Home » Public Forums » GMCnet » LP vs. Gas
| LP vs. Gas [message #301738] |
Mon, 06 June 2016 21:33  |
jor
Messages: 43
Registered: June 2016
Location: Tucson
Karma: 0
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First Post
I'm looking at a 455 that's run only on propane. It is relatively low miles (around 70K). What problems are likely? I've heard that heads could be an issue in that 70s engines aren't likely to have hardened valve seats. I'm thinking the gas system (fuel pump, tank, lines) could also be an issue. Anyone with experience in this area? Advice? Thanks.
jor
John O'Reilly
76 Eleganza II (quad bags, disc brakes w/ reaction arm. 3.70 gears, manny trans, headers, Patterson dist.)
Tucson, AZ
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| Re: LP vs. Gas [message #301743 is a reply to message #301738] |
Mon, 06 June 2016 21:58  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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jortucson wrote on Mon, 06 June 2016 19:33First Post
I'm looking at a 455 that's run only on propane. It is relatively low miles (around 70K). What problems are likely? I've heard that heads could be an issue in that 70s engines aren't likely to have hardened valve seats. I'm thinking the gas system (fuel pump, tank, lines) could also be an issue. Anyone with experience in this area? Advice? Thanks.
jor
John, Welcome to the group from a fellow Tucsonan. I know ZERO about the effects of propane on an engine except that it should be nice and clean and carbon free.
There are several of us in the Tucson area and a small but active club (the GMC Saguaro Jetset). We would love to get to know you. Please contact me if I can be of any help. (five two 0) two 4 0- nine 8 three six.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: LP vs. Gas [message #301750 is a reply to message #301738] |
Mon, 06 June 2016 22:23 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I've run a number of Ford engines of the same era (300 c.i.d. sixes) in Onan gensets on propane and natural gas, and they ran cleaner internally and held up better than the ones run on gasoline. I don't know if there was/is any difference in the valves and seats from the over - the - road engines. Our fave Onan dealer might could ask Onan about them. We never had any problems with the valves at any rate.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] LP vs. Gas [message #301755 is a reply to message #301750] |
Mon, 06 June 2016 22:42 |
James Hupy
Messages: 6806
Registered: May 2010
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I have maintained a number of Miller welders with Onan NH engines similar
to the ones in our generators that had been converted to propane after
manufacture. They ran at top governed speed for years and I never saw any
valve or seat problems with them. Not exactly an Oldsmobile engine, I know.
As an aside, Ak Miller, a famous pikes peak racer had several race cars
powered on propane. He wrote a book on the use of it on high performance
applications. Some good info there for racers, not sure if it applies well
to GMC's in this case. What I know.
Jim Hupy
Salem, Oregon
78 GMC ROYALE 403
On Jun 6, 2016 8:24 PM, "Johnny Bridges via Gmclist" <
gmclist@list.gmcnet.org> wrote:
> I've run a number of Ford engines of the same era (300 c.i.d. sixes) in
> Onan gensets on propane and natural gas, and they ran cleaner internally and
> held up better than the ones run on gasoline. I don't know if there
> was/is any difference in the valves and seats from the over - the - road
> engines.
> Our fave Onan dealer might could ask Onan about them. We never had any
> problems with the valves at any rate.
>
> --johnny
> --
> '76 23' transmode Norris upfit, 76 26' Eleganza(?) with beaucoup mods and
> add - ons.
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
> dirty life and times" --Warren Zevon
>
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| Re: [GMCnet] LP vs. Gas [message #301773 is a reply to message #301755] |
Tue, 07 June 2016 10:24 |
jor
Messages: 43
Registered: June 2016
Location: Tucson
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Thanks to all for your replies. I'll do some research but it doesn't sound like running on LP is an issue. I'm thinking I'll just switch to gas (in the driveway) and see what happens! Carl, I'll give you a call. Great to know that there are other GMCs here in Tucson.
jor
John O'Reilly
76 Eleganza II (quad bags, disc brakes w/ reaction arm. 3.70 gears, manny trans, headers, Patterson dist.)
Tucson, AZ
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| Re: LP vs. Gas [message #301774 is a reply to message #301738] |
Tue, 07 June 2016 10:28 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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jortucson wrote on Mon, 06 June 2016 22:33First Post
I'm looking at a 455 that's run only on propane. It is relatively low miles (around 70K). What problems are likely? I've heard that heads could be an issue in that 70s engines aren't likely to have hardened valve seats. I'm thinking the gas system (fuel pump, tank, lines) could also be an issue. Anyone with experience in this area? Advice? Thanks.
jor
Joran,
I do not know about Oldsmobile specifically, but in the time period of the 455 production, most manufactures put hard inserts in the exhaust seat of engines destined for non-motorfuel service. This was still leaded fuel times and exhaust valve wear was a big issue. The industrial power version of the 455 was a very respected unit. That being the case, I would expect that the engine has at least hardened seats in not insert seats.
