--===============0949548515789620891==
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Does this happen in both right and left turns, on such a small run try the
opposite direction, could be float hinge problems if it always quits in a
corner.
Carl Stenquist
On Fri, Aug 9, 2024 at 5:44=E2=80=AFPM Andrew Devenish via Fot <fot@autox.t=
eam.net>
wrote:
> Hi Mike,
> The first question is a good one. The car was built for
> autocross by a guy in Indiana who knew his stuff. However, I bought it fr=
om
> a guy who had bought it to run PIB, but knew nothing about race engines. =
He
> had run it lean and holed #4. He told me he had not changed anything, but
> that is turning out not to be the case. (I suspect it holed the piston
> because I found he had fitted gros jets with the float level way too low)=
.
> I rebuilt it to same mechanical spec. It ran great but a little
> lean on the AAU needles for road course, so I=E2=80=99m now on AAA. It st=
ill runs
> great, unless it doesn=E2=80=99t =F0=9F=98=81.
> The car has had this issue since I built it. At first I thought
> the obvious - float heights, needle/seat, regulator pressure etc etc but
> while it always runs great I have this issues after a few =E2=80=9Claps=
=E2=80=9D.
> 2) The car had a Summit racing 3136 pump which has around 90GPH
> and an internal blow off at 7PSI, my regulator is at 4 PSI. Today I had
> taken the pump apart and checked it but all looked OK. I fitted a cheap
> solenoid pump in its place. Issue still there.
> I had checked both the Summit and now the solenoid pump for flow, there i=
s
> plenty.
> As I noted the float bowls are full when it quits running.
> 3) Great point - could be what I have. I know the fuel level in the
> jets is fine when not running, but a poor flow from bowl to jet would
> change that when running. My O2 is in the collector, so I can=E2=80=99t b=
e sure if
> it=E2=80=99s both carbs or just one. All 4 plugs look very similar, but t=
hat is
> possible as this =E2=80=9Clean=E2=80=9D condition is only for a few cycle=
s before it stops
> - not enough to color the plug. Will check when I can ( unfortunately a
> busy weekend coming up as I race sailboats too ). I=E2=80=99ve been think=
ing it is
> heat related, but it could just as easily be time. When I tried to run
> autocross it started to play up after 10 or so seconds of full throttle
> (which I can=E2=80=99t do in my yard). On autocross it would pull like cr=
azy, then
> go very flat, and then come back on, repeat. Your idea would do just that=
!
> 4) always worth a check, but it would have to be something that shows
> up only when hot.
> 5) yes, compression good. Between 220 and 225 for all, measured on
> crank with throttles open.
>
>
> Thanks also to the other responses that I received, I didn=E2=80=
=99t cc all
> on my replies in order to reduce the clutter=E2=80=A6
>
> Thank you,
> Andrew Devenish
>
> Sent from my iPad
>
> On Aug 9, 2024, at 3:51=E2=80=AFPM, Mike Harmuth <ofracer@gmail.com> wrot=
e:
>
> =EF=BB=BF
> Hi Andrew, a couple of things to check.
> 1st, is this a new problem? if so, what did you touch last?
>
> 2d Verify fuel flow, not just pressure i.e Gallons per hour? Disconnect
> the fuel line at the carbs, and stick it into a 1 quart or one gallon
> clean/clear bottle/jug. Turn the fuel pump on and time how long it takes =
to
> fill (1 Qt/ 1Gal whatever size container you're using). If you're gettin=
g
> more than 20 gallons per hour, the flow is OK. Set the bottle aside and l=
et
> it settle out, look for particles, rubber, fuel cell foam, dirt. If so, s=
ee
> where that's coming from. For example, old fuel cell foam will break down
> and clog the intake. When the pump turns off, the fuel in the lines drops
> back flushing the intake clear until next time. Fuel filter clean? Fuel
> pressure reg OK? Not just holding pressure (I run 3.5 on my HS4s) but
> actually sending fuel down the line? The gallons per hour test will
> indicate if you need to look into any of these areas, if you're gelling
> enough fuel, more down the list for now.
