Hi all,
I've thrown all i can at this one without resorting to the dreaded"
substitute with known workling unit" aproach. Read on...
One of our local guys had his cyl. head redone by a reputable machine shop
last summer sometime. He didthe R&R and drove "A few thousand miles". By
then, the idle was poor and the car sputtered and was gutless in the
acceleration department. The car is a 74 model wit hte EGR piping in place
but the vacuum connections not connected.
Timing at 12 BTDC static , no retatrd. With unit connnected, timing at
idle returnd to 2 deg ATDC (unit obviously works, sucks power like you'd
never beleive). Dwell 34 degrees, points good (reset, not filed).
It took me a while to realize that there was no valve train noise. Hot,
most clearances were less than .005, some valves may not have been closing.
So much for power problem, reseting to .010 hot gave the car some zip.
Compression test was aborted at #2 with a 75 psi reading, both at cranking
speed and "running on 5", ditto for #1. this was prior to the valve set, I
did not go back to that test for time reasons.
The carbs are set full rich. There are vacuum leaks (audible with
stethescope) on the emission controls for the front carb. They show some
soott on the plugs. Leaning the mixture about 1.5 turns makes the "air
valve test" show a lean condition of a slow drop in revs, but also makes
another problem much worse:
The car, on light throttle, sputters and pops, almost like a burned valve,
but only on light throttle. My experience with bad valves is a poor idle
AND loss of power. The power is there. Even more once I found the open
vacuum port under the front carb that had not been attached to anything.
The gentelman wishes to take a 3500 mile road test to Ottawa next week.
Notwithstanding the light throttle miss (btw, not an ignition miss, timing
lite fires all cyliders ALL the time) does anyone have a suggestion? Min
was to get some miles on the unit with a correct valve lash for starters -
that is my worry. Concurrence? Other opinions? I know that te small
vacuum leaks will ruin an otherwise good idling car, but it should not
affect steady stste oprtations at speed.
Ideas from those who've been there?
Dave T
Winnipeg
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