Eric,
I am sure someone has already answered. Nonetheless, I will toss in my two
cents.
I would guess one of two things- either lean mixture on top or late timing.
Try pulling your choke at high rpm. If the car runs better, fatten up the
mixture a flat or two. It is common for older, worn carbs to run lean on
top end if they are adjusted for a smooth idle. My car lopes at idle a bit
due to a rich mixture but it pull hard at top end and the plugs look good.
If pulling the choke doesn't help, check to see if your choke works ;-)
Seriously, though, if mixture doesn't effect top end and you have the car
timed correctly at idle or statically, I would suspect frozen advance
weights. The vacuum advance does not effect full power operation so the
problem would have to be mechanical. I always time my cars by ear.
Factory specs are set to the lowest common denominator. Most cars will
benefit from more spark advance. Warm the car up fully and advance the
timing until it either kicks back against the starter or knocks under high
load, low rpm conditions such as climbing a hill in 4th gear. Then back
off a bit. If you do this in the winter you may want to do it again in the
summer because the higher air temperature will make the car more likely to
knock.
One other possible wildcard would be a weak coil or too wide of spark plug
gap. This will more likely cause missing at high rpm though. Smooth but
weak performance is more likely from mixture or timing.
Good Luck
Bill Eastman
61 MGA
|