Engine Won't Idle

[Mark Stolzenburg]

On Saturday a friend (who owns two TC's) came over to set up the engine - especially the SU carbs. I have started the engine prior but have never run it for a long period of time until Saturday. The engine started right up with no problems using the choke. After bringing the engine to operating temperature and releasing the choke, the engine will not continue to run, at least not for very long. It starts dying and sputters through the carbs. If the choke is pulled the engine will continue to run obviously at a very rich mixture. If you let go of the choke the engine will sputter. Using the choke the engine will start right up. Even setting the jets at 9-10 flats did not seem to help. The carbs where rebuilt according the Carburetor Tuning article by Chip Old in "The T-Type Restoration Handbook". The engine timing was set by the static method.

Things that were checked include: The fuel pump is pumping plenty of fuel indicating no clogged fuel lines, Carb flanges milled to insure a flat mating surface, Intake Manifold surface also checked, Jets re-centered, Float levels re-checked for 7/16" clearance. Any suggestion from the list member?

Thanks,

Mark Stolzenburg

[Robert Johnson]

Suggestions for further checks follow:

1. Are you absolutely sure the correct carb needles and jets were in fact fitted on rebuild?

2. Are the carb needles properly installed with shoulders flush to the dashpot piston?

3. I've found that setting the float levels by "clearance" as often as not will not provide a proper fuel height in the jets. Pull the dashpots and pisons/needles out and with the fuel pump on, look down to see if the fuel level in the jets is between 1/16" and 1/8" down from the bridge in the carb body. If not, adjust the forks until the fuel level is within that height range in the jets and equal to one another. Running lean as it would seem yours are suggests that you will find that the fuel level is too low in the jets. As an aside, the jet height will typically end up just slightly below this bridge and slightly above the fuel level on final tuning.

4. Have the idle speed adjustment screws been set individually and then the inter-carb throttle linkage tightened?

5. Have you tried setting the idle speed screws and the mixture (jet height test via slight raising of the dashpot piston) using an independent electronic tachometer with a 1000rpm full-scale range in order to clearly see subtle differences?

With everything set correctly in a basically healthy engine (valves adjusted, timing set, good compression, etc.) it should idle smoothly around 750rpm. Some prefer a little higher, some prefer slightly lower.

Bob Johnson

Crescent City, CA

[AndyJ]

You might do well to suspect air leakage at the spindles or intake maifold joints. The symptoms you describe sound like the choke is "balancing" the amount of air getting in, but when you take off the choke the air leaking in is greater than the fuel part of the mixture can balance out. TC Syd

----- Original Message ----- [b]From:[/b] stolzy40@peoplepc.com [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, June 04, 2001 6:09 AM [b]Subject:[/b] [mg-tabc] Engine Won't Idle On Saturday a friend (who owns two TC's) came over to set up the engine - especially the SU carbs. I have started the engine prior but have never run it for a long period of time until Saturday. The engine started right up with no problems using the choke. After bringing the engine to operating temperature and releasing the choke, the engine will not continue to run, at least not for very long. It starts dying and sputters through the carbs. If the choke is pulled the engine will continue to run obviously at a very rich mixture. If you let go of the choke the engine will sputter. Using the choke the engine will start right up. Even setting the jets at 9-10 flats did not seem to help. The carbs where rebuilt according the Carburetor Tuning article by Chip Old in "The T-Type Restoration Handbook". The engine timing was set by the static method. Things that were checked include: The fuel pump is pumping plenty of fuel indicating no clogged fuel lines, Carb flanges milled to insure a flat mating surface, Intake Manifold surface also checked, Jets re-centered, Float levels re-checked for 7/16" clearance. Any suggestion from the list member? Thanks, Mark Stolzenburg Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Neil Nelson]

In addition to all the other hints you will no doubt receive, here are a few things to take into consideration. This one is pretty elementary but since you didn t mention it I have to ask, did you balance the carbs for proper air flow using either a Unisyn or the good old rubber hose method? Was the carb linkage disconnected when this was done so each carb reacts individually? Second, when the jet adjusting screw is all the way up, do the pistons in the bells when raised and dropped hit the bridge with a metallic click? In not, the jets are not centered properly. Do the pistons move freely in the bells except for some resistance do to the oil in the dashpots? Did you oil the dashpots? What oil did you use? Since the engine is running lean without choke, check that the jets are flush with the bridge when the adjusting screw is all the way up, then back off about 5-6 flats. This will give you a baseline to start adjusting further. You will still need the choke to start the car. I have found that many times it takes more than 9 10 flats to get the engine rich enough to run at the proper mixture. You may not have had the jets open (rich) enough if you stopped at 9 10 flats. Open them up until you get a too rich indication on the piston lift test and then close back down to the proper rpm rise (25 50 rpm rise when slightly lifted.) Check for air leaks in the manifold gasket, carb gaskets and shafts. (Wiggle the shafts, there should be little or no movement up and down or side to side.) Check to see if you have the correct needles. They are stamped on the shank of the needle. TC standard needles are ES, rich are EM and lean are AP. One other thing, be sure the needles are installed properly in the pistons. The shoulder of the needle should be flush with the bottom of the piston on the squared off shouldered needle. When the jet adjusting nut is all the way up, the needle should just mate with the jet and the piston should be resting on the bridge of the carb. If the jet is holding the piston away from the bridge it will take more flats on the adjusting nut to open the jet orifice enough to allow an idle. Hope this helps and good luck. It is always exciting when the engine comes to life after a rebuild.

