POLL: 3.8 owners who have installed Retro/Classic Auto Air a/c

[NDZWORK (Bob Kwartin - 1964 FHC)]

I’ve begun the process of installing a Classic Auto Air (formerly RetroAir) a/c system on my 1964 FHC, and I have a couple of questions about other 3.8 owners’ experiences with the drive belt(s). No disrespect for you 4.2 owners: it’s just that the 3.8 a/c system is set up differently from the 4.2, and I want to focus on what works for the 3.8 arrangement.

1. Did you do a 1-belt installation or a 2-belt installation?
2. How many miles have you gone since installing the a/c system?
3. Have you experienced any belt issues?

I’m running this poll because I’ve been told by a certified Jaguar oracle (who shall remain nameless here) that RetroAir’s 1-belt solution is flawed because the belt runs backside down over an idler and he’s seen more than one example of the belt failing at under 1500 miles. I want to see if that is a widely-shared experience. This should be useful to future 3.8 owners considering how to proceed.

I’m going to tag a few 3.8 owners who have commented about Retro/Classic Auto Air in previous threads to try to drum up some responses. (@64etype, @Brian_Mix, @Bar_One).

Thanks in advance.

Bob

[64etype (Eric)]

First of all the failures that I’m aware of are on the double idler 4.2 kit. An installer at Lippincott’s Garage advised me on those. Part of that problem was pulley misalignment per Rock Browning (Mr. Retro Air). Rock also advised that the vast majority of 3.8 kits are on sedans…Classic Auto Air told me the same. So you might want to poll that community for a more complete picture. Same engine bracket. (There was one 3.8 photo I saw here on the forum where the cogs were running against the idler and were chunking…odd belt routing).

I spoke with Rock Browning about backside idlers before I installed the kit. He said there were no reported issues on 3.8 sedans. Not satisfied, I spoke with a Gates engineer on their tech line. He advised as follows. 1. Run a top quality belt. 2. Back side idlers are OK if the pulley radius is large enough. He sent me a table with guidelines, which I can’t find at the moment. The idler in the Retro Air kit was much too small per the guidelines. So I found the largest diameter replacement available at the time (approximately 4" versus the original 2"). It fits with the original idler bracket…barely. No signs of cracking between the cogs @ 1100+ miles, and I don’t expect to see any. That said, a double cogged belt (both sides) in conjunction with a V-belt idler would be the obvious modification if an issue did arise. And of course, a serpentine belt setup would be even better…looks easy enough to implement.

There have been discussions of double belt installations and some photos of mockups, but I haven’t seen photos of one installed. I suppose the original 4.2 factory bracket could be adapted. I don’t see a need if the idler pulley is upsized.

As an aside, I recently upgraded to a 70 amp alternator from the optional 55amp unit available from Rock at the time. (Fits on the generator bracket with a minor bit of machining…$20

[Brian_Mix]

I will be very interested in this thread. I had to go with 2 belts and a unique set-up as I installed one of Ray’s EDIS kits as well. I’ve only got about 100 mi on this setup. I also was warned about a backside pulley on these style belts but I figured just to always carry and extra set. I’d be interested in any comments.

[64etype (Eric)]

Hi Brian, I’m not clear how the alternator belt is tensioned…looks like it would contact the side frame rail before any appreciable downward movement of the pully.

I take it you slotted the idler pully bracket? (looks like a slightly upsized idler pulley or is it the one from the kit?)

[Brian_Mix]

You have a very good eye. The alternator did hit the frame rail once in the car. Here it is installed. I used the kit idler, but I’d like to upgrade.

[NDZWORK (Bob Kwartin - 1964 FHC)]

Eric,

Thanks for the detailed reply. I should have thought to ask the sedan people about their 3.8 installs, but I wonder if they are fully comparable. Not the engine and pulleys, but rather the frame rails, steering shaft angle and bonnet geometry, which also constrain the solution set. I have had very little exposure to sedans.

Otherwise, your reply suggests that the idler supplied with the kit may be serviceable but less than ideal; a larger idler has worked well for you; and, the 2-belt method may be unnecessary.

I will likely end up with a 2-belt solution, although it will look different from Brian’s.

Bob

[NDZWORK (Bob Kwartin - 1964 FHC)]

Brian,

Thanks for your reply. How much clearance do you have between the alternator and the steering shaft? Also, the angle of your photos doesn’t show the outer side (furthest from the cylinder head) of the barrel of the compressor, but I’m wondering how much clearance you have between the compressor and the bonnet air duct baffle on that side.

