Home » Public Forums » GMCnet » 1973 Cadillac Eldorado w/500 ci Motor
| 1973 Cadillac Eldorado w/500 ci Motor [message #102949] |
Thu, 14 October 2010 09:55  |
Firefly
Messages: 98
Registered: May 2008
Location: Augusta, Maine
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A close friend told me that he owns a 1973 Eldorado with the 500 ci motor - a true "field car," and it got me wondering whether this would be a good model for conversion to the GMC coach, or if there was an alternative, preferred year for this? I can't afford that kind of project yet, and I still have my heart set of an 8.1L motor conversion, but you cannot ignore the potential if it is there.
I have downloaded a lot of material on the C500 swaps, but can't recall the best model years to consider the "big picture" of adaptability, performance constraints, etc.
Thanks!!
PS: I DID look for anything regarding Caddy 500 on this forum, but there are lots of opinions on the subject and 1971-1976 was as close as I could get!
My stretch is also a 1973, so it might have some significance to adaptability. I just wish I had known about the Wallace Bearing and 1-Ton Truck Hub Conversions before I had JB rebuild my stock front end - would have been nice to upgrade everything at once. Maybe even cheaper.
Mark Scoble, Lunenburg, MA - 1973 23' Palm Beach Stretched to 32' and in residence at the GMC Co-Op in Orlando, FL
[Updated on: Thu, 14 October 2010 10:03] Report message to a moderator |
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #102956 is a reply to message #102949] |
Thu, 14 October 2010 12:17  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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Mark,
The main difference in the Caddy 500 is in the compression ratios. This was
controlled by the heads and pistons. Some heads were 96cc others were 120cc.
Some pistons were dished some were flat top. I do know that you don't want
to use flat top pistons in an engine with 96cc heads as the compression
ratio will be through the roof!
The engine that I've got here in Humble which will be shipped to Sydney
shortly that is setup to run on AutoGas is a 1972 that has 96cc heads. I
don't know what the 1973 has.
There are probably some differences in the cam too, however, if you go with
a Caddy 500 you'll select an after market cam for an RV.
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mark Scoble
Sent: Thursday, October 14, 2010 9:55 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor
A close friend told me that he owns a 1973 Eldorado with the 500 ci motor -
a true "field car," and it got me wondering whether this would be a good
model for conversion to the GMC coach, or if there was an alternative,
preferred year for this? I can't afford that kind of project yet, and I
still have my heart set of an 8.1L motor conversion, but you cannot ignore
the potential if it is there.
I have downloaded a lot of material on the C500 swaps, but can't recall the
best model years to consider the "big picture" of adaptability, performance
constraints, etc.
Thanks!!
--
Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and
undergoing complete renovation at the GMC Co-Op
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: 1973 Cadillac Eldorado w/500 ci Motor [message #102961 is a reply to message #102949] |
Thu, 14 October 2010 13:10 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
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The 73 would be a good choice. Look at larry W. tech article on the Western States web site. You want to grab,,,engine, trans, all 4 control arms, right side bearing bracket, diff AND brackets between diff and engine, front motor mount, rear mounts, drive shafts as spares(not long enough of course), shoot, just get the whole car and sell the extra!!! Rob,,,500,s came with 76cc and 120cc heads and I think the last 76,s were 73. The mid size 90+ are of 425 later engines. (pretty sure0 The cadillac book by Doc Frommer is a big help.,,, If you don't want it I'm looking for another one,,,,PL
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #102962 is a reply to message #102949] |
Thu, 14 October 2010 13:13 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Mark,
It doesn't make any difference which year Cad 500 you use if you are going
to rebuild it before installing it. You select the pistons that give you
the compression ratio you want. Most go with 8.5:1 which is great for the
crap gas we have available to us nowadays.
On Thu, Oct 14, 2010 at 7:55 AM, Mark Scoble <worldnet@aol.com> wrote:
>
>
> A close friend told me that he owns a 1973 Eldorado with the 500 ci motor
> - a true "field car," and it got me wondering whether this would be a good
> model for conversion to the GMC coach, or if there was an alternative,
> preferred year for this? I can't afford that kind of project yet, and I
> still have my heart set of an 8.1L motor conversion, but you cannot ignore
> the potential if it is there.
>
> I have downloaded a lot of material on the C500 swaps, but can't recall the
> best model years to consider the "big picture" of adaptability, performance
> constraints, etc.
>
> Thanks!!
> --
> Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and
> undergoing complete renovation at the GMC Co-Op
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #102963 is a reply to message #102962] |
Thu, 14 October 2010 13:35 |
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If you tune it well you could probably go as high as 9:1 and still use 87. IIRC flat top pistons and 120 CC heads will get you like 8.8-9:1CR I know probe industries makes replacement caddy pistons, I would also go with forged for extra strength, also if you decide to boost it, forged rods and pistons are a must, but generally a good idea for any heavy duty motor, Forced induction or Natrually Asperated. I have 2 compleate Caddy 500 engines, with around 100k on the blocks, I will eventually part with one and build the other...
| Steven Ferguson wrote on Thu, 14 October 2010 13:13 |
Mark,
It doesn't make any difference which year Cad 500 you use if you are going
to rebuild it before installing it. You select the pistons that give you
the compression ratio you want. Most go with 8.5:1 which is great for the
crap gas we have available to us nowadays.
