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That=E2=80=99s reversion which is exhaust pulses running back up through =
the exhaust & back through the motor.
Weber carbies do not like cams with less than 110 degree cam lob centers =
for that reason.
Is there more fuel present at the filter now than before ? Without the =
tail pipe you are missing out
on some amount of extraction. Greg Solow has done a ton of dyno work =
with exhaust systems
and he found that an 18=E2=80=9D, slight megaphone shape, was superior =
to just a straight pipe for HP=20
and it=E2=80=99s ability to extract so exhaust coming straight out of a =
muffler cannot be good and will
affect how the entire system performs.
Jim g
=20
From: Fot [mailto:fot-bounces@autox.team.net] On Behalf Of Duncan =
Charlton
Sent: Sunday, October 16, 2016 8:07 AM
To: D V <explore8@outlook.com>
Cc: fot@autox.team.net
Subject: Re: [Fot] Stutter at 4K rpm
=20
Derek,
I=E2=80=99m not sure the fuel in that location tells you much. With =
some carbs you can see a fuel/air fog standing in the trumpets and this =
can condense and be visible as droplets when you have the engine =
stopped.
=20
Duncan Charlton
Elgin, Texas USA
=20
=20
=20
On Oct 15, 2016, at 10:51 PM, D V <explore8@outlook.com =
=20
Thanks everyone for the replies. I will inspect the pipe to manifold and =
manifold to head to see if anything is loose or any leaks apparent in =
the morning.
=20
I actually went down a main jet 145 to 140 and that seemed like it =
helped some but didn't clear up the issue (which is going leaner; =
opposite of what Greg said).=20
=20
It is missing and backfiring when I am full on the gas. I can prevent it =
by easing into the gas.
=20
I did notice some gas at my air cleaner to velocity stack connection. I =
wonder if it is a float issue?
=20
Sent from my iPhone
On Oct 15, 2016, at 7:35 PM, Greg Blake <gblake58tr3@icloud.com =
Don't know if my other email made it to you. Backfires on deceleration =
can be a lean condition. Have you checked your plugs? Maybe something =
got "adjusted" with the bump.=20
Sent from my iPhone
On Oct 15, 2016, at 12:27 PM, D V <explore8@outlook.com =
Sent from my iPhone
Begin forwarded message:
Date: October 15, 2016 at 10:30:51 AM CDT
Subject: Stutter at 4K rpm
Two races ago I went off track and bent my exhaust pipe enough to break =
the welded joint near the muffler. In the interest of time, I cut the =
exhaust at the muffler and secured the pipe to the frame.
At the last race, I noticed the car would backfire at deceleration which =
I am not surprised but I also noticed a stutter around 4-5k rpm.=20
At NOLA this weekend it is more pronounced and comes in when shifting =
hard from 3rd to 4th. After 5k, it clears up and pulls normally.
It doesn't seem to be affected by turns and more related to full =
throttle vs easing into the gas.
Backpressure from the loss of muffler or unrelated issues?
1300 spitfire with single Weber 40.
Sent from my iPhone
_______________________________________________
http://www.fot-racing.com <http://www.fot-racing.com/>=20
Archive: http://www.team.net/archive
http://autox.team.net/mailman/options/fot/gblake58tr3@icloud.com
_______________________________________________
http://www.fot-racing.com
Archive: http://www.team.net/archive
http://autox.team.net/mailman/options/fot/duncan.charlton54@gmail.com
=20
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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue =
vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>That=E2=80=99=
s reversion which is exhaust pulses running back up through the exhaust =
& back through the motor.<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>Weber =
carbies do not like cams with less than 110 degree cam lob centers for =
that reason.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>Is there =
more fuel present at the filter now than before ? Without the tail pipe =
you are missing out<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>on some =
amount of extraction. Greg Solow has done a ton of dyno work with =
exhaust systems<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>and he found =
that an 18=E2=80=9D, slight megaphone shape, was superior to just a =
straight pipe for HP <o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>and =
it=E2=80=99s ability to extract so exhaust coming straight out of a =
muffler cannot be good and will<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>affect how =
the entire system performs.<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>Jim =
g<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </=
o:p></span></p><div><div style=3D'border:none;border-top:solid #E1E1E1 =
1.0pt;padding:3.0pt 0in 0in 0in'><p class=3DMsoNormal><b><span =
style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span><=
/b><span style=3D'font-size:11.0pt;font-family:"Calibri",sans-serif'> =
Fot [mailto:fot-bounces@autox.team.net] <b>On Behalf Of </b>Duncan =
Charlton<br><b>Sent:</b> Sunday, October 16, 2016 8:07 AM<br><b>To:</b> =
D V <explore8@outlook.com><br><b>Cc:</b> =
fot@autox.team.net<br><b>Subject:</b> Re: [Fot] Stutter at 4K =
rpm<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p> </o:p></p><p =
class=3DMsoNormal>Derek,<o:p></o:p></p><div><p =
class=3DMsoNormal>I=E2=80=99m not sure the fuel in that location tells =
