Hi Chip,
First, sorry to hear about your situation. I know how the excitement can
clash hard with disappointment when an engine gets back together but doesn't
run right (or at all). But it can always be worked out.
Even before I got to the part in your email about the coil the symptoms were
leading me to thinking about the coil, as that is one of the two most common
time/temperature dependent issues surrounding the degradation of how an
engine runs. But most often the engine just dies when contact is lost. The
second is overheated fuel lines which lead to vapor lock, a situation where
the fuel vaporizes inside the fuel line and stops or slows the feed to the
carbs.
First, coils should not get too hot on their own to touch. Of course since
the TR6 coil is mounted to the engine it does get hotter than in other cars.
If you have another coil that you know works, and that can handle a
6-cylinder engine, by all means swap that out to see how that does.
But don't discount that drop in fuel pressure either. That is telling you
something. I don't believe that the fuel pressure should drop as such.
Someone please correct me if I am wrong. Where is your in-line fuel
pressure gauge located?
A simple test is to rig a line of fuel that goes directly to the
carburettors, simply pressure fed. Do this: run the car as you currently
have it until it starts to run badly. Then, disconnect the car's fuel line
and attach an external fuel line (even a gravity fed one) to the metal fuel
line that feeds the carbs. This can be done in under a minute if you have
everything prepared and an extra set of hands. Then start 'er up. If it
runs better at idle it is a fuel supply problem, and you've narrowed it
down. Keep in mind a gravity feed tank (elevated at least 3 feet above the
carbs) will supply carbs for idle and off idle but maybe not at continued
high RPM, as it can't produce the flow. But since you noted that the idle
sours too, then you may be able to use this as a simple test. If using a
gravity fed external tank the minimum ID of the fuel tubing that you are
using needs to be at least the ID of the line that runs to the carbs.
Also don't discount the possibility of both the coil and the fuel system
being flawed at elevated temperatures. Then also consider the wires. Since
you just had the engine work done is there a possibility of overly tight
pistons (aluminum expands quite differently than steel), or other internal
issues. I'm not saying that you should worry or take apart the motor or
anything. It is unlikely that it is something like this, especially since
the car runs good for 20 minutes. Binding pistons usually show up after a
few minutes (or less).
Good luck,
Dave Herbert
>From: Chip19474@aol.com
>Reply-To: Chip19474@aol.com
>To: 6pack@autox.team.net
>Subject: TR6 Running Rich - New Motor Rebuild
>Date: Sat, 7 Jun 2003 17:37:35 EDT
>
>This is sort of a continuation of the "diminishing fuel pressure from my
>Carter fuel pump" thread I started 2 weeks ago.....
>
>It's my '76 TR6 - just completed 3+ year restoration - engine rebuilt with
>mild lift cam, .030" over pistons, head shaved, ports matched & polished,
>stainless steel headers, Richard Goodparts 3 Stromberg carb setup,
>lightened
>flywheel, Carter electric fuel pump....
Shortened to minimize bandwidth.
>Chip Krout
>Skippack, PA USA
>
>1976 TR6 #CF57822U - one of the last 500 built!
>1970 Spitfire Mk3 #FDU78512L - on the road again - 33 years young!
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