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Hi - I've seen this before. Mostly on American V8's but the principle is t=
he same... It's almost always a loose chain or worn teeth on the crank gear=
. If the=C2=A0 crank gear has really sharp teeth, the gear is probably worn=
. Note that this is really easy to overlook. And I've had this problem with=
TR6 engines a couple of times. Especially if you sourced the inexpensive g=
ears. Seems like the hardening of the metal is wrong on some of the parts o=
ut there.
That said, the numbers look like you jumped more than one tooth. If the "ju=
mp" occurred on the crank end one tooth is about 17 degrees (360/21 teeth).=
Your mention of 150ish for your lobe center sound more like more than 34 d=
egrees or retard, the progression would be (roughly) 104 - good, 121 - not =
good, 138 - bad, 155 - really bad, etc. Note that I have seen engines run w=
ith more than 30 degrees of retard, but they ran very poorly!
I'd double check your crank gear for wear... actually, I'd just replace it =
along with the tensioner. Note that the current chain tensioners seem to be=
not as good as the OEM ones as the new ones wear fairly rapidly.
On the plus side, at least you didn't bend a valve in the process.
C ya,Bob Lang339-927-4489
On Sunday, November 24, 2019, 10:38:49 PM EST, Mathieu W. Huovinen via =
Fot <fot@autox.team.net> wrote: =20
=20
Fellas,
Sounds like we have the bearing cap strap issue resolved...who is up for an=
other mystery? Has anyone ever has their timing chain skip a tooth??
Final race on Saturday at the Turlkey Bowl this weekend at Summit Point. Tr=
iumph Spitfire..1296 engine. Double roller chain set. Car was running well =
all weekend, was out twice earlier that day. We leave false grid for the to=
set up for the first lap and I begin to accelerate. All of a sudden the ca=
r just dies and I coast off the track even before turn one. On the side of =
the track I couldn't start the car. In my mind I'm thinking my perrtonix di=
stributor just took a shit. Got towed in and all I'm thinking in pertronix.=
I swap in a points distributor and nothing. Perhaps my coil? Swap in a new=
coil. Nothing. Plugs perhaps? Swap in a good set of NGKs. Nothing. Not eve=
n a cough out of the engine. By this time I had run down the battery from t=
rying to start it so much. At this point I was jumping the racecar battery =
from my Tundra truck battery thinking perhaps a weak spark from a shot batt=
ery. Nothing. Was getting plenty of fuel because the plugs were wet. I even=
pulled and cleaned all the jets out of the Weber 45 DCOE just to make sure=
I was getting correct fuel. Fuel. Air. Spark. COMPRESSION. This next day (=
this morning) I did a compression test at the track. 80/70/70/70. What the =
heck? Thats not a blown head gasket..the cam HAS to be out of timing. I spe=
nt the majority of the 5 hour drive home trying to figure it out. Got home,=
car off trailer, straight to work. Pulled radiator, pulley, timing chain c=
over. No damage. Find TDC and put on my degree wheel. Pulled rockers and se=
t dial indicator on #1 intake. Tuned engine over to where cam sheet says wh=
ere #1 centerline is- 104 degrees after TDC while watching dial indicator. =
Went past 104 and dial was still climbing. Made it to to about 150ish degre=
es past TDC til indicator started to drop back down so I know I had went ri=
ght past the peak of the lobe. Pulled chain off carefully and rotated camsh=
aft until I found peak of lobe and moved crank back to 104 and set the chai=
n back on...about one tooth =C2=A0Put rockers back on and checked compressi=
on on #1. 160 PSI. That's as far as I got before my wife came down to yell =
art me. It was already 2130 at this point. More tomorrow as I put it back t=
ogether.=C2=A0
Thoughts? Ideas? Can the timing chain "float" at high revs? Thank-you in ad=
vance for any input!
