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Idle problem IE wont

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Stewart

Stewart

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I've got a rather annoying problem once the B has been driven at freeway speeds or high rpm through the gears the idle becomes erratic and will die if the gas is not goosed once or twice when coming to a stop particularly a hard stop. If I push in the clutch and hold if for a few seconds she will also die. Stop and go traffic is getting very hard to drive in.

Symptoms

Stalls while stopping clutch out car in neutral. If it does not stall idle will drop to 500 or so and then recover.

Stalls when clutch is engaged. Crankshaft does not appear to be moving with the application of the clutch. Previously would drop 200 rpm with the clutch engaged. Did the pre rebuild and post rebuild.

RPM via the Tach will read 12 to 1300 when idle is set to 900 via timing light. Also the tach is rather erratic bouncing 1 to 200 rpm.

Occasional pop through the carb. Generally will kill the engine when it happens.

Stumbles when trying to keep the engine alive.

Settings
Idle at 850 to 900
Timing 15deg at 800
Weber 38 outlaw low end needles a hair under 1 turn out.
New 45d4 euro spec with new Lucas sport coil and wires.
Idle mixture seems to be good. Car transitions clean from a normal idle. Gunson was reading 3.8 at idle
Plugs look great
Runs fantastic otherwise.
Runs cold but I am about to change to a 180 degree t-stat when the car cools off.
Getting ready to readjust the valves

Any ideas on an attack plan?
 
some thoughts......

1) carb float sticking, or sticky needle/seat
2) sticky distributor advance mechanisms
3) choke flap getting pulled shut at idle
4) vacuum leaks
5) decel diaphram / circuit in the carb

hope there's one or two things in there that helps. Sounds to me like the key is that it recovers if it doesn't die - like something is sticky, instead of plugged or broken.

keep us posted!
 
Re: some thoughts......

I had a similar problem on my B (hopefully it's cured now), which has the Weber 32/36 on it. I replaced/refreshed all the components of the ignition system, but what really seemed to help was carefully adjusting the valves. The problem I had wasn't as severe as the one you're describing, however.
 
Re: some thoughts......

/ubbthreads/images/graemlins/iagree.gif You're already adjusting the valves, so that's good. I agree with Eric's assessment on the carb also.

One other thing: You said the EuroSpec dizzy is new. How new is it? Could there be any correlation between its installation and this problem? I've seen mixed reviews on those, some really good and some... well... not.

If you just plain run out of stuff to check, drop the old distributor back in for a test. I suggest this out of experience. I had a similar problem and other than setting the idle ridiculously high (1100 rpm) I couldn't get it to behave. I dropped in a new dizzy and instantly things were back to normal. This was after putting new points, condensor, wires, cap and rotor on the old one - which didn't help.

However - and this is where Eric's suggestions come into play - I was (still am, actually) running too lean. This had to have an impact and I've only partially fixed the problem in my car.

Could be worth a try if all else fails.

R.
 
Re: some thoughts......

This is gonna sound a bit silly but... remove and disassemble the Weber, clean and set it. Rationale: You'll spend as much or more time chasing the problem. Added benefit is; you'll know what it is NOT after that. That carb is simple enough to detach and go thru, likely an hour or two.
A "One beer job." /ubbthreads/images/graemlins/devilgrin.gif

The "pop" would suggest a lean condition.

If that hasn't cured it the dizzy is next. You're running an electronic iggy setup, IIRC?
 
Re: some thoughts......

Cleaned the carb up and didn't see anything so I moved to the dizzy and found the point gap to be non existent. Cleaned up the point and reset the gap to .016 and she's running great again. The tach has also become steady once again and is matching the timing light. Still not sure how it was running in the first place though as I could not get the smallest feeler between the points.
 
Re: some thoughts......

wow... that's god to know stuff... I'm amazed it was running with effectively no gap too! /ubbthreads/images/graemlins/eek.gif
 
Re: some thoughts......

Finaly got everything sorted out. The point gap was most of it and after reseting the valves everything is running fantastic. Pressing the clutch no longer effects rpm and traffic jams are a breeze so to speak.
 
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