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April 01, 2003

You have the Haynes SU book on the way.......good man!! :)
It's "ok" to "go on about" something you
do not undersand, Jens. I was a flight
instructor for over 1500 hours and am
familiar with the "learning process". :)
However, I am certainly not an engineer
and not familiar with mechanical pumps
in an automotive sense. However, it still
would not surprise me if there was a
partial vacuum within the line as fuel
flowed backward downward toward the
pump, assuming the "bleed back" valve
in the pump was defective. This is what
I meant by "siphoning effect" in my
earlier post, Jens. This thinking is based
strictly on the contents of Margaret's
post on the subject. In this respect, it
is nothing more than an educated guess
as to what is going on in there!
Being that this is an open post on the list,
I am hoping other listers more familiar
with mechanical pumps and the problems
encountered with same may join in here.
I have no problem with another knowing
more than I chiming in here....I have no
problem being wrong! I welcome all comers, the objective being to help
out, not showing you what I or another may or may not know.
The only ones that have thus far are
Jeremy Cogman and Margaret....and
fortunately, Margaret had the exact
same symptoms as you!! She was even
kind enough to explain the source of the
problem. And logically, it makes sense,
considering the engine starts just fine except for the first start of
the day after
the car sits for an extended period of time,
as in "overnight".
Now either this is happening, or the fuel
level in the bowls is mis-set very much
on the low side, or the problem is elsewhere (very weak spark, as you
yourself, previously mentioned initially).
So naturally, it is best to proceed logically
based upon Margaret's information since
she has "BTDT" with respect to the exact
symptoms and problem you are experiencing. This then, is my thinking
at this point in time based upon the information I currently have
With respect to the head (gasket) and the
amount of clearance there is from these
"holes" to their respective adjacent combuston chambers, I am at a
distinct dis-advantage....I cannot "see" what you
"see" in this respect but, I do hear you!!
In consulting my Vizard bible, I see no
mention of a 12G296 head. I do see a
12G295 head. It has a largish 28.3cc
combustion chamber as it comes from
the factory. It came stock on the 998cc
Cooper Mini, the 1098 MG 1100 & the
MKll MG Midget/Mklll Sprite (1098).
Heads for the 1275/1300 engines all
came with 21.4cc combustion chambers
as stock (substantially less than what
you would see on a stock 948 or 1098 (1100) motor) and are listed as:
12G940, 12G940 (1.4 intake valves),
12G185 or 163 (1.4 Cooper "S" castings),
& "later" 12G940 casting for Turbo Metro
with stock 1.3+ intake valves sodium
cooled exhaust valves...improved cooling
but thinner deck).
Now...it sounds like you are using a
"small bore" head (1100) on a "large bore"
(1275) engine? Is this wha't going on, Jens? Or, have I misunderstood?
Cap'n. Bob
'60 :{)

PilotRob@... 20755

Posted on April 1, 2003 03:29 PM
Posted to category(s) Braking System | Carburetor | Cooling System | Cylinder Head | Engine (external) | Engine (internal) | Exhaust System | Forced Induction | Fuel System | Gauges | Ignition System | Intake System | Lubrication System | Miscellaneous | Restoration | Specifications | Technical Info | Tuning

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