Well, I have been through through the whole fuel system from stern to
stem, and I'm satisfied that gas is getting to the cylinders in
appropriate amounts. I have changed to AAE needles and I now have a
gen-you-whine SU fool pump (yay!).
I still have my clatter/pinging/rattle problem though.
Symptoms are:
1) Clatter above 3000 RPM while accellerating with steady throttle.
2) Advancing throttle rapidly in the suspect RPM range results in good
operation for a few seconds, then reversion to mode 1.
3) Retarding the timing massively (to 5 degrees BTDC) reduces the problem
quite a bit, but doesn't eliminate it. Low end accelleration and top end
power is compromised.
4) Retarding even more (to 0 TDC) eliminates the noise but overheats the
car, won't go over 45 mph, etc.
5) Movement of the timing mark just doesn't seem to be in sync with RPM
change... trailing throttle seems to cause a slow reduction in advance
(could be vacuum advance offsetting centrifugal advance, though).
6) The vacuum advance only moves the Pirhana sensor about 1/2 way through
the available arc.
7) When we first started suspecting the distributor, I did my "wiggle the
rotor" test for frozen advance. It felt "strange", not springy but
movement without resistance and a click-over.
So here's my theory... a-hem... this theory, which is mine, is....
I have a wonky mechanical advance, a slightly bent breaker plate, and dog
only knows what all. The mechanical advance is dialing in a whole bunch
of advance all at once, and is slow to bring it back off.
Well, it is the latest in a series of theories.
Anyhow, I seem to have a number of options:
1) Scream, cry, and pine away for lack of a top-down autocrosser.
2) Try it with just the mechanical advance to see if I can get away with
a compromise positon.
3) Order a stock distributor "new" for ca. $165.
4) Look for a used/rebuilt one for ca. $90-100.
5) Order a "modified distributor for performance use". This claims to be
re-curved to work with fast-road and mild race cams (I have the Kent
715). It also claims to be worth $220 and work best with 9:1 compression
(mine is a touch lower).
What I do NOT want to do is race it with pinging above 3K rpm... noooo...
that's where I spend most of my time.
John M. Trindle | jtrindle@tsquare.com | Tidewater Sports Car Club
'73 MGB DSP | '69 Spitfire E Stock | '88 RX-7 C Stock
Home Page: http://www.widomaker.com/~trindle
"Vique's Law:
A man without a religion is like a fish without a bicycle."
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