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Dual 12v / 6v 1947 Cadillac

Started by 47bigcadillac, July 30, 2008, 09:48:10 PM

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47bigcadillac

Hi everyone, just wanted to share the modifications I made to my 1947 Caddie to make it more reliable while keeping it somehow original

Since I live in a big city with lots of very slow traffic and it gets very hot in summer, the stock mechanical fan could not keep up with the airflow needed to cool the beast.
I added 3 electrical cooling fans that pull a lot more air at idle and low speed, compared to the mechanical fan.
My car has the Hydramatic, idling speed needs to be set 375 rpm to allow smooth switching to/from reverse. At 375 rpm, even a high blade mechanical fan with a good shroud will not pull a lot of air.

This is what I did:
1) removed the Mech Fan
2) added a 12v small size alternator under the fuel pump
3) added 3 electric cooling fans that pull over 3000cfm when needed, connected to a thermo switch on the engine head.
4) Installed a 6v alternator in place of the 6v generator which did not charge much at idle.
5) I have 2 Optima batteries, one 12v in the tray, and one 6v placed flat on top of it.
6) the 12 v is used for the fans and CD player only. All the rest of the circuit is stock 6v, running and starting fine, even when hot.
7) I also Advanced timing to the max, rebuilt waterpump. fuel pump, distributor and carb. Heat-insulated the rear exhaust manifold top section.

I have been using this setup for  2 years and drive the car most week-ends.
Water does not boil now, I can let the car idle in mid summer heat for hours,  radiator cap removed.

See detailed photos in : http://cadillac.gs/engine/

Rob
R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

Justin Norwood

#1
Rob,
I am VERY interested in your dual 12v/6v setup, as you described it nearly a decade ago (wow!). However, the link to the pictures no longer works. Are you able to repost the pictures? I am sitting on the edge of my seat!
Thanks
-Justin
1947 Cadillac Series 62 Sedan

47bigcadillac

#2
I drove my 47 for about 7 years with the dual setup, but 3 years ago I decided to just convert it 12 V to be able to use a large alternator for the fans, and streamline the system overall, and also get more power for starting the car & filling the carb since I only use the original mechanical fuel pump - and not needing two batteries as well...the dual setup was using a 12v yellow optima with a red 6v optima put on its side sitting on top of the 12v..

I found a place that does rebuild starters with a 12v solenoid and the engine spins real fast and starts very well now, even after sitting for weeks in winter.

Converting these cars to 12v is not too much work as long as the starter job is done correctly

I drove the car today Saturday as well.

And even rebuilding the starter may not be needed - I later found other, simpler ways of slowing down the bendix hitting the flywheel using the original 6v starter - which I now use on my 1932 Auburn also converted to 12 v .


R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

Carl Fielding

Hi Rob ! I am curious as to how much advance over stock you have timed your Car(s). Not all people realize how important this is to do with an old low compression engine running on today's much higher octane gasoline. I have advanced my 1924 and 1927 Cadillacs , 4.5 and 4.7 C.R. 5 - 7 degrees or so. I have wondered if I should advance even more. Octane was around 45 when these cars were built , but it was rather foul stuff. Some skepticism prevailed against cracked gasoline , so bets were hedged by  invading gasoline with some of the more volatile components of kerosene , up to and including dodecane , C 12. Prior to 1915 or 1916 or so , gasoline , though about 40 octane , was quite good. (Information contained in the previous two sentences is from "Marks' Mechanical Engineers Handbook" , 2nd ed. 1924 , and 3rd ed. 1930). In order to make cars of the late 'teens through early '30s run properly these days , you must disable the "ovens" which had to be used to vaporize these "pollutants". The clue to the necessity of doing this is if the ancient car runs significantly better while it is warming up , than it does fully hot. Cars in this category should have all heat to the intake blocked off , whether it is direct exhaust ported to the intake , or thermal bridging to manifold and carb. Some of this fruit hangs lower than other.   - Carl

47bigcadillac

#4
Hi Carl - I have advanced my 1947 timing to the maximum to run the engine cooler and run it on high octane fuel to prevent pinging - by maximum I mean just short of the point where starting the car cold becomes difficult..not sure how many degrees that is but I spent a lot time tuning the ignition timing, and points as well.

