[Bmcu] FW: MGB Owner Needs Help

[Ron Christensen]

What????!!!!  “Gap settings can change on one as you adjust the next.” ????  Not!

From: bmcu-bounces at autox.team.net [mailto:bmcu-bounces at autox.team.net] On Behalf Of Richard Sanders
Sent: Tuesday, October 18, 2011 8:24 PM
To: DUFF LAWSON
Cc: bmcu
Subject: Re: [Bmcu] FW: MGB Owner Needs Help

this is a longshot, but the symptoms might support it. Have you considered that the gap on one of the exhaust valves is too wide? Gap settings can change on one as you adjust the next. The reason I'm thinking about this is your comment about the start then stall and also the miss and especially the backfire out the carb. An overgapped exhaust valve would cause chamber pressure on one cylinder to build up and burp back out into the intake manifold as other cylinders are trying to inhale. If this theory is correct then that would interfere with the mixture going into other cylinders causing no fire or intermittent firing. It could also explain the backfire out the carb if the exhaust valve is not opening until well after the moment of combustion on the overgapped cylinder.

Just a theory and not advice, for sure as I'm a fellow tinkerer.

Rich Sanders
BMCU expat currently serving time with Minnesota Triumphs



Sent from my iPad

On Oct 18, 2011, at 9:49 AM, DUFF LAWSON <duff_lawson at msn.com<mailto:duff_lawson at msn.com>> wrote:

________________________________
Date: Thu, 13 Oct 2011 17:45:35 -0700
From: sabner at yahoo.com<mailto:sabner at yahoo.com>
Subject: MGB Owner Needs Help
To: duff_lawson at msn.com<mailto:duff_lawson at msn.com>
Hey Duff, would you please forward this to team?  I'm having problems with my MGBGT, and I'm totally out of ideas.  Let me recap:  My MG hasn't been driven much this year due to health problems (mine), and when I took it in for inspection and emissions testing, it failed the idle part of the test, too much HC.  Now when I fired it up to take it for testing in August, it fired right up and ran great.  I'm thinking maybe I didn't get it warmed up well enough before they put the probe in tail pipe.  But recently, as my physical problems have abated, I've replace the spark plugs, one at a time, changed the oil and filter, checked the timing and adjusted the valves.  After all that, it did start briefly, but immediately died.  After much cranking it restarted, but it had ahuge miss and backfire.  I checked that I still ahd correct firing order and distributor rotation, and all of that is okay.  I replaced the coil, and now I get a strong blue spark that will jump a 3/8" gap from the spark plug end of all the spark plug wires, so the spark is good.  I checked spark through my new spark plugs, and it was yellow and feeble, so I bought some more (better) spark plugs.  But it still won't start.  It does get an occasional pop back through the carbs.  I'm out of ideas; does someone have a suggestion?  Now that my health is returning, I'm going back to work and I need the car for my daily driver.  If anyone has any suggestions, please let me know at sabner at yahoo.com<mailto:sabner at yahoo.com>.
Thank you very much in advance, I appreciate any suggestions.
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