you much. With some carbs you can see a fuel/air fog standing in =
the trumpets and this can condense and be visible as droplets when you =
have the engine stopped.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p><div><div><p =
class=3DMsoNormal>Duncan Charlton<o:p></o:p></p></div><div><p =
class=3DMsoNormal>Elgin, Texas USA<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><p =
class=3DMsoNormal><o:p> </o:p></p></div><p =
class=3DMsoNormal><o:p> </o:p></p><div><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><p =
class=3DMsoNormal>On Oct 15, 2016, at 10:51 PM, D V <<a =
href=3D"mailto:explore8@outlook.com";>explore8@outlook.com</a>> =
wrote:<o:p></o:p></p></div><p =
class=3DMsoNormal><o:p> </o:p></p><div><div><div><div><p =
class=3DMsoNormal>Thanks everyone for the replies. I will inspect the =
pipe to manifold and manifold to head to see if anything is loose or any =
leaks apparent in the morning.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p class=3DMsoNormal>I =
actually went down a main jet 145 to 140 and that seemed like it helped =
some but didn't clear up the issue (which is going leaner; opposite of =
what Greg said). <o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal>It is missing and backfiring when I am full on the =
gas. I can prevent it by easing into the =
gas.<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p class=3DMsoNormal>I =
did notice some gas at my air cleaner to velocity stack connection. I =
wonder if it is a float issue?<o:p></o:p></p></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div><div><p =
class=3DMsoNormal><br>Sent from my iPhone<o:p></o:p></p></div><div><p =
class=3DMsoNormal style=3D'margin-bottom:12.0pt'><br>On Oct 15, 2016, at =
7:35 PM, Greg Blake <<a =
href=3D"mailto:gblake58tr3@icloud.com";>gblake58tr3@icloud.com</a>> =
wrote:<o:p></o:p></p></div><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p =
class=3DMsoNormal>Don't know if my other email made it to you. Backfires =
on deceleration can be a lean condition. Have you checked your plugs? =
Maybe something got "adjusted" with the =
bump. <br><br>Sent from my iPhone<o:p></o:p></p></div><div><p =
class=3DMsoNormal style=3D'margin-bottom:12.0pt'><br>On Oct 15, 2016, at =
12:27 PM, D V <<a =
href=3D"mailto:explore8@outlook.com";>explore8@outlook.com</a>> =
wrote:<o:p></o:p></p></div><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p =
class=3DMsoNormal><br><br>Sent from my =
iPhone<o:p></o:p></p></div><div><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'><br>Begin forwarded =
message:<o:p></o:p></p></div><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'><b>From:</b> <<a =
href=3D"mailto:explore8@outlook.com";>explore8@outlook.com</a>><br><b>D=
ate:</b> October 15, 2016 at 10:30:51 AM CDT<br><b>To:</b> <<a =
href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a>><br><b>Subje=
ct:</b> <b>Stutter at 4K =
rpm</b><o:p></o:p></p></div></blockquote><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><p =
class=3DMsoNormal>Two races ago I went off track and bent my exhaust =
pipe enough to break the welded joint near the muffler. In the interest =
of time, I cut the exhaust at the muffler and secured the pipe to the =
frame.<br><br>At the last race, I noticed the car would backfire at =
deceleration which I am not surprised but I also noticed a stutter =
around 4-5k rpm. <br><br>At NOLA this weekend it is more pronounced and =
comes in when shifting hard from 3rd to 4th. After 5k, it clears up and =
pulls normally.<br><br>It doesn't seem to be affected by turns and more =
related to full throttle vs easing into the gas.<br><br>Backpressure =
from the loss of muffler or unrelated issues?<br><br>1300 spitfire with =
single Weber 40.<br><br>Sent from my =
iPhone<o:p></o:p></p></div></blockquote></div></blockquote><blockquote =
style=3D'margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'>__________________________________________=
_____<br><a =
href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a><br><br><a =
href=3D"http://www.fot-racing.com/";>http://www.fot-racing.com</a><br><br>=
href=3D"http://www.team.net/donate.html";>http://www.team.net/donate.html<=
/a><br>Archive: <a =
href=3D"http://www.team.net/archive";>http://www.team.net/archive</a><br>F=
orums: <a =
href=3D"http://www.team.net/forums";>http://www.team.net/forums</a><br>Uns=
ubscribe/Manage: <a =
href=3D"http://autox.team.net/mailman/options/fot/gblake58tr3@icloud.com"=
>http://autox.team.net/mailman/options/fot/gblake58tr3@icloud.com</a><br>=
<br><o:p></o:p></p></div></blockquote></div></blockquote></div></div><p =
class=3DMsoNormal =
style=3D'margin-bottom:12.0pt'>__________________________________________=
_____<br><a =
href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a><br><br><a =
href=3D"http://www.fot-racing.com";>http://www.fot-racing.com</a><br><br>D=
onate: <a =
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/a><br>Archive: <a =
href=3D"http://www.team.net/archive";>http://www.team.net/archive</a><br>F=
orums: <a =
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om</a><br><br><o:p></o:p></p></div></blockquote></div><p =
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http://www.fot-racing.com
Archive: http://www.team.net/archive
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