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Post-Rebuild problems

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aapitten Avatar
aapitten Aaron Pittenger
Cleveland, OH, USA   USA
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Hey everyone,
I'm waving the white flag. I need some help.

I got my newly rebuilt GK engine into my 1971B, cranked without plugs till I got oil pressure, and then fired up. She started with relatively little trouble. I immediately got the RPMs up (I actually was a bit high at 3500) and varied between 3500 and 2000 RPM for 20 minutes to break in the cam. I had to stop 3-4 times due to coolant temp and what I later discovered was an intermittent fuel pump problem.

A couple days later, I fired up again, ran for another 15 minutes at 2000 rpm, just to make myself feel good about getting the cam set, and get things up to temp, then I started tuning. Got the timing set, and got one carb pretty well set. I had idle pretty smooth at 600 RPM (which I couldn't do pre-rebuild.) Went to do the second carb and then the car died. After lots of cranking and troubleshooting, I figured out the fuel pump was totally dead and not pumping.

The next morning I got a new pump and put it in and replaced all the old fuel line with new (went from 5/16" to 1/4"winking smiley, also reconnected my cleaned (vinegar method) gas tank (had been pulling from a plastic can previously.) Went to start the car and it was REALLY hard to get going. Once it was running it was SUPER rough and wouldn't rev at all when you gave it throttle (remember when I shut it down the last time it was running pretty smooth.)

I changed my fuel filter (thinking I got some crud from the tank) and dropped the hose back into the plastic can instead of the actual gas tank. Still nothing.

Basically I can get it running if I try really hard, but it won't rev and won't smooth out, and it coughs with the occasional backfire through the carbs. I have A) statically reset the timing, B) Verified Spark, C) Verified Fuel, D) Checked fuel bowls for crud E) Pulled the plug wires one at a time while running (didn't get smoother or rougher), F) looked into the oil fill (couldn't see a whole lot to verify.)

What should my next step be? I'm at a loss as to what happened here. Did I somehow wipe out my cam?

Thanks,
Aaron

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13401h Greg Mouritz
Mentone, Victoria, Australia   AUS
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Hi Aaron,

I would be surprised if the cam has been damaged based on your comments. Certainly not enough to cause your no start and rough running as described. But for piece of mind, before any further cranking, lift the rocker cover and recheck & set tappet clearances.

If I understand the above description correctly - all was well until you used fuel from your just cleaned fuel tank. Perhaps you should drain your float bowls and re-prime the fuel system with fuel that has not been in your tank previously. Then start the engine using the remote plastic fuel can you were using on your initial start-ups.

I am thinking you have contaminated fuel from your tank repair.

Hope this helps

Greg

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rntanner Avatar
rntanner Roger N. Tanner (Disabled)
Oxnard, CA, USA   USA
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1970 MG MGB
1977 MG MGB
I have to put this out, almost every day:

If your local gasoline includes alcohol, this is what you will have to do next:

Fixing Rusted Gas Tank and New Fuel Line:

Your car is about 40 years old.

When your fuel tank is low on gasoline, drop it and have the radiator shop clean it.

Have them change the small tube that is part of the fuel line to the front of the car, to the new fuel line that does not rust.

Replace the fuel line that goes up to the front of the car. Your auto supply will have fuel line that is not steel. I bought mine from the local NAPA auto store.

Now, my 1977 MGB lives in California, who directs that gasoline now has 10% alcohol.

Before alcohol, the gasoline would float on top of the water that comes in as water vapor from the air, every night, for 14,600 cooling down cycles.

Unless you have cleaned it, the alcohol in the gasoline has picked up "all the water" and mixed it with the gasoline, and rusted the inside of the fuel tank, and rusted the fuel line that goes up front, all the way shut.

The short line on the tank has to be removed and a piece of the modern fuel line has to be soldered on to the tank.

The rest of the modern fuel line just has to be removed and replaced all the way to the carburetor(s).

NO, I DIDN'T READ THIS IN A BOOK. IT HAPPENED TO ME!

The materials (tube), gas tank cleaning cost me less than $50.

I removed and replaced the fuel tank at home and installed the long piece of fuel line up to the carburetor (one on a 1977).

Roger N. Tanner, Professional Engineer, Retired
Oxnard, CA
rntanner1939@gmail.com



Roger N. Tanner
Professional Engineer, Retired

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B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
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Try around 15 BTDC timing at idle, or more. Turn the distributor CW and try to restart. Static timing is NOT accurate. Stock settings are awful. Make sure your chokes are both working, actually dropping the jets the same amount at both carbs. You should be able to actuate it in the engine bay and watch by turning the linkage.

Are the float bowls both full? Are you set at roughly 12 flats down from the bridge on both jets? Set a baseline!



jeff@advanceddistributors.com

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