On Thu, Oct 14, 2010 at 7:55 AM, Mark Scoble <worldnet@aol.com> wrote:
>
>
> A close friend told me that he owns a 1973 Eldorado with the 500 ci motor
> - a true "field car," and it got me wondering whether this would be a good
> model for conversion to the GMC coach, or if there was an alternative,
> preferred year for this? I can't afford that kind of project yet, and I
> still have my heart set of an 8.1L motor conversion, but you cannot ignore
> the potential if it is there.
>
> I have downloaded a lot of material on the C500 swaps, but can't recall the
> best model years to consider the "big picture" of adaptability, performance
> constraints, etc.
>
> Thanks!!
> --
> Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and
> undergoing complete renovation at the GMC Co-Op
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #102970 is a reply to message #102961] |
Thu, 14 October 2010 14:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Paul,
OOPS - You're correct it is 76cc NOT 96cc! Bloody CRS! I knew I should have
checked Doc's book!
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Paul Leavitt
Sent: Thursday, October 14, 2010 1:11 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor
The 73 would be a good choice. Look at larry W. tech article on the Western
States web site. You want to grab,,,engine, trans, all 4 control arms, right
side bearing bracket, diff AND brackets between diff and engine, front motor
mount, rear mounts, drive shafts as spares(not long enough of course),
shoot, just get the whole car and sell the extra!!! Rob,,,500,s came with
76cc and 120cc heads and I think the last 76,s were 73. The mid size 90+ are
of 425 later engines. (pretty sure0 The cadillac book by Doc Frommer is a
big help.,,, If you don't want it I'm looking for another one,,,,PL
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GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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GMCnet mailing list
List Information and Subscription Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #102971 is a reply to message #102963] |
Thu, 14 October 2010 14:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Shan,
Jerry Potter built a set of heads for the Caddy 500 I'm sending to Australia
they are 76cc and with the pistons and cam I bought to go with it the
dynamic compression ratio will be 10.5 to one.
I'll be running it on AutoGas which is a mix of 60% LPG and 40% Butane that
the Australian Government mandates to be the same octane rating as hi-test
petrol.
Ford Australia builds a UTE that runs only on LPG and it has a compression
ratio of 10.75 to 1.
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Shan Rose
Sent: Thursday, October 14, 2010 1:35 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor
If you tune it well you could probably go as high as 9:1 and still use 87.
IIRC flat top pistons and 120 CC heads will get you like 8.8-9:1CR I know
probe industries makes replacement caddy pistons, I would also go with
forged for extra strength, also if you decide to boost it, forged rods and
pistons are a must, but generally a good idea for any heavy duty motor,
Forced induction or Natrually Asperated. I have 2 compleate Caddy 500
engines, with around 100k on the blocks, I will eventually part with one and
build the other...
Steven Ferguson wrote on Thu, 14 October 2010 13:13
> Mark,
> It doesn't make any difference which year Cad 500 you use if you are
going
> to rebuild it before installing it. You select the pistons that give you
> the compression ratio you want. Most go with 8.5:1 which is great for the
> crap gas we have available to us nowadays.
>
> On Thu, Oct 14, 2010 at 7:55 AM, Mark Scoble <worldnet@aol.com> wrote:
>
> >
> >
> > A close friend told me that he owns a 1973 Eldorado with the 500 ci
motor
> > - a true "field car," and it got me wondering whether this would be a
good
> > model for conversion to the GMC coach, or if there was an alternative,
> > preferred year for this? I can't afford that kind of project yet, and I
> > still have my heart set of an 8.1L motor conversion, but you cannot
ignore
> > the potential if it is there.
> >
> > I have downloaded a lot of material on the C500 swaps, but can't recall
the
> > best model years to consider the "big picture" of adaptability,
performance
> > constraints, etc.
> >
> > Thanks!!
> > --
> > Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and
> > undergoing complete renovation at the GMC Co-Op
> >
> > _______________________________________________
> > GMCnet mailing list
> > List Information and Subscription Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
>
>
>
> --
> Steve Ferguson
> Sierra Vista, AZ
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: 1973 Cadillac Eldorado w/500 ci Motor [message #103005 is a reply to message #102949] |
Thu, 14 October 2010 20:33 |
Firefly
Messages: 98
Registered: May 2008
Location: Augusta, Maine
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Thanks a bunch guys! I want to run this on liquid propane, so the higher compression will be an option to get the most from it - however, as was mentioned by Larry, I found out that 1973 was probably going to be a 472 ci motor and I think the only way to boost it up past 500 is by stroking it…
I did have Larry's PDF as well a sa few others, but the latest info is usually the greatest.
I also could not find Doc Frommer references on the Googlenet … any suggestions?
