum leak and cause of my issue?</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
><BR=20
    clear=3Dnone></SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyui_3_16_0_1_1430599258577_4359>Thanks,</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_5026>Alan</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
><BR=20
    clear=3Dnone></SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_5014>67-1600 (with a 67.5=
=20
    engine)</SPAN></DIV>
    <DIV id=3Dyiv2199568988yui_3_16_0_1_1430588092886_4465 dir=3Dltr><SPAN=
=20
    id=3Dyiv2199568988yui_3_16_0_1_1430588092886_5045>Portland, OR</SPAN><=
/DIV>
    <DIV class=3DqtdSeparateBR><BR><BR></DIV>
    <DIV id=3Dyiv2199568988yqtfd47683 class=3Dyiv2199568988yqt3367531350>
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