Sorry you said a specialist made this? Who were they? A potential apprentice for BL could have made a better job of this. The workmanship used to make this unit is appalling and could have been made by a school boy in his metal work class or put together by a Blue Peter presenter. Not an aside at you, just at the workmanship put into this unit which was then put into a new Triumph Stag. No wonder they covered it in black felt to make it less obvious.

 

In mild Mediterranean climate Cape Town all one would need is a fan & evapourator. A clean S Type/420 heater radiator/heat exchanger is absolutely adequate for winter heating. One could pipe the evapourator into the structural cross member behind the dash that doubles as an air channel/duct or just recirculate cabin air via the evapourator with fresh air coming from the existing system. Provision would be required for the evapourator drain.

 

There are a few 'nice to haves' in the evaporator-heater core layout and air distribution if we are going down to individual components and designing a climate box. Most are obvious, but, in the heat of trying to fit things together, it's easy to forget them.

It's nice if the air can flow through the evaporator before the heater. Then if both are turned on, they are very effective at reducing humidity and demisting the windscreen. If they are in the same box, It's desirable for the evaporator be placed such that condensation on it can drain away without dripping down on to the heater. That usually means putting the evaporator underneath the heater or behind it with its base lower than the heater. It makes life easier if the drainage is placed where it's easy to unblock. Though the air has a path where it goes through the evaporator before the heater, it helps with cooling if the face level air outlet can receive air that has by-passed the heater. Even with a closed tap on the hot water, it takes time to cool the heater core.

I'd be inclined not to use the structural member to carry air for heating or cooling. These systems always have some humidity around. The corresponding member in a Mk2, where it doesn't seem to have a heat-ventilation-aircon role, is most often very rusty. As a structural component, I don't think it's primary in that the two ends don't have much possibility for taking loads out; however, it does support the steering wheel and stiffen the dash-bulkhead structure. As such, I'd try to maintain its integrity and use a PVC RHS attached to it for HVAC.

These are just suggestions.

 

All good points & nice to haves. Personally it is why I like the thought of building an air duct onto the rear of the parcel shelf of the S Type & 420. I have a strong preference for being able to use "ball" outlets or whatever to blow cold air onto my face. The only negative would be a reduction in the area of the shelf.

I do think the extra bracing of the scuttle is important both vertically & horizontally. Crouch mentions in one of the many books that it reduced some slight scuttle shake carried over from Mk1 to Mk2 ~ everyone was still learning about monocoque construction at the time without the benefits of CAD. e.g. 3 piece sills for added stiffness.

Parcel shelf butts hard against that structural stiffener/duct. (old car photographed to see placement of the Hardura felt that carpeting very partially covers.). Steerable ducts shown here bolt to the underside of the stiffener/duct.

















Modern Integrated system with many stepper motor driven flaps.


1) Charcoal & paper filters
3) Evapourator
4) Heater matrix/heat exchanger.

 

I spent some time laying in the passenger footwell today and decided that I was not going to be happy with an under-dash install of the AC. This picture is at a bad angle but the bottom of the lower shelf is labeled 'A' and the passenger side vent outlet is labeled B.


Another bad picture but the AC unit hangs down way too much. I thought the parcel shelf hung down lower than it actually does. If I move the AC unit to a position that I could feasibly use the parcel shelf as part of the air distribution system then I'm eating up a ton of footwell space.


If I move the AC unit to the front edge of the lower parcel shelf I recover some leg room but I have an ugly AC unit staring the passenger in their face.


When you're not happy with the options I have found it best to step back and think about it some more. I'm still opposed to the idea of an evaporator mounted in the engine compartment so I emailed Old Air to get details about their two trunk mounted systems.

Next I turned my attention to the heater box. I have it completely disassembled except for the air distribution flap. How do I remove the flap from the air box?


Here's the other end of the flap rod.


Here's the flap itself.


I could not find anyone selling a new 420 heater core so I did some searching online and I think I have a reasonable substitute at a reasonable price. More to come on this later.


