MG Car Repair: fuel problem>?, back fire, fuel hose

Question
QUESTION: HI, it's Jon with the 76 Midget (1275 motor in it). So, the car is running, however--I have a problem to diagnose. I can fire the car really without using the choke, however--the car seems to take a bit to even idle. If I blip the throttle, or engage into gear early (2 mins or less)--it will try to stall out. Once it is running for a bit--I get a "popping" sound from exhaust. Not really a back-fire, but sounds sort of rythmic pop; and and every 5 or so seconds you will hear the same sound from the exhaust--kinda like a "lumpy cam". Under load, the engine sounds good at 2000 rmp; in neutral, above that it sounds allmost like if misses. I took out for a quick drive in the parking lot, and if in 1st; over 2800 rpm it looses power and sounds like it misses. Am I lean, am I too rich? The exhaust at idle is strong...smelly. I have, as you may recall--had problems with the fuel pump (I replaced it), but it is noisy. If I pinch the fuel hose at bit (after pump) on and off-and it has been running for a bit it goes silent. Allmost like air in the system and needing to be primed. It is a electric cube style (1.5-3.0 gpm type). Is it time to try adjusting the jets? Or something else here? I have not really checked timing, as there are no markings on the pulley to mark or use to adjust (however; it is at TDC from looking at position of distributer and manually cranking pulley to top of #1 cylinder) Thanks again!
JGP

ANSWER: Hi Jon,
The timing marks on a 1275 are on the bottom of the timing cover only can be viewed from under the front of the car. You can't adjust the SU carburetors until you set the timing and adjust the valves. Also you need to check the fuel pressure of that aftermarket pump. It should be about 1.5 to 3 PSI but not more.
You should do a compression test too and tell me what you get. (Throttle open and at least 4 or 5 revolutions)
Let me know,
Howard

---------- FOLLOW-UP ----------

QUESTION: Compression is solid--150 psi across all 4...give or take 5 psi. I think, although the pump is rated at 1.5-3.0 I am a bit more. I will re-check. Prehaps I need a regulator. I will look on the bottom of the block. I am a bit confused how to adjust the timing with a "gun" from the bottom of the block. Would I need a static gun or a adjustable gun?

Much thanks.
JGP

ANSWER: The compression sounds good and you do need to test the pump pressure as when it is too high it over powers the float needle and floods the carburetor.

You can use a 12v test light to set the timing statically or you can use a timing light to set it statically or dynamically.
I found it best to do with the plugs out and put the car in 4th gear. After you set the point gap at .015", roll the car forward with your thumb over the plug hole of # 1 cylinder (using the front tire as leverage). When you feel compression on your thumb, put the test light on the negative side of the coil and turn the key on. (the light will be out). Slowly bump the car forward using the top of the front tire until the exact point that the light lights. If you moved it too far back the car up a little and do it again so that you are at the exact point that the light lit. Then take a light (flash light works well) and go look at the timing marks under the front. The one long pointer is TDC and each smaller one is 5 deg each. Static timing is 7 Deg BTDC which can be done with a timing light by putting the pick-up on # 1 plug wire and bump the car forward until you see a single flash from the timing light. And if you chose to use a timing light running, it is 13 deg at 1000 RPM.
Howard

---------- FOLLOW-UP ----------

QUESTION: I follow the beginning. So, compression on thumb--no light..., roll forward till light lights--check to see what the mark is at. At this point, I am aiming for TDC. Then, attach lead from "gun" to wire #1...roll till I see 1 blip of the light. Now, if I look back at the marks, TDC mark on pulley should line up with 7 degrees, or slightly past 5 degree mark. Now, This may sound stupid--but I will ask anyways. I looked at the pulley. It is below the one running the fan. I would call it the crank pulley. There was no markings above or below. Just a pulley painted red (aftermarket) and no small groves on it of anysort or markers. Am I without a paddle?

Final note, pressure ok...however, seat on the carb is much lower in setting then the front carb. I pushed the piston "lever, button" under the carb while running--front carb ever so slightly raises RPM, not noticeable- really...and rear increased idle (noticed) and then dropped when released.

Thanks again.

Answer
Jon, I never seen an aftermarket crankshaft pulley. The crankshaft pulley should have a notch in the edge of the pulley. If it has been painted, it may have made the notch hard to see. Do this, with #1 plug out put a rod like a coat hanger or such in the plug hole to feel when the piston gets to the exact top (TDC) then look at the long pointer on the bottom of the timing cover and see if you can spot the notch in the edge of the pulley. The notch will line up with the long pointer when the piston is at TDC. When you are setting the timing you will have the notch line up in between the first small pointer and the second small pointer. (7 degrees) Each small pointer is 5 degrees.

When setting the jets you lift the front carb pin and if it speeds up the REAR carb is too rich meaning you have to adjust the REAR jet up by no more than 3 flats (the adjusting nut has 6 flats)
Then repeat the process until when you lift the front carb pin you get a drop off in RPM and it will sound like it is just running on two cylinders.
Then you can lift the rear carb pin to check the front carb. and repeat the process until you can lift either front or rear carb pin and it will sound like a two cylinder engine.

Howard