Author Topic: Installing A/C Compressor + Brackets to Olds 350 / 403  (Read 16321 times)


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Installing A/C Compressor + Brackets to Olds 350 / 403
« on: March 05, 2012, 07:41:22 AM »
As with my Alternator/Power Steering bracket fitment guide, I thought it may be of use to others to also see how the Air-Condtioning compressor mounts up on Olds-powered F-bodies.

For starters, here's the original diagram from the Factory Manual. Ignore the numbers in reference to my photos. Also, some fastener sizes may have to be swapped out or more suitable items used, they sometimes called for some odd sizes for no good reason, and of course metric compressors can be found also!

Here's your starting point, be it a 1977 350 or 1977-79 403 Oldsmobile, ready for brackets:

This is the first bracket to mount up, the aluminium support:

13. 1/2" UNC Head stud with 7/16" UNF Accsesory stud.

14. 7/16" Flat Washer.

15. 7/16" UNF Nut.

16. 3/8" Flat Washer.

17. 3/8" x 1-1/4" UNC Bolt.

(Note: Part numbers not in order of sequence, I started other photos first!)

And here are the mounting holes for the alloy support bracket. You can see the two 3/8" UNC holes above the fuel pump with paint worn off and between the spark plugs is the head bolt with accessory stud:

And with the bracket fitted, 2 bolts/washers in the front, washers and nut on rear, just visible.

Next, we move onto the two V-shaped brackets that mount off the intake:

They are bolted together in the centre, it may help leaving this bolt loose until after fitting to intake or it can be hard to get it the holes lined up.

1. 3/8" UNC x 1" Bolt. (Factory calls for 7/8" long but I have added a washer to each side)

2. 3/8" Flat Washer.

3. 3/8" UNC nut.

With the two brackets combined we then bolt it to the intake manifold, here's the fasteners:

4. 5/16" Flat Washer.

5. 3/8" Flat Washer.

6. 5/16" UNC x 3/4" Bolt.

7. 3/8" UNC x 3/4" Bolt.

8. 3/8" UNC x 1" Bolt.

The Edelbrock Performer intake uses the same stock #16 cast iron intake mounting points for A/C, however there are some minor clearance issues with the F-body brackets and some molded on detail and runners. Here's some early photos of how I overcame it before the engine was even built:

In this photo the bracket is sitting up in the air, the molded traingular block is fouling it more than it actually looks:

Simply file it down flat until it is level or below the mounting pad:

This is the rear bracket mount, looking from behind the distributor. It is already modified in this photo, the corner of the bracket rested on top of the intake runner. I simply cut the underside of the bracket flush and level with the runner, partly hidden in the shadow:

Back to standard assembly...!

This is the front intake mounting hole for 3/8" Bolt. You can see the wear-mark groove on the modified pad to the right of the bolt hole where brackets have been test fit in the past:

And the Rear bracket mount to intake, for 5/16" Bolt.

And with the top brackets installed on intake, and bolt into front of head. Once these 3 bolts are started you can tighten the bolt that holds the two brackets together, then finish tightening the other 3 mounting points fully.

Next are the brackets that mount to the compressor itself. Originally, the threaded holes in the compressor ends were Imperial but later models switched to the Metric equivalent. If you use a rebuilt unit like I did here, you could get Imperial or Metric so be sure to check, I have included both sizes.

This small triangular bracket mounts to the rear base of the compressor. The 3rd hole faces downwards and meets the alloy bracket mounted onto the head earlier.

11. 3/8" UNC x 1" Bolt (M10 x 30mm) Factory manual calls for shorter bolts that only thread half way through the alloy, best to use it all for strength.

12. 3/8" Flat Washers  (M10 Flat Washers)

* (Not shown here but the 3rd bolt hole uses 3/8" UNC x 1-1/2" Bolt and Flat Washer for mounting to the alloy bracket shortly. Again, the factory only called for a bolt that went half way through the thread alloy!)

This is the front surround bracket for the compressor, again a mixture of Imperial and Metric threads so check first:

9. 5/16" UNC x 3/4" Bolt.  (M8 x 15mm)

10. 5/16" Flat Washer.  (M8 Flat Washer)

And the compressor complete with mounted triangle bracket and front suround bracket. Both brackets bolt from the rear into the compressor itself.

There are two spacer tubes, front and rear of the compressor. These both have a clearance hole for 3/8" (or M10). I machined mine up to suit required lengths as didn't have the original spacers. You may find you need a flat washer as a shim if you use a spacer that is too short.

Front Spacer : Diameter  25mm, Length 15mm, Bore 7/16" / 11mm.

Rear Spacer : Diameter 20mm, Length 27mm (One original spacer was apparently 25mm / 1" long, I adjusted mine as required), Bore 7/16" / 11mm.

