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Junkyard HEI upgrade
https://slantsix.org/forum/viewtopic.php?t=23552		 Page 1 of 1
Author:  Miser [ Sun Jun 10, 2007 1:51 pm ]
Post subject:  Junkyard HEI upgrade
if this could be done, it would be cheap. what parts would i need, off what? is there any way to tell if you have a working part before you install it?
Author:  SlantSixDan [ Sun Jun 10, 2007 2:37 pm ]
Post subject: 
Unless there's extreme, visually obvious damage to parts (burnt, melted, brutalised, etc.) you can't really tell whether the electronic modules are good or not in the wrecking yard. Here are the HEI upgrade instructions. Install a NAPA Echlin long-tip rotor # MO-3000 long-tip distributor rotor and Standard-Bluestreak CH410X cap and (if you have a '74-down head w/spark plug tubes) put in NGK ZFR5N plugs gapped to 0.045". I like to use the MSD Blaster 2 coil, but if you're shoppin' wrecking yards, maybe one of these combination module/bracket/coil assemblies would be more appropriate.
Author:  70valiant [ Sun Jun 10, 2007 5:10 pm ]
Post subject: 
When I did my HEI swap I went to the yard and grabbed the distributer from a 74 Duster and pulled the HEI module from under the cap of a firebird. I stopped on the way home and picked up an internal resistor coil. I got home drilled 2 holes in my inner fender, mounted the module, made 5 wires, swapped distributers, hooked up the wires, gapped the plugs to 45 thousandths, and went for a ride.
Author:  SlantSixDan [ Sun Jun 10, 2007 9:58 pm ]
Post subject: 
Quote:
I stopped on the way home and picked up an internal resistor coil.
H'mm. How come? HEI is meant to work without a coil resistor, internal or external.
Author:  70valiant [ Mon Jun 11, 2007 4:07 am ]
Post subject: 
When I did the conversion there was some controversy as to weather a resistor was needed or not (I did the conversion 4 years ago) so I decided to err on the side of caution. Not long after I was given a race coil that I have been using ever since.
Author:  Miser [ Tue Jun 12, 2007 8:06 pm ]
Post subject: 
i thought i'd ask this here: today, i plugged the port on my BBD for the vacuum signal to the computer, i noticed when i opened that port on the carb while idling, my rpms increased 50-200 or so. opening that port would have made the fuel mixture leaner, but when i attempt to make the mixture leaner by backing off the fuel/air adjustment screws 1/8 of a turn clockwise, it runs rougher and slower. what gives?

BTW i think i have a vacuum leak, because my truck seems to idle about 200 rpms faster when it's warm, and idles a little rough, the rough idle is worse when it's cold. my fuel/air adjustment screws are three turns out.
Author:  440_Magnum [ Wed Jun 13, 2007 12:51 pm ]
Post subject: 
Quote:
I like to use the MSD Blaster 2 coil, but if you're shoppin' wrecking yards, maybe one of these combination module/bracket/coil assemblies would be more appropriate.
That is a pretty nice heat sink, but that gets me thinking (Danger, Will Robinson!) about ignition modules and heat in general.

1) The orignal HEI went inside the distrubutor. On Chevy v8s. On top of the engine. 80s-vintage smogged-to-death Chevy engines- Freaking HOT even without electronics.

2) ANYWHERE you put it under the engine bay is going to be on the order of 200 degrees F ambient temp


That kinda leads me to conclude that the HEI itself doesn't really generate all that much heat, and is very tolerant of high temperatures so long as it can shed away what heat it does generate so it stays somewhere under the temperature of molten lead.

;-)
Author:  AnotherSix [ Wed Jun 13, 2007 1:30 pm ]
Post subject: 
From what I have seen with chevys it is heat and/or a breakdown of the secondary ignition circuit that kills HEI modules. It is not uncommon to see carbon tracks under the rotor and on the module itself. Using it on a slant should not expose it to much of either of these problems. Usually when they go bad they misfire or the engine pings after it gets hot. Checking the timing at idle will not show the problem.

Aside from the under hood temp, a normal HEI distributor is aluminum and has hot oil flowing around the bottom end. It is likely hotter inside than the ambient under hood temp. Still some reasonable heat sink will be needed.

My only concern with an HEI module for the slant (and I am switching to one) is keeping the connections protected from dirt and moisture. This should not be too difficult to deal with.
Author:  emsvitil [ Wed Jun 13, 2007 2:34 pm ]
Post subject: 
Quote:
i thought i'd ask this here: today, i plugged the port on my BBD for the vacuum signal to the computer, i noticed when i opened that port on the carb while idling, my rpms increased 50-200 or so. opening that port would have made the fuel mixture leaner, but when i attempt to make the mixture leaner by backing off the fuel/air adjustment screws 1/8 of a turn clockwise, it runs rougher and slower. what gives?
You not only made it leaner, you also added more air.

The idle mixture screw only makes it leaner.
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