These low compression engines generate a lot of heat - the issue is that the 1947 Cadillac has a narrow front by design, and the radiator is rather small. The engine at idle turns slow, so in the end there is simply not enough airflow given the heat generated. The issue is at idle or slow traffic, where electric fans work well. For the highway part I just switch the fans off and drive with no fans turning at all since I removed the mechanical fan as you can see in the photo.

But I never had issues with gasoline boiling, percolation or vapor lock in the 1947 though.

As comparison, my 1932 v8 - basically a similar engine design and displacement to the 346 , has a much larger "tombstone radiator" right in front  , a much larger fan pulling a lot of air even at idle therefore it never boils over on the stock mechanical fan, and this without even using a shroud.

Even in the middle of very hot summer city traffic. The passengers will overheat much earlier than the engine itself

The 1932 fuel system is another story - it is designed to heat older heavier fuel like you mentioned above, which is guaranteed to lead to frequent percolation on modern winter fuel with the butane  that gasoline retailers like to add these days, to reduce costs and make more profit .

I did a lot of work to get the fuel temp down, insulation of the carb, carb spacer, fuel lines wrap, thick exhaust header wrap, cold air intake  etc.. and also use a mix of 20% kerosene which helps overall and also gives more power and torque to the engine.


R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

Carl Fielding

Thanks for the info Rob , and the advice on 20% kerosene. I have been hearing of this , and think I will try it. Do you simply run 20% kerosene , or is it diesel , or other ? I seem to remember there is an extremely small amount of heavier distillates , up to dodecane in the incredibly complex modern gasoline.   - Carl

47bigcadillac

20% kerosene mixed to gasoline, because it is sold in gas stations near my home so I carry some in the truck and top-up the fuel tank to the correct ratio. - but diesel would work too, maybe using less such as 15% as its even heavier than Kero.

It works well with those low compression, long strong engines.

The increase in power is quite noticeable..I guess it makes the fuel closer to what it was back then, when those engines were designed. Never had issues with plugs or smoke, the exhaust smell is a bit different though.
R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

jackworstell

Rob...do you add  20% kerosene to the '47 as well as the '32 ?    Or just to the '32 ?

Jack Worstell      jlwmaster@aol.com

47bigcadillac

Just the 32

The 47 runs fine on today's high octane fuel
R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

Justin Norwood

great stuff about the gasoline, but switching back to the 12v/6v subject...

Rob,
Do you remember what models of the 12v and 6v alternators were you using?
Thanks
-Justin
1947 Cadillac Series 62 Sedan

47bigcadillac

R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

Justin Norwood

Thanks Rob!

btw, I talked to a local Vintage Air installer who has done work on old Caddy's before...and he suggested a dual circuit using two 6V batteries - leaving the current wiring harness(es) hooked up to the existing 6V battery and running the two 6Vs *in series* in order to fuel my higher voltage needs (e.g. AC). Essentially, you still have dual 6v/12v circuits, but powered via a single ALT.

I welcome any thoughts on this!!!
1947 Cadillac Series 62 Sedan

47bigcadillac

that as my first idea - and I had detailed discussions with an engineer at Optima batteries and his conclusion was that over time both batteries are not going to charge properly if only one is used to draw 6 v as there will be an unbalance.




R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207

jackworstell

If you want to use two 6V batteries ( and operate only the starter on 12v...the rest of the circuits remains unchanged )
then the answer is to use a parallel/series switch.   The charging problem is solved.

Delco Remy used to sell these ready to go.     Texas Industrial Electric now sells them but they are about $500 as
recall ( expensive because the 6V coils have to be almost hand-wound )
But buy a couple of the right kind of solenoids and wire them up yourself for maybe $200

Jack Worstell      jlwmaster@aol.com

( I haven't installed one of these myself but after looking over the wiring diagram.....do doubt in my mind that this will work.......others have installed this set-up with success )

Justin Norwood

#14
Rob -
FASCINATING! Very cool that you talked this over with an engineer at Optima!

