Howdy Folks, I've got a puzzler that I need help with. Don't get to drive
my '76 6 often enough, but lately when I do it almost always experiences a
"power loss" where the engine loses massive quantities of power. This usually
occurs after about twenty minutes of driving and most often on the highway.
Tonight I was driving some back roads at around 50mph when it occurred again.
About twenty minutes in to the ride it started running very rough and I had to
downshift to get any power. I ended up foot to the floor in 2nd doing 35
struggling to make it up a small grade with the engine backfiring
occasionally... Pulled over to let people by and let it idle for less than two
minutes and it was fine again. It acted like there was never a problem... I
tried running it up to 5000 rpm to see if that helped as maybe the plugs were
fouling. Didn't really seem to help, but I did notice that it really didn't
want to go above 5000. Started breaking up very badly. Built in rev limiter?!
Timing was checked earlier in the year at a local tech session and I believe
it's at 10 deg BTDC at idle. Idle is around 650 rpm. Vacuum retard unit was
tested and found to be inoperative, but was left connected to avoid vacuum leak
(no plug for hose at the time). Ignition is an Allison XR-700. Cap, rotor,
plugs and wires have been swapped for new several times now. Coil was a Lucas
Sport that I swapped out for a Pertronix brand with no difference noted.
Carbs are stock ZSs that were richened up some during their adjustment at the
tech session when timing and idle speed were corrected. Fuel pump is an
aftermarket electric of unknown flow (no name) mounted next to the tank. There
is a pressure regulator mounted near the front carb that I've set to about
2.5lbs per some list discussions from back in March '04. Checked fuel pressure
while running down the road with gauge taped to windshield and saw no
fluctuations when the power loss occurred. Air filters are clean and oiled
K&Ns. Fuel filter is glass see-through type and it's clean too... The car's
got a header and duals of unknown origin, the EGR was removed as was the air
pump, if that helps... With the exception of swapping the plugs, wires,
cap, rotor and coil and replacing the carbs with another set of similar
vintage, the other modifications were done by the previous owner. Anyone got
any ideas? We've got a local show to attend on the 12th (Battle of the Brits
in Sterling Hts, MI) and plan on trucking the 6 out to the TRials in WI the
following week. I need to get it running better or it'll be no fun at all...
Thanks for any help you can offer!
Stu Ehrhardt, Davisburg, MI1976 Mimosa/Chestnut with TR4 A-Type O/D
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