--===============8500147881450076376==
boundary="----=_Part_5333603_894430009.1598362327126"
------=_Part_5333603_894430009.1598362327126
Content-Transfer-Encoding: quoted-printable
Check your cranking pressure for each cylinder first.
I suspect you either have either a bad hole or a spring issue, both are eas=
y to check. The piston is drawn up by the velocity / CFM being pulled into =
the engine.
Rick
=C2=A0"Doing the right thing is always the right thing, regardless of conse=
quences"
=20
On Tuesday, August 25, 2020, 09:00:49 AM EDT, Paul Ricco via Fot <fot@a=
utox.team.net> wrote: =20
=20
Phil,=20
Wr went through this with SU=E2=80=99s about five years ago. We had the rea=
r SU piston =E2=80=9Cwinking=E2=80=9D at us on the dyno on high rev pulls.=
=C2=A0 We resolved it.=20
1. When is the last time the carbs were totally rebuilt?=C2=A0 Any chance y=
ou have any air leaks at shafts or anywhere else?
2.=C2=A0 What are you using for a manifold gasket?=C2=A0 Any chance of a va=
cuum leak?=C2=A0=20
3.=C2=A0 Same for the carb/isolator block end of the manifold. If you added=
a heat shield that is two more faces that need to seal well with gaskets. =
It starts to get thick and the studs are not very long.=20
4. What are you running for dashpot oil?
5. Which weight springs do you run in the carbs?
6. Any other vacuum leaks anywhere?
All can be factors. However I would be looking for an air leak. Including a=
t the carb shafts depending on the age.=20
Just my two sense from having been through this and resolving it successful=
ly.=20
Paul Ricco
Sent from my iPhone
> On Aug 25, 2020, at 7:34 AM, Chris Marx via Fot <fot@autox.team.net> wrot=
e:
>=20
> =EF=BB=BFHi Phil,
>=20
> interesting you are having visible vibrations. My engine doesn't show thi=
ngs like this.
> I guess the rear carb drops from a lack of flow. Maybe fuel supply is not=
working properly, valve springs too soft with valve bounce.
>=20
> Something like that.
>=20
> To help the crank....making everything as light as possible:
> Piston with rod - 1000gr
> Flywheel with ring gear - 3500gr
> Clutch with plate - 1000gr
> Pulley - 400 gr
>=20
> Seems to work fine. I let balance the crank all 2-3 years.
>=20
> Cheers
> Chris
>=20
>=20
>=20
> -----Urspr=C3=BCngliche Nachricht-----
> Von: Fot <fot-bounces@autox.team.net> Im Auftrag von Phil Gott via Fot
> Gesendet: Dienstag, 25. August 2020 13:50
> An: Friends Of Triumph <fot@autox.team.net>
> Betreff: [Fot] Crank Harmonics and Carburetion
>=20
> Can anyone help with this weird phenomenon? The discussion of the second =
harmonic being at 5200 rpm on the TR4 crank got me thinking:
> On a chassis dyno we could watch the SU (HS 6)=C2=A0 pistons during the d=
yno Pulls. We started each pull at 3000 rpm. The pistons went all the way t=
o the top almost immediately after going to full throttle. The front carb p=
iston stayed all the way up for the entire run. The piston in the rear carb=
DROPPED DOWN to about 3/4 open at around 5300 rpm and stayed there for the=
rest of the pull. This repeated consistently.
> As these depend on air flow via Bernouli=E2=80=99s law, I examined the va=
lve train thoroughly, fearing a stuck valve, problems with the valve train,=
a bad lifter etc. but everything looked fine. No noises from errant valve =
operation either.=20
> The crank harmonic discussion got me thinking. Could it be something to d=
o with vibration that would upset the air flow or cause the piston to drop?=
Note that the piston was steady when it dropped. No apparent fluttering. I=
=E2=80=99m stumped.
> The car runs very strong nonetheless. You see the results in Dave=E2=80=
=99s latest video at Thompson. He and I are thinking about putting a go pro=
camera and a light under the hood to watch that carb in real life track si=
tuations to see what happens.
