I think you'll find that the reality is that the impact with the tree
root and the change in performance are unrelated. I can't imagine the
severity of an impact of sufficient force to actually change the spark
timing. If you were running extremely high RPMs, as in racing
conditions, then you MIGHT create enough vibration to make the timing
"walk" a little bit.
That having been said, I'd suggest start by checking the dwell angle.
If it isn't pretty much exactly where you previously set it, the points
may have moved (you wouldn't be the first to THINK he'd gotten the set
screw correctly tightened, only to find the points had sort of closed
up........don't ask me how I know this, as it was nearly 40 years ago,
and I'll deny all responsibility). Also, if the little aluminum flange,
on the bottom of the dizzy, that the clamp rides on, has partially
broken off the bottom of the dizzy, the timing may/will move, a bit.
If all of that checks out, ask yourself this: is it possible that the
choke cable/linkage was slightly hung up, when you did your "dialing
in"? If so, when it finally did release, and allow the jets to return
to their full, upward position, the effect would be a lean mixture.
Is it possible that you flattened the "down-pipe"/manifold pipe, where
it exits & turns 90 degrees under the car? You'd have REALLY had to
flatten that sucker to effect your idle, however.
Hope this helps. Weather's too nice to have one's Spridget laid up for
[mailto:email@example.com] On Behalf Of Phil Nase
Sent: Monday, June 12, 2006 8:26 AM
Subject: No idle
I did a full tune up on the 1275 last week. Adjusted valves,
25D dizzy, set dwell and timing. It was never running this well.
Pulling into the Hellertown show field very slowly I smacked the bottom
on a tree root but no damage was apparent.
On the drive home after warm up the car won't idle, I choke it and it
idles. Runs fine at speed. The only thing I can think could have been
knocked out by a jolt is the timing.
I haven't rechecked the timing yet but any other ideas what could be
out? Maybe the manifold now has a leak? Nothing there visibly wrong