V/r,
Mathieu Huovinen_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
@yahoo.com
=20
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<html><head></head><body><div class=3D"ydpc7a6ebd8yahoo-style-wrap" style=
=3D"font-family: Helvetica Neue, Helvetica, Arial, sans-serif; font-size: 1=
3px;"><div></div>
<div dir=3D"ltr" data-setdir=3D"false">Hi - I've seen this before. =
Mostly on American V8's but the principle is the same... It's almost always=
a loose chain or worn teeth on the crank gear. If the crank gear has=
really sharp teeth, the gear is probably worn. Note that this is really ea=
sy to overlook. And I've had this problem with TR6 engines a couple of time=
s. Especially if you sourced the inexpensive gears. Seems like the hardenin=
g of the metal is wrong on some of the parts out there.<br></div><div dir=
=3D"ltr" data-setdir=3D"false"><br></div><div dir=3D"ltr" data-setdir=3D"fa=
lse">That said, the numbers look like you jumped more than one tooth. If th=
e "jump" occurred on the crank end one tooth is about 17 degrees (360/21 te=
eth). Your mention of 150ish for your lobe center sound more like more than=
34 degrees or retard, the progression would be (roughly) 104 - good, 121 -=
not good, 138 - bad, 155 - really bad, etc. Note that I have seen engines =
run with more than 30 degrees of retard, but they ran very poorly!</div><di=
v dir=3D"ltr" data-setdir=3D"false"><br></div><div dir=3D"ltr" data-setdir=
=3D"false">I'd double check your crank gear for wear... actually, I'd just =
replace it along with the tensioner. Note that the current chain tensioners=
seem to be not as good as the OEM ones as the new ones wear fairly rapidly=
.</div><div dir=3D"ltr" data-setdir=3D"false"><br></div><div dir=3D"ltr" da=
ta-setdir=3D"false">On the plus side, at least you didn't bend a valve in t=
he process.</div><div dir=3D"ltr" data-setdir=3D"false"><br></div><div dir=
=3D"ltr" data-setdir=3D"false">C ya,</div><div dir=3D"ltr" data-setdir=3D"f=
alse">Bob Lang</div><div dir=3D"ltr" data-setdir=3D"false">339-927-4489<br>=
</div><div><br></div>
=20
</div><div id=3D"ydpc2efc1c9yahoo_quoted_5402201527" class=3D"ydpc2=
efc1c9yahoo_quoted">
<div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
=20
<div>
On Sunday, November 24, 2019, 10:38:49 PM EST, Mathieu =
W. Huovinen via Fot <fot@autox.team.net> wrote:
</div>
<div><br></div>
<div><br></div>
<div><div id=3D"ydpc2efc1c9yiv0645507289">
<div style=3D"color: black; font-style: normal; font-weight: normal; font-s=
tretch: normal; font-size: 10pt; line-height: normal; font-family: arial; f=
ont-size-adjust: none;">Fellas,
<div><br>
</div>
<div>Sounds like we have the bearing cap strap issue resolved...who is up f=
or another mystery? Has anyone ever has their timing chain skip a tooth??</=
div>
<div><br>
</div>
<div>Final race on Saturday at the Turlkey Bowl this weekend at Summit Poin=
t. Triumph Spitfire..1296 engine. Double roller chain set. Car was running =
well all weekend, was out twice earlier that day. We leave false grid for t=
he to set up for the first lap and I begin to accelerate. All of a sudden t=
he car just dies and I coast off the track even before turn one. On the sid=
e of the track I couldn't start the car. In my mind I'm thinking my perrton=
ix distributor just took a shit. Got towed in and all I'm thinking in pertr=
onix. I swap in a points distributor and nothing. Perhaps my coil? Swap in =
a new coil. Nothing. Plugs perhaps? Swap in a good set of NGKs. Nothing. No=
t even a cough out of the engine. By this time I had run down the battery f=
rom trying to start it so much. At this point I was jumping the racecar bat=
tery from my Tundra truck battery thinking perhaps a weak spark from a shot=
battery. Nothing. Was getting plenty of fuel because the plugs were wet. I=
even pulled and cleaned all the jets out of the Weber 45 DCOE just to make=
sure I was getting correct fuel. Fuel. Air. Spark. COMPRESSION. This next =
day (this morning) I did a compression test at the track. 80/70/70/70. What=
the heck? Thats not a blown head gasket..the cam HAS to be out of timing. =
I spent the majority of the 5 hour drive home trying to figure it out. Got =
home, car off trailer, straight to work. Pulled radiator, pulley, timing ch=
ain cover. No damage. Find TDC and put on my degree wheel. Pulled rockers a=
nd set dial indicator on #1 intake. Tuned engine over to where cam sheet sa=
ys where #1 centerline is- 104 degrees after TDC while watching dial indica=
tor. Went past 104 and dial was still climbing. Made it to to about 150ish =
degrees past TDC til indicator started to drop back down so I know I had we=
nt right past the peak of the lobe. Pulled chain off carefully and rotated =
camshaft until I found peak of lobe and moved crank back to 104 and set the=
chain back on...about one tooth Put rockers back on and checked comp=
ression on #1. 160 PSI. That's as far as I got before my wife came down to =
yell art me. It was already 2130 at this point. More tomorrow as I put it b=
ack together. </div>
<div><br>
</div>
<div>Thoughts? Ideas? Can the timing chain "float" at high revs? Thank-you =
in advance for any input!</div>
<div><br>
</div>
<div>V/r,</div>
<div><br>
</div>
<div>Mathieu Huovinen</div>
</div></div>_______________________________________________<br><a href=3D"m=
ailto:fot@autox.team.net" rel=3D"nofollow" target=3D"_blank">fot@autox.team=
.net</a><br><br><a href=3D"http://www.fot-racing.com"; rel=3D"nofollow" targ=
et=3D"_blank">http://www.fot-racing.com</a><br><br>Donate: <a href=3D"http:=
//www.team.net/donate.html" rel=3D"nofollow" target=3D"_blank">http://www.t=
eam.net/donate.html</a><br>Archive: <a href=3D"http://autox.team.net/archiv=
e " rel=3D"nofollow" target=3D"_blank">http://autox.team.net/archive </a><a=
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nk">http://www.team.net/pipermail/fot</a><br>Unsubscribe/Manage: <a href=3D=
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tlangtr6@yahoo.com</a><br><br><br></div>
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_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
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