Dave---Some of the performance parts that are installed can affect the
smoothness at idle. Even detract from acceleration at low speeds.
It's not unusual for engines to hunt for an idle with your below
mentioned, but the ign. timing variation shouldn't be one of them.
Having changed the front sprockets and chain should eliminate this as
the source of the variation, assuming the chain tensioner is in place.
You can also try moving the inductive pickup over to #6 sparkplug
wire, to see if this variation is identical to what you see at #1 wire.
Be careful when running with a "cold" intake manifold, as this does
not lend itself to a smooth running engine at low speeds. (Fuel droplets
can fall out of suspension)
Check the oil in the carb dampers. Sometimes a different viscosity
can change the way the engine behaves during low speed acceleration.
And yes. Do give the rotor the "reverse test".
Dick
From: murr32@shaw.ca(Dave Murray) Date: tr6taylor@webtv.net ('Sally or
Dick Taylor') Cc: 6pack@autox.team.net
Dick,
Thanks for the suggestions regarding the timing chain, etc. I will
definitely check.
Some additional information I stupidly left out:
Engine has just been completely rebuilt including timing gears and
chain. Modifications include:
Goodparts GP2 cam and 1.65:1 roller rockers 0.030" oversize pistons
Head milled to provide just under 10:1 compression Head ported as per
Kastner competition manual Headers and free flow exhaust
I have also tried new cap, shaved rotor, several different coils, and
new plug wires.
Found a combination that allows the car to pull strongly from 2k up to
5k rpm: points, alternate distributor (not original), Magnecor plug
wires, new cap, shaved rotor, bypass coolant through intake manifold,
however the timing instability is still present (at idle also), the car
does not want to idle smoothly and will stall on occasion, and is
extremely sluggish up to 2k rpm even with no load.
Dave
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