[Mgs] Acceleration problem

[Councill, David]

I would make sure the carb pistons can travel up and down freely the
full travel. They should also drop down with a mild clunk at the bottom.
My guess is that the pistons stick or bind partway on their rise. My
67BGT had this problem at one time. Make sure the carb damper oil is
adequate and of a motor oil type and viscosity similar to the engine,
too light or too heavy can cause problems.

David Councill
67 BGT
72 B

-----Original Message-----
From: mgs-bounces+dcouncill=msubillings.edu at autox.team.net
[mailto:mgs-bounces+dcouncill=msubillings.edu at autox.team.net] On Behalf
Of Pat Leask
Sent: Thursday, August 09, 2007 9:57 PM
To: mgs at autox.team.net
Subject: [Mgs] Acceleration problem

My 1800cc motor runs flat at a specific spot when accelerating and I've
run
out of ideas.. HELP!

I know this is an MG list, but I have a 1964 TVR Grantura that runs a
MGB
1800cc motor and trans. So I am appealing to your collective wisdom on
this
problem if I may. I got this car about a year ago after it sat for 6
years
and was not driven and was 100% stock, never seen a DPO. I have
"Spiffed" it
up, replaced all brakes and so forth and the motor idles very smooth and
strong.

The problem is when accelerating it goes fine until ONE SPECIFIC SPOT
where
it flattens out. Speed is maintained but no more acceleration, you can
hear
and feel it wanting more of something, like a high speed miss. There is
a
"Sweet spot" on the throttle where it will or will not do this, very
definitive.

Here is what I have done and can verify:

The timing is spot on
When I suck on the hose to the Dizzy I can see the plate advance
The shaft of the dizzy is not bent
There is good suction on the intake manifold
Changed spark plugs from new Champion to new Bosh (Told Champion can
have
problems) at .025
Plugs are a nice colour, good mix of fuel/air
Carbs are rebuilt (new jets)
Needles are "MB" (standard)
Pots seem to rise and fall okay.. Not fully sure on this
Light oil in carb dash pots
New electric fuel pump
New points .015
New condenser (after a new one, thought defective but not)
New plug wires
New Lucas Sports Coil (Gold one) tried another coil same results
Gas tank cleaned, no obstruction in supply line


The only thing left I can think of is a Pertronix unit or different jet
needles. What really bugs me is the "Sweat spot" where it craps out on
me
thoughts please?

Thanks, Pat
Victoria BC