Neil Nelson

TC 0526

-----Original Message----- [b]From:[/b] Mark Stolzenburg [mailto:stolzy40@peoplepc.com] [b]Sent:[/b] Monday, June 04, 2001 9:10 AM [b]To:[/b] mg-tabc List [b]Subject:[/b] [mg-tabc] Engine Won't Idle

On Saturday a friend (who owns two TC's) came over to set up the engine - especially the SU carbs. I have started the engine prior but have never run it for a long period of time until Saturday. The engine started right up with no problems using the choke. After bringing the engine to operating temperature and releasing the choke, the engine will not continue to run, at least not for very long. It starts dying and sputters through the carbs. If the choke is pulled the engine will continue to run obviously at a very rich mixture. If you let go of the choke the engine will sputter. Using the choke the engine will start right up. Even setting the jets at 9-10 flats did not seem to help. The carbs where rebuilt according the Carburetor Tuning article by Chip Old in "The T-Type Restoration Handbook". The engine timing was set by the static method.

Things that were checked include: The fuel pump is pumping plenty of fuel indicating no clogged fuel lines, Carb flanges milled to insure a flat mating surface, Intake Manifold surface also checked, Jets re-centered, Float levels re-checked for 7/16" clearance. Any suggestion from the list member?

Thanks,

Mark Stolzenburg

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Steve Rankin]

I had the same problem with my B yesterday. The way to find out if your intake is leaking somewhere, is to use a unlit propane lpg torch to blow gas around potential leaks. If there is a leak, the engine revs will pick up when the gas is sucked in. Amazing how easy it was to balance the carbs once I tightened up the manifolds. Steve Rankin TC 6646 68 MGB 74 MGB

----- Original Message ----- [b]From:[/b] tcsyd@ix.netcom.com [b]To:[/b] mg-tabc@yahoogroups.com ; stolzy40@peoplepc.com [b]Sent:[/b] Monday, June 04, 2001 8:00 PM [b]Subject:[/b] Re: [mg-tabc] Engine Won't Idle You might do well to suspect air leakage at the spindles or intake maifold joints. The symptoms you describe sound like the choke is "balancing" the amount of air getting in, but when you take off the choke the air leaking in is greater than the fuel part of the mixture can balance out. TC Syd ----- Original Message ----- [b]From:[/b] stolzy40@peoplepc.com [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, June 04, 2001 6:09 AM [b]Subject:[/b] [mg-tabc] Engine Won't Idle On Saturday a friend (who owns two TC's) came over to set up the engine - especially the SU carbs. I have started the engine prior but have never run it for a long period of time until Saturday. The engine started right up with no problems using the choke. After bringing the engine to operating temperature and releasing the choke, the engine will not continue to run, at least not for very long. It starts dying and sputters through the carbs. If the choke is pulled the engine will continue to run obviously at a very rich mixture. If you let go of the choke the engine will sputter. Using the choke the engine will start right up. Even setting the jets at 9-10 flats did not seem to help. The carbs where rebuilt according the Carburetor Tuning article by Chip Old in "The T-Type Restoration Handbook". The engine timing was set by the static method. Things that were checked include: The fuel pump is pumping plenty of fuel indicating no clogged fuel lines, Carb flanges milled to insure a flat mating surface, Intake Manifold surface also checked, Jets re-centered, Float levels re-checked for 7/16" clearance. Any suggestion from the list member? Thanks, Mark Stolzenburg Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Paul Huck]

Please highlight the word "[b]UNLIT[/b]" in your message.

----- Original Message ----- [b]From:[/b] srankin@island.net [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, June 04, 2001 10:57 PM [b]Subject:[/b] Re: [mg-tabc] Engine Won't Idle I had the same problem with my B yesterday. The way to find out if your intake is leaking somewhere, is to use a unlit propane lpg torch to blow gas around potential leaks. If there is a leak, the engine revs will pick up when the gas is sucked in. Amazing how easy it was to balance the carbs once I tightened up the manifolds. Steve Rankin TC 6646 68 MGB 74 MGB ----- Original Message ----- [b]From:[/b] tcsyd@ix.netcom.com [b]To:[/b] mg-tabc@yahoogroups.com ; stolzy40@peoplepc.com [b]Sent:[/b] Monday, June 04, 2001 8:00 PM [b]Subject:[/b] Re: [mg-tabc] Engine Won't Idle You might do well to suspect air leakage at the spindles or intake maifold joints. The symptoms you describe sound like the choke is "balancing" the amount of air getting in, but when you take off the choke the air leaking in is greater than the fuel part of the mixture can balance out. TC Syd ----- Original Message ----- [b]From:[/b] stolzy40@peoplepc.com [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, June 04, 2001 6:09 AM [b]Subject:[/b] [mg-tabc] Engine Won't Idle On Saturday a friend (who owns two TC's) came over to set up the engine - especially the SU carbs. I have started the engine prior but have never run it for a long period of time until Saturday. The engine started right up with no problems using the choke. After bringing the engine to operating temperature and releasing the choke, the engine will not continue to run, at least not for very long. It starts dying and sputters through the carbs. If the choke is pulled the engine will continue to run obviously at a very rich mixture. If you let go of the choke the engine will sputter. Using the choke the engine will start right up. Even setting the jets at 9-10 flats did not seem to help. The carbs where rebuilt according the Carburetor Tuning article by Chip Old in "The T-Type Restoration Handbook". The engine timing was set by the static method. Things that were checked include: The fuel pump is pumping plenty of fuel indicating no clogged fuel lines, Carb flanges milled to insure a flat mating surface, Intake Manifold surface also checked, Jets re-centered, Float levels re-checked for 7/16" clearance. Any suggestion from the list member? Thanks, Mark Stolzenburg Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.