Brad,
With the head work you recently had done --valves and guides, along with
everything else you've checked out, it sounds like you may have a valve
sticking open. The valves and guides may not be quite broken in yet, or
there may be a bit of a misfit. I had this happen to me on an MGTD, and the
symptoms were identical to what you describe. Does the sputtering usually
clear up if you slow the engine down?
Its pretty easy to find out. Run the idle speed up to 2500 rpm or so and
either remove the valve cover and watch closely (messy), or spay some
fogging oil into the carb(s) when it starts missing (direct manual oiling
system).
I eventually cleared up the problem by running the engine just below the
threshold rpm for the sputtering/missing, standing by with fogging oil. I
gradually raised the rpm until it started missing, and sprayed the fogging
oil when needed to keep it running smoothly at the higher speed. It took
about 3-hours to get it to run smoothly at about 3000 rpm. Its gradually
improved more since then. May not be much harder to pull the head if a
valve really turns out to be the problem.
I've also seen these symptoms when the valve clearances (gaps) are adjusted
too tight on a newly reworked head. Valve overheat if they don't seat
completely. This can cause preignition and decrease the valve - guide
clearances. Easy to check.
I also had similar symptoms resulting from the gas tank outlet being
partially blocked with accumulated junk. I blew air through the fuel line
the front of the car to clear it. My fuel filter was clean, the tank outlet
was the problem. I have since added an electric fuel pump mounted in the
trunk, under the tank. I switch it on if needed (very rarely).
And, of course, depending on lots of things, including the routing of the
fuel lines, partial vapor lock.
Well Brad, this has been a fun quiz. I'll be interested to see what the
problem turns out to be. Probably something like a mouse nest in the air
cleaner.
Regards
Marty Klein
1967 Austin Mini
1977 Spitfire
1950 MGTD
1953 MGTD/2
drzzzz@csi.com
----- Original Message -----
From: Brad Kahler <brad.kahler@141.com>
To: <triumphs@autox.team.net>
Cc: <spitfires@autox.team.net>
Sent: Thursday, April 22, 1999 8:59 PM
Subject: Sputtering and a popping
>
> Listers,
>
> Got a problem with my spitfire that really has me baffled.
>
> First my setup.
>
> Stock 1147 motor including carbs, points and coil. Just had the head done
> with new valves and guides. New plugs and plug wires. The points and
> condensor have about 500 miles or so on them but are probably about 8
> years old. Distributor cap new within 500 miles. No wobble noticeable in
> the distributor shaft. Carbs rebuilt about 500 miles ago including
oversized
> throttle shafts installed. Fuel pump rebuilt 500 miles ago. Fuel filter
> replaced 500 miles ago. New timing chain and gears. Vacuum advance
> seems to function fine.
>
> Symptoms.
>
> At anything above idle speed the engine will randomly sputter and
> sometimes pop or I guess you could call it a cough or hesitation. This
> happens when the car is stopped or moving. You can push the gas pedal
> and the engine revs up nicely but at just about any given rpm above say
> 1500 it will randomly start the sputtering. When driving there is almost
no
> power available and the sputtering and coughing is real bad then.
>
> Tomorrow I will try and locate a set of points and a new condensor to see
if
> they are bad. I will also replace the fuel filter.
>
> Any other suggestions would be greatly appreciated.
>
> TIA
>
> Brad (Lincoln Nebraska 402-464-1502)
> My Triumph Web Site Http://www.141.com/triumphs (updated 4/9/99)
> My Dodge Web Site Http://www.141.com/dodge (updated 4/7/99)
>
> 1964 Spitfire4 BFC25720L
> 1962 TR4 CT288L -- 1965 TR4 CT38888LO parts car?
> 1959 TR3A TS41311L -- 1959 TR3A TS53523L parts car
> 1951 1/2 ton Dodge Truck B-3-B-108
>
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