> Any thoughts as to why the Piston in the rear carb only should drop at ab=
out 5300 and above?
> Phil Gott
>=20
>=20
> Sent from my iPhone
> _______________________________________________
> fot@autox.team.net
>=20
> http://www.fot-racing.com
>=20
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
> Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/tr4racing@g=
ooglemail.com
>=20
>=20
>=20
> _______________________________________________
> fot@autox.team.net
>=20
> http://www.fot-racing.com
>=20
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
> Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/paulricco@a=
tt.net
>=20
>=20
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
tt.net
=20
------=_Part_5333603_894430009.1598362327126
Content-Transfer-Encoding: quoted-printable
<html><head></head><body><div class=3D"ydpcdaf918fyahoo-style-wrap" style=
=3D"font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px=
;"><div><div dir=3D"ltr" data-setdir=3D"false">Check your cranking pressure=
for each cylinder first.</div><div dir=3D"ltr" data-setdir=3D"false"><br><=
/div><div dir=3D"ltr" data-setdir=3D"false">I suspect you either have eithe=
r a bad hole or a spring issue, both are easy to check. The piston is drawn=
up by the velocity / CFM being pulled into the engine.</div><div dir=3D"lt=
r" data-setdir=3D"false"><br></div><div dir=3D"ltr" data-setdir=3D"false">R=
ick</div><div><br></div><div class=3D"ydpcdaf918fsignature"><div style=3D"f=
ont-family:Helvetica, Arial, sans-serif;font-size:16px;"><div dir=3D"ltr"><=
br></div><div dir=3D"ltr"> "<i>Doing the right thing is always the rig=
ht thing, regardless of consequences</i>"</div><div dir=3D"ltr"><br></div><=
div dir=3D"ltr"><br></div></div></div></div>
<div><br></div><div><br></div>
=20
</div><div id=3D"yahoo_quoted_8620968807" class=3D"yahoo_quoted">
<div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
=20
<div>
On Tuesday, August 25, 2020, 09:00:49 AM EDT, Paul Ricc=
o via Fot <fot@autox.team.net> wrote:
</div>
<div><br></div>
<div><br></div>
<div><div dir=3D"ltr">Phil, <br clear=3D"none"><br clear=3D=
"none">Wr went through this with SU=E2=80=99s about five years ago. We had =
the rear SU piston =E2=80=9Cwinking=E2=80=9D at us on the dyno on high rev =
pulls. We resolved it. <br clear=3D"none"><br clear=3D"none">1. When =
is the last time the carbs were totally rebuilt? Any chance you have =
any air leaks at shafts or anywhere else?<br clear=3D"none"><br clear=3D"no=
ne">2. What are you using for a manifold gasket? Any chance of =
a vacuum leak? <br clear=3D"none"><br clear=3D"none">3. Same fo=
r the carb/isolator block end of the manifold. If you added a heat shield t=
hat is two more faces that need to seal well with gaskets. It starts to get=
thick and the studs are not very long. <br clear=3D"none"><br clear=3D"non=
e">4. What are you running for dashpot oil?<br clear=3D"none"><br clear=3D"=
none">5. Which weight springs do you run in the carbs?<br clear=3D"none"><b=
r clear=3D"none">6. Any other vacuum leaks anywhere?<br clear=3D"none"><br =
clear=3D"none">All can be factors. However I would be looking for an air le=
ak. Including at the carb shafts depending on the age. <br clear=3D"none"><=
br clear=3D"none">Just my two sense from having been through this and resol=
ving it successfully. <br clear=3D"none"><br clear=3D"none">Paul Ricco<br c=
lear=3D"none"><br clear=3D"none">Sent from my iPhone<br clear=3D"none"><br =
