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...Speaking of electronic ignition...

Started by 71 Fleetwood, October 21, 2021, 02:00:37 PM

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71 Fleetwood

I have a 1971 with a 472, stock ignition, wires and carb.  I'm thinking of converting to HEI (Davis Unified with the integrated coil cap) or Pertronix conversion with Flamethrower coil.  Both on existing distributor.

I have installed the D.U.I. from Davis on my Corvette and like it very much.  I have installed Pertronix on my Mustang and like it too.  I haven't used MSD products but I think they have a good reputation.

Does the 472 seem to have a preference that anyone has noticed?
1971 Fleetwood Sixty Special Brougham

Poncholover

The HEI is super reliable. If using Pertronics, it is imperative to keep the old parts in the glove box for on the road repairs.
Been thee, done that!
Flattie Caddy

dn010

Agreed to the "keep the old parts" comment above. One time I installed a pertronix with flamethrower coil (can't remember if I also put in a MSD ignition box) and it kept melting the rotor. I had to downgrade the coil.
-----Dan Benedek
'57 Cadillac Sedan Deville 6239DX
'81 DMC DeLorean

signart

You remind me of myself at times...
"If it ain't broke, I can fix that"
Art D. Woody

Caddyholic

I run the pertronix it was on the car when I bought it. Been on at least 15 years no problems. Will the dui fit a 71 472? I think There maybe a clearance issue.
I got myself a Cadillac but I can't afford the gasoline (AC/DC Down Payment Blues)

1961 Series 62 Convertible Coupe http://bit.ly/1RCYsVZ
1962 Coupe Deville

The Tassie Devil(le)

I have a GM HEI Distributor on my '72, and experienced clearance problems with the AIR Pump crossover tubing.   It would appear that the engines that were factory-fit with the HEI used a different shaped tube.   But, as I was removing mine, it wasn't a problem.

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

TJ Hopland

Not all the AIR tubes seem to be in the way.   If it is in the way its only very slightly and only takes a slight tweak to make room.   The bigger clearance issue is with the dual belts.   

If you get it timed in just the right place the belt just clears the main part of the cap but you for sure have to get it so one of the holddown nubs isn't pointing to the belts.  The factory solved that problem by going to a slightly wider single belt that was more in the forward position. 

If you have no AC you can run a belt direct to the PS, there is even a factory part number for that.   Not sure how well a single narrow belt would work if you have working AC.   
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

Cape Cod Fleetwood

There are 2 kinds of cars in the world, Cadillac and everything else....

The Present -1970 Fleetwood Brougham

The Past -
1996 Deville Concours
1987 Sedan De Ville "Commonwealth Edition"
1981 Coupe De Ville (8-6-4)
1976 Sedan De Ville
1975 Sedan De Ville

The Daily Driver and work slave -
2008 GMC Acadia SLT *options/all

71 Fleetwood

Thank you.  The HEI was a major pain to fit under the cowling of my other car but it ran perfectly.  I think I'll go with the Pertronix so that I don't mess with the AIR and belts.  My Pertronix on the 2nd car has also been perfect since the product first became available.

You are much appreciated!
1971 Fleetwood Sixty Special Brougham

"Cadillac Kid" Greg Surfas 15364

If I am not wrong (I thought I w wrong once but I found out I was Mistaken) no one seems to have pointed out the difference between the Pertronics "breaker-less" ignition and the HEI.
Where as the Pertronics eliminates the points with a magnetic pick up it leaves the ignition system essentially the same.
The HEI be it factory, or DUI you have a magnetic pick up "feeding a solid state module then to an high output ignition coil.
Other than the difficulties involved with trying to miss the belts on pre-74 double belt motors, the end result with the HEI is far superior.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Lexi

Hey Greg, pardon my ignorance, but if you install Pertronix and also install the recommended flame thrower ignitor coil, would the differences between the 2 systems discussed be more or less consistent? Any comments as I am not sure myself. Thanks. Clay/Lexi

Cape Cod Fleetwood

Quote from: lexi on October 22, 2021, 12:30:12 PM
Hey Greg, pardon my ignorance, but if you install Pertronix and also install the recommended flame thrower ignitor coil, would the differences between the 2 systems discussed be more or less consistent? Any comments as I am not sure myself. Thanks. Clay/Lexi

Clay The Ark uses Pertronix #1181 with the standard "factory" coil.
There are 2 kinds of cars in the world, Cadillac and everything else....

