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Join Date: Mar 2005
Location: Jeannette Pa. near pittsburgh
Re: The LS swap A/C blues
Here is what I know. I have a 70 with a 468 B.B. I converted my system to R-134. FIRST: R-134 has a different expansion rate than R-12. When the Comp. is engaged the P. Flow condenser NEEDS AIRFLOW.
If you can not COOL DOWN the R-134 with the cond. you will have issues.
This is what I have in my 70, Alum. 10 Cyl. R-134 compressor, From the Fla. Guys. Same parts as you have. POA, adjusted for 134---P. Flow Condenser built for a 70-72 (uses all org. nuts bolts & brackets) 134-dryer.
I also have the 4 row copper /brass rad. ( Standard cooling system for a 70-72 with A/C. My fan blade is a 3947772 on a clutch. My engine temp never goes over 185 / 190. NOTE: VERY IMPORTANT--- A factory C-60 system takes a R-12 Charge of " 60 OZs " When you convert to the R-134 system with all the correct parts. The R-134 has a VERY DIFFERENT EXPENSION RATE than R-12.
Using the R-12--60 Oz. when you convert you use the 80% RULE, What the HELL is the 80% RULE????
80% of the 60oz = 48 OZs. Put it in simple terms. Charge your system with " 48 " OZs of R-134......... YES,,, Charge your system with 48 OZs AKA 3 LBS. of 134...... Dont even look at the gauges, Just shoot it up with 48 OZs of R-134..
I just tested my converted system yesterday, I am getting 38 to 40 degrees out of the center vent in my 1970 FRAUD SS 468 Nomad Sta. Wgn.
Bottom line when the Comp. clutch kicks in,,, You need a " TON " of air going over the P. Flow Condenser.
I am leaving for the OHIO Chevelle show at 8:00 AM in the Morn.
REMEMBER- 48 OZs of R-134 NO more NO less for a 60 OZ. G.M. system .
80% of the factory R-12. Due to the fact, R-134 has a VERY different expansion rate, OR it runs a lot hotter than the R-12. Suck it out and SHOOT it up with 48 OZs of R-134. Remember LOTTSA AIR over the Cond.
The above information is for 69-72 Chevelles. I also have a 70 El Camino SS 454 /M-22 that I ordered in Feb. of 70. I will get back to you on Monday!
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1970 SS LS-5/M-22 El Camino- Org. Owner-AACA 2016-Senior Grand National Winner---MCACN-GOLD-2013
1970 ( FRAUD) SS 468 Station Wagon - Driver.