Running rich

[Sally Carroll]

In the old days ( when TC's were new cars) we had choices of heat ranges of spark plugs . . . . Now I have a TF, TC and Morris pickup (with Midget 1098 engine and one carb) with the same symptoms . . .running rich, pronounced rough, and guzzling gas like crazy.

Since Jim isn't here, anymore. . . I'm not sure of the next step to correct for this problem. My son and several friends from our local Club have been trying but we still find we're 'loading up' and acceleration is poopy. Timing has been checked, plugs cleaned, grose jets installed. You will be going along at 50 and when you put demand on the pedal, not much responce. We had to place a helper spring on the choke return but it only made it more difficult for my daughter to start.

How's that for a new 'thread' for you guys?

Sally Carroll 48 TC 52 YB 55 TF 1500 60 MGA 1600 71 MGBGT

and 59 Morris Pickup.

[sculptart@aol.com]

Sally, I almost sounds as if the carburetors are not set correctly. Has this been checked? As far as acceleration is concerned, in the case of the TC, acceleration is best described as "leisurely." Removing the air cleaner and manifold, then lifting the carburetor piston about 1/32" while running should result in a slight rise in RPM's then dropping back immediately. If you find the RPM's increase and remain that way, the carburetors are running rich and by backing the adjustment nut off this will be corrected. Don't forget to "balance" the carburetors. Specific tools are available for this or a length of tubing and careful comparison in the air flow (hiss) will give you the correct balance. The SU carburetors are really very reliable and simple units and once tuned correctly will give miles and miles of good gas mileage and performance. If you do not have any shop manuals that describe the tuning steps, let me know and I will scan one of mine and e-mail the text to you. My best, Ben Cordsen, TC 4260

[Robert Johnson]

Two suggestions, Sally.

1. Check the fuel level in the jets by removing the dashpots and withdrawing their pistons and needles. Turn the ignition on long enough for the fuel pump to stop ticking and turn it off. Look down in each jet. The fuel should be at equal height in both at 1/16 to 1/8 inch down from the top. If not, adjust the forks in the float bowls as req'd and repeat the test. You may find that you have a bad float at this point. While you have the pistons and needles out, examine them to make sure the needles are installed with their shoulders flush with the bottom of the pistons. When you replace the pistons and dashpots, if you raise the pistons and let them go, they should come down with a definite clunk as the piston contacts the bridge of the carburetor body. If they don't fall freely, they are binding, either in the dashpot or the needle is not centered in the jet and the engine will run rich. Finally adjust the jet heights at idle individually and don't forget to retighten the link between the carbs when finished.

2. Pull the distributor and take it to an auto electric shop and have them service it and set the advance curve to factory specs on their distributor machine. More than likely the advance weights are either sticking or the springs have become out of spec. Static timing may be set fine but the symptoms you describe sound like the engine doesn't have enough advance at higher speed under load. High mileage distributors also usually need a new bushing installed to get rid of excess play.

Cheers.

Bob Johnson

Crescent City, CA

[brian bax]

Hi Sally, In addition to the other advice you've been given, the booklet "Your SU Companion" by Donald Jackson (who worked at the factory) states that the original standard needle (ES) is far too rich for modern fuels and higher compression ratios. As suggested in the booklet I have used weaker EU needles for some time amd they work well giving 38 miles per gallon. Hope this helps, Brian Bax TC3550

[Zissel-Kreuztal@t-online.de]

Hi Sally, hi T-Typers! If you have all the "normal" Points checked and the cars runs well before with this setup, there was was only one point left: The pistons of the carbs with their dampers. Are they clean, move they free, is enough (correct) oil in the dampers reservoir? A testing set, created special for SU-Carbs, is at the market and ideal for this: It contains two tubes and two wires to make the working of the SU-Pistons visible. You remove the dampers, stick the tubes into the holes of the dampers and put the wires into the tubes (sounds good, ehh?). The wires must be bent, that the ends comes together, but without contact. When you start the engine, you see the tubes with the wires moving up and down when you open/close the trottle. They must work syncron. If they do not, you know where your problem is. 2nd test: You can lift the pistons with the tubes. They must fall free and stop with a "plongg". If one do not, the needle have contact with the jet. ---> Adjusting the jet.

Check the throttle shafts for leaks: put a drop oil over every side of the shafts, during the engine is running. The engine should not change it RPM s. Some people enriched their idling mixture over the years when they carbs worn out. In fact, the carbs would be to rich above the idling revs.

Another view: Since the intoduction of lead free petrol, I must change my spark plugs to Bosch W8AC. The BP6ES was always black and oily. But this was specific for MY engine, maybe to hot for other engine.

Greeting lozi (TC3762)

Sally Carroll schrieb:

#ygrps-yiv-73535989 { BACKGROUND-POSITION:center top;BACKGROUND-REPEAT:repeat;COLOR:#000000;FONT-FAMILY:Comic Sans MS;FONT-SIZE:10pt;MARGIN-LEFT:50px;} In the old days ( when TC's were new cars) we had choices of heat ranges of spark plugs . . . . Now I have a TF, TC and Morris pickup (with Midget 1098 engine and one carb) with the same symptoms . . .running rich, pronounced rough, and guzzling gas like crazy. Since Jim isn't here, anymore. . . I'm not sure of the next step to correct for this problem. My son and several friends from our local Club have been trying but we still find we're 'loading up' and acceleration is poopy. Timing has been checked, plugs cleaned, grose jets installed. You will be going along at 50 and when you put demand on the pedal, not much responce. We had to place a helper spring on the choke return but it only made it more difficult for my daughter to start. How's that for a new 'thread' for you guys?Sally Carroll 48 TC 52 YB 55 TF 1500 60 MGA 1600 71 MGBGTand 59 Morris Pickup.