I was able to finish fabbing up the bracket for a CS-130 alternator. I cheated and used a universal mounting bracket to get my distances right. I'll fab one out of 1/4" steel later.


This alternator was laying on my shelf and it has the adjusting ear in the wrong position. Remy 91323 has the mounting lugs spaced at 180° degrees for better mounting. At less than $80 for 105 amps it's a good deal.

 

As I mentioned earlier the heater motor and fan are pretty hard to source for the 420 and the ones for the Mk2 did not look like they would fit.
But what is available is the PM130 fan and motor from early 1990's GM products. I picked this up on RockAuto for $40.
PM130 on the left, stock Jaguar fan and motor on the right.


I had to make two modifications to the heater box to fit the PM130. First, since the PM130 fan is slightly larger in diameter than the stock fan, I had to open up the hole in the heater box. I used a nibbler to cut it to the correct size.
Next I had to flatten the section where the heater box mounts to the firewall. I presume that was made to help direct air flow to the fan but I was getting some light rubbing so I flattened it out.
I'm using some screws to temporarily mount the fan for testing; I'll weld some nuts to the inside for a more permanent installation.


The fan never really worked before so I don't know how much better the PM130 works, but it does move quite a bit of air.

I spent some time looking at the flap and I think it's going to have to come out in pieces. But it should be easy to create a new one.

 

Today was a bit of a swing and a miss. Since 420 heater cores are hard to find and the good radiator shops near me closed, I spent some time with the heater core catalog looking for one that might fit. Four Seasons 98787 looked like it had the right dimensions and at $40 it was worth a roll of the dice.
98787 in the front; original core in the back.


It was at this point that I realized the catalog measurements must have been for just the core and did not include the end tanks. I can make this work but I think I can do better.

 

Santa Claus keeps bringing more car parts. Today the correct alternator showed up as well as the new controller for the electric radiator fans. I've been using these fan controllers for years and they're really impressive. They are pulse-width modulated so they only spin the fan(s) as fast as needed to maintain water temp and they have a soft start feature to keep voltage spikes down.


It's going to be a busy weekend in the garage!

 

There's a little bit of room to make the heater box a little wider (longer ?) so the new core can fit in squarely _ will it be enough though ?
The space opposite the motor next to the upper inner fender-well.

 

I'm taking care of a sick wife today but I was able to sneak into the garage for a few minutes to try out my new alternator. I had the old alternator adjuster from my XJS on the shelf and while it would be cool to reuse it, it's not exactly the right size/shape. It did allow me to measure out what I need to do it the right way.

 

The adjuster for my upgraded alternator is done. I used a pair of left- and right-hand threaded ball joint ends, jam nuts, and a turn-buckle style connecting rod.


In position and hand-tight. It's been a few years since I've made one of these but it makes properly tensioning the belt quick and easy.

 

I'm clicking 'like', but falling over with admiration is more accurate. For the last two posts, I thought the XJS tensioner was pretty neat, but the turn-buckle and rose joints are way beyond that - properly beautiful!

 

It was a busy day out in the garage today - task #1 was planning out the wiring for the alternator. I replaced the ammeter in my car with a voltage gauge a few months back and I have no intention of running the bigger alternator through the factory wiring - especially into the dash area. The plan is to run a 4 gauge wire from the alternator straight to the battery. 4 gauge is good for 110 amps so there is a little extra capacity.
I also like to run a dedicated ground from the alternator to the chassis.


Next up was to decide what to do about a heater core. Cutting the box to fit something seems inelegant, so this afternoon was spent looking through all 1,028 heater cores in the catalog. If there was one that looked like it was about the right size and shape, I looked up the part number on RockAuto to get the measurements. FedEx is delivering heater cores from a 1985 Ford Bronco, a 1968 Ford Custom, and a 1970 Chevy Blazer this week so I am hopeful I can move this to the next step in the process.


