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MG MGB Technical - Help My B!!!!

Ok my 1970 mgb has been running bad almost since i have got it. When i got the car about 3 years ago it was sitting for about a year. The previuos owner had put on one of those solid state fuel pumps. When i got the car i put on a set of rebuilt su carbs.(new oversized shafts,jets and gaskets). I recently just got done putting on a peter burgess fast road head.
Matt Kaser

Sorry for double post. It was an accident!

The car runs ok up to 2500rpm and after that it starts cutting out, or it feals like it is hitting a wall.
I adjusted the points,valves, carbs are balanced, mixture is right but maybe a tad rich. Timing have not looked at but it was set right last year. I have a tiny exhuast leak where the headers pipe meets the pipe that goes to the muffler.

What could be cuasing this? Carbs? Fuel pump? Ignition?

Any help would be much appreciated!!
matt Kaser

Matt,

Sounds like you could be running out of fuel. Have you checked the flow rate? Disconnect the fuel line to carbs, insert the hose into a can & measure time & volume. I don't know what the flowrate is supposed to be, but you should be able to check in a manual.

Good luck,

Bud - 67 roadster
Bud G

The timing changes when you adjust the points, so checking the static timing would be the first line of attack. Make sure the TDC mark on the front pulley is actually at TDC and that the vacuum line to the distributor is disconnected and and plugged when you test the dynamic timing. Also you might try removing the exhaust system from the headpipe back and making a run to verify that excessive back pressure isn't the problem.
George B.

With the car sitting for a tear, the advance mechanism on the distributor may be seized. If you have a timing light, check that you have 34 degrees of advance at 3000 rpm. (Assuming you have a light that allows you to do this).

Pete
Pete

Thanks guys for the responses. I will check all of that and get back with you to see where i am at.
Matt Kaser

OK went out and check all of that. My fuel pump is showing 4.5 psi. Which i think is ok. I set my timing about 12btdc. Have not checked vaccuum advance but the cars still runs horriblely
Matt kaser

When you check the timing, I assume the vacum advance is disconected and the idle is no more than 700rpm. If you bring up the idle, does the timing advance (mechanical advance NOT vacum). If it does not, then your engine will be running WAY to retarded at high rpm and make no power. Your fuel pressure is fine unless it is lossing pressure under load( obstruction in the line) Can your "T" in the pressure gauge while driving the car?

Pete
Pete

With your vacuum disconnected and plugged at either your manifold or rear carb, depending on your carb model,and your timing light connected, you should be aiming at 20 degrees at 1000 RPM for a 1970 model, minus a couple of degrees because you are using unleaded fuel. That could well be your problem.
Ken R
Ken R
Ken Rich

This thread was discussed between 01/03/2002 and 02/03/2002

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