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69 caddy LPG conversion

Started by 1969cadillac, August 28, 2013, 07:23:04 AM

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1969cadillac

hello !

I own a 69 cad deville 472 motor and am thinkin of putting it on liquid petroleum gas

my question is :

are these engines suitable for this fuel ??

and are there any pitfalls? anything to watch out for ??

do I really need hardened valve seats ???

Murray Mules

TJ Hopland

Are you in the USA? 
What is your primary goal or reason for wanting to do this?

There is really nothing unique about this engine.   Any kit designed for a large displacement 'old school' engine and a spread bore intake should work.    Also note that a 69 472 would be high compression so there may be different options that need to be selected when setting up the system compared to if it was a 71+ motor at 8.5:1 compression. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

The Tassie Devil(le)

Murray is in Australia.

The good thing in favour for the conversion is the relatively high compression of the 472.

Personally, I would be going for something like 12.5 to 1 for straight LPG.   And replacing the valves with larger ones, and hardened seats.   LPG has no "softness" in it to protect the seats.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Jim Stamper


     Back in the 50s my grandfather ran a propane business in Michigan. All of the delivery trucks ran on propane. When grandpa bought a new 56 Dodge car he immediately had it converted to propane.  I don't recall any problems and the engines are always quite spotless inside, propane burns very cleanly.

                                                           CLC# 13470

SixDucks

Hello all,
I would highly recommend the use of stainless steel valves, hardened seats,and replacement guides. This is due to LPG  being a dry fuel. Liquid propane isn't a liquid at all by the time it enters the runners in the cylinder head. You may be able to find a system that allows the introduction of a top lubricant to help with valve, piston, and ring wear. If you do eventually do a conversion I would also recommend adding larger valves and the appropriate bowl work to enhance the performance of your 472. 
On a side note propane has a very high octane rating that will require tuning.  It should be noted that the higher the octane rating, the more resistant to igniting and to over octane an engine may hinder peak performance.
Hope this helps.
- Terry
Current:
1941 coupe
1962 Fleetwood
1988 Brougham
Previous:
1956 Series 62 Sedan
1963 Fleetwood
1975 Fleetwood Brougham D'Elegance
1989 Brougham