> link to flow and fuel requirements chart
> https://historicracinggroup.com/resources/Reference_Material/Canton/Fuel%=
20Consumption%20and%20Flow%20Quick%20Ref%20by%20CM%20Filters.pdf
>
> 3. A problem I had with an identical set up, was rubber hose breaking dow=
n
> and settling into the little box shaped well in the carb bowl where the
> line to the jet connects. It's happened to me twice now, last time was in
> June with fairly new hose feeding the carbs. It restricted the flow to th=
e
> jet, even though the bowl was full. At high load, not enough fuel could g=
et
> past the blockage.
> <IMG_20240630_112925914.jpg>
>
> 4. Vacuum leak- Is there a crack or loose bolt on the intake manifold?
> With the engine running, spray carb cleaner around the manifold to block,
> carbs to manifold. A change in engine RPM means something was drawn in
> through a gap.
>
> 5. Compression check- Are all the cylinders within 5-10% of each other?
>
> Happy hunting
>
> mike h
>
> On Fri, Aug 9, 2024 at 3:03=E2=80=AFPM Andrew Devenish via Fot <fot@autox=
.team.net>
> wrote:
>
>> Guys,
>> My car ( 1300, 12.5:1 comp on Sunoco 110 race gas, dual HS4 )
>> is still giving me grief. I=E2=80=99ve chased all the things I can think=
of, but
>> still same problem. It starts and runs great, but after a few laps of th=
e
>> yard ( 5-6, only 1000ft or so per up/down lap, so quick accels then
>> braking to turn ) it goes very lean ( I have O2 sensor ) and stops. I=E2=
=80=99m
>> running it without the hood for these test runs. It always stops at the
>> entry to a turn.
>> I=E2=80=99ve been working on it a lot, so know it has fuel pres=
sure, and
>> the float bowls are full of fuel. All plugs look very similar. The needl=
es
>> (AAA) are the spring type, and the slides move freely. I use ATF as flui=
d,
>> but have tried 50 weight too.
>> After a minute or so it will fire back up, but only run enough t=
o
>> get back to the shop before going lean again. If I pull out the choke it
>> will run, but is unstable.
>> I have wrapped headers and a heat shield around the carbs but the=
y
>> do still get hot.
>>
>> Any ideas ? Thinking to try some less volatile fuel as it seems
>> heat related and the Sunoco evaporates so fast !
>>
>>
>> Thank you,
>> Andrew Devenish
>>
>> Sent from my iPad_______________________________________________
>> fot@autox.team.net
>>
>> http://www.fot-racing.com
>>
>> Donate: http://www.team.net/donate.html
>> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
>> Unsubscribe/Manage <http://www.team.net/pipermail/fotUnsubscribe/Manage>=
:
>> http://autox.team.net/mailman/options/fot/ofracer@gmail.com
>>
>>
>> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
> Unsubscribe/Manage <http://www.team.net/pipermail/fotUnsubscribe/Manage>:
> http://autox.team.net/mailman/options/fot/cmstenquist@gmail.com
>
>
>
--000000000000ac2cf0061f4731ed
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><font size=3D"4">Does this happen in both right and left t=
urns,=C2=A0 on such a small run try the opposite direction, could be float =
hinge problems if it always=C2=A0quits in a corner.</font><div><font size=
=3D"4">Carl Stenquist</font></div></div><br><div class=3D"gmail_quote"><div=
dir=3D"ltr" class=3D"gmail_attr">On Fri, Aug 9, 2024 at 5:44=E2=80=AFPM An=
drew Devenish via Fot <<a href=3D"mailto:fot@autox.team.net";>fot@autox.t=
eam.net</a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-lef=
t:1ex">
<div dir=3D"auto">
Hi Mike,
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 The first question is a good one. T=
he car was built for autocross by a guy in Indiana who knew his stuff. Howe=
ver, I bought it from a guy who had bought it to run PIB, but knew nothing =
about race engines. He had run it lean and holed #4. He told
me he had not changed anything, but that is turning out not to be the case=
. (I suspect it holed the piston because I found he had fitted gros jets wi=
th the float level way too low).=C2=A0</div>
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 I rebuilt it to same mechanical spec. It r=
an great but a little lean on the AAU needles for road course, so I=E2=80=
