It Lives! Removed the ZS carb, manifold, cat converter, and down pipe from
my 80 MGB LE. While it was apart, I removed the leaking tappet covers and
valve cover.
Tried to replace the tappet valve covers, but I had the cork ones and they do
not fit. Originals were in fair shape, so I cleaned everything up and
reinstalled them with a smidgen of dressing on the gasket. Replaced the valve
cover gasket with a new cork gasket. PO had laid a huge bead of that silicone
gasket goop in there instead. That stuff was a real bear to remove and clean
up.
I got an old style exhaust manifold, and had a shop glass bead it, belt sand
the mating surfaces, and mill out the broken off, rusty stud remnants. They
also painted it. Installed it with a new gasket, and bolted on a Pierce
aluminum intake manifold, and a Weber DGEV carb. The throttle cable mount
bracket and wheel supplied with the carb worked out pretty well. There was
also a throttle return spring bracket supplied, which goes on one of the
manifold studs. The original spring is supposed to be re-used.
I adjusted the float per the directions, and worked out some plumbing issues.
I'm not completely satisfied with the plumbing, but I'll nitpick that later.
I plugged the end of a piece of hose to blank out one side of the water
connection that was used for the water choke. I made a blanking plate for the
water connection on the back of the block, and cut a gasket for it. Still have
to make some decisions on the emissions connections, but it's together
more-or-less.
So, 13 hours later, I'm ready to test it, so I turn on the ignition, wait
for the fuel pump to stop clicking, and hit the starter. It fires right up!
Test-driving it showed a few problems - Idle speed keeps "creeping up", and
it's hard to start when hot. The first problem gave itself away when I
noticed that if I tapped the gas pedal, the idle speed would drop back down.
I figured the linkage must be hanging up. I decided to put a stronger return
spring on, since I felt it was too light anyway. Problem is a little better,
but still there. I notice that the position of the return spring bracket
causes the spring to pull the linkage at a slight angle. Loosened the
manifold bolt, rotate the bracket about 15 degrees, and put it back together.
With the spring pulling straight, the problem is solved.
I was thinking I had a bit of a vapor lock problem, and I felt the car ran
fairly hot anyway. Took another drive today, and stopped at a store to get a
soda. My passenger went in, while I sat in the car with the engine running.
Sat there about 5 minutes, when the radiator started to boil over. Glanced at
the temp gauge while turning off the motor, and the needle was pegged. While
we waited for it to cool, I thought about the situation. Seems like I hadn't
heard the electric fan running! I turned on the ignition, and the fan didn't
run, although it should have been. After it cooled off, I headed down the
road. This was starting to make sense; the car would be fine while it was
moving, although a bit warmer than it should have been.
I found that the thermal switch is bad. I jumped it out, and test-drove
again. Not only is it running cooler, but the hard starting problem seems
to be vastly improved.
Another thing I ran into - The Pierce manifold flanges are about 1 to 1.5mm
thicker than the exhaust manifold flanges. I think the intake may need to be
machined down a hair so they are flush with each other. The large washer that
clamps the manifolds to the head is a little higher on the side that clamps
the intake manifold.
I had some good advice from several sources, I believe that to be the reason
that this went as well as it did!
All in all, a good weekend!
--
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Marc Siegel, ABSnet Internet Services eMail: smarc@abs.net
Baltimore, MD http://www.abs.net voice: 410/361-8160
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