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Rough Idle and Sputtering

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H

healeygal

Jedi Warrior
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Hello all,

Just to follow up from a couple weeks ago, thanks to everyones helpful suggestions and info, the distributor wire problem got solved, and the car starts up fine now, so on to the next problem:

For about the last year, during those rare moments on the road between breakdowns (the car, not me), my car has been having a problem with idling smoothly when the engine gets to around 190 degrees. When the temp warms up, the car will not idle smoothly - kind of sputters along - have to keep hitting the gas to keep it going (very ungraceful and uncool when taking off from a stop light). Also, after turning the engine off and the temp rises to about 190, when the engine is re-started, have to keep gunning the accelerator to get it going, but once it's been on the road and the temp comes down, starts running fine again.

Is this a carburetor adjustment problem, or could it have something to do with the gas formulation, or an attack of the Healey gremlins, or what??

Sharon
 
Hi Sharon I think you have an adjustment problem with the carbs you might try richening them up just a small bit at a time to see if that helps the problem. It this exaggerates the problem it may take a bit of leaning out. Let us know how it goes.---Fwiw--Keoke
 
Hi Keoke,
Uh oh - I've adjusted the idle in the past, but not the mixture. There's a section in the service manual titled Tuning Twin Carburetors - is that the mixture adjustment? Sorry I missed the Ventura meet - coulda had somebody take a look at it there!

Sharon
 
I should like to add somthing here which I am sure has nothing to do with your problem but it should catch the eye of owners who are thinking about it. On advice from a very experienced car (60yrs!) he suggested I lighened the oil in my '63 BJ7's carb. dashpots from the Manual recommended engine oil. I put in transmission fluid: remarkable improvement both in acceleration and shut off.He had heard of brake fluid being used for racing.
 
I should like to add somthing here which I am sure has nothing to do with your problem but it should catch the eye of owners who are thinking about it. On advice from a very experienced car machanic (60yrs!) he suggested I lightened the oil in my '63 BJ7's carb. dashpots from the Manual recommended engine oil. I put in transmission fluid: remarkable improvement both in acceleration and shut off.He had heard of brake fluid being used for racing.
 
I had a similar problem after re-installing and tuning the carbs this Spring. The idle just wouldn't settle down consistently at different temperatures. That is until after I re-installed the "Choke Return Springs".

There's no mention of them in the work shop manual, that I could find, and they're not shown in Moss, but they made a world of difference at stoplights!
 
Sharon -

In my experience this type of problem indicates that the throttle bushes in your carbs are worn and when the car gets hot the throttle bodies expand faster than the brass throttle pin, and opens up an air leak gap, causing the mixture to lean out ... causing the idle to drop.

If you have a BJ8, the fix is pretty easy, just get the teflon bushes the Nocks sell at British Car Specialists in Stockton, CA. If you have older carbs, you will have to have your carbs rebushed, reamed and matched to a throttle shaft. This should be done by an SU carb specialist like Joe Curto.

/bcforum/images/%%GRAEMLIN_URL%%/driving.gif
 
Yeah, Sharon. you blew it We could have had that carb problem all ironed out. Carbs and their set up was the tech session this time. Yes the factory manual defines the mixture adjustment for the carbs its not to difficult to pull off.---Keoke
 
Thanks to all for the thoughts and suggestions.
Alan and Keoke,
It's a BN1 and the carbs were totally rebuilt about 8 years ago, but maybe it's time for another go-round? In the meantime, for starters, will try adjusting the mixture. Got the service manual out, have been reading it over and over (it really is starting to make sense to me), and a friend is coming over Wednesday to give it a go.

So disappointed I missed the tech session. If you're at the Golden Cove Coffee Meet in July, Keoke, maybe you can check out our work - we should have it figured out by then!

Sharon
 
Didn't someone, a while ago, suggest a test of applying oil or grease on the outside of the shaft to see if it stopped the air leak temporarily?
 
Sharon,

Just some ideas.

Go back through all your settings

Ignition system.

- Clean and gap plugs
- Check points carefully (replace if you find a pit on one side and a bump on the other)
- Check timing (adjust if required)
- Make sure rotor, cap, wires, condenser are good
- Check for a hot coil (make sure it is connected in right polarity)
- check that your distributor does not have alot of play (have rebuilt or rebushed if really sloppy)
- make sure there is a ground wire in the distributor and the coil contact lead is not frayed
- run it in the dark and look at the plug wires for arcing

Fuel

- be sure your fuel lines do not have leaks
- check the fuel filter for clogs
- clean or replace air filter
- make sure your float bowls are not boiling (insulation from header

- adjust carbs as per service manual

Valves

- adjust backlash per manual
 
Hi Tracy,
Thanks for the check list - sounds like a fun project. Will go thru the steps before tackling the carbs & report back in a few days. One thing I do know already is distributor doesn't have a lot of play. My "chief mechanic" kept mentioning that the other day. Also, something weird - we could not get the rotor off by hand or with pliers. Didn't want to break it, so quit trying, altho' I do have three spares (two different brands).

Sharon
BN1
 
Hi Sharon get that rotor out of the dizzy there is no reason that a rotor should fit that tight unless it has been positioned incorrectly. When you get it off check the slot in the cam that positions the rotor and make sure there are no burrs on it.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif



P.S. Destructive removal: Place a rag over the dizzy with the cap removed so bits will not fall down inside. Take a pair of channel locks and crush the rotor.
 
Don't recall hearing that TH, But you can spray carb cleaner WD 40 etc on the shaft entries and see what happens to the engine speed. If they are not leaking there will be no perceptible change.--Fwiw---Keoke
 
I had a similar problem, wouldn't idle, had to keep blipping the throttle. Worse when warm. Turned out to be a partly clogged fuel filter.
 
Eight years doesn't sound like very long if you only drive your Healey like most of us, about 2K miles a year.
I always thought an "hour meter" should be fitted to restored Healey's, much like Airplane engines. In that way we would know precisly how long we've driven
 
Try this: after the car is warmed up and the choke is all the way in, open the hood and push down on the choke levers where they attach to the carbs. If they move down at all the mixture is running rich which will cause poor idle. Fix is the springs and cleaning the jet. Also make sure the cables are free.
 
The chief mechanic and assistant (me) finally went thru the checklist and the other items suggested (thanks everyone), then adjusted the mixture and idle. Afterwards on a short test drive, car behaved better. During a longer one in today's hot weather, seemed like it was on the verge of acting up, but didn't actually do it - maybe needs a little more adjusting...will get around to it later this week and report back.

Sharon
BN1
 
Hi Sharon

As I have the same troubles on my BN2 I'm wondering if you achieved to solve this problem. I already have changed the coil and all the spark plugs as well as the fuel filter. I also checked the mixture and the ignition timing seems to be ok. The carbs are well synchronized.

I also installed a heat shield between the float chamber and the exhaust - nothing has changed. Any additional comments are welcome.

Thomas
 
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