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

To: "datsun-roadsters@autox.team.net" <datsun-roadsters@autox.team.net>
Subject: Re: [Roadsters] High Speed Hesitation / Potential Fix?
From: wattaj via Datsun-roadsters <datsun-roadsters@autox.team.net>
Date: Sat, 2 May 2015 20:55:32 +0000 (UTC)
Delivered-to: mharc@autox.team.net
Delivered-to: datsun-roadsters@autox.team.net
References: <2000612961.340972.1430588949443.JavaMail.yahoo@mail.yahoo.com>
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Update: =C2=A0Reassembled and plugged the lifter piston hole, and no improv=
ement.
Things I have done:  =20
   - Verified the timing and vacuum advance are set and working correctly. =
 =20

   - Adjusted the valves to correct clearance.  =20

   - Changed the dashpot oil to ATF.  =20

   - Disassembled the Domes, Pistons, Needles and cleaned.  =20

   - Reset the needles to correct depth according the Z-Therapy video metho=
d.  =20

   - Checked to make sure SU pistons are moving at the same pace within the=
 domes.  =20

   - Checked for a kinked fuel lines from the float chambers to the nozzles=
.  =20

   - 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 accel=
erate once at speed is to pull the choke out or set the mixture to very ric=
h.
I would maybe suspect the distributor is worn out, but if that were the cas=
e I wouldn't think pulling the choke out would make any difference.
Thanks,Alan


      From: wattaj via Datsun-roadsters <datsun-roadsters@autox.team.net>
 To: "datsun-roadsters@autox.team.net" <datsun-roadsters@autox.team.net>=20
 Sent: Saturday, May 2, 2015 10:49 AM
 Subject: [Roadsters] High Speed Hesitation / Potential Fix?
  =20
I have been chasing this issue for a while and I am hoping I may have found=
 something but would like your feedback. =C2=A0(Thanks in advance!)
When cruising around 3000 to 3200 RPM, if I press on the accelerator, the m=
otor wants to hesitate or cough, it will eventually get beyond this, but is=
 annoying. =C2=A0I 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 #=C2=A016324-10400)=C2=A0that you can use to test the =
lean/rich mixture from the bottom of the carb without having to put your fi=
nger into the throat of the carb. =C2=A0
Could that be creating a vacuum leak and cause of my issue?
Thanks,Alan
67-1600 (with a 67.5 engine)Portland, OR


