GT4 AC: R12 vs R134

I manufactured a new pulley for the 60° V-belt on the Ferrari.
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"Lets not turn this thread into "why people should not go to R134"



Then why title the thread "R12 vs 134" when your question has nothing at all to do with that?

Getting a pulley machined is not that big a deal - lot's of shops can do work like this - most machine shops could do it if it's really a "problem." But is it? Do these belts fail regularly?

 

What's wrong with what came with the car?

 

I am by no means an expert on the A/C systems of the 308, nor am I a mechanic, not sure I'm smart either, regardless. I am just jumping into the A/C myself.
However, to say that a belt can't be adjusted makes no sense, 40 or 60. You see on the picture here that the pulley is adjustable.
Someone will no doubt chime in here with more grey matter than I. I think the 40 60 thing is something else... Your links don't work in your original post.

From the workshop manual
and the tav

Do you have the Workshop manual and owner manual?
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I think the author meant that without adjusting the quantity of R-134A into a system originally spec'd for R12, problems will arise. As in, it will not work properly.

 

Uh ok, guess I got confused with the 60 40 thing ???

 

Well then I'm also totally confused. I thought it was a reference to the machined angle of the pulley walls vs the angle of the edge of the V belt and concern that the different angles (if there is a difference) would cause rapid belt wear/failure.

 

I have not found the pulley groove to be an issue. I installed a Sanden compressor in my 77 and eliminated the idler/tension adjuster assembly. The belt adjustment is done on the compressor bracket. As for the belt I just measured it up using a 1/4" dia rope and had the compressor at the lowest setting. Went to the auto parts store and measured up a gates belt and put it on and adjusted it. It has been working for the last few years without a problem. 134 works OK but I don't use it to much until mid August. Other then that the open windows work OK.

 

Ok so this about the sanden having a different pulley angle from the belt adjuster / crank pulley wheel on the engine?

 

I think it is but to me the ACTUAL question is, "Does it matter?" I realize that in theory the angle should be the same but in practice, for this application, does it actually have any ill affect?

 

I can't answer that, but man that was allot of work. Anytime you want to pop in Kanga, save allot of guess work.

 

R134 is great if you want it to blow even less cool

 

My AC didn't work when I bought my QV, but one look at the puny factory system made me drop any notion of investing a penny in fixing it. Why? To cool my right knee? Luckily I live near the coast and can live without it. The 308's AC installation reminds me of the bolt-on aftermarket kits sold by Sear or JC Whitney before AC became standard eqpt. I was shocked to see on a 1979 price sheet that it was a $1500 option (though I assume all US cars were delivered with it). $1500 that was big money in 1979. AC on a '79 Corvette added maybe $600 to the MSRP and would make your lips blue.

From reading Fchat posts it seems even when the 308 system works properly, its submarginal. Has anyone come up with an AC mod that provides truly adequate cooling for a 308? Is there not enough room for a truly adequate compressor? Is the limitation perhaps not the compressor but the limitations in evaporator or condenser sizes? Or the cheesy air distribution box under the dash? Certainly some reefer or AC guys must own 308s and have looked into it.

Searches bring up so many AC threads that finding answers to these questions is like looking for the "needle in haystack".

 

From what I've read and be told the original system using R12, old parts replaced, with a new compressor works quite well.
Dr Tommy seems to be a good authority on this.

 

I am not an expert but took a class at the local college on AC and got an A. I remember getting very cool temps coming out of my vent but the AC only worked great on a cool day and in the heat was just marginal at best. I kept it as I into originality and when my engine is running again will get it recharged.

A few points I remember a figure that the AC will only drop the temp about 20 degrees from the outside temps.

Also ferrari recommended the system be charged annually because gas leaks out the seals and R-12 was very cheap and considered safe back then. Mine held a charge for over 3 years, but you have to use it weekly-monthly to circulate the gas and oil to keep everything lubed.

Also there were some technical revisions that Ferrari tried, but overall my suggestion is just to roll down the windows, less strain on the engine more power....
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Hi Dr. Kananga,

No problem to make a 60° V-belt pulley for your compressor (Sanden?).

Pricing depends on final design (single groove or double groove, Sanden or something else, etc...), material (aluminum or steel), and finish (anodized for aluminum, black oxide or cadmium for steel).

An aluminum pulley would require less time to machine and weight less than steel but will require a steel insert for the face that engages with the clutch to stop galling.

 

I converted my AC back in 2006. Have not had any problems to date. AC seems to work just as well as before. If I start out from a cool garage and the car is cool, it will stay that way. Even when it is 90 outside. If I stop the car and let it sit a while and heat up, it takes a long time to cool back off inside, but it does get back to comfortable. Just takes a while. Long while compared to my newer cars. I really do hate to drive with the windows closed. I don't use the AC much. Even when it is hot outside.

 

avoiding the r134 vs r12 and the BTU thermal efficiency issue. The pulley question is a bit confusing, however hopefully I can shed some light on the profile aspect of the groove.

all SAE pulley grooves have a specific profile to them to properly mate with the belt to insure service life and proper torque under load. there are numerous SAE engineering papers that cover each specific belt, sadly though not available to the public.

with that said, if you have two different pulleys that will cause problems as you can't physically run a belt that would work. the pulleys need to match the belt used and vise versa. simply cutting a grove can be a gamble unless the machinist has the needed data for the groove. it really isn't a simple straight cut groove of 'x' degrees, they have a crown on the slope to insure the belt rides at the correct location for contact and traction. if the crown is mismatched from side to side the belt has the propensity to 'toss' or 'ride' incorrectly causing wear problems.

the factory setup is not in need of improvement unless one wanted to move to a multirib serpentine belt, yet a completely different animal and a fairly large undertaking. the belt size was chosen based on torque and HP requirements of the system, without that specific data changing the belt is not recommended as the risk is far to great that a different belt will either not be up to the job or actually increase the load on the engine.

 

couple yrs back there was an f-chatter working on an updated condenser and exchanger fan assy. the difference between r12 and r134 is BTU and pressures. the r12 operates under lower pressures then r134 and you can't pressurize the r12 system with r134 to the needed pressures for r134 to be efficient. then there is the CFM and condenser size issue for the space being cooled. bottom line the r12 was marginal at best and going over to r134 only saves you the cost of r12 without really getting any improvement.

what really needs to be done is a complete overhaul of the system. I think some have looked into the A/C aftermarket setups for the hotrod guys but the problem is space in the 308's to fit the eq.

my mondial has r12 still and will have vent temps of 38*F easily, problem is airflow past that point and the thermal losses from the expansive amount of glass. more fan speed would only reduce the efficiency. One day I'll do something about it...one day.....