=99m now on AAA. It still runs great, unless it doesn=E2=80=99t =F0=9F=98=
=81.</div>
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 The car has had this issue since I built i=
t. At first I thought the obvious - float heights, needle/seat, regulator p=
ressure etc etc but while it always runs great I have this issues after a f=
ew =E2=80=9Claps=E2=80=9D.</div>
<div>=C2=A0 =C2=A0 =C2=A0 2) =C2=A0 The car had a Summit racing 3136 pump w=
hich has around 90GPH and an internal blow off at 7PSI, my regulator is at =
4 PSI. Today I had taken the pump apart and checked it but all looked OK. I=
fitted a cheap solenoid pump in its place. Issue still
there.</div>
<div>I had checked both the Summit and now the solenoid pump for flow, ther=
e is plenty.=C2=A0</div>
<div>=C2=A0 =C2=A0 =C2=A0 As I noted the float bowls are full when it quits=
running.</div>
<div>=C2=A0 =C2=A0 3) Great point - could be what I have. I know the fuel l=
evel in the jets is fine when not running, but a poor flow from bowl to jet=
would change that when running. My O2 is in the collector, so I can=E2=80=
=99t be sure if it=E2=80=99s both carbs or just one. All 4
plugs look very similar, but that is possible as this =E2=80=9Clean=E2=80=
=9D condition is only for a few cycles before it stops - not enough to colo=
r the plug. Will check when I can ( unfortunately a busy weekend coming up =
as I race sailboats too ). I=E2=80=99ve been thinking it
is heat related, but it could just as easily be time. When I tried to run =
autocross it started to play up after 10 or so seconds of full throttle (wh=
ich I can=E2=80=99t do in my yard). On autocross it would pull like crazy, =
then go very flat, and then come back on,
repeat. Your idea would do just that !=C2=A0</div>
<div>=C2=A0 =C2=A0 4) always worth a check, but it would have to be somethi=
ng that shows up only when hot.=C2=A0</div>
<div>=C2=A0 =C2=A0 5) yes, compression good. Between 220 and 225 for all, m=
easured on crank with throttles open.</div>
<div><br>
</div>
<div>=C2=A0 =C2=A0 =C2=A0</div>
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0Thanks also to the other responses that I r=
eceived, I didn=E2=80=99t cc all on my replies in order to reduce the clutt=
er=E2=80=A6</div>
<div><br id=3D"m_-2787019193713537lineBreakAtBeginningOfSignature">
<div dir=3D"ltr">Thank you,=C2=A0
<div>=C2=A0 =C2=A0 =C2=A0 Andrew Devenish</div>
<div>
<div><br>
</div>
<div>Sent from my iPad</div>
</div>
</div>
<div dir=3D"ltr"><br>
<blockquote type=3D"cite">On Aug 9, 2024, at 3:51=E2=80=AFPM, Mike Harmuth =
<<a href=3D"mailto:ofracer@gmail.com"; target=3D"_blank">ofracer@gmail.co=
m</a>> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type=3D"cite">
<div dir=3D"ltr">=EF=BB=BF
<div dir=3D"ltr">Hi Andrew, a couple of things to check.
<div>1st, is this a new problem? if so, what did you touch last?</div>
<div><br>
</div>
<div>2d Verify fuel flow, not just pressure=C2=A0i.e Gallons per hour? Disc=
onnect the fuel line at the carbs, and stick it into a 1 quart or one gallo=
n clean/clear bottle/jug. Turn the fuel pump on and time how long it takes =
to fill (1 Qt/ 1Gal whatever size container
you're using).=C2=A0 If you're getting more than 20 gallons per ho=
ur, the flow is OK. Set the bottle aside and let it settle out, look for pa=
rticles, rubber, fuel cell foam, dirt. If so, see where that's coming f=
rom. For example, old fuel cell foam will break down
and clog the intake. When the pump turns off, the fuel in the lines drops =
back flushing the intake clear until next time. Fuel filter clean? Fuel pre=
ssure reg OK? Not just holding pressure (I run 3.5 on my HS4s) but actually=
sending fuel down the line? The
gallons per hour test will indicate if you need to look into any of these =
areas, if you're gelling enough fuel, more down the list for now.</div>
<div>link to flow and fuel requirements chart=C2=A0<a href=3D"https://histo=
ricracinggroup.com/resources/Reference_Material/Canton/Fuel%20Consumption%2=
0and%20Flow%20Quick%20Ref%20by%20CM%20Filters.pdf" target=3D"_blank">https:=
//historicracinggroup.com/resources/Reference_Material/Canton/Fuel%20Consum=
