Working on the restoration of a Jaguar MK2 at the moment and I have a question for you.

I am air conditioning this car. My first configuration of pulleys and belts can be seen in Image 1. All on one 1/2” “V” belt. This approach continues to use the original “jockey” pulley (to the left and above the crank pulley) for tensioning the belt although I suppose that it is not really needed since in this approach the tension can be adjusted by rotating the alternator.

However, I wonder about having the alternator and the compressor on one “V” belt as in image 2 (An Austin-Healey), and then have the crank pulley, water pump pulley, compressor and idler pulley (not tensioned) on a second “V” belt. I could accomplish this easily as the compressor has two “V” belt pulleys (one double) and I could shift the alternator to the rear to get the proper alignment.

Do I gain much of anything by moving to the two belts?

I have seen several Healeys with the stacked alternator and compressor on their own belt. Unlike in the Healey configuration, in my case the compressor would be on top and the alternator below.

What are your thoughts? I would appreciate hearing your views about this.

Lin Rose

 

As in picture number 1, I would think that routing a "V" belt around that idler pulley going from the alternator to the crank shaft pulley would be very hard on the "V" belt.

"V" belts are not serpentine belts and are not meant to routed in that way.
Maybe a segmented one would be better, but photo number 2 looks more practicle and cleaner.

 

I am running the picture 1 configuration on my 1960 3.8 MK2. The only draw back that I see is that it becomes very difficult (impossible) to tension the belt or change it without removing the radiator fairing. This aside, the compressor creates so much drag (it's an old one) at idle that the voltmeter drops sharply to the left. So far it did not affect the life of the belt (segmented) but I do agree that it does not look very tidy. Staking the compressor on top of the alternator makes also life difficult if you want to remove the front exhaust manifold.. But it's not an easy car to work on anyway :-)
JP

 

I have also installed my compressor above the alternator as per you picture 1 but instead of looping the belts around the alternator I added a double v belt pulley wheel to the crankshaft. This pulley came from a series 2 or 3 XJ6 ( part number C27754) but as the crankshaft arrangement is virtually the same it just need a little machining to fit. The only disadvantage from this is that I cannot now get a large socket on this pulley to turn the engine.


I do not have a "full frontal" of this arrangement but the attached pictures show this including with the radiator installed.


It is also correct that to get the A/C compressor in with this arrangement you have to remove the front exhaust manifold, relocate the washer bottle and also adjust ( means beat the crap out of it to provide clearance!!!!!) the inner wing of the engine bay.


The other advantage of locating here is my A/C unit has been installed under the passenger glove box and all the pipes are on one side of the engine.

 

in my opinion two belts are better than just one.

 

Ray,
Very helpful. Thanks. So no jockey pulley or idler in your set up?
Lin

 

I used the old aftermarket (as were all early Jag A/C installations) parts with some new components.

The auto tensioner was superfluous to this design and was removed. The key is obtaining the double pulley and other v belt pulleys. It is possible that some installations used a single sheave pulley, 1/2" V belt , bolted on top of the original "W" belt main pulley. Therefore the car had the original "W" jaguar belt and pulleys for all but the compressor which used the 1/2 V belt.

See photo of my installation.

bob

 

Bob,
On the crank, idler, compressor track how do you adjust belt tension? With your brackets is the compressor adjustable?
Lin

 

Ray --

Two questions:

Are you running a mechanical fan, or just electric?

Can you provide any details on the machining needed to adapt the XJ6 double pulley?

Thanks.

 

The belt which drives the compressor is tensioned using the idler pulley. The idler arm is held to a metal plate which is bolted to the front of the block. The idler arm is secured with a single bolt. When loose the arm can rotate. Its movement will tighten the belt. It requires selecting the correct length belt. I was a regular at the local NAPA store requesting various sizes.


The idler arm is available online. Apparently it is a universal part used in other A/C systems. The plate would have to be made. I used drill bushings as stand offs to position the idler assembly.

I will run a mechanical and electric fan. I do not know what would be required to get the single sheave XJ6 pulley to work. I am looking for more double crank pulleys. If enough people were interested I am sure the double pulley (two single V sheaves) could be manufactured. I would estimate 250 to 400 dollars each unless many were ordered.

Bob

 

I was looking at the flex-a-lite steel fan. Apparently "XJS unlimited" and "Anglo Parts" a Belgium company, offered the flex-a-lite. It is my understanding they are not available now. I did have concerns that the depth of the blades might contact the belts or more. The standard fan depth is very thin.

A proper engine driven fan can move a lot of air. Of course less at idle. That is why I had interest in the flex-a-lite it has a large pitch at slower speeds.

I have yet to see any posts about the flex-a-lite used on a MK2.

Bob

 

I will attempt to post pictures of the idler, compressor bracket and double crank pulley.

 

I plan to have just an electric fan in front of the condenser which has been fitted in front of the radiator. With my set up there is no space left for a mechanical fan.


I attach a picture I found of this set up.


For the machining I seem to remember that I need to open up the 4 holes to allow longer but UNC bolts (not metric) go through and screw to the block and remove some material from the flange that fits in the old pulley.

 

Ray--

Very helpful. How is the compressor belt tightened?