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Frayed distributor ground wire sheathing

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AlanR Alan R
Seattle, WA, USA   USA
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1972 MG MGB
My car has been sporadically stuttering recently. It seems to happen most when accelerating between 2k and 3k rpm, but does sometimes happen at constant speed. The is no noticeable effect on the tach reading, and the car seems to run happily along otherwise. I had a chance to quickly poke around a bit tonight and noticed that the sheathing on the distributor ground wire has frayed, leaving a section exposed. The wire itself appears to be in good condition. I know little about distributors, and am curious if this could potentially be the cause of my troubles.

For reference, I have replaced the points, condenser, rotor, cap and wires along with the coil in the last few hundred miles. The carbs were recently rebuilt and the timing is set to spec, and the valve clearances adjusted.

Thanks in advance to all who took the time to read my post.

Alan.


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Rod H. Avatar
Amity, OR, USA   USA
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1964 MG MGB
1968 MG MGB GT
Being a ground wire it's unlikely to cause problems unless the bare area is contacting something with power. That insulation does tend to come detached and look like yours...have seen many like that with no issues!



Friends talking around a fire is the history of mankind.

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dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
Probably not the problem. Ace Hardware has liquid insulation that can be wiped on to replace the insulation. The ground wire from breaker plate to body screw appears to be very short, and may be limiting your breaker plate rotation.



Be safe out there.
Kenny


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ohlord Avatar
ohlord Platinum Member Rob C
A tiny Island off the coast of Washington State, N.W., USA   USA
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1957 Land Rover Series I "EYEYIYI"
1957 Land Rover Series I "OVRLND"
1971 MG MGB
1971 MG MGB "Bedouin 2"    & more
Timing spec is no longer timing spec
It's just a base line at which to begin the process of maximising timing.
Not your problem currently
However can assure you the timing is anything from ideal .
What plugs and gap?
What points and gap
You don't have a quality rotor installed
What weight oil in carb dampers?
Check free travel of breaker plate assembly?



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1957 Series 1 Land Rover electric VEHICLE CONVERSION

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VIETNAM 1969-1972

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spikemichael Platinum Member Michael Caputo
Canton, IL, USA   USA
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1973 MG MGB "Freebie"
1973 MG MGB
1974 MG MGB "Spike"
1976 MG MGB "Cecil"    & more
Rob that rotor is the better black one, not the best red one but not the end of his world.



Michael J. Caputo
'79, '77, '76, '74.5 (rubber dual SU), and '73 owner. Extensive experience in 12v Audio System design and installation. Vendor of Regalia and Promotional Products since 1993. Supplier of Accessories to MOSS. Forum Member since 2009; with a warped sense of humor since birth. Publisher of the annual MGB & GT Calendar, mailed worldwide.


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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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Good advice, as always from Kenny. FWIW, a bottle of nail polish from the Dollar Store has many uses in cars, including such insulation... winking smiley

Dick

In reply to # 3476047 by dipstick Probably not the problem. Ace Hardware has liquid insulation that can be wiped on to replace the insulation.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
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See the loose crimp on your condenser? I'd start by fixing that.
The ground wire can be bare. Its a ground. But make sure its actually doing its job.
Check your newer vac unit to see if the diaphragm leaks, because the problem you have sure sounds like a lean misfire. I'd thoroughly check everywhere for vacuum leaks. Tighten all intake and carb bolts/nuts. Check and replace every vacuum line to be certain they are extremely tight, including any smog hoses you might have.



jeff@advanceddistributors.com

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AlanR Alan R
Seattle, WA, USA   USA
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1972 MG MGB
Thanks everyone. On Jeff's advice I went out and checked the vacuum advance unit and found that the diaphragm has failed. The is pretty frustrating as it is the second new unit that has failed in the past 2 years. Is it possible that I am doing something on my end that is causing the unit to fail? Aside from removing the smog equipment, everything else is standard on my car.

Since I will have to put in an order to exchange the vacuum advance unit, is there anything else I should look at replacing on the distributor at this point? As a reminder the points, condenser, rotor, cap, plug wires and coil are all new in the last few hundred miles.

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HiPowerShooter James Booker
Lake Winneconne, WI, USA   USA
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1973 MG MGB
If you're buying new Chinese vacuum units...that's the mistake. Find a good OEM used one(or send yours if you still have it) and send it to Jeff to rebuild. It'll last a long, long time...



"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

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ohlord Avatar
ohlord Platinum Member Rob C
A tiny Island off the coast of Washington State, N.W., USA   USA
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1957 Land Rover Series I "EYEYIYI"
1957 Land Rover Series I "OVRLND"
1971 MG MGB
1971 MG MGB "Bedouin 2"    & more
Have Jeff rebuild it.
He can fix the diaphragm



LNDRVR4X4.COM
Home of Project "INCARN8'


1957 Series 1 Land Rover electric VEHICLE CONVERSION

FIXITUPCHAP.COM
FIXITUPCHAP INCORPORATED

RD3 Radar/ Electronic Warfare Technician
VIETNAM 1969-1972

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dipstick Avatar
dipstick Kenny Snyder (RIP)
La Center, WA, USA   USA
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1941 Ford N-Series
1958 MG MGA 1500 Coupe "Rosie"
1970 MG MGB GT "Pat's GT"
1971 MG MGB "Gifted To Me"    & more
"... is there anything else I should look at replacing on the distributor at this point?"

Yes.
- Given a '72 distributor the centrifugal advance springs are likely stretched causing the advance to be inaccurate.
- The underside of the breaker plate may be worn in the sliding post area allowing the plate to tip.
- The centrifugal advance curve is a factory emissions compromise and not the optimum for your engine.
I suggest sending the distributor to Advanced Distributor (Jeff) to be refurbished.



Be safe out there.
Kenny

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Steven 67GT Avatar
Steven 67GT Steven Rechter
Jackson, CA, USA   USA
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In reply to # 3476240 by dickmoritz FWIW, a bottle of nail polish from the Dollar Store has many uses in cars, including such insulation... winking smiley

Yes exactly. I've used clear nail polish for years for electrical repairs.

It also works well to repair tears in speaker cones.

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B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
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Its a problem with both the materials being used and the quality of the assembly. Since the guy making them refuses to use any form of adhesive, they don't last long.
Its inexpensive to rebuild the original and I can usually make them last many, many years by simply using exceptional materials. I can repair the advance curve at the same time to be optimal for your specific engine build as Kenny mentioned.

The same guy who builds those new vac units also rebuilds Lucas distributors. I suspect those last a year or two as well. I've repaired quite a few of them after they didn't work as expected. That's why I suggested you check to see if the vac unit leaks. Its an ongoing issue. When people offer a 2 year warranty, they're telling you how long the part is designed to last. I stand behind my builds for years. I have yet to see a diaphragm fail on a vac rebuild, although a few didn't seal on the first try. I've ironed out those issues with new techniques and tooling.



jeff@advanceddistributors.com

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BumbleB74 William Milholen
Tidewater, Tidewater VA, USA   USA
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List to what Jeff says, he can be WELL trusted!



1974-1/2 Roadster, "Bumble Bee", Corvette Yellow - in shambles, wire wheels
1976 Roadster, "Virus", Sandglow - "driver" condition (stock + 32/36 Weber DGEV, cast iron header, 25D distributor), bolt on wheels, ON the road!

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