The Present -1970 Fleetwood Brougham

The Past -
1996 Deville Concours
1987 Sedan De Ville "Commonwealth Edition"
1981 Coupe De Ville (8-6-4)
1976 Sedan De Ville
1975 Sedan De Ville

The Daily Driver and work slave -
2008 GMC Acadia SLT *options/all

Lexi

Laurie thanks, I assume you are happy with it. Lexi also has Pertronix as well as the flame thrower coil. No issues. Was just wondering how that combination would  compare to what Greg was talking about, (i.e. Pertonix with just the OEM coil vs the HEI system he described). Clay/Lexi

"Cadillac Kid" Greg Surfas 15364

FWIW the module in the HEI actually changes the "dwell" in direct relationship to engine speed, thus providing a bit of "fine tuning".
While I have used the Pertroniocs in my '66 with great success (always had a set of points in the glove box), and it provided a "waterproof" ignition system, I do not believe the Pertronics will continuously handle as high an output coil.
Big advantage of HEI is instant starting and long lasting plugs.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

klinebau

I have had problems with the points ignition this past Summer and am seriously considering a conversion.  Apparently, the Pertronix 3 when used with the flame thrower coil can provide high energy spark along with multiple spark, adaptive dwell, and rev limiter.

I have had multiple condenser failures and attribute these to a possible bad/loose ground in the distributor.  I have since rebuilt the distributor, but if I continue to experience problems, I am going to make the switch.
1970 Cadillac Deville Convertible
Detroit, MI

71 Fleetwood

...Speaking of Plugs... :)  I am using copper spark plugs (I don't mind annual replacement).  With my other Pertronix and DUI the spark plugs are NGK platinum.  I understand that higher voltage = faster wear.  Do you think that the copper can handle 40,000 monstrous volts?
1971 Fleetwood Sixty Special Brougham

wheikkila

I have used Pertronix ignitions on most of my old 12 volt cars with little problems. I have always keep a set of points and condenser in my cars tool box. As far as the 6 volt, that is a different story. The nice thing about the Pertronix system is should if fail. It is a simple repair to get you back on the road. Not so easy if you have to replace the whole disturber on the side of the road.
             Thanks Wayne     

Finndorado

When using Pertronix keep in mind to use that exact coil
which is meant for your version.
Pertronix 3 didn't work with my -73 500cid (hard start up +
one exploded muffler) so changed to Pertronix 2,
runs smooth now.
Finland
1973 Eldorado convertible

wheikkila

Yes, you have to purchase for the make model and engine that you have.
Thanks Wayne

The Tassie Devil(le)

Quote from: "Cadillac Kid"  Greg Surfas 15364 on October 22, 2021, 01:35:33 PM
FWIW the module in the HEI actually changes the "dwell" in direct relationship to engine speed, thus providing a bit of "fine tuning".
While I have used the Pertroniocs in my '66 with great success (always had a set of points in the glove box), and it provided a "waterproof" ignition system, I do not believe the Pertronics will continuously handle as high an output coil.
Big advantage of HEI is instant starting and long lasting plugs.
Greg Surfas
G'day Greg,

Thank you very much for that intriguing explanation of the HEI Module.

Makes sense, or GM would have never changed the system.

I installed an Acell coil on the top of my HEI, but had to trim the cover so as to not destroy the hood lining.

The Race Tape is there to seal out any nasties, but it has worked so well that I left it.   One day I will plastic weld a nice cover in place.

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