New thread...EST/ESC and knock sensor questions...

[Jon Pickens]

Ok...I think I've identified the burned up pigtail coming off the back
of my HEI.

Again, this is an '86 K5 Blazer, with the weird-ass 5-pin ignition
module. On the back of the HEI enters a small pigtail/wiring harness.
It plugs into 3 of the pins on the ignition module.

Does this go back to the Electronic Spark Timing / Control? I know it
shouldn't have a real "ECM" because it was carbureted, but I believe it
does have the EST. I don't know to what degree electronics played a
part in the original Quadrajet. That carb is off the truck and it's
running an Edelbrock Performer 600cfm. There ARE a couple of unused
wires/connectors that end up in the vicinity of the carb that I assume
would've been attached at some point.

If the harness I'm referring to does indeed go to an EST unit, is it
necessary to get the truck to run? Can it be bypassed in any way?

The pickup wires connect in between this connector and the actual
ignition module. A picture of all the parts can be seen here...
http://www.absolutepickens.com/K5/Damage/Distrib_guts.jpg

Thanks,
~jp

[Charles Bendig]

Yes it is the ESC pigtail. Yes your truck does have a ECM. You can
convert to the older NON-ESC module and pig tail by using a NON-ESC
magnetic pick-up. With out the CCC, ESC isn't doing you one bit of good
(not that it ever did with a vaccume advance distributor)
Charles

[Jon Pickens]

Just sent you an email to your Yahoo account...

~jp

[Shades at dot]

If you want to simplify things, scrap the ESC distributor! Get a regular
HEI and drop it in. Less to go wrong.

"Jon Pickens" <jonr...@yahoo.com> wrote in message
news:1138232350.7...@g44g2000cwa.googlegroups.com...

[Jon Pickens]

Well, simple is always better...but a replacement pigtail is on the
way. I did manage to piece one together using a replacement connector
and new pins with the other original (unmelted) connector. I don't
feel good about using it though. I know the actual electrical
connections will be fine, but it's designed to fill the square hole in
the back of the HEI and I'd have to figure out a way to duplicate that
part first.

Charles found the pigtail in his stash. I may try mine just to verify
connectivity and all but, again, I'd feel better about using a factory
part.

It's 9:30am now, and I'm just making the first cup of coffee.
Hopefully I'll get a good deal done today. Sucks though, cause I have
to walk to a parts store if I need anything...

~jp

[Charles Bendig]

Jon Pickens wrote:
> Just sent you an email to your Yahoo account...
>
> ~jp
>

Got it. Ill send it out tomorrow (since I have to ship stuff then anywho).
Charles

[Jon Pickens]

Thanks again...

~jp

[Jon Pickens]

Ok, I've been screwing with the truck, trying my damndest to get the
heater / a/c harness out from the dash. I've damn near disassembled
the whole dash. Not fun, considering I'm sick.

Anyhow, was doing some thinking on the ignition module situation. It's
the 5-pin module made to connect to the ESC to detect spark knock and
then retard timing as needed. The 3-pin side connects to the pickup
coil via a pass-thru connector (which only uses 2 of the 3 pins). The
3 pins "pass through" this connector, which allows the ESC harness to
be connected.

I have a new 4-pin module already. Would using the 4 pin module and
just not connecting the ESC allow the truck to run until I get the new
5-pin module and harness?

~jp

[Shades at dot]

Never used an ECS HEI. Any vehicle I ever had that had one, I installed a
standard HEI. so I'm not 100 sure if not having every wire hooked up would
be fine or not. Sorry.

"Jon Pickens" <jonr...@yahoo.com> wrote in message

news:1138480548.3...@f14g2000cwb.googlegroups.com...

[Jon Pickens]

Well I found bypass instructions for the ESC.

Apparently the ESC was such a POS that Chevy released a service
bulletin on doing that exact thing. But that procedure still involved
the 5-pin module.

I'm suggesting switching to the 4-pin module.

However as likely as it is, there's no way of knowing if my module is
toast till I try to start it. I have my home-made ESC harness until
the replacement from Charles arrives. It's not perfect, but it would
let the truck run at least. So we'll see.

~jp

[Charles Bendig]

If you use a 4-pin moudle's matching magnetic pick-up.
Differance between ESC and NON-ESC HEI one wireing stub harness, one
magnetic pick up and one module.
Charles

[Jon R. Pickens]

What's different about the pickup besides the fact that there's a
different connector?

~jp

[Shades at dot]

A standard HEI is completely self contained. The only hookup needed is a 12V
power source and a timed vacuum source. The ESC HEI has a computer
controlled timing retard that I have never heard good things about.

"Jon R. Pickens" <jonr...@yahoo.com> wrote in message
news:1138625212.3...@z14g2000cwz.googlegroups.com...

[Jon R. Pickens]

Well that's exactly my point... eliminate the rear harness altogether.
That's what goes to the ESC. There's also a special connector on the
12V Pink wire that runs to the cap that you're refering to, that splits
the pink wire off to ALSO go to the ESC.

So...how about removing that 12V feed to the ESC, and disconnecting the
harness to the HEI.

At that point you'd still have a 5-pin module, and it probably wouldn't
run. HOWEVER, replace the 5-pin module with the 4-pin. As I stated
earlier, the pickup coil connects BETWEEN the module and the ESC. It
uses a 3-pin connector, but only 2 of the wires go to the pick up. The
3rd is straight from the ESC to the module.

Again, regarding the pickup coil ONLY, what is the difference besides
the connector that goes to the module. It's a coil of wire with 2
leads coming off it.

I think converting it to a 4-pin module is easier than we think. I did
a little Googling, and found many performance kits that do this very
thing. Many say specifically that "the knock sensor is not retained",
thus eliminating the ESC from the picture.

To summarize...from what I can tell, the difference between an ESC HEI
and standard HEI is the addition of the ESC and an extra pin on the
module. Remove the ESC altogether, replace the module with a 4-pin
model, and it should work fine....

....In theory....

~jp

[Shades at dot]

Not having the dist in front of me, I cant give accurate advise. Trying
something new is always exciting. If it looks like it would work, go for it.
What's the worst that could happen? It wont run...wait, its not running now,
so, nothing to lose!

"Jon R. Pickens" <jonr...@yahoo.com> wrote in message

news:1138631045.5...@z14g2000cwz.googlegroups.com...

[Jon R. Pickens]

Well I made a replacement harness to go back to the ESC from the
remnants of the old one and a new connector. It should work fine, but
I don't like the fact that it doesn't seal between the distributor base
and cap.

I've been Googling the newsgroups all this morning, and from what I can
tell, replacing the ESC HEI setup for a non-ESC setup will require the
timing to be pulled back (retarded) some. Some folks are even talking
about setting timing with the ESC harness disconnected, as if it'll
still run without it.

This is all just making me ponder even more. And everybody seems to
find a way around the ESC. Apparently it's a real performance killer,
and has no emissions value to it.

I'll post the results whichever way I decide to go. I had a relapse
with my cold, and may reluctantly go to see the Doc today...Ugh... I
hate being sick when I could be wrenching.

~jp

[Shades at dot]

Well good luck with it and I pray you get better soon!

"Jon R. Pickens" <jonr...@yahoo.com> wrote in message

news:1138634924.5...@o13g2000cwo.googlegroups.com...