triumphs
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Re: [TR] Vacuum Leak

To: "'TERRY SMITH'" <terryrs@comcast.net>, <triumphs@autox.team.net>
Subject: Re: [TR] Vacuum Leak
From: "Randall" <TR3driver@ca.rr.com>
Date: Fri, 31 May 2019 14:36:44 -0700
Delivered-to: mharc@autox.team.net
Delivered-to: triumphs@autox.team.net
References: <9caba7dc27955d4c0578025ab5adf13c@mail.gmail.com> <45169D326FA442D893E46EA557139B64@RYPC> <3c7adb156b86225de273049cde412ac5@mail.gmail.com> <0FE483ED97B5459085043FB55F4DA6AB@RYPC> <005e01d517da$7f59f950$7e0debf0$@net>, <9BE1F86A-A821-4EAC-84A8-BF620BCBA115@flash.net> <DM6PR01MB500347EA365952D376E2787EEC190@DM6PR01MB5003.prod.exchangelabs.com> <1803963313.393364.1559333749969@connect.xfinity.com>
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> Question:  with the carbs off and using the solenoid to crank 
> the engine, how much should one feel suction against ones 
> hand at the ports of the intake manifold?  I'm barely feeling 
> any if at all.  Certainly not enough to draw gas in.  

With only one hand, almost nothing would be normal.  There is a balance tube
in the manifold, so you would have to block both openings at the same time.
If you only block one, it just draws from the other.

One trick that works well with recalcitrant engines is to squirt a dollop of
carb cleaner (eg Gumout) into each carb throat just before cranking the
engine.  Gumout is actually more flammable than "starting fluid" these days
(they don't sell real ether any more no matter what it says on the can).

If it starts and dies, then you're not getting fuel to the cylinders for
some reason.  Blocked jets, not enough choke, or whatever.  Lift the float
bowl caps off and check actual fuel level in the bowl; it's not un-heard of
for the float valves to stick closed (especially with the fuel we get here
in CA, which seems to dry to an extremely hard white substance instead of
the old brown gummy varnish).

If it won't fire at all, you're either not getting ignition, or it's at the
wrong time.  Clean or change the plugs, test for spark right at a plug
connector, double check that the valves are closed and the piston is near
the top when #1 tries to fire.  Note that it's possible to have fire at the
coil and not at the plugs (bad rotor).  It's also possible to have a spark
that will jump the gap with the plug out of the engine, but won't make it
under compression.  I've had a bad condenser do that to me several times
now, but a bad coil wire (or coil) can do it too.

It's easy for even new plugs to get fouled enough to not fire under
compression.  Just being wet with fuel (or oil) can do it.  Another trick
that sometimes works is to remove each plug in turn and hold it gently with
pliers while you heat the business end with a propane torch.  Keep heating
until there is no more yellow in the flame, or if you never see yellow, the
side electrode glows red.  Reinstall the plug and do the next one.  Don't
forget it's hot!

-- Randall

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