FC 13B. How the (bleep) do I put a fan on it?
 

So the 13B is nestled in my '81, with a Series 4 water pump housing and Series 4 water pump. And I dropped the nearly new short Modine radiator in the car and bolted everything up and then looked at the fan situation and realized, even if I could put the old 12A fan adapter on the old 12A fan, it's going to have negative clearance with the radiator and oil cooler.

What's the solution for putting a 13B in a short-radiator car? I'd really prefer to not put an electric fan in this because I'm aiming for simplicity, and I'm sort of stuck with the 40 amp alternator.

I think if you use the GSL-SE fan spacer it might work. I don't have my GSL-SE any longer or I could measure the distance.

I have however put an S4 water pump housing with S4 water pump on several 12A. I had to drill the 12A spacer holes a little bigger because the spacer holes don't align with the S4 water pump pulley. I also used the 12A fan clutch and fan.

Another option might be the 1979/1980 fan spacer. It's a lot smaller then the 1884/1985 and is steal vs aluminum.

Just for reference, here is a pic of my old GSL-SE. All the parts of this one are GSL-SE factory parts.

https://cimg8.ibsrv.net/gimg/www.rx7...f2f4d00172.jpg

Interesting that you have the same A/C compressor as me and Rock Auto claims that this compressor is for port installed A/C, while all GSL-SE had the A/C installed at the factory. And it looks like the upper radiator panel is held in with flanged bolts and not captivated-washer bolts, which confused me a little at first because I only had four of them in my "radiator hardware" parts box.

Details I pay attention to now...

You have a 40a alternator in the car?! I didn't even know they made them in that low of amperage.

Maybe try an SE fan or you'd have to go electric I would think. I'm running dual 12" pullers on my short radiator setup.

If youre aiming for simplicity just run an efan with a thermo switch.

Why do you only have a 40A alternator? Stock is 55 if I remember right. Just go dual electric so you clear the engine. I'm using a dual setup from a 1st gen MR2.

The compressor pictured is correct for SE cars. Rock Auto is somewhat correct in claiming it is a port installed compressor. ALL SE cars came with this Sanden unit and all had the factory hard and soft hoses and brackets to hold them in place. I worked in a Mazda dealership in the Northeast and all Mazda vehicles at that time could be dealer fitted with A/C. Glc,then323,626 & Rx7 . The SE was only car delivered to the dealer that had the "factory" A/C installed. I installed a lot(in the hundreds) of A/C units in all the different models and the components in the kits(including compressors) were different(hoses,clamps,brackets,etc) depending on the vendor that supplied the kits. Several of the kits used Sanden compressors but they had different barbed head fittings that accommodated refrigerant hose and clamps instead of the SE threaded,pre bent specific lines. I had occasion to replace a few of these non SE compressors under warranty and sometimes you had to switch the original head fittings to the new compressor that came with SE threaded head fittings. I do believe other than that the Sandens were interchangeable. There was another compressor(Sankyo) that came in some of the kits that was also set up for refrigerant hose and clamps and these systems looked the part of dealer installed A/C,universal cut to fit hoses,etc. Replaced a lot more Sankyo compressors under warranty than Sandens. Regarding the panel bolts,correct bolt has the captive washer. I can't tell in pic for sure,but they may be correct bolts just painted.

I wonder if his alt. is from an older/earlier Mazda,possibly GLC. I'm certain all FB alternators were 55amp,SE being 60 amp. Not 100% sure about Sa after all these years,but would certainly swap in at least the FB alternator.

I have an early build '81. It has (well, had) the SA steering box too, and has the 85mph speedo.

I have zero interest in running an electric fan. I already have an FB with an electric fan and it's a pain in the ass sometimes, like running into a traffic jam at night in the summer and i have to alternate between overheating with my headlights on or cooling the engine down with the headlights off. That's a worthwhile sacrifice for the ability to cool the engine down in grid, though.

That is the polar opposite of the goal for this car. What I'd like to have is minimal complexity. A belt can drive the fan and that's plenty good. I'll probably chuck an air pump on it just to give the water pump something to drive it with decent belt wrap.

If I could put points and a pair of SU carbs on the 13B, I would. :)

would the FC fan not fit?

Dunno, I don't have any FC parts aside from this engine and another bare block. And the subframe in my '84. And some electrical parts.
So maybe I do have some FC parts, but no fans.

I'm thinking of just bunging a $15 flex fan from Summit on the water pump and calling it a day.

Just get an S4 NA fan. I've made them fit a 13B in an FB with the short rad.

You have to pull the 6mm x 1.0 studs before setting the fan on the hub. Then thread them in with fingertips. Then put the nuts on. It is a little tedious but very doable.

Pro tip: drop the studs into the fan's hub before you set it on the impeller hub. You'll see what I'm talking about when you get one.

Mazdatrix has hubs for $250ish, no fans themselves, no generic parts available that I can find... Flex fan it is :)

Sounds like a problem with your car, not a problem with the fan.

Epilogue: I got a S4 13B fan from Dave (forget his screenname, mazdave-somethingorother) who is Da Man. Also a S4 air pump that I will use as an expedient idler pulley since the air pump belt does most of the work driving the water pump, and am looking into using as a pressure source to actuate the aux ports since I can't just remove them like I usually do. That, and a belt from Rock Auto (like $1.something) and it's sorted.

...yeah, this didn't make any sense to me until I tried it. There isn't enough room between the ends of the studs and the radiator to get the clutch hub over the studs. So, yes, slip fan in place, install studs, install nuts.

If you spend any significant length of time over 6000rpm, you NEED underdrive pullies, because the water pumps stall around that point with the stock pulleys, leaving you with a thermal-sink type cooling system instead of a heat-exchanging one. When I upshift the revs drop down to 6500-7000rpm. So I have a 4" crank pulley. Any decent fan that actually moves air is going to pull 30-40 amps, 30-40 amps is way more than the alternator can provide at 900-1100rpm with a 4" crank pulley. I also suspect that the water pump flow is "marginal" at those engine speeds. Plus the nature of idling at effectively "near WOT" probably puts a lot of stress on the system as well.

As you can see, I have a car that is object example of what happens when you improve to the point of being awful to live with, which is exactly why I want something simple. Again, if I could, I'd have a pair of SUs on the intake manifold and points in the distributor...

The S4 13B fan hit the shroud hard.

I swapped the 12A fan on the S4 clutch last night. It still hit the shroud hard.

It's like the engine is sitting an inch too high or something. I'm using a modified 12A mount bracket, but I do have a Racing Beat 13B conversion bracket, and it's the same height.

I gave up and just yanked the shroud for now. The car will be getting a 12A over the winter like a 1st-gen should have.

https://s3.us-east-2.amazonaws.com/p...36_mmthumb.jpg

Epilogue epilogue. I have a stockport 12A in there now. The fan clutch is stuck, it was burning up the alternator AND air pump belts over 4000rpm.


15" Black Magic fan draws 24 amps startup current, 13 amps continuous, and with the temp probe positioned at the bottom of the radiator near the outlet, it cycles just fine. The main reason I'd been against electric fans for so long, I've never had one of those not have such a wide window of operation that it either overheats or it never shuts off.

When the fan is running, even at 750rpm idle, the system voltages barely drops. I call it good!