High Performance Big Block Cadillacs
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Author Topic: CADILLAC ENGINE SWAP TECH  (Read 14827 times)
~JM~
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« on: June 18, 2008, 02:59:29 PM »

 Every engine swap will present several challenges that must be overcome to be successful. Some of these are fairly common to every swap. Then there are the individual challenges that are produced by your unique choice of engine and chassis combination.

It is the level of ingenuity and fabrication skills displayed to resolve these obstacles that will define whether your swap will be considered a clean swap, a hack job, or somewhere between the two.

The Cadillac engine has a few fairly unique traits that will present a few obstacles that most likely would not be an issue compared to some of the more common V-8 engines.
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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« Reply #1 on: June 18, 2008, 03:22:32 PM »

SWAP TECH: Heater Hose Returns & Water Pump Modifications

One of these head scratchers is what to do about the heater return line?  Undecided

This topic originally began as a correction to an incorrect piece of information that I had posted in an earlier post. It then evolved into a very informative topic on several possible solutions of how to route the heater return line.

The source of heated engine coolant used to provide heat for the climate control system is taken from one of two locations on the Cadillac engine. The earlier engines (pre 1970) were typical of other V-8 engines with an outlet near the thermostat housing.

The later engines (1971 and later) were changed to provide for a faster source of heat to the climate control system. The passengers of a Cadillac must not endure the cold interior of a car, any longer then necessary. After all, this IS a Cadillac!

The 1971 and later engines are designed to route the coolant across the passenger side head during the initial cold start up. This was done to supply warm coolant to the climate control system (heater) as quickly as possible.

The warmed engine coolant then exits the engine from a discharge port located at the back of the passenger side cylinder head. From there it is routed through the firewall and into the heat exchanger located in the climate control system. From there it is routed through the firewall once more, and returns directly to a port located at the upper end of the passenger side radiator tank.

Most engines from other manufacturers, have the heater return line routed to an inlet port on the engine and most radiators do not provide a port for the return.

The problem presented by the Cadillac arrangement is, what options are available to route the heater return line? I suppose you could just plug the outlet on the passenger side head and do without the heater. If you think about it though, it is a nice feature. Might as well benefit from it and enjoy a heater and de-frosters that warm up faster than the previous engine was able to provide.

If you are fortunate enough that your swap allows you to use a Cadillac radiator. You may stop reading now. You’re all set. Another option is to have a radiator shop install a heater return line port into the radiator you will be using.

The link below offers several very sharp solutions to this problem.
http://caddy500.com/index.php?topic=552.msg152#msg152


* Heater out.JPG (103 KB, 700x525 - viewed 418 times.)

* 425 heater outletA.jpg (115.14 KB, 700x525 - viewed 640 times.)
« Last Edit: June 18, 2008, 05:00:21 PM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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Posts: 1849


« Reply #2 on: June 18, 2008, 05:03:10 PM »

This leads us to a fairly common mistake. The Cadillac 500/472/425 family requires a Cadillac specific thermostat. This thermostat has a skirted section below that seals off a port located in the block after the engine has warmed to normal operating temperature. If you drop a standard Chevy 'stat in there, you most likely will have overheating issues. A non Cadillac specific thermostat may be used but the bypass port in the block either needs to have a reducer installed or blocked completely. Most of the time it is just blocked completely with the correct sized freeze plug.


* Caddy T'statB.png (27 KB, 252x252 - viewed 218 times.)

* Chevy T'StatB.png (29.62 KB, 252x252 - viewed 191 times.)
« Last Edit: June 18, 2008, 05:08:18 PM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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Posts: 1849


« Reply #3 on: June 18, 2008, 05:10:16 PM »

Comparison between a Cadillac thermostat and a common small block Chevrolet thermostat above.

The Cadillac thermostat is in top picture. Notice the section below the framework of the thermostat compared to the Chevy thermostat in the bottom picture. This is the section that closes the bypass port  (pictured below) in the block once normal operating temperature has been reached.



