1974 original 455 stage 1 AC compressor

[Houtan]

Hi everyone,

I have question about about original 1974 Century 455 GS stage 1 original AC compressor, when I bought the car there was no AC compressor and it`s wiring on the car. Please help me witch model A6 is correct original on this engine, If I good remember stage 1 models have bigger belt pulley but I haven`t exact model and part number, Also I guess they had super heat switch on them on 1974 models?

 

[rcull]

My 1979 parts book only shows two pullys, 5914745, and 6550750, but it only associates them with compressor models. It shows 3 compressors, associated with 6 cyl, superheat type and non-superheat type. Both the SH and the non-SH share the same part number?!

 

[Houtan]

I have only 1975 Service manual, on this manual Frigidaire A6 for 455 engines have Super Heat sensor on them, But on 1975 we don`t have any stage 1 engine anymore, I remember in some years stage 1 compressors have bigger clutch pulley and their AC belt size are different from non stage 1 455 engines but I din`t remember exact years.

 

[rcull]

I see no reference to Stage I in my manual, however there is a reference to GS 67-71 using 6550819.
1972 does not show a specific pulley for GS, however it does exempt GS from the standard A body pulley 6550750.
I would not be surprised if the '72 should use the 6550819.

My '67 GS400 AC pulley should be a 6550819. It measures about 5-5/8" OD. The belt width appears standard and the groove depth also appears standard.
I have a '66 Riviera GS which should have a 5914753 pulley. It measures about 4.75" OD.

Most of the pulleys I have kickin' around are about 5-1/16" OD, but I can not identify them.

 

[TODD]

Attached are pages from the 1974 Delco Air Cond parts catalog. Two pulleys show up for use on the big block Buicks. The regular one is Delco 15-224 (GM 6550750) which has a 5" nominal dia. The large pulley is Delco 15-216 (GM 5914745, formerly 6550819) which has a 5.58" nominal dia. The larger pulley slows the compressor RPM down about 10%.

Belts were standard 7/16" type. Regular pulley on the '74 Century 455 used a 9433777 code HK belt 62.5" long. The large pulley used a 9433779 code HM belt 63.5" long.

Attached is a Dealer Service Bulletin describing an oversize a/c pulley for the '65 Riviera GS.

The common theme here is cars with the 3.42 rear axle get the larger pulley. This prevents overspeeding the compressor.

The superheat switch first appeared on A body Buicks for '72 and would be found on '74 models as well.

 

[Houtan]

Thanks guys, Those information was really helpful, I always asked myself why compressor pulley must be different? now I have the answer!

I must go for 6550819 my engine is stage 1 also I changed camshaft a little bit higher from stage 1 numbers also my rear axle is 3.42 .