At this point the factory suction hose is already suspect because of the weeping dye. It could have a partially collapsed liner. If this was a POA system I would suspect the POA valve. I don't remember much about that model year. Only that 69/70 was a 2 year run before they changed things again. As ...

I am still trying to wrap my head around a 2bbl 389 Pontiac that gets 12 mpg I had a 1970 Catalina with a 400 2bbl that got 18 around town & 24 or so on the highway. With 4 people in it headed from Las Vegas to Salt Lake City at 75 MPH we never stopped for gas. And never went under 75 mph either...

The V7 is a GM variable displacement compressor, with more displacement than many compressors. Oddly enough GM chose to use it in some S10 pickups, and those have ear type mounting - but they are not a direct replacement for a Sanden SD508 - so you would be making brackets. The V7 comes with a 6 rib...

That is a significant leak. You should be able to find one that big with soapy water.

If there is no dye or hits on the sniffer under the hood, you need to check the evaporator. Try the sniffer in the vents inside the car.

Which EFI are you running? 13mpg sounds way off, unless you have a huge cam in it... i had a 455 that got 12mpg with a Quadrajet. Your 2nd gear / 3rd gear test shows the volume issue. Even with road speed & ram air, you still can't produce enough volume. You could swap out to a V7 compressor &am...

Uh, do NOT poke holes in refrigeration lines! That has to be the worst "fix" I have heard in years. There are various tools to add dye or oil to a charged system. You have a York. 45 years ago we serviced the oil in those by isolating the charge in the system with the valves. Front seat th...

This would be a lot easier with a sight glass, but someone already fixed that for you. It may be a little undercharged. Your 12psi low side makes it look that way. If it was an orifice tube system I would say the OT was too small. You can add small amounts of refrigerant while looking at the pressur...

R152a is not used in any commercial system. I don't know of any published P/T charts for 152a in refrigeration. R152a is a Flammable Refrigerant Let's start with the basics. We measure refrigerant charges by weight, because there is no easy way to measure out 15 ounces of liquid. Old guys like me ha...

Well, a couple of things come to mind. Compressor Speed & Compressor displacement. Your fan speed was way down, and you have corrected some of that. But I can't seem to find any info on your compressor in this thread. Ice touched on this in his earlier post, where he describes using a 138cc/rev ...

Well since you have PAG in it already, you can call your pressure check with keyboard duster a success.

Now evacuate it & charge it with 134a & it should work just fine.