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[joecurto@aol.com]

Sally have the gang check out the coil and the related system as a weak ignition causes a rich mixture, as for aux spring on choke assembly probably the cork packing have gotten stiff or jets have some corrosion, I have proper tension choke springs in stock but if rest of system is stiff than you will have troubles as you described. while I do not advocate excessive reving but perhaps the cars need to be driven with a bit more "elan" chose 3000 rpm as your shift point and when cruising around town keep the RPM at the 3000 area no matter which gear you are in. I had a customer with 4.3 gears and a 5 speed and was driving at 2000 RPM in 5th and was having similar problems. Joe curto

[Steve S]

Other than having the wrong jets, is there anything to look for if I'm running rich? I have the adjusters leaned out all the way and even tried removing the air filters. I have rich-smelling exhaust and plenty of it, plus black moist plugs. Any suggestions welcome! - Steve S, TC8975, LA, CA -

[John Patterson]

Steve, make sure the needles are not rubbing on the side of the jets as they will file them into a oblong shape and you will never get lean enough. There is a jet centering tool available to fix this problem when you replace the oblong jets. GCC6101X in the Moss cat. It bolts in the needle slot in the SU piston and lowers into the jet to center it when you tighten the adjusting nut. Good luck! If that's not the problem, then maybe the jets are the wrong size. John TC 7025 -----Original Message----- From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com]On Behalf Of Steve S Sent: Tuesday, June 27, 2006 10:11 PM To: mg-tabc@yahoogroups.com Subject: [mg-tabc] Running Rich Other than having the wrong jets, is there anything to look for if I'm running rich? I have the adjusters leaned out all the way and even tried removing the air filters. I have rich-smelling exhaust and plenty of it, plus black moist plugs. Any suggestions welcome! - Steve S, TC8975, LA, CA - [Non-text portions of this message have been removed]

[Maurice Paton]

A likely cause of running rich would be the level of fuel in the float bowls. You can easily check this by removing the dash pots and observing the fuel level in the top of the jets. You first need to screw the jets up so they are flush with bridge in the carb body and then turn the fuel pump on to fully fill the float chambers (wait until it stops ticking). The fuel level in the top of the jets should be down about 1/8inch. If the level is higher than the top of the jet, fuel will just be being pumped straight into the engine and you SU will continue ticking! Removing the air cleaners should make no difference to the richness of the mixture, just the amount of air (and therefore fuel) that enters the carb. The fuel is sucked from the jet by the drop in air pressure as it is accelerated through the venturie formed between the carb bridge and the carb piston. More air equals more fuel. Maurice TC9357 NZ -----Original Message----- From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf Of Steve S Sent: Wednesday, 28 June 2006 2:11 p.m. To: mg-tabc@yahoogroups.com Subject: [mg-tabc] Running Rich Other than having the wrong jets, is there anything to look for if I'm running rich? I have the adjusters leaned out all the way and even tried removing the air filters. I have rich-smelling exhaust and plenty of it, plus black moist plugs. Any suggestions welcome! - Steve S, TC8975, LA, CA - Yahoo! Groups Links

[1939mgtb]

The high float level question is one that bit me this last weekend in my M type... If the fuel level is too high, no matter which needle is in the carb, you will have rich running. The old SU's have a certain "fiddle factor", and you start with fuel level in the bowl, then to the jet setting, then finally to the needle for over-all mixture strength. Best, Ray "The friendliness and charity of our countrymen can always be relied upon to relieve their fellow-citizens in misfortune. Federal aid in such cases encourages the expectation of paternal care on the part of the government and weakens the sturdiness of our national character."

----- Original Message ----- From: Maurice Paton To: Steve S ; mg-tabc@yahoogroups.com Sent: Tuesday, June 27, 2006 10:01 PM Subject: RE: [mg-tabc] Running Rich A likely cause of running rich would be the level of fuel in the float bowls. You can easily check this by removing the dash pots and observing the fuel level in the top of the jets. You first need to screw the jets up so they are flush with bridge in the carb body and then turn the fuel pump on to fully fill the float chambers (wait until it stops ticking). The fuel level in the top of the jets should be down about 1/8inch. If the level is higher than the top of the jet, fuel will just be being pumped straight into the engine and you SU will continue ticking! Removing the air cleaners should make no difference to the richness of the mixture, just the amount of air (and therefore fuel) that enters the carb. The fuel is sucked from the jet by the drop in air pressure as it is accelerated through the venturie formed between the carb bridge and the carb piston. More air equals more fuel. Maurice TC9357 NZ -----Original Message----- From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf Of Steve S Sent: Wednesday, 28 June 2006 2:11 p.m. To: mg-tabc@yahoogroups.com Subject: [mg-tabc] Running Rich Other than having the wrong jets, is there anything to look for if I'm running rich? I have the adjusters leaned out all the way and even tried removing the air filters. I have rich-smelling exhaust and plenty of it, plus black moist plugs. Any suggestions welcome! - Steve S, TC8975, LA, CA - Yahoo! Groups Links [Non-text portions of this message have been removed]