HEI Conversion

[patrick flowers]

>
> I've done several HEI conversions. The nice thing about HEI is
> that there's only one wire to run.
>
> First get a roll of red #10 AWG wire. The HEI draws quite a bit
> of current. With any smaller wire, you will get too much IR voltage
> drop.

Wouldn't 10AWG wire be overkill for this, as it would be good for some
30a. I imagine 14AWG would be more than adequate(10a). There should be
insignificant voltage loss if the wire is sized properly and connections
well made. The sheer weight of 10AWG wire would put a lot of strain on
the connections if not properly supported.

> Pirate an HEI "batt" terminal pigtail from a late model GM car.
> That's the one that plugs into the distributor cap and has a clip on
> it so it cannot come off. I just get them from the junk yard. Cut
> off enough wire to splice to your #10 wire.
>
> Run the #10 wire inside your coach and over to your fuse box.
> Splice a 1/4 inch spade terminal onto the other end and plug it
> into the "ign" terminal in the center of your fuse box. That's all
> there is to the hook up. Don't worry about putting a fuse in
> the circuit. It doesn't need one. The module is "self fusing".

A fuse is not only to protect the device, but also to protect the
wiring. Every circuit except the primary cables connected to the
battery should be fused. Running a 10AWG wire through the firewall
without fusing could result in a fire should the wire short out
anywhere along its length. I would definitely use a fuse sized to match
the wire gauge(10a in the case of 14AWG).

Otherwise, I agree with Scott's outline of the procedure.
Patrick
- --
Patrick Flowers
Mailtoatri63

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[scott woodworth]

Patrick,

I don't want anyone to think that I don't know what I'm talking
about. I've performed half a dozen HEI conversions in the last 20
years. I do things the right way and always use factory type parts
wherever possible. One of my specialties was Olds diesel to gas
conversions. When I get finished, you can't even tell the car ever had
a diesel engine in it. I would scour the junkyards for the correct
factory parts to perform the conversion. I would unwrap the wiring
harness and remove all the diesel wiring, putting new terminals in those
44 way firewall connectors as necessary. Afterwards, I would re-wrap
the harness and put on new protective sheathing.

If #10 gauge wire and no fuse in the circuit is good enough for GM,
then it's good enough for me. Just to be sure, I went out and looked at
both my Cadillacs. They both use #10 gauge wire for that circuit.
Looking at the schematic in the Cadillac shop manual shows the +12V
coming directly off the IGN1 terminal on the ignition switch. There is
no fuse in the circuit. I looked at several other GM shop manuals.
Same circuit.



Before I reply to anyone's technical question on this group, I refer
to a source of information such as a factory shop manual, electronics
reference book or back issues of the GMC Motorhome News. I spent the
money and bought the GMC Motorhome shop manual set and the factory parts
book from Cinnabar so I could read up on the subject and make
intelligent posts. I know what it takes to build an Olds 403 and 455
having built them. I have the hands on practical experience with the GM
FWD powertrain from overhauling my Cadillac Seville engine, transaxle
and chassis which has exactly the same equipment as the GMC Motorhome.

We each have something to contribute to this group. I'll be the
first to admit that I don't know one wit about ceiling coverings or
awnings, but ask me a question pertaining to electrical systems, chassis
or powertrain and there's an excellent chance I've done it and/or have
the book on it.



Thank you, drive through!

- -Scott Woodworth

 

[thomas g. warner]

Anyone know where to get good new or remanufactured 455 engines for the GMC?
How about price?

>>
>> I've done several HEI conversions. The nice thing about HEI is
>> that there's only one wire to run.
>>
>> First get a roll of red #10 AWG wire. The HEI draws quite a bit
>> of current. With any smaller wire, you will get too much IR voltage
>> drop.
>
>Wouldn't 10AWG wire be overkill for this, as it would be good for some
>30a. I imagine 14AWG would be more than adequate(10a). There should be
>insignificant voltage loss if the wire is sized properly and connections
>well made. The sheer weight of 10AWG wire would put a lot of strain on
>the connections if not properly supported.
>
>> Pirate an HEI "batt" terminal pigtail from a late model GM car.
>> That's the one that plugs into the distributor cap and has a clip on
>> it so it cannot come off. I just get them from the junk yard. Cut
>> off enough wire to splice to your #10 wire.
>>
>> Run the #10 wire inside your coach and over to your fuse box.
>> Splice a 1/4 inch spade terminal onto the other end and plug it
>> into the "ign" terminal in the center of your fuse box. That's all
>> there is to the hook up. Don't worry about putting a fuse in
>> the circuit. It doesn't need one. The module is "self fusing".
>
>A fuse is not only to protect the device, but also to protect the
>wiring. Every circuit except the primary cables connected to the
>battery should be fused. Running a 10AWG wire through the firewall
>without fusing could result in a fire should the wire short out
>anywhere along its length. I would definitely use a fuse sized to match
>the wire gauge(10a in the case of 14AWG).
>
>Otherwise, I agree with Scott's outline of the procedure.
>Patrick
>--
>Patrick Flowers
>Mailtoatri63
>
>The GMC Motorhome Page
>http://www.gmcmotorhome.com
>
>
>
>
>

 

[scott woodworth]

Thomas,

You can never go wrong by going directly to the source. Joe
Mondello that is. He's very familar with the power requirements of the
GMC motorhome. He's built quite a few over the years.

MONDELLO PERFORMANCE PRODUCTS, INC.
1103 Paso Robles Street,
Paso Robles, California 93446
(805) 237-8808 - Fax (805) 237-8814
http://www.tcsn.net/mondello/

- -Scott Woodworth