Mark Scoble, Lunenburg, MA - 1973 23' Palm Beach Stretched to 32' and in residence at the GMC Co-Op in Orlando, FL
[Updated on: Thu, 14 October 2010 20:34] Report message to a moderator |
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| Re: 1973 Cadillac Eldorado w/500 ci Motor [message #103009 is a reply to message #103005] |
Thu, 14 October 2010 20:50 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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| Firefly wrote on Thu, 14 October 2010 20:33 |
I want to run this on liquid propane, so the higher compression will be an option to get the most from it - however, as was mentioned by Larry, I found out that 1973 was probably going to be a 472 ci motor and I think the only way to boost it up past 500 is by stroking it…
|
Nope, didn't say that. If the motor came from a 73 Eldo, it IS a 500, but does not have the correct Motor mount for the conversion. Maybe a 70 eldo with a 500 might be what you are looking for. A front clip would have everything you need for conversion and has a 10.5/1 CR that you are looking for to do the LP.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #103014 is a reply to message #103005] |
Thu, 14 October 2010 21:08 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Mark,
Doc Frohmader's book is called BIG INCH CADDY and can be purchased off eBay:
320581238769.
You won't find anything about running it off propane in that book, however.
Despite the fact that the Caddy valve seats were induction hardened it's a
very good idea to have satellite exhaust valve seats installed and running
the extreme duty SS valves.
Make sure you find a competent machine shop to install the seats, the guys I
picked in Houston never did it before and used the wrong seats and hit water
in one head. I scrapped the other one and wound up having Jerry Potter build
me a set of heads. Don't ask me how much they cost!
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mark Scoble
Sent: Thursday, October 14, 2010 8:34 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor
Thanks a bunch guys! I want to run this on liquid propane, so the higher
compression will be an option to get the most from it - however, as was
mentioned by one person, I found out that 1973 was probably going to be a
472 ci motor and I think the only way to boost it up past 500 is by stroking
it…
I did have Larry's PDF as well a sa few others, but the latest info is
usually the greatest.
I also could not find Doc Frommer references on the Googlenet … any
suggestions?
--
Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to 32' and
undergoing complete renovation at the GMC Co-Op
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: 1973 Cadillac Eldorado w/500 ci Motor [message #103022 is a reply to message #102949] |
Thu, 14 October 2010 21:42 |
Firefly
Messages: 98
Registered: May 2008
Location: Augusta, Maine
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Looky what I found at:
http://cad500parts.com/tech/EngineIDPages.pdf
It looks like a definitive explanation of Caddy engine ID information, with different piston styles, casting number locations and integral timing cover details.
For 1971-1973, it states If there is an "R" in the VIN it is supposed to be a 472; if "S" then a 500; described as "Early/Low Compression" (8.8:1 or 8.5:1).
Rob: I guess spelling the name as 'Frommer' was the wrong way to find the book!
I have the information I needed thanks to you all and appreciate it very much. hopefully my submittal of this reference PDF will contribute to someone else's needs in the future.
Mark Scoble, Lunenburg, MA - 1973 23' Palm Beach Stretched to 32' and in residence at the GMC Co-Op in Orlando, FL
[Updated on: Thu, 14 October 2010 21:44] Report message to a moderator |
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| Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor [message #103023 is a reply to message #103022] |
Thu, 14 October 2010 22:14 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Mark,
Don't take that chart as absolute gospel. It has a couple of
glaring errors, which they haven't bothered to correct.
For your purpose, get an Eldo motor from 70 to 76. They will all
be 500s. They're all low compression, except
for the 70 model, They are pricey, because of the compression
and no smog pump.
In my opinion, the best motor to get is the 76 model. Usually,
no smog pump, correct pulleys, HEI ignition and
the motor mounts are no problem. I've got 6 or 8 out in the
shop. You should rebuild it anyway and that's the
time to change pistons to get the compression you want. Parts
are readily available and will not be too expensive.
Gary Kosier
77EII & 77PB
Newark, Ohio
Original Message -----
From: "Mark Scoble" <worldnet@aol.com>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, October 14, 2010 10:42 PM
Subject: Re: [GMCnet] 1973 Cadillac Eldorado w/500 ci Motor
>
>
> Looky what I found! (attached PDF from
> http://cad500parts.com/tech/EngineIDPages.pdf)
>
> It looks like a definitive explanation of Caddy engine ID
> information, with different piston styles, casting number
> locations and integral timing cover details.
>
> For 1971-1973, it states If there is an "R" in the VIN it is
> supposed to be a 472; if "S" then a 500; described as
> "Early/Low Compression" (8.8:1 or 8.5:1).
>
> Rob: I guess spelling the name as 'Frommer' was the wrong way
> to find the book!
>
> I have the information I needed thanks to you all and
> appreciate it very much. hopefully my submittal of this
> reference PDF will contribute to someone else's needs in the
> future.
> --
> Mark Scoble, Augusta, Maine - 1973 23' Palm Beach Stretched to
> 32' and undergoing complete renovation at the GMC Co-Op
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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List Information and Subscription Options:
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