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High Idle - Electronic Ignition

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jmayled

jmayled

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I have just replaced the points on my '75 TR6 with a pertronix electronic ignition (The ignitor model) & while it cured my rough idling issues, it rasied the idle from around 1000 rpm to 1800 rpm.

This issue is constant and remains at 1800rpm whether the car is cold or warm.

I have checked the choke conenctions to make sure they are not sticking, checked for Vaccuum leaks, tried the carb cleaner trick although I'm still at a loss why this car is idling at such high rpm's.

At this poin I'm not sure what my next step would be to reduce the idle. Can I adjust the idle by rotating the distributor until the lower rpm is reached? Can this be done while the car is running?

Any help would be greatly appreciated! (Thanks again Guys!)
 
Hello Jaymled,
don't try and set idle speed with timing, you are looking at the wrong thing. Your idle speed of 1,000 was too high and 1,800 is miles off, there must be a problem with the throttle setting.
What carburettors have you?

Alec
 
J,

If you have the standard carb set up on that TR-6, there are idle set screws to lower the idle. It should be about 800 RPM with the engine warmed up.

Mark
 
I'm not familiar with the Petronix set-up as mine is Crane. But the conversion from points to electronic almost certainly changed the timing. Sounds like it's now advanced. Get the timing light out and see where you are (or buy one), then resync & adjust the carbs.
 
Thank you for the prompt feedback. I have Zenith Stromberg carbs,although in looking at them, the fast-idle screws do not come in contact with the choke cam lever when idling.
Should I simply adjust the Idling-screw to lower the RPM's?
 
Very possible the regular idle needs adjustment. If the points were getting bad, you may not have been getting the full spark, then the idle may have been turned up to compensate. Just a wild guess
 
J,
I would have to say if no changes were made to the carbs during the ign upgrade, the change in idle would be related to the Petronix . I am not familiar with the Petronix unit but I'm sure they have a tech line or some one else more experienced with this install could chime in.
When somethings wrong , my rule book always goes back to what I changed last.
 
Seems like you just need to check/adjust timing, then sync the carbs (which will also put you at the correct idle). Carb mixture shuldn't have been affected by any of this so only bears the usual watching.

If you don't want to set the timing static you can just adjust it for maximum idle, then retard for about a 100 RPM drop.
 
Thank you all for your feedback. I'll be sure to check / adjust the timing this weekend to address this issue.

On a different note, it's somewhat amusing the steps I've taken to correct a seemingly simple rough idle issue! First came the new airfilters, the new fuel filter, then synching the carbs, then adjusting the mixture, followed by gapping the plugs, then replacing the plugs, then the coil until finally I said 'Wow' it must be the points, which I replaces with an electronic ignition, until finally it boils down to the timing!

At this point I'm very hesitant to trace down the reason why the light in my glove box does not work! But then again, aren't these some of the reasons why we own LBC's!

Thanks again all.
 
So now you know - start with the basics, such as timing in this case. Guess you need to go buy a light? /ubbthreads/images/graemlins/wink.gif
 
Hello Jmaylad,
your idle was too high before you fitted the Pertronix. Certainly you need to check your timing, but using a strobe you need to get the idle down first to about 700 rpm (don't forget to disconnect the vacuum advance when checking the timing). If you have the figures to hand, check the timing at about 3,000 rpm also to verify that the mechanical advance is working correctly. I'm not sure for the spec of your engine but around 30 degrees won't be too far out.

Alec
 
Hi JMAYLED' Did you say this all started because of a rough Idle? sounds like you should have started out by looking for a vacume leak. I would check for vacume leaks anyways, even when your able to get your idle rpms down it may still be rough.
 
I would have to go with Banjo's thought on the idle being set a little high to compensate for some points that were going south. Bear in mind that even with the vacuum advance disconnected, the centrifugal advance will be affecting the timing at 1800 RPM, so you might need to get the idle speed down to 800 (or what your service manuals specify for normal idle) to check the ignition timing. I have the Pertronix in my Midget and it works great. As far as statically timing the Pertronix, there is a dot on the pickup to line up with the dot on the rotor, and when I installed it I was only off by 2 degrees when I got the timing light on. Hope this helps!
 
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