* T'stat & Byp port.JPG (122.91 KB, 700x525 - viewed 412 times.)
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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Posts: 1849


« Reply #4 on: June 18, 2008, 05:15:29 PM »

No telling how many hours and dollars have been spent trying to chase down an overheating problem that may have been caused by a simple thermostat.  Cry
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
cruiser
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« Reply #5 on: June 18, 2008, 07:28:35 PM »

Good post.  I was planning to drill an old water pump for the return...now I see that terry has done it.  Also wasn't aware of the thermostat.

Dick
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Life's too short to drive a slow car
~JM~
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Posts: 1849


« Reply #6 on: June 18, 2008, 08:57:56 PM »

Glad you found it helpful. That information was buried at the end of my old Jeep post where it wouldn't be easy to find. I thought the information was good enough, that it deserved to be a post of its own.

I had planned to write up a post like this to bring it out for more exposure when I discovered that the forum software, date & time stamps every post. This prevented me from writing a lead in & then adding the post to the end. It's taken me this long to figure out how to make it work the way that I did.

I have several pictures of exhaust manifolds & a block hugger type header that I plan to use to address what often may be (depending upon chassis selection) the most difficult aspect of the Cadillac swaps. Hopefully I will be able to complete this in the next day or two.
« Last Edit: June 18, 2008, 09:06:45 PM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
dave brode
C5
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Posts: 1074


Best of 11.66, 113.96, 1.59 sixty


« Reply #7 on: June 19, 2008, 05:40:37 AM »

Good info, esp the source for brass tees. The cheap plastic tees scare me.

Info on oil pans and motor mounts would go nicely here Wink

Dave

edit: another common parts store item that scares me are the rubber caps to plug off a heater hose nipple. No thread reinforcement like in hoses. While the head gaskets were exiting my turbo'd engine, I had one one the rear of the head blow out. Water under one tire under power = quick turn  Shocked
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3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
~JM~
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Posts: 1849


« Reply #8 on: June 19, 2008, 10:41:23 AM »

A bit more information on heater hose routing.

This information applies to the 472/500 engines. I believe that the 425 engines heater outlet is a press fit and not threaded.

One of the pictures above shows the heater outlet fitting in its normal location at the back of the passenger side cylinder head. If your swap has limited engine to firewall clearance. The heater outlet fitting will more than likely require removal to provide for proper clearance.

Fortunately we have several options available to resolve this issue. When Cadillacs finest engineers decided to re-route the coolant to exit the rear of the passenger side head. They chose to use 1" MPT pipe thread and a common iron plumbing fitting. Shocked Grin 

This provides us with the opportunity to pick up whatever fittings we may need from the local plumbing supply store. Cheesy


In picture 1A below. You will see the original Cadillac heater outlet fitting.

If your swap doesn't include a heater. The outlet port can easily be blocked off completely with a 1" Plug fitting like the one in picture 2A below.


* 1A.JPG (115.55 KB, 700x525 - viewed 175 times.)

* 2A.JPG (117.06 KB, 700x525 - viewed 182 times.)
« Last Edit: June 26, 2008, 12:14:37 AM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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C5
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Posts: 1849


« Reply #9 on: June 25, 2008, 11:53:53 PM »

Not only will your local plumbing supply store provide a variety of fittings to choose from. There are also several material choices available.

For the CSOB and Rat Rod crowd. There is the common black iron fitting.
If you'd like an upgrade for your 4X4 or Street Machine. There are the galvanized fittings.
Now if neither of those two materials are suitable for your Street Rod. You might consider brass or possibly even stainless steel.  Cool Cheesy

Many swaps may benefit from a hard 90 degree turn in the heater outlet. This can easily be accomplished with the use of a 1" X 1/2" Bushing plus a 1/2" Barb X 1/2" MPT Elbow as shown in the pictures below.

A couple of things to keep in mind, is that these fittings are usually a taper fit. Whether or not there is the possibility of over-tightening the fitting to the point of causing a crack in the cylinder head is unknown. A sealing compound or possibly some simple Teflon tape would most likely be beneficial. Not only to prevent leakage but to also provide some form of anti-seize.