It's also time to pivot back to the AC. After deciding I don't want to ruin the look of the dash I took the same path that Jaguar did back in the day. I took advantage of the Cyber Monday deals and picked up an Old Air dual evaporator trunk mounted AC unit.


It has twin 365 CFM blowers that operate at high/medium/low speeds.


The engineer at Old Air thought this would work well in my application and the Sanden 709 will easily run it. After test running it today I am no longer concerned about the vents by the rear window being able to cool the front seat.

 

My neighbor is a hot rod guy and brought over a couple of radiators to see if they would fit. The 27.x 15.5" radiator fit, but the 31x16" was too wide. It's nice to have good neighbors but I'm going to stick with the stock radiator.


I do need to address the cooling fan setup, especially with the addition of air conditioning. I have had this fan hanging on the wall for over 10 years - I think I bought it for my 1972 Mercedes 250C project - but I never used. It's the fan package from a 2004 Ford Focus. It fits well on the radiator but this one came from a junkyard and is broken in several places. If I decide to go this way I can pick up a new one for about $100.


I also had a Volvo fan on my wall that I bought for the v6 conversion on my MGB. This one is too big for the Jaguar radiator.


Option 3 are two 12" Spal fans. It helps that I already have one hanging on my wall so that means I only have to buy one more. Each one is rated about 1,600 CFM and pulls about 20 amps so doubled up I have quite a bit of airflow and amp draw.
If that's not enough Spal also makes a high-output 12" fan that almost 1,900 CFM and pulls about 40 amps. Two of those are probably overkill and a big stress on the electrical system.


I'm going to run each of them and see what the noise levels are then make my decision from there.

If you guys are thinking "this weirdo sure has a lot of fans on the wall" you would be correct. There are probably another 3 or 4 that I've collected over the years but didn't make the cut for this post.

 

Hi Thorsen,
That looks like a suck through system i.e. the recirc (return) air enters the center opening, passes through the evaporator and the blower, blows the air into the car. One major concern with a suck through system is, will the condenser drain out of the system? The condensate drain is on the low pressure side of the fan (suction side). It can be very tricky to get the condensate to drain out of this type of system. If it doesn't drain properly the fans could spray water out of the blower outlet, condensate leak out the seams and cause gurgling noises.

 

Thank you for the information Bob. I can test that out over the kitchen sink before I install it.

 

I'm getting closer with the heater core but still not all the way there. First up is APDI/PRO 9010065 from a 1970 Chevy Blazer. It looked promising on paper but it's even bigger than the first heater core I tried. This one is not going to work.


Next up is APDI/PRO 9010166 from a 1985 Ford Bronco with the 5.0 engine. We have a heater core that fits quite well in the heater box and while it will work the hose connections are unfortunately placed. I'd have to either weld on extensions or run rubber heater hoses through the lid on the box and I don't want to do that.


Tomorrow I'm supposed to get my final heater core delivery and I have high hopes that it's the one for me.

 

Hi Thorsen,
Take a look at the ~1989-1997 T-bird core. The tube would be on the end of the cores tank, 90 degrees from the bronco you have there,



1994 Lincoln MKVIII


Also look at the 1989-97 Hyundai Sonata heater core. You would have to use a/c pipe with Ford spring lock coupling to extend the pipes through the case.
Sonata core

 

The shape of the heater box in the 420 means the short sides of the core rest against the sides of the box, and the long sides sit against the back and lid of the box. If the pipes exit from the short side of the core then you would have to cut into the side of the heater box to connect the heater hoses to the core. While not the end of the world I would consider that a modification of last resort.

 

I believe we have a winner for the best non-original heater core to replace the one in the 420. APDI/PRO 9010048 from a 1968 Ford LTD. I don't know that I've ever seen a 1968 LTD but I am thankful for it's heater core. The inlet/outlet pipes are in the correct orientation and very close to the correct size. The long side could stand to be a 1/4" longer but that difference can be made up with foam.


I think I want to fabricate a small bracket to keep it in place but I think we can get this ready for the powder coater in the next few days.