ption%20and%20Flow%20Quick%20Ref%20by%20CM%20Filters.pdf</a></div>
<div><br>
</div>
<div>3. A problem I had with an identical=C2=A0set up, was rubber hose brea=
king down and settling into the little box shaped=C2=A0well in the carb bow=
l where the line to the jet connects. It's happened=C2=A0to me twice no=
w, last time was in June with fairly new hose feeding
the carbs. It restricted the flow to the jet, even though the bowl was ful=
l. At high load, not enough fuel could get past the blockage.</div>
<div>
<div><IMG_20240630_112925914.jpg></div>
</div>
<div><br>
</div>
<div>4. Vacuum leak- Is there a crack or loose bolt on the intake manifold?=
With the engine running, spray carb cleaner around the manifold to block, =
carbs to manifold. A change in engine RPM means something was drawn in thro=
ugh a gap.<br>
</div>
<div><br>
</div>
<div>5. Compression check- Are all the cylinders within 5-10% of each other=
?</div>
<div><br>
</div>
<div>Happy hunting</div>
<div><br>
</div>
<div>mike h</div>
</div>
<br>
<div class=3D"gmail_quote">
<div dir=3D"ltr" class=3D"gmail_attr">On Fri, Aug 9, 2024 at 3:03=E2=80=AFP=
M Andrew Devenish via Fot <<a href=3D"mailto:fot@autox.team.net"; target=
=3D"_blank">fot@autox.team.net</a>> wrote:<br>
</div>
<blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-=
left:1px solid rgb(204,204,204);padding-left:1ex">
Guys, <br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 My car ( 1300, 12.5:1 comp on Sunoco 110=
race gas, dual HS4 ) is still giving me grief. I=E2=80=99ve chased all the=
things I can think of, but still same problem. It starts and runs great, b=
ut after a few laps of the yard ( 5-6, only 1000ft=C2=A0 or so per up/down
lap, so quick accels then braking to turn ) it goes very lean ( I have O2 =
sensor ) and stops. I=E2=80=99m running it without the hood for these test =
runs. It always stops at the entry to a turn.
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0I=E2=80=99ve been working on it a lot, so=
know it has fuel pressure, and the float bowls are full of fuel. All plugs=
look very similar. The needles (AAA) are the spring type, and the slides m=
ove freely. I use ATF as fluid, but have tried 50 weight too.<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 After a minute or so it will fire back up, but =
only run enough to get back to the shop before going lean again. If I pull =
out the choke it will run, but is unstable.
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0I have wrapped headers and a heat shield around =
the carbs but they do still get hot.<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0Any ideas ?=C2=A0 Thinking to try some less vola=
tile fuel as it seems heat related and the Sunoco evaporates so fast !<br>
<br>
<br>
Thank you, <br>
=C2=A0 =C2=A0 =C2=A0 Andrew Devenish<br>
<br>
Sent from my iPad_______________________________________________<br>
<a href=3D"mailto:fot@autox.team.net"; target=3D"_blank">fot@autox.team.net<=
/a><br>
<br>
<a href=3D"http://www.fot-racing.com/"; rel=3D"noreferrer" target=3D"_blank"=
>http://www.fot-racing.com</a><br>
<br>
et=3D"_blank">
Archive: <a href=3D"http://autox.team.net/archive"; rel=3D"noreferrer" targe=
t=3D"_blank">
http://autox.team.net/archive</a> <a href=3D"http://www.team.net/pipermail/=
fotUnsubscribe/Manage" rel=3D"noreferrer" target=3D"_blank">
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http://autox.team.net/mailman/options/fot/ofracer@gmail.com</a><br>
<br>
<br>
</blockquote>
</div>
</div>
</blockquote>
</div>
</div>
_______________________________________________<br>
<a href=3D"mailto:fot@autox.team.net"; target=3D"_blank">fot@autox.team.net<=
/a><br>
<br>
<a href=3D"http://www.fot-racing.com"; rel=3D"noreferrer" target=3D"_blank">=
http://www.fot-racing.com</a><br>
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et=3D"_blank">http://www.team.net/donate.html</a><br>
Archive: <a href=3D"http://autox.team.net/archive"; rel=3D"noreferrer" targe=
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</blockquote></div>
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