We’re still mocking up my a/c system but the current setup assumes no idler, one belt running from the compressor to the crank pulley and the other belt running around the alternator, the water pump pulley and a second groove on the crank pulley. But it’s early days yet and much may change.

Thanks,

Bob

[64etype (Eric)]

Bob,

Obviously, the trick is incorporating a way to tension the belts, whether for the alternator or the compressor. I’m guessing that’s why you’re asking about clearances.

As you probably know, the main compressor bracket in the kit does not secure the rear of the unit to the engine. Retro Air had a small bracket for the lower rear ear, which was supposed to keep the unit steady when running. (It will flex and vibrate without rear support). That bracket didn’t fit, so I made a support arrangement for the rear. It consists of a long, adjustable threaded rod, which attaches to a stud that I welded to the motor mount at the bottom, and the lower, inside rear ear on the compressor at the top. A second adjustable horizontal link between the rod and the aft stud on the timing chain cover provides lateral stability but does not carry any weight…stabilization only. The adjustable vertical rod on the other hand is in slight compression. I installed a longer than normal stud in the head so that the normal nut would supply clamping force. The latera link (basically a short alternator tensioner) slides on next, and then a lock nut secures that link to the engine stud. The slot in the flat link clamps to the threaded rod.

Long winded explanation to suggest that the combination of the long threaded support rod and the lateral link to the engine provide a rigid rear compressor support if your intention is to pivot/rotate the compressor for belt tensioning purposes. Should also work if sliding the compressor laterally via a slotted bracket. Unfortunately, I don’t have an answer to the question as to clearances to bonnet sheet metal. I can say that the compressor case is very close to the engine…so close that .installing the rear mounting bolt for the support rod is a real chore with the heat shielding in place.

Sorry I don’t have better photos of the rear support arrangement…the car is in storage for a few of months. (You have to click on the blue text for the first photo)

DSCN2051|668x500

[Brian_Mix]

It’s close but it clears.

[NDZWORK (Bob Kwartin - 1964 FHC)]

Thanks Brian. If you have any additional photos of your “as-installed” system, I’d sure like to see them. Eric’s pictures have been really helpful, but it seems that each of us is doing a certain amount of customization, so every installation has a story to tell.

[NDZWORK (Bob Kwartin - 1964 FHC)]

Eric,

Thanks for this photo as well as the ones you’ve posted on the parallel thread regarding hose routing. They have all been highly instructive.

I spent about 5 hours on my a/c system today, and want to show you what my setup looks like so far.

First, going back to 2020, the shop that did all of my sheet metal repair/replacement also did a lot of prep for the future a/c system: they cut the hole through the firewall for the hoses and carved out the space for the evaporator motor above the passenger’s knees. As part of the job, they also welded a mounting bracket for the alternator onto the driver’s side motor mount (viewed from above in the photo). Note how close it is to the steering shaft.

Fast forward to 5/8/21. Mounted onto that bracket, the alternator was quite close to the steering shaft, so we had to carve off some of the metal from the alternator casing. It wasn’t a full “de-earring” but we had to shape some new curves in the case. We also gained a bit more clearance over the steering shaft by putting one washer under the engine mounting block to shim it (and thus the attached alternator bracket) up slightly.

We made more progress this afternoon (5/15). First, the compressor. You’ll see that the compressor’s rear ear closest to the engine is bolted to a bracket mounted on the front-most exhaust manifold studs. The front ear closest to the engine is mounted to the RetroAir timing cover bracket (that’s more visible in a later photo). The front ear further from the engine is attached to the engine bracket via an adjustable rod.

Here’s a rear view of the compressor, with the alternator below. Note that the bolt securing the rear of the alternator runs (front to back) through the lower mounting yoke of the alternator, then through a black spacer, then through the mounting bracket welded onto the engine mount, and is finally secured by a locknut.

Taking the top view, you can see the two-belt arrangement. One belt runs around the crank pulley and the compressor. The other runs around the alternator, water pump pulley and crank pulley. No idlers anywhere. We were able to tension the belts and they did not foul each other nor did they foul anything else.

We’re now moving on to setting up the condensor, receiver/drier, evaporator, hoses and heat shielding.

Thanks again.

Bob

[64etype (Eric)]

Nicely done, Bob. I looked at those manifold studs as an option for the rear compressor mount, but got nervous about loading up any studs threaded into the aluminum head, hence the threaded strut rod to carry most of the loads at the rear of the compressor. Rock Browning later told me he had used a vertical strut rod on early kits for the sedans. He later tied into the rear vertical stud at the left rear corner of the timing case, which puts side loads on the stud. In any case a bracket suitable for doing that was not in my kit… Anyway, there are definitely vibratory loads on the compressor if you’ve ever watched it run without a bracket. That’s in addition to tension loads from the belt. I’d keep avery close eye on those studs.