As to any damage that might have been caused by the LP fuel, I never ever heard of any LP fueled engine that had reliability issues related to the LP fuel. Many manufactures of parts that are not internal engine parts use LP fueled engines for the durability testing becuase the engines are then more reliable.
Matt - the Dyno land refugee - Doing Parking at GLAMARAMA
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] LP vs. Gas [message #301788 is a reply to message #301774] |
Mon, 06 June 2016 20:47 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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I had Jerry Potter (Soddy-Daisy Tennessee) build a pair of heads for the Caddy 500 I have in Australia which will be run on AutoGas.
AutoGas is 60% LPG and 40% butane and is 100 octane so I ran the compression ratio up to 10 to 1.
Jerry noted that the Caddy valve seats were either flame or induction hardened and I'll bet that's what Olds did with the 455 as
well.
He noted that the valve seats could take the higher exhaust gas temps generated by AutoGas; however, for the best longevity stellite
seats would be the way to go.
Since I'm the Pedantic Mechanic that's what was done. Also the valves used were the same as the ones used in funny cars!
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Matt Colie
Sent: Wednesday, June 08, 2016 1:28 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] LP vs. Gas
jortucson wrote on Mon, 06 June 2016 22:33
> First Post
> I'm looking at a 455 that's run only on propane. It is relatively low miles (around 70K). What problems are likely? I've heard
that heads could be
> an issue in that 70s engines aren't likely to have hardened valve seats. I'm thinking the gas system (fuel pump, tank, lines)
could also be an
> issue. Anyone with experience in this area? Advice? Thanks.
> jor
Joran,
I do not know about Oldsmobile specifically, but in the time period of the 455 production, most manufactures put hard inserts in the
exhaust seat of engines destined for non-motorfuel service. This was still leaded fuel times and exhaust valve wear was a big
issue. The industrial power version of the 455 was a very respected unit. That being the case, I would expect that the engine has
at least hardened seats in not insert seats.
As to any damage that might have been caused by the LP fuel, I never ever heard of any LP fueled engine that had reliability issues
related to the LP fuel. Many manufactures of parts that are not internal engine parts use LP fueled engines for the durability
testing becuase the engines are then more reliable.
Matt - the Dyno land refugee - Doing Parking at GLAMARAMA
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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: LP vs. Gas [message #301791 is a reply to message #301738] |
Tue, 07 June 2016 14:02 |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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You will have reduced output. There is less energy in LPG vs Gasoline. About 25% less IIRC, depending on Octane of gasoline in comparison...
You will find a much cleaner engine.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: LP vs. Gas [message #301819 is a reply to message #301738] |
Wed, 08 June 2016 06:17 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
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Are you intending to run the 455 on gasoline or continue to use propane?
Many OEM SOBs came with dual fuel options.THey worked pretty well, but there was a liability scare back in the 80s [thanks lawyers] and many dealerships [including Lazydays] removed the systems from used coaches. I have a complete system off a Holliday Rambler class A less the tank I might get around to using someday.
Never saw any engine problems with the dual fuel systems. A lot of coaches ran propane gensets that ran forever.
As far as less power from propane, it is true that it has less energy than an equivalent mass of gasoline. Your milage would decrease, but in an engine with the proper advance and air/fuel ratio, it should be about the same or even more if the comprssion ratio is increased as in the Caddy example cited as the octane value [as opposed to energy content] is higher.
AK Miller did several propane / turbo engines that ran very well. Years ago, one of my friends basicly copied his Pinto setup and took a lot of peoples money in street races.
76 Glenbrook
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| Re: LP vs. Gas [message #301820 is a reply to message #301819] |
Wed, 08 June 2016 06:39 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Hundreds of pick-ups in Texas were run on propane in my younger years. Propane was almost free, especially if you had oil or gas rig on your property.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: LP vs. Gas [message #301840 is a reply to message #301820] |
Wed, 08 June 2016 11:34 |
jor
Messages: 43
Registered: June 2016
Location: Tucson
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Quote:Are you intending to run the 455 on gasoline or continue to use propane?
Not sure. I'd probably go to gasoline once I'm confident of the tank, pump and lines. I've asked the current owner if the rig was ever run on gas. I think it's been straight propane for 25 years or so but I'll find out for sure. It hasn't seen much action; just one trip a year and monthly run for two hours each time.
Re the 80s and the propane rigs, I used to see a lot of them down in West Texas. Some pretty crazy setups, some with a loose or barely mounted propane bottle in the trunk of a car.
jor
John O'Reilly
76 Eleganza II (quad bags, disc brakes w/ reaction arm. 3.70 gears, manny trans, headers, Patterson dist.)
Tucson, AZ
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| Re: LP vs. Gas [message #301869 is a reply to message #301840] |
Wed, 08 June 2016 16:03 |
Justin Brady
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
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Out of curiosity, how much range does that coach get with the 2 propane tanks?
Seems like a real pain in the you know what to have to stop and search for a propane filling place when on the road...
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455
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