  =20
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:He=
lveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;fo=
nt-size:16px"><div id=3D"yui_3_16_0_1_1430599258577_3492">Update: &nbsp;Rea=
ssembled and plugged the lifter piston hole, and no improvement.</div><div =
id=3D"yui_3_16_0_1_1430599258577_3492"><br></div><div id=3D"yui_3_16_0_1_14=
30599258577_3492">Things I have done:</div><ol dir=3D"ltr" id=3D"yui_3_16_0=
_1_1430599258577_4440"><li id=3D"yui_3_16_0_1_1430599258577_4446">Verified =
the timing and vacuum advance are set and working correctly.<br></li><li id=
=3D"yui_3_16_0_1_1430599258577_4445">Adjusted the valves to correct clearan=
ce.<br></li><li id=3D"yui_3_16_0_1_1430599258577_4444">Changed the dashpot =
oil to ATF.<br></li><li id=3D"yui_3_16_0_1_1430599258577_4443">Disassembled=
 the Domes, Pistons, Needles and cleaned.<br></li><li id=3D"yui_3_16_0_1_14=
30599258577_4442">Reset the needles to correct depth according the Z-Therap=
y video method.<br></li><li id=3D"yui_3_16_0_1_1430599258577_4441">Checked =
to make sure SU pistons are moving at the same pace within the domes.<br></=
li><li id=3D"yui_3_16_0_1_1430599258577_4439">Checked for a kinked fuel lin=
es from the float chambers to the nozzles.<br></li><li id=3D"yui_3_16_0_1_1=
430599258577_4439">Set/Tuned the carbs according the write-up by Keith Will=
iams.</li></ol><div id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D"ltr"><br>=
</div><div id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D"ltr">The only thin=
g 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.</div><div =
id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D"ltr"><br></div><div id=3D"yui=
_3_16_0_1_1430599258577_3492" dir=3D"ltr">I would maybe suspect the distrib=
utor is worn out, but if that were the case I wouldn't think pulling the ch=
oke out would make any difference.</div><div id=3D"yui_3_16_0_1_14305992585=
77_3492" dir=3D"ltr"><br></div><div id=3D"yui_3_16_0_1_1430599258577_3492" =
dir=3D"ltr">Thanks,</div><div id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D=
"ltr">Alan</div><div id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D"ltr"><br=
></div><div id=3D"yui_3_16_0_1_1430599258577_3492" dir=3D"ltr"><br></div><d=
iv id=3D"yui_3_16_0_1_1430599258577_3492"><br></div>  <div style=3D"font-fa=
mily: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-=
serif; font-size: 16px;" id=3D"yui_3_16_0_1_1430599258577_3821"> <div style=
=3D"font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Gr=
ande, sans-serif; font-size: 16px;" id=3D"yui_3_16_0_1_1430599258577_3820">=
 <div dir=3D"ltr" id=3D"yui_3_16_0_1_1430599258577_3819"> <hr size=3D"1" id=
=3D"yui_3_16_0_1_1430599258577_3867">  <font size=3D"2" face=3D"Arial" id=
=3D"yui_3_16_0_1_1430599258577_3866"> <b><span style=3D"font-weight:bold;">=
From:</span></b> wattaj via Datsun-roadsters &lt;datsun-roadsters@autox.tea=
m.net&gt;<br> <b><span style=3D"font-weight: bold;">To:</span></b> "datsun-=
roadsters@autox.team.net" &lt;datsun-roadsters@autox.team.net&gt; <br> <b><=
span style=3D"font-weight: bold;">Sent:</span></b> Saturday, May 2, 2015 10=
:49 AM<br> <b><span style=3D"font-weight: bold;">Subject:</span></b> [Roads=
ters] High Speed Hesitation / Potential Fix?<br> </font> </div> <div class=
=3D"y_msg_container" id=3D"yui_3_16_0_1_1430599258577_3824"><br><div id=3D"=
yiv2199568988"><div id=3D"yui_3_16_0_1_1430599258577_3828"><div style=3D"co=
lor:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, H=
elvetica, Arial, Lucida Grande, sans-serif;font-size:16px;" id=3D"yui_3_16_=
0_1_1430599258577_3827"><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_14=
30588092886_4465"><span id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4642"=
>I have been chasing this issue for a while and I am hoping I may have foun=
d something but would like your feedback. &nbsp;(Thanks in advance!)</span>=
</div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4465">=
<span><br clear=3D"none"></span></div><div dir=3D"ltr" id=3D"yiv2199568988y=
ui_3_16_0_1_1430588092886_4465"><span id=3D"yiv2199568988yui_3_16_0_1_14305=
88092886_4643">When cruising around 3000 to 3200 RPM, if I press on the acc=
elerator, the motor wants to hesitate or cough, it will eventually get beyo=
nd this, but is annoying. &nbsp;I have done my best to tune things and the =
only thing that helps is making the front carb run very rich.</span></div><=
div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4465"><span><=
br clear=3D"none"></span></div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16=
_0_1_1430588092886_4465"><span class=3D"yiv2199568988" id=3D"yiv2199568988y=
ui_3_16_0_1_1430588092886_4699" style=3D"">Today, when dissembling the carb=
s, I noticed the front carb was missing the Lifter Piston (part #<font id=
=3D"yiv2199568988yui_3_16_0_1_1430588092886_4955" size=3D"3">&nbsp;</font><=
/span><font id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4954" size=3D"3">=
<span class=3D"yiv2199568988" id=3D"yiv2199568988yui_3_16_0_1_1430588092886=
_4857" style=3D"font-family:Arial, Helvetica;">16324-10400)</span>&nbsp;</f=
ont>that you can use to test the lean/rich mixture from the bottom of the c=
arb without having to put your finger into the throat of the carb. &nbsp;</=
div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4465"><s=
pan><br clear=3D"none"></span></div><div dir=3D"ltr" id=3D"yiv2199568988yui=
_3_16_0_1_1430588092886_4465"><span id=3D"yiv2199568988yui_3_16_0_1_1430588=
092886_4806">Could that be creating a vacuum leak and cause of my issue?</s=
pan></div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_1430588092886_44=
65"><span><br clear=3D"none"></span></div><div dir=3D"ltr" id=3D"yiv2199568=
988yui_3_16_0_1_1430588092886_4465"><span id=3D"yui_3_16_0_1_1430599258577_=
4359">Thanks,</span></div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_=
1430588092886_4465"><span id=3D"yiv2199568988yui_3_16_0_1_1430588092886_502=
6">Alan</span></div><div dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_143058=
8092886_4465"><span><br clear=3D"none"></span></div><div dir=3D"ltr" id=3D"=
yiv2199568988yui_3_16_0_1_1430588092886_4465"><span id=3D"yiv2199568988yui_=
3_16_0_1_1430588092886_5014">67-1600 (with a 67.5 engine)</span></div><div =
dir=3D"ltr" id=3D"yiv2199568988yui_3_16_0_1_1430588092886_4465"><span id=3D=
"yiv2199568988yui_3_16_0_1_1430588092886_5045">Portland, OR</span></div><di=
v class=3D"qtdSeparateBR"><br><br></div><div class=3D"yiv2199568988yqt33675=
31350" id=3D"yiv2199568988yqtfd47683"><div id=3D"yiv2199568988yui_3_16_0_1_=
1430588092886_4568" style=3D"font-family:HelveticaNeue, Helvetica Neue, Hel=
vetica, Arial, Lucida Grande, sans-serif;font-size:16px;"><div id=3D"yiv219=
9568988yui_3_16_0_1_1430588092886_4567" style=3D"font-family:HelveticaNeue,=
 Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px=
;"><div class=3D"yiv2199568988y_msg_container" id=3D"yiv2199568988yui_3_16_=
0_1_1430588092886_4574"><br clear=3D"none"></div> </div> </div>  </div></di=
v></div></div><br><div class=3D"yqt3367531350" id=3D"yqtfd78272">__________=
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