Good luck on your swaps.


* 3A.JPG (123 KB, 700x525 - viewed 196 times.)

* 4A.JPG (114.63 KB, 700x525 - viewed 178 times.)

* 5A.JPG (114.29 KB, 700x525 - viewed 182 times.)
« Last Edit: June 26, 2008, 10:09:56 AM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
dave brode
C5
*****
Posts: 1074


Best of 11.66, 113.96, 1.59 sixty


« Reply #10 on: June 26, 2008, 10:29:17 AM »

fwiw, the late heater hose fitting can be tapped to 1/8" npt and sealed with an allen pipe plug. That way, if it's ever needed, it's still there.

Where did you get the right angle fitting in post #9? Know the brand?

Dave
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3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
~JM~
Shop Keeper
C5
*****
Posts: 1849


« Reply #11 on: June 26, 2008, 12:37:03 PM »

...Where did you get the right angle fitting in post #9? Know the brand?

Dave

Would you believe Home Depot of all places. I think it cost about $3. Grin

The information that I have on the part is:
Manufacturer: QESTPEXTM
Part Description: 1/2" BARB X 1/2" MPT
Part#: QPEX F1807

A few years back when I built my engine. I was not able to find a fitting like this in any of the local hardware/plumbing stores. I ended up ordering a high dollar trick anodized aluminum fitting from Summit.

One potential problem that I can see with the QPex fitting above, is the barbed section is only 5/8" long. Will this provide enough surface area for a hose clamp to be secure?

While I was at Home Depot. I looked for a 1/2" BARB X 1" MPT elbow fitting that would eliminate the need for the separate bushing. I also looked for a "T" fitting with threads on the short leg and barbs on each end of the long section. This type of fitting might be handy for the back cylinder coolant cross tie. Neither part was a stocked item. I have not contacted the manufacturer to see if these fittings are available.

I just did a quickie Google and found this.
http://www.pep-plastic.com/manufacturers/Zurn/qestpex/QestPex_Main.htm
« Last Edit: June 26, 2008, 12:42:44 PM by ~JM~ » Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
dave brode
C5
*****
Posts: 1074


Best of 11.66, 113.96, 1.59 sixty


« Reply #12 on: June 27, 2008, 06:58:10 AM »

Figured it was a fitting for plastic pipe that uses the crimp clamps. Thanks
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3960 lb '71 C-10. 11.7-1 CR 514". PEP I beam rods floating MTS 18cc dish Probes, Elgin solid cam, home ported heads, MTS 2.19/1.84", Potter/Probe shaft rockers, edel 2115, 4781 850. Switch-pitch TH400, 12" 1800/3200 Tri-Shield convertor, 4.30 gears. Best so far of 11.66, 114.8 mph and 1.59 sixty
steelybill
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Posts: 190


« Reply #13 on: February 23, 2010, 08:46:08 PM »

I realize that this is an old thread, but a question I have is about the vacuum operated shut-off valve for heater water.  Seems like the heat would be in the heater core all the time with the direct route from the head, even if it wasn't flowing.  I suppose a valve could be plumbed in there with hoses etc.
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Cadillac Kid
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« Reply #14 on: February 24, 2010, 09:12:30 AM »

The heating hot water flow control valve does exactly that, controls the flow.  With an Automatic Temperature Control (ATC) system, heat is required to reheat the air, after it goes through the cooling coil to warm it up to the temperature the system requires to delliver to the car interior.  Without this reheat, the system would deliver 40 degree air directly to the interior, and although lots of people advertize "ice cold air" when they sell their cars, that's not what you want to provide comfortable conditions to the passangers.
When the ATC control system  is set on maximum cooling, the hot water valve is closed, giving the system its maximum ability to cool.
That said, if you have modified the system so that the ATC no longer blends the air as intended, you can put a manual valve in the water return line, but on those cars that I have seen it done, it frequently leads to a rusted out heater core, probably because with constant flow rust has little opportunity to grow.
Greg
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Greg
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