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2000 miles in my "B"

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8NFord

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Greetings!

I just returned from a road trip of over 2000 miles in my 1977 MG-B. For the record, it now has slightly over 9000 miles on a very complete engine, trans, and front end rebuild. It has the standard 4-speed (no O/D), two inch exhaust, Weber DGV carbs, and an earlier style distributor with points.

I need to seek any aand all types of advice as to a problem that I discovered during the initial part of the trip and was never able to resolve and would appreciate any and all comments.

All during the trip I was never able to operate at a speed above 72-73 MPH or about 4000 RPM on the tach. If I tried to do so, the car would shudder and shake and generally miss on the motor. Toward the end of the trip, the motor would ocassionally spit or backfire up through the intake when I attempted to increase the speed. I could run fairly smooth (but not over 70 mph) on the level or downhill. However, at the slightest bit of a grade the motor would begin to exhibit the symptoms indicated within a short period of upgrade acceleration

Initially at about 600 miles I replaced the fuel filter. Later at about 1200 miles I replaced the points and condenser at a road side rest stop on US HWY 75. This was the extent of any roadside work performed. I would really appreciate any tips aor advice to get this sorted out before the next trip.

Thanks in advance for any and all assistance!
/ubbthreads/images/graemlins/driving.gif
Ray Hill
1977 MG-B
 
does it sound like it runs out of fuel or is it missing? probably fuel delivery or timing problem.....
 
I am sure there will be a lot of help from others here but as a start, Webers should have about 3.5 psi fuel pump pressure. Can or have you checked that?

Float levels are correct and floats are working?

It all sounds like carburation but who knows for sure until you find it.

Distributor cap is OK even though it is "new". Plugs are all Ok? Wires are all OK? Just because soemthing is new does not mean it is working right.

Vacuum advance working?
 
[ QUOTE ]
I am sure there will be a lot of help from others here but as a start,
.
A> Webers should have about 3.5 psi fuel pump pressure. Can or have you checked that?
.
B> Float levels are correct and floats are working?
.
C> It all sounds like carburation but who knows for sure until you find it.
.
I have not started on the Weber, but that is my next step. As for fuel I have been using the upper grade. I ran two tanks of the Shell "V-Power" fuel. I don't supposed this could have affected anything, could it?
.
<Distributor cap is OK even though it is "new". Plugs are all Ok? Wires are all OK? Just because soemthing is new does not mean it is working right. >
.
I have now replaced the cap & rotor and the plugs. I also adjusted the timing to 12 degrees. It seems to be a bit more peppy at the low end of the RPM range, but no change now at the upper range of say about 3600 on up. Actually, it will not even go past the 4000 RPM mark. The plug wires were replaced about 2000 miles ago.
.
<Vacuum advance working?
Yes, I used a timing light to verify the vacuum advance function.
.


[/ QUOTE ]>
.
 
Sure sounds like a fuel problem but with these cars it could wind up to be a tail light bulb (kidding sort of). Can you get it over 4000 rpm with no load - in neutral so to speak?

Did you install the Weber? Did the car ever run correctly with the Weber or is this something new?
 
Verify that you are getting proper mechanical ignition advance. You can do this with the timing light and observe the advance on the harmonic damper/timing mark as you increase the RPM to 3000. If this does not give you significant advance (25 DEG) that might be your problem.
 
Ray, here's something out of left-field but it cured a similar episode I was having with my 79. Check the small brown/yellow wire that is at the bottom of the 3-wire plug in the back of the alternator. It is not fixed well in the plug and can back out when you think you're hooking up the alternator and make a poor connection or fall out completely- it's hard to see. This wire is the circuit that goes through the ignition warning light and ultimately to the fuel pump. The fuel pump also gets power from the ignition switch but my theory is that it wasn't sufficient in itself to give the pump enough amperage to keep proper fuel pressure at times of peak demand. It's worth checking. LOL
 
Ray - B runnning correctly? If so what was the problem(s)?
 
I am absolutely no car expert but can't the problem be caused by bad wheel alignment / balancing?
 
Greetings All,

I just wanted to let everyone on this board know that the miss has been cured!

Basically the problem went down to being a fuel issue. My B had a Weber DGV carb on it when I bought it.

It had two issues, the first being that the choke ROD was not connected correctly which would only allow the plate to open about 1/2 to 2/3 of the way. The lower end of the rod has a place for a very small hair pin or cotter key which was missing. This in turn allowed the rod to come out of the lower arm.

The second issue was the float level adjustment. This was set in such a manner that the fuel bowl level would only be no more than about 1/4 to 3/8 of an inch deep at any time. This in turn would actually allow the lower jets (size .140 & .145) to become uncovered when under a hard pull going uphill, thus causing a fuel starvation miss. I reset the float to 1.5 & 2.0 inches which will now allow the bowl to fill correctly. The B will now run up to 6000RPM, and was "tested" at 5000 (or about 90MPH) on the interstate (I still had pedal, but sanity and a light front end prevailed.)
/ubbthreads/images/graemlins/driving.gif

Happy trails!
Ray
 
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