swapping points for electronic ignition
Thread Starter
Advanced
Joined: Jul 2007
Posts: 66
Likes: 2
From: Covington Georgia
swapping points for electronic ignition
any hints? location of 1st cylinder is different on the points to HEI. we can get it to run, but won't idle. eliminated vacuum, carburator.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Thread Starter
Advanced
Joined: Jul 2007
Posts: 66
Likes: 2
From: Covington Georgia
it has an aftermarket cam, unknown size, Edelbrock I think 1405 carburator, timing seems to run 12 BTDC and will not idle for long, it will not run at all at 8 BTDC which is the recommended.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
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From: charlotte north carolina
i've changed two cars to hei. both times (even though i took care ) i had to move all the wires over one position. could be i just wasn't careful enough. that being said, set the distributor (with vacuum off) to 36 degrees advance at 3000 rpm and forget about idle setting. see what that does.
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Team Owner
Joined: Jan 2006
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From: Crossville TN
There is NO need to swap your plug wire positions when changing to HEI. You can do so, if you shift all of the plug wires the same direction on the cap...but there is no need to do so.
As mentioned above, all that is necessary is that the rotor contact be aligned with the cap contact which sends the signal out to the correct plug wire/plug. If your engine is rotated to be at TDC on cylinder #1, then the rotor contact had better be adjacent to the #1 contact in the distributor cap...and the wire in that location on the cap must be going to the #1 plug.
As mentioned above, all that is necessary is that the rotor contact be aligned with the cap contact which sends the signal out to the correct plug wire/plug. If your engine is rotated to be at TDC on cylinder #1, then the rotor contact had better be adjacent to the #1 contact in the distributor cap...and the wire in that location on the cap must be going to the #1 plug.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
if the number 3, 5 or 7 wire was used to trigger the timing light, the timing would be at least 45 degrees off. would the engine even start?
Last edited by jnb5101; Apr 14, 2010 at 12:08 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
The TDC mark on the damper is only for cylinder #1. Timing for the other cylinders is in various locations [at 45 degree increments] on the damper and in sequence with the ignition firing order.
Instructor
Joined: Mar 2009
Posts: 187
Likes: 1
From: WA
If you are going from 12* to 0*, then you must be set at 12 ATDC, not BTDC because revving the engine increases timing. This would easily explain why you won't idle. Otherwise, you may be off 180* on your distributor.
Tech Contributor
Joined: Aug 1999
Posts: 14,373
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From: At my Bar drinking and wrenching in Lafayette Colorado
If you eliminated the vacuum advance your idle quality is going the suffer and idle speed will be much lower.
Forget initial timing and set your total timing to 36. Then hook your vacuum advance up.
Lars
Forget initial timing and set your total timing to 36. Then hook your vacuum advance up.
Lars
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
You got the pickup wires reversed...
Swap the wires, then re-time and watch the timing mark on the damper as you raise the rpm - the timing should advance smoothly without jumping back to zero. Remember that the ignition fires when the 8 starred points of the reluctor meet those of the magnetic pickup.
Swap the wires, then re-time and watch the timing mark on the damper as you raise the rpm - the timing should advance smoothly without jumping back to zero. Remember that the ignition fires when the 8 starred points of the reluctor meet those of the magnetic pickup.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
I found my earlier explanation of why the spark can retard when the engine rpm is increased, but didn't want to retype the whole thing again...
See Post #28:
http://forums.corvetteforum.com/c3-t...-timing-2.html
Cheers!
See Post #28:
http://forums.corvetteforum.com/c3-t...-timing-2.html
Cheers!
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
larry
i follow your explaination, but what do you mean "switch the pick-up wire"? are you referring to the trigger pick-up? or internal wires on the unit? and if so, what do you switch it to?
i follow your explaination, but what do you mean "switch the pick-up wire"? are you referring to the trigger pick-up? or internal wires on the unit? and if so, what do you switch it to?
Tech Contributor
Joined: Jun 2004
Posts: 20,850
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
OP: I don't understand how it's possible to get the two wires swapped around in an HEI distributor. Is this an actual HEI, or some aftermarket setup claiming to be an HEI?