I'm having a problem with backfiring on my TR8. The dynamic timing was
set to about 5deg before with the vacuum connected and about 10deg before
with the vacuum disconnected. According to the manual, timing should be
TDC with the vacuum disconnected, but that seemed to suck some of the
power away. I set the timing to about 5 deg before with the vacuum
disconnected, and that seems to have eliminated the backfiring for the
most part, at least at speed. However, I still have a serious problem
with backrap whenever I step off the gas, and have quite a bit of rumble
in the exhaust even at speed. It sounds great, but I don't even want to
think about what its doing to my exhaust (not to mention my MPG) and I've
got to pass emissions in the next couple weeks. The engine runs smoothly,
but I've got a lot of fuel going out my exhaust.
It's been suggested that I'm running too rich, but I've adjusted the
mixture from one end of the spectrum to the other without an appreciable
difference. It's also been suggested that I won't be able to lean the
mixture enough because of the elevation (I'm in Salt Lake City, at about
3500 ft but I had this problem when I was in Chicago, too) and that I
should replace the stock jets.
FWIW I've also replaced the plugs with Bosch platinums, the rotor, and
cap, and I'm waiting for a set of wires to arrive in the mail. Plugs and
pieces were all replaced about 2000 miles ago and looked ok and I haven't
noticed any difference since switching to the Bosch except a slight
increase in the backfiring, which was pretty much corrected by adjusting
the timing.
Any suggestions on where to look to eliminate this problem?
-jason
Jason Clark
gjclark@uxa.ecn.bgu.edu
1980 TR7 30th Anniversary Edition DHC
1980 TR8 DHC
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