You can run the SU's with the dashpot plungers completely removed.
All that will do it let the pistons rise very quickly which would not allow
the mixture to richen properly upon quick throttle openings and perhaps create
other oddities such as idle float.
You shouldn't need to tighten the jet to float bowl connection that tight to
crush it.
Are you referring to the inner most o-ring seal? The nut around the tube
should have a small
brass washer between it and the o-ring that acts as a skirt as the nut is
tightened down
so it doesn't drag the o-ring around in a circle as you tighten it.
It does sound like fuel starvation. Have you check float levels.
You should be able to 'blow' into the float bowl vent pipes and have gas flow
up into the throat
of the carb.
Check your fuel filter and line all the way back to the tank for blockage.
I've seen clogged vent systems that would create a vacuum on the float
chambers, stopping
fuel from flowing. This is actually part of the design of the later emission
controls with the
carbon canister. When you shut off the ignition, a solenoid opens briefly
(until oil pressure drops)
which allows the intake vacuum to be applied to the tank and float bowls to
control run-on.
Paul Tegler wizardz@toad.net http://www.teglerizer.com
----- Original Message -----
From: "Dereck C" <derex39@hotmail.com>
To: <Lawrie@britcars.com>
Cc: <mgs@autox.team.net>
Sent: Thursday, August 17, 2000 8:20 AM
Subject: 70 MGB no start after complete rebuild UPDATE
I got a little further last night before the sun went down and I could no
longer see. I retimed to TDC and the rotor pointed directly at number one
piston. I timed it so the points where just opening (counter clockwise) and
attached the wires in the 1-3-4-2 arrangement. Cranked it and nothing
changed. Then I cranked it with a bit of starter fluid - vroom for about 2
seconds. So I deduced that there was a fuel starvation problem, which I
already thought was a problem because I never really smelled gas on the
plugs or in the carbs. So I took the twin SU HS4's off and checked out the
jet to float bowl connection. Seems that the rubber washer was interfering
with the flow, it was crushed into the float bowl. It seems to me that the
jet fuel-lines are a bit short (same size as the old ones). Then I
reinstalled the carbs after carefully insuring that the rubber washers did
not get crushed into the float bowl (still not sure that it worked). I
attempted to start the car, no go. Then with starter fluid - vroom for 2
seconds. By this time it was too dark outside and I had to close up shop.
To things that I believe did not help the final attempt was that the battery
was getting very weak (trickle charged last night) and I forgot to top up
the dashpots. Will lack of oil in the dashpots result in fuel starvation?
How do you keep from crushing the carb-jet-to-float-bowl washer?
Dereck
70 B
----Original Message Follows----
From: "Lawrie Alexander" <Lawrie@britcars.com>
To: "Dereck C" <derex39@hotmail.com>, <mgs@autox.team.net>
Subject: Re: 70 MGB no start after complete rebuild
Date: Wed, 16 Aug 2000 07:35:26 -0700
Instead of guessing at the ignition timing, why not set it properly and
eliminate the possibility that incorrect timing is the reason for your
non-starting? Here's what you do.........
Bring the engine to top dead center on Nos. 1 and 4.
Take off the valve cover and see which pair of rocker arms are loose on
their valves, No. 1 or No.4.
Replace the valve cover.
Take off the distributor cap.
Look at the points; the rubbing block should be on one of the lobes of the
distributor cam and the points should be just opened. (Remember, the
distributor cam rotates counter clockwise). If this is not so, loosen the
distributor and make it so.
Look at the distributor cap. Remember which cylinder had the loose rockers
(Step 2, above). Determine which of the four contacts in the cap is closest
to the brass end of the rotor, then take the plug wire from that terminal to
whichever of No. 1 or No. 4 had the loose rockers. Then replace the cap and,
going counter clockwise, fit the rest of the wires in the order 1-3-4-2.
Now you know the timing is in a near-enough position that the engine should
start so you can then set the timing correctly. Incidentally, timing with a
timing light should be done when the engine is running, not statically.
Lawrie
British Sportscar Center
-----Original Message-----
From: Dereck C <derex39@hotmail.com>
To: dcouncil@imt.net <dcouncil@imt.net>; derex39@hotmail.com
<derex39@hotmail.com>; mgs@autox.team.net <mgs@autox.team.net>
Date: Wednesday, August 16, 2000 7:27 AM
Subject: Re: 70 MGB no start after complete rebuild
>
>Sorry, I changed the wires too. When you say remove the distributor and
put
>it in 180 the other way, there is only one way that the chuck (proper
term?)
>will line up on this model - the slots are offset. I was just going to
>rotate the wires 180 degrees. Won't that work? Or should I remove the
>distributor drive gear and reinsert it 180 degrees. Honestly, I don't see
>how that would make a difference. If it does please please enlighten me.
I
>am close to my wits end.
>
>Dereck
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