clear=3D"none">> On Aug 25, 2020, at 7:34 AM, Chris Marx via Fot <<a =
shape=3D"rect" ymailto=3D"mailto:fot@autox.team.net"; href=3D"mailto:fot@aut=
ox.team.net">fot@autox.team.net</a>> wrote:<br clear=3D"none">> <br c=
lear=3D"none">> =EF=BB=BFHi Phil,<br clear=3D"none">> <br clear=3D"no=
ne">> interesting you are having visible vibrations. My engine doesn't s=
how things like this.<br clear=3D"none">> I guess the rear carb drops fr=
om a lack of flow. Maybe fuel supply is not working properly, valve springs=
too soft with valve bounce.<br clear=3D"none">> <br clear=3D"none">>=
Something like that.<br clear=3D"none">> <br clear=3D"none">> To hel=
p the crank....making everything as light as possible:<br clear=3D"none">&g=
t; Piston with rod - 1000gr<br clear=3D"none">> Flywheel with ring gear =
- 3500gr<br clear=3D"none">> Clutch with plate - 1000gr<br clear=3D"none=
">> Pulley - 400 gr<br clear=3D"none">> <br clear=3D"none">> Seems=
to work fine. I let balance the crank all 2-3 years.<br clear=3D"none">>=
; <br clear=3D"none">> Cheers<br clear=3D"none">> Chris<br clear=3D"n=
one">> <br clear=3D"none">> <br clear=3D"none">> <br clear=3D"none=
">> -----Urspr=C3=BCngliche Nachricht-----<br clear=3D"none">> Von: F=
ot <<a shape=3D"rect" ymailto=3D"mailto:fot-bounces@autox.team.net"; href=
=3D"mailto:fot-bounces@autox.team.net";>fot-bounces@autox.team.net</a>> I=
m Auftrag von Phil Gott via Fot<br clear=3D"none">> Gesendet: Dienstag, =
25. August 2020 13:50<br clear=3D"none">> An: Friends Of Triumph <<a =
shape=3D"rect" ymailto=3D"mailto:fot@autox.team.net"; href=3D"mailto:fot@aut=
ox.team.net">fot@autox.team.net</a>><br clear=3D"none">> Betreff: [Fo=
t] Crank Harmonics and Carburetion<br clear=3D"none">> <br clear=3D"none=
">> Can anyone help with this weird phenomenon? The discussion of the se=
cond harmonic being at 5200 rpm on the TR4 crank got me thinking:<br clear=
=3D"none">> On a chassis dyno we could watch the SU (HS 6) pistons=
during the dyno Pulls. We started each pull at 3000 rpm. The pistons went =
all the way to the top almost immediately after going to full throttle. The=
front carb piston stayed all the way up for the entire run. The piston in =
the rear carb DROPPED DOWN to about 3/4 open at around 5300 rpm and stayed =
there for the rest of the pull. This repeated consistently.<br clear=3D"non=
e">> As these depend on air flow via Bernouli=E2=80=99s law, I examined =
the valve train thoroughly, fearing a stuck valve, problems with the valve =
train, a bad lifter etc. but everything looked fine. No noises from errant =
valve operation either. <br clear=3D"none">> The crank harmonic discussi=
on got me thinking. Could it be something to do with vibration that would u=
pset the air flow or cause the piston to drop? Note that the piston was ste=
ady when it dropped. No apparent fluttering. I=E2=80=99m stumped.<br clear=
=3D"none">> The car runs very strong nonetheless. You see the results in=
Dave=E2=80=99s latest video at Thompson. He and I are thinking about putti=
ng a go pro camera and a light under the hood to watch that carb in real li=
fe track situations to see what happens.<br clear=3D"none">> Any thought=
s as to why the Piston in the rear carb only should drop at about 5300 and =
above?<br clear=3D"none">> Phil Gott<br clear=3D"none">> <br clear=3D=
"none">> <br clear=3D"none">> Sent from my iPhone<br clear=3D"none">&=
