| 4k Onan Pentronics Upgrade [message #116205] |
Wed, 23 February 2011 09:36  |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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Last summer I upgraded my 4k Onan with a Pentronics module. I "found" my camera and pictures and finally posted the pictures. I was guided by the postings of others but a 4k is smaller so to positioning ended up a bit different.
It makes the Onan run MUCH better and gets those poorly designed points out of the circuit.
TWO NOTES:
SAFETY: It doesn't take much for the Pentronics module to fire the plugs. If there is any fuel vapor near the spark plugs it can fire unexpectantly. If in the cylinder, the generator may fire with 'bad' results.
--- I had a backfire, but it could have started from turning the flywheel by hand. ---
Caution: After getting the first module in and during the wrap-up of the install, I killed the module by shorting the wires to the hot terminal on the starter. $63 mistake. I had to wait for another module in the mail. 
<http://www.gmcmhphotos.com/photos/showphoto.php?photo=37858>
While any 12volt negitive ground module (see below) should work, I used the lowest priced module that had the mounting bracket (rivets) on the side away from the "hot" side of the sensor. It is the "1181" listed for use in most GM products 50's to 80's.
The cheap module I used doesn't have built in burn out protection that is built into the slightly more expensive Petrionics II (red) module. While the Onan control board SHOULD provide keep this from being a problem... it is 60's tech. Next time I MIGHT spring for the few dollars more to get this added protection.
I suspect that even a magnet-less "lobe sensor" (LS) module would work if you used a small chunk of steel in place of a magnet. But I haven't tried it... it cost more than to other two types.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] 4k Onan Pentronics Upgrade [message #116213 is a reply to message #116205] |
Wed, 23 February 2011 10:19  |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Mike,
Thanks for the photos and description. I plan to do the Pertronix on my 4kw Onan as well -- and it will be easier with your tutorial.
Did you change the timing advance from what is recommended?
Dennis
Dennis Sexton
73 GMC 230 Painted Desert
Germantown, TN
USA
-----Original Message-----
From: Mike Miller <m000035@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Wed, Feb 23, 2011 9:36 am
Subject: [GMCnet] 4k Onan Pentronics Upgrade
Last summer I upgraded my 4k Onan with a Pentronics module. I "found" my camera
nd pictures and finally posted the pictures. I was guided by the postings of
thers but a 4k is smaller so to positioning ended up a bit different.
It makes the Onan run MUCH better and gets those poorly designed points out of
he circuit.
TWO NOTES:
SAFETY: It doesn't take much for the Pentronics module to fire the plugs. If
here is any fuel vapor near the spark plugs it can fire unexpectantly. If in
he cylinder, the generator may fire with 'bad' results.
--- I had a backfire, but it could have started from turning the flywheel by
and. ---
Caution: After getting the first module in and during the wrap-up of the
nstall, I killed the module by shorting the wires to the hot terminal on the
tarter. $63 mistake. I had to wait for another module in the mail. :cry:
<http://www.gmcmhphotos.com/photos/showphoto.php?photo=37858>
While any 12volt negitive ground module (see below) should work, I used the
owest priced module that had the mounting bracket (rivets) on the side away
rom the "hot" side of the sensor. It is the "1181" listed for use in most GM
roducts 50's to 80's.
The cheap module I used doesn't have built in burn out protection that is built
nto the slightly more expensive Petrionics II (red) module. While the Onan
ontrol board SHOULD provide keep this from being a problem... it is 60's tech.
ext time I MIGHT spring for the few dollars more to get this added protection.
I suspect that even a magnet-less "lobe sensor" (LS) module would work if you
sed a small chunk of steel in place of a magnet. But I haven't tried it... it
ost more than to other two types.
-
ike Miller -- Hillsboro, OR -- on the Black list
73 26' exPainted D. -- `78 23' Birchaven Rear Bath -- `77 23' Birchaven Side
ath
ttp://m000035.blogspot.com
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] 4k Onan Pentronics Upgrade [message #116215 is a reply to message #116213] |
Wed, 23 February 2011 11:09 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| Dennis S wrote on Wed, 23 February 2011 08:19 |
... Did you change the timing advance from what is recommended?
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Dennis,
Yes I did... (I remember that much) ...but I do not remember how much I advanced it. One of the pictures shows a mark that was where I expected it to be and how far I moved it when it was running. (I think I retarded it a bit from where I thought it would be from my static tests.)
<http://www.gmcmhphotos.com/photos/showphoto.php?photo=37852>
I understand than Onan retarded the spec from optimum due to inconsistent timing from the stock points. The Pentronics is very stable.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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