Three years ago, when my Spit engine problem first developed, I had found a
very small tear in the piston diaphragm and replaced it with a new one. That
didn't fix the problem, and I ended up letting the whole thing go at the time.
So, last week, when I took the carb apart piece by piece, I concentrated on
everything but the diaphragm, especially the intricate autochoke with its
bimetal spring, stepped cams, vacuum piston, etc. I did look at the diaphragm,
but since it looked good, I left it alone. Yesterday I unscrewed the chamber
cover again and lifted out the piston and diaphragm. The diaphragm has two
little raised tabs, one that fits into an indent in the ring around the piston
and one for an indent in the outer ring of the chamber body. The one for the
body wasn't in place. I was careless 3 years ago, and then again last week. I
put it right, tightened the cover down, and gave the key a turn. It started
immediately! The engine was smooth, the rpms were just about right, and as it
warmed the rpms dropped as they should if the autochoke is working. I guess
that misplaced tab made for a small vacuum leak, just like the original
problem. It probably needs a little adjustment with the timing light, and I
plan to do that later, but it is very close to perfect now. Finally.
Tim Gaines
Clinton, SC
1980 Spitfire
1974 TR6
----- Original Message -----
From: "Tim Gaines" <mtgaines@presby.edu>
To: triumphs@autox.team.net
Sent: Sunday, March 15, 2015 11:47:46 PM
Subject: Re: [TR] weird distributor "out of phase" problem
Thanks to all who have ruled out my timing chain theory. I'm relieved I don't
have to get into that! Though I WAS sure at the time that I had cylinder #1 at
tdc on the compression stroke, I am backtracking now. I had been checking the
clearances on all of the valves and after that I really thought I had cycled
back to the compression stroke on #1 but . . . I guess I'll find out tomorrow
when I go out and take a look.
My big surprise was that the distributor would only fit in one orientation.
That would be a very good design I guess, but I had always heard that it was
very easy to get it wrong. Was it really designed that way, or is there
something special (damage) about mine?
Thanks again,
Tim
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