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crash741
New User

Jun 26, 2009, 2:46 AM

Post #1 of 4 (1717 views)
Engine Change Sign In

I have a 1979 Chevy pickup in which I have changed motors. The new motor came out of a 74 chevy pickup. The 79 had electronic ignition but the 74 didn't. I was wondering are there wires that have to be eliminated with the change? The 79 wiring was kind of a mess and we are trying to figure it out. Thanks


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 26, 2009, 4:23 AM

Post #2 of 4 (1713 views)
Re: Engine Change Sign In

Right - 75 started HEI ingnitions. I'd try hard to keep it as there are just four wires that link to it and damn I don't know which is which - one plain power, one for tach and sources for others have to be simple ign and perhaps from a ballast resistor but not sure enabled just while starter is cranking. Hope someone here can tell you which does which better as HEI is the better dist even though old one worked fine too - just had to fool with points now and then,

T



Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Jun 26, 2009, 8:46 AM

Post #3 of 4 (1705 views)
Re: Engine Change Sign In

crash; First, I'd recommend using the HEI distributor that came out of the original engine. As Tom said, it is by far better than the old point type. And, the vehicle is already wired for it. If you must switch distributors and use the point type: 12V with ignition on goes to the + side of the conventional coil that you'll have to buy. The distributor will have one lead in wire which connects to the - side of the coil. You can use the large red wire from the OE harness that would have plugged into the coil for the 12V source as it should be already wired correctly (hot only when key is on). If you have a tachometer, the small brown wire with the female connector that plugged into the OE distributor cap can be connected to the - side of the coil.
Loren
SW Washington


chickenhouse
Enthusiast

Jun 26, 2009, 10:44 AM

Post #4 of 4 (1699 views)
Re: Engine Change Sign In

Use the H E I system your truck is set up for by all means. Also use plugs designed for H E I. Different heat range I believe.






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