Jack -
First question: Is this the switch you were referring to? http://www.texasindustrialelectric.com/relays_1119845_6V.asp
Second question: In what way does the parallel/series switch solve the charging problem? Is it that the switch stays in the 12v position during startup, then switches to 6v after the motor starts running?
Third question: What triggers the switch to know that you are starting the car? Do you wire a signal from the ignition button into the switch?

Thanks
-Justin
1947 Cadillac Series 62 Sedan

Oliver Betker

Hello
it was a very interesting tread, but unfortunatly I believe not understanding everything in the exact way. My English isn't good enough.
My main question ís:
What is the different between the old flathead engine, which runs better with 20%Kerosine against the 47 flathead? I also have the 150hp in my 1946 Series 61. Should I try the mixure or do you said, it is useless?
Regards from Europe
Oliver
1946 Cadillac Series 61 Coupe
1958 Chevrolet Bel Air 4door Sedan
1958 Wartburg 311 4door Sedan 900
1961 Wartburg 311 4door Sedan 1000
1963 Trabant 500 2door Sedan
1989 Trabant 601 2door Sedan
1966 Bulldozer T 100 MGP
1968 Bulldozer T 100 MGP
1998 Nissan Pickup Navara
2015 Ford Ranger Pickup
1978 MZ T 250/1
1992 Harley Davidson Fat boy

Jay Friedman

Another possibility is either the 6/12 volt battery or the 12/6 battery made by Antique Auto Battery in Ohio. 

The 6/12 volt battery supplies 12 volts for starting and 6 volts for everything else.  Your charging system remains 6 volts and 12 volts is momentarily supplied to the 6 volt starter for starting.  6 volt starters don't mind a short 12 volt jolt; it just makes them turn faster.  The battery operates through a series-parallel switch which switches the voltage.

The 12/6 battery is a regular 12 volt battery with a 6 volt post in the middle for accessories.  Your charging system must be 12 volts.

http://www.antiqueautobattery.com/accessories.html
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

jackworstell

Revvies

......The way the series parallel/series set-up works

Using a couple of double pole relays.....the set-up puts two   6V batteries in series when starting ( for 12V starting )
Once the engine has started....the set-up switches the two 6V batteries back into parallel....for straight-forward
charging.   Clever and fairly straightforward.

One of these gadgets from Texas Industrial Electric costs maybe $500.......they explained that since
they are 6v application they have to be almost hand-wound.
But you can buy two on the shelf  double pole relays ( of sufficient amperage )   and do a little extra simple wiring
have have the same thing for maybe $200.....you just don't end up with a self contained single gadget

I haven't installed one of these myself but still I'm surprised that this solution is not widely used.
Fast 12v starting and no charging issues.   The car basically remains  6v.   No modifications needed
other than the addition of the series/parallel switch....except maybe some people might choose
to change out the starter solenoid from a 6V one to a 12V one ( and other than that leave the 6V starer
as is   )

Jack Worstell

tripwire

Rob,
What are you using for the belt pulleys?

Wes in VT
Driving now:
2013 CTS4 Performance Coupe
1940 LaSalle 5229 C4D

A few I used to drive:
1976 Cadillac Ambulance
1969 Cadillac Hearse, Superior Body
1966 Buick Wildcat Hearse
1957 Ford Thunderbird x 3, 1 E code, 2 D code
1956 Oldsmobile Rocket 88 Sedan
1949 Mercury Convertible
1949 Mercury Coupe, Mild Custom
1936 Buick Special Sedan

Classic

Last time I checked (a while ago), Antique Auto Battery will sell just their 6/12 series/parallel switch without their special battery, and it was a lot less then $500.  They don't list it on their website, but it is/was available.

Gene
Gene Menne
CLC #474