I really like your approach using three pulleys on the alternator versus three on the compressor. Interesting variation for the alternator mount. Is there a reason that the original 3.8 generator mount was not used?

Thanks for the additional ideas, Eric

P.S. Which crankshaft pully did you use?

[64etype (Eric)]

Bob, Here are some recent photos of the evaporator mounting that I used in lieu of the lip brackets in the RetroAir kit. They allow for adjusting the angle of the evaporator, which I found to be necessary for an exact fit. The rod/slotted bracket that drops down on the left attaches at the top to an extended pivot pin for the heater controls. (I lost a whole batch of those photos when a hard drive crashed a couple years ago). Anyway, the cream colored longitudinal brace sets/maintains the for and aft position of the evaporator on that side. The slotted bracket allows for adjustment vertically.

The two adjustable braces on the right side serve to suspend the case, but also set the angle of the unit. Fore and aft position is set via the bolt holes in the sides of the case. Again, my photos from the top (inside the dash cavity) are lost. One way to achieve full adjustment capability.

[NDZWORK (Bob Kwartin - 1964 FHC)]

Eric,

Thanks for your detailed replies. I’ll do my best to answer your questions/respond to your comments in order:

1. I hadn’t thought about the implications of tying into the manifold studs; I guess I’ll have to see how badly they get stressed and whether they damage the threads in the head (nooooo…). This is one of the reasons that I’m trying to gather more empirical data. Unfortunately, I’ve gotten no replies on the XK and Saloon forums, so we have a very small sample of experience to work from: your 1100 miles, @Brian_Mix’s 100 miles, and my 0 miles.

2. It makes sense to me to have the compressor isolated on one belt. If that belt breaks, I lose a/c, but nothing else. If I had one belt on the compressor and water pump (for example) and the other on the alternator, if either belt broke I’d be stuck. Fewer fatal points of failure.

3. I’m trying to remember (from Summer 2020) the rationale for the modified alternator mount. This was all driven by the goal of moving to two belts…I know that they mocked up my system on a spare 3.8 engine in the shop, including some framing to represent the steering shaft and bonnet geometry. I don’t think it improved clearance from either the steering shaft or the compressor compared with what I see in the side view of your setup. I’d have to ask Steve to remind me I guess. As noted at the start of this thread, I’m still not certain that all of this effort was necessary.

4. IIRC, Steve purchased an aftermarket pulley and then lathed it to fit, including drilling some additional bolt holes.

5. I’ve seen your evaporator mounting photos in other threads and will be referring to them regularly when we get to the interior. But do you have detailed photos of how you set up your condensor? I found this photo, which seems to show some brackets on the top, but I can’t make out much of the detail of how you managed the attachment on top, nor what you did for the other three sides. I have a Ron Davis radiator and I don’t want to drill into the sides (see photo below) to mount any brackets.

Thanks,

Bob

[64etype (Eric)]

Bob, Two recent photos of the condenser…not very detailed, but the best I can find. Two (fabricated) brackets at the top, one at the bottom. Take note of the downward angle of the top brackets. They were originally straight out from the top of the radiator with a right angle down to the evaporator, which resulted in contact with the bonnet. Subsequently modified with the downward angle. The top of the brackets have an “L” shape to reach over to the studs. You might have a larger condenser, which would require a variation on the top mount approach. The S2 used side brackets and the ones supplied in my early kit were for an S2. Definitely not a “bolt in” kit as you know. Mine was the second if I remember correctly.

I had forgotten about that earlier post…thanks for finding those old photos.

[NDZWORK (Bob Kwartin - 1964 FHC)]

Thanks Eric. Those photos are helpful.

[JoelStobbe]

P

Here are some pictures from my current set up. I would desperately like to switch it to 2 pulley system.

Joel

[REBUILD61OTS (Danny Lee)]

Would a double pulley on water pump ….rear to drive water pump and alternator front to drive ac compressor …. Clearances could be an issue and you’ll need to move compressor forward……. You may need to have the water pump pulley made…. Those with more knowledge than me will be able to say if there is a standard pulley that will fit

[64etype (Eric)]

@JoelStobbe

P

Here are some pictures from my current set up. I would desperately like to switch it to 2 pulley system.

Joel

Joel, Is that an original 3.8 crankshaft pully as used with the old double ribbed belt? Thanks

[Wiggles (Paul Wigton)]

The inner cracks, inside the belt’s normal cutouts, tells the story.