Here's the Oldsmobile A/C compressor loom. The twin-terminal plug goes to the compressor clutch, the single ring terminal is the earth that mounts to the front compressor support bracket. The long green wire is the idle-solenoid on the carburettor, increases idle when A/C is on. The three-terminal plug sits under the top brackets on the valve cover, connects to the rest of the A/C and Heater harness that is secured by the wire retainer on the valve cover bolt.

Finally, the compressor assembly can be mounted onto the alloy support bracket. The rear base of the Triangular bracket bolt to secure is 3/8" UNC x 1-1/2" Bolt and 3/8" Flat Washer. The 3/8" fuel hose runs to the charcoal canister on 78-79 models, maybe some 77. Diagrams show it simply runs around behind the compressor, I like to keep it off the valve covers by routing like this over the rear hose pipe for support.

There are two bolts fitted through the front of the compressor surround bracket into the alloy support bracket. These are both 3/8" UNC x 1-1/2" Bolts with a matching Flat Washer on each. Again, the factory bolts are shorter and use only part of the alloy threaded hole. These bolt/s can be seen in some of the completed photos below.

Finally, the spacers can be fitted between the top brackets and bolts fitted to secure. The front spacer bolt is 3/8" UNC x 1-1/2" with 3/8" Flat Washer, with another flat washer and nut on rear. You can see where the earth for the Wiring harness mounts also.

The rear spacer bolt is 3/8" UNC x 2" with 3/8" Flat Washer (M10 x 50mm and M10 Flat Washer).

The wiring loom and fanbelt can be fitted now also. Depending on where the clutch was fitted you may end up with the plug closer to the earth terminal giving extra length for your wiring harness down the valve cover. The installed unit should look something like this:

There are two variations of the fan-belt routing depending on if the engine was fitted with a Smog/Air-pump from factory for emissions. Those without the pump used the second diagram here, the belt being 60" / 1530 mm long and ran around both water pump and crank pullies on the rear grooves.

The engines with pumps fitted from factory used the 4th layout of fan-belt. It only ran around the crank pulley and was 57" / 1450mm long. This was due to the water pump pulley being shorter in offset by the depth of one belt groove and enabled a 4th accessory to be used on the front. My engine photos are of this 4th diagram, still has the same pullies but pump removed.

Here's a blurry photo showing the smog-pump belt version running behind the water pump pulley to crank only:

And here's a beautifully restored engine with original non-pump setup, belt running around water pump as well. Saved sample photo off net.

Hopefully, some of that assists in fitting your brackets and making sense of the factory diagrams and parts required. Thanks also to Edward and Steve for their input. If any has been left out or not clear let me know so I can correct or clarify.
« Last Edit: November 24, 2013, 07:12:11 AM by Aus78Formula »


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #1 on: March 05, 2012, 08:10:54 AM »
Another "sticky-worthy" presentation by Ben. Great job! Thanks for taking the time to do it.
Steve F.


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #2 on: March 05, 2012, 12:19:13 PM »
Excellent, as before... Thanks!

Aussie 1977 Trans am

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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #3 on: March 06, 2012, 05:59:24 AM »
Ben Good job well presented when is your "how to build a Trans Am from scratch" going to be published reserve me a copy :D
Here is LHD version with smog pump

« Last Edit: March 06, 2012, 07:05:39 AM by Aussie 1977 Trans am »
Regards Edward
Melbourne, Australia
1977 Trans am TA  Olds 350 Th350 A/C Snow Flakes 15 x 7 8 track, Fisher T-Tops


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #4 on: December 05, 2012, 06:49:05 PM »
This is great and I for one thank you. I realized I have all of the correct A/C brackets even if all my other ones are wrong,they were in the trunk.  Thanks again Aussie.   Steve
" If you didn't build it, it ain't yours. "

Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #4 on: December 05, 2012, 06:49:05 PM »


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #5 on: December 05, 2012, 06:53:40 PM »
Good one Steve, glad you got it sorted.


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #6 on: December 16, 2012, 11:00:03 PM »
Adding my clapping to the applause. Many thanks Ben!
1978 W72/WS6 SE 4-spd (restored)
1980 Turbo SE (restored)
1977 Black TA (LS1 transplant)
1978 W72 Martinique Blue (awaiting resto)
1978 Esprit 305 (parts car)
1989 GTA 350 (DD)

Have nots:
1977 Black TA (resto/sold 2015)
1978 W72 SE 4-spd (resto/sold 2014)
1978 W72 SE (resto/sold 2014)
1981 Turbo Pace (resto/sold 2012)
1979 10th auto (resto/sold 2012)
1979 10th auto (resto/sold 2010)


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Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #7 on: March 11, 2018, 10:20:12 PM »
Super old thread. I've been asked a few times for the photos so in time I'll update the images but will be several hours work. If urgent PM me.

Re: Installing A/C Compressor + Brackets to Olds 350 / 403
« Reply #7 on: March 11, 2018, 10:20:12 PM »
You can help support TAC!