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54K views 18 replies 12 participants last post by  the APEMAN 
#1 ·
This thread will be used to contain any and all important, interesting, or otherwise helpful information about the Cadillac 368/425/472/500. Topics will be added as they come. If you have anything you would like to add, feel free to PM me or create a thread :).
 
#3 ·
Making the Switch From Points to HEI:


To start off, the earlier Caddys used a points type distributer. I'm not quite sure, but I think the HEI ( High Energy Ignition) was introduced in '73 or '74. Upgrading from points to HEI is not hard, and will really help performance on the cheap. However, there are a few things you will need to know and do to make the switch.

Just for some physical recognition, here are pictures of each:


Points type distributor


HEI distributor




HEI distributors can be found pretty cheap on Ebay and in the yard. Accel and MSD also make HEI units that fit the Cad 500, but won't be of any real gain unless you are racing or have a very high performance build. Almost any HEI unit you find on Ebay or wherever will be in need of a freshining up. MSD, Proform, and Pertronix all make "hop up" kits. A word of advice. Use the STOCK springs. The proform kit (and maybe pertronix) come with a "performance spring and weight set". These are chineese crap, and not nearly as good as what is in there already. Don't worry, the stock springs and weights aren't going to be worn out. Also, something that may not be included in these kits is a vacuum advance unit. If you pick up an HEI distributor with one that no longer works, you can usually find one on the net or at the parts store pretty easily.

The HEI distributor is a direct drop in, but you have to remember about some things:

SPARK PLUGS. With points, your BBCad will have plugs with a gap of, if I remember correctly, .035. If you were to visit a parts store, you would see that later Cads, such as the '76 Eldorado, have spark plugs with a much bigger gap due to the fact that they have HEI. Replacement spark plugs for a vehicle with HEI will be those with a .060 gap, so remember to get the larger-gap plugs! I would also suggest getting resistor type plugs to increase the spark duration and get the most out of your points to HEI switch.

SPARK PLUG WIRES. Yep, you will need some new spark plug wires as well. One Item overlooked in the HEI swap, is the need for new plug wires. The GM HEI, and a lot of aftermarket replacements, use a male connection on the cap, kinda like the top pf a spark plug, while the point's style has a female connection on the cap. Therefore, you need to get HEI type spark plug wires.

INSTALLATION. You can't forget about the physical installation of the HEI unit. Use pieces of tape, or scribe lines, to mark where the rotor is. If you don't, you'll have to find TDC on the compression stroke. Not a big deal, but it's easier if you mark it. You then gently pull the old distributor. Try not to turn the oil pump gear, if you do, you'll have to use a long flat head screwdriver & a flashlight to get it right. When you install the new distributor, turn the rotor about 90 degrees counter clockwise to where it needs to point. Gently press it down all of the way. Make sure you get the distributor body close to where it was. After this, you will be ready to hook it up and adjust your timing.

After you have everything back where it needs to be and your timing adjusted, get ready to feel the difference!
 
#4 ·
For those folks doing an overhaul on the 500/472 (don't know about the others) , cad500parts.com (Flashcraft) has a stainless steel front plate to replace the often rusted/pitted original front plate, which can be a leak problem, where the water pump mounts on the block. It's priced at $125 last time I looked.

BILL
 
#6 ·
The HEI was first offered as an option mid way through the '73 model year. It was listed as a regular production option for the '74's and became standard in '75. Primitive and low powered by today's standards, it was quite the system back in '75. Ironically, in the late 70's and early 80's most hot rodders didn't understand it's usefulness and frequently REMOVED the system only to replace it with a points/condenser type unit! Obviously this was before anyone truly understood the benefits of a truly hot spark and solid state system!
 
#10 ·
well as the first post says, interesting and helpfull information about 368, 425, 472 engines, i believe this would be very interesting, if we could use headers they sell for the 472 on the 368... because most sellers on ebay and on cadillac performance sites, announces only 500 and 472, and we all know they also fit on the 425, as the 368 is the same block, they should fit also.

the only way to add stuff to this topic is to raise questions and look for answers.

So, again, does anyone knows if it fits? it is the same flange?

If you dont know the answer dont bother replying...
 
#11 ·
the only way to add stuff to this topic is to raise questions and look for answers.
Actually, the correct way to add to this topic is to post a separate thread with your question. Then, when the answer is known, add that info here. If this thread is for posting questions, then there is no point in having ANY threads in this section. That is how a FAQs works. Important, relevant information is condensed in a manner that is quick to reference. I would think that you would know that from the RWD section where I have assisted with many of your questions.
 
#12 ·
i Know Jay and i apologize for my behavior, i wasnt in the best mood that day, i really apologize, please edit my posts and remove them, lets make this topic the right way it should be done.

And yes i know you helped me a lot in the past months, actually, not only you, the whole forum has been a great help for me, including but not only, Bruce Roe (amazing guy), deville33 (super fast poster and helper) among of lot of others.

I also contributed some months ago, i posted a hotfile link for the 77-79 service manual for all models, there is a lot of good info, which could add to this topic.

Again, lets forget about my bad behavior in this post, i always try to be corteous and right as you can see in those 6-7 years i access the forum, and i am very correct doing business, ask bruce roe.

Jay once again very sorry, if you could use your magic rubber and clean out this topic.

;);)
 
#14 ·
For the 472/500 with the AIR pump / Smog pump a 11/16ths hammer in plug (or a dime for really cheap) from Napa or other parts stores can plug the front holes in the head where the air system attached. This same hammer in plug is used on the rear of the heads on these engines.

A 32 or 32.5 3/8th v belt can bypass the adjustability of the smog pup but you have to remove the pulley to get it on without damaging the belt. I was also told a 33 3/8 v belt will work also but it was too loose.
 
#16 ·
A tidbit of info on the 368 engine. Often overlooked because it's so darned hard to see.The EFE valve which is on the exhaust manifold, passenger side.The purpose is to direct hot exhaust gases through the intake manifold during cold startup. The shaft on this valve must be kept lubricated and moving freely because it is operated on vacuum only.Some of the symptoms of a sticky or non functioning EFE are as follows. Poor operation at start-up(rough idle, stumble) Poor operation after warm-up (lack of high speed performance,surge,miss at all speeds) The EFE is controlled by the TVS (Thermostatic Vacuum Switch) on the 6.0 and electronically on the 4.1 engine. The TVS is located on the left front of the cylinder block . Make sure the vac. lines to the EFE are sound and have tight connections.
 
#18 ·
Hello all ,

I have just joined this cadi group. My neighbour has roped me into doing some repairs on his old 73 cadi sedan with a 472 in it.

The first repair is a leaking welsh (I think you guys call them freeze) plugs.

So my question : Do the inner guards come off easy to allow access up under the exhaust manifolds ?. Are the freeze plugs a exhaust manifold off job ?

I have a two post hoist but I think the cadi is to big/heavy for it.

Thanks in advance from Troy in Australia
 
#19 ·
Depends on what you are using to replace the failed one(s) with and which ones are bad.

The expandable brass ones with the nut for tightening can be placed in some of the block holes without taking much apart but they are not always the best.

If the owner plans to keep the car the best repair is to pull the engine and replace ALL core plugs with brass ones.

The rubber ones are crapola and will only hold if the radiator cap pressure is reduce considerably.
 
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