gt; _______________________________________________<br clear=3D"none">> =
<a shape=3D"rect" ymailto=3D"mailto:fot@autox.team.net"; href=3D"mailto:fot@=
autox.team.net">fot@autox.team.net</a><br clear=3D"none">> <br clear=3D"=
none">> <a shape=3D"rect" href=3D"http://www.fot-racing.com"; target=3D"_=
blank">http://www.fot-racing.com</a><br clear=3D"none">> <br clear=3D"no=
ne">> Donate: <a shape=3D"rect" href=3D"http://www.team.net/donate.html"=
target=3D"_blank">http://www.team.net/donate.html</a><br clear=3D"none">&g=
t; Archive: <a shape=3D"rect" href=3D"http://autox.team.net/archive " targe=
t=3D"_blank">http://autox.team.net/archive </a><a shape=3D"rect" href=3D"ht=
tp://www.team.net/pipermail/fot" target=3D"_blank">http://www.team.net/pipe=
rmail/fot</a><br clear=3D"none">> Unsubscribe/Manage: <a shape=3D"rect" =
href=3D"http://autox.team.net/mailman/options/fot/tr4racing@googlemail.com"=
target=3D"_blank">http://autox.team.net/mailman/options/fot/tr4racing@goog=
lemail.com</a><br clear=3D"none">> <br clear=3D"none">> <br clear=3D"=
none">> <br clear=3D"none">> ________________________________________=
_______<br clear=3D"none">> <a shape=3D"rect" ymailto=3D"mailto:fot@auto=
x.team.net" href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a><br cl=
ear=3D"none">> <br clear=3D"none">> <a shape=3D"rect" href=3D"http://=
www.fot-racing.com" target=3D"_blank">http://www.fot-racing.com</a><br clea=
r=3D"none">> <br clear=3D"none">> Donate: <a shape=3D"rect" href=3D"h=
ttp://www.team.net/donate.html" target=3D"_blank">http://www.team.net/donat=
e.html</a><br clear=3D"none">> Archive: <a shape=3D"rect" href=3D"http:/=
/autox.team.net/archive " target=3D"_blank">http://autox.team.net/archive <=
/a><a shape=3D"rect" href=3D"http://www.team.net/pipermail/fot"; target=3D"_=
blank">http://www.team.net/pipermail/fot</a><br clear=3D"none">> Unsubsc=
ribe/Manage: <a shape=3D"rect" href=3D"http://autox.team.net/mailman/option=
s/fot/paulricco@att.net" target=3D"_blank">http://autox.team.net/mailman/op=
tions/fot/paulricco@att.net</a><div class=3D"yqt5754651089" id=3D"yqtfd3223=
5"><br clear=3D"none">> <br clear=3D"none">> <br clear=3D"none"><br c=
lear=3D"none">_______________________________________________<br clear=3D"n=
one"><a shape=3D"rect" ymailto=3D"mailto:fot@autox.team.net"; href=3D"mailto=
:fot@autox.team.net">fot@autox.team.net</a><br clear=3D"none"><br clear=3D"=
none"><a shape=3D"rect" href=3D"http://www.fot-racing.com"; target=3D"_blank=
">http://www.fot-racing.com</a><br clear=3D"none"><br clear=3D"none">Donate=
: <a shape=3D"rect" href=3D"http://www.team.net/donate.html"; target=3D"_bla=
nk">http://www.team.net/donate.html</a><br clear=3D"none">Archive: <a shape=
=3D"rect" href=3D"http://autox.team.net/archive " target=3D"_blank">http://=
autox.team.net/archive </a><a shape=3D"rect" href=3D"http://www.team.net/pi=
permail/fot" target=3D"_blank">http://www.team.net/pipermail/fot</a><br cle=
ar=3D"none">Unsubscribe/Manage: <a shape=3D"rect" href=3D"http://autox.team=
.net/mailman/options/fot/rick.parent@att.net" target=3D"_blank">http://auto=
x.team.net/mailman/options/fot/rick.parent@att.net</a><br clear=3D"none"><b=
r clear=3D"none"><br clear=3D"none"></div></div></div>
</div>
</div></body></html>
------=_Part_5333603_894430009.1598362327126--
--===============8500147881450076376==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
--===============8500147881450076376==--
|