Compressor Mounting - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 6 (permalink) Old 02-18-2018, 07:39 AM Thread Starter
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Compressor Mounting

I'm swapping my '86 Bosch EFI (greasy photo below) for a '73 with Euro manifold and front cover (not greasy photo below).

Re the A/C compressor, are the bolts securing the block-off plate sturdy enough to mount the '86 bracket to support the compressor?

Thanks for your thoughts in advance. Ken
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1986 Spider Grad (one owner) converted to 1973 2L w/dual Webers in 2018, 2007 Honda Spirit VT1100C, 1980 Honda CX500 Custom, 2017 Triumph Tiger Explorer XRt, 1971 VW Beetle Convertible (complete restoration in progress for the wife)
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post #2 of 6 (permalink) Old 02-18-2018, 07:58 AM
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I haven't done a detailed stress analysis on this question, but my gut says "no, two 8 mm bolts threaded into aluminum won't support the mass and vibration loads of an A/C compressor".

A slightly better approach would be to use a Spica front cover, which has four, 8 mm threaded holes designed to secure the Spica pump. You could fabricate a bracket for the A/C compressor that mounted on those four bolts. But I can't guarantee whether that would be strong enough.

A proven approach would be to use the factory bracket that mounts to the two, large holes at the top/front of the cylinder head. That's where Alfa mounted the compressor on the early 115's with A/C. Admittedly, moving the compressor to the upper left, instead of lower right of the engine would entail a lot of re-plumbing.

Jay Mackro
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post #3 of 6 (permalink) Old 02-18-2018, 11:23 AM Thread Starter
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Quote:
Originally Posted by Alfajay View Post
I haven't done a detailed stress analysis on this question, but my gut says "no, two 8 mm bolts threaded into aluminum won't support the mass and vibration loads of an A/C compressor".

A slightly better approach would be to use a Spica front cover, which has four, 8 mm threaded holes designed to secure the Spica pump. You could fabricate a bracket for the A/C compressor that mounted on those four bolts. But I can't guarantee whether that would be strong enough.

A proven approach would be to use the factory bracket that mounts to the two, large holes at the top/front of the cylinder head. That's where Alfa mounted the compressor on the early 115's with A/C. Admittedly, moving the compressor to the upper left, instead of lower right of the engine would entail a lot of re-plumbing.
Thanks Jay. I'm not inclined to change anything on this beautifully newly rebuilt motor or the newly restored bay.

Coming soon...A/C components for sale.
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1986 Spider Grad (one owner) converted to 1973 2L w/dual Webers in 2018, 2007 Honda Spirit VT1100C, 1980 Honda CX500 Custom, 2017 Triumph Tiger Explorer XRt, 1971 VW Beetle Convertible (complete restoration in progress for the wife)
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post #4 of 6 (permalink) Old 02-18-2018, 02:07 PM
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The S3 upper oil pan has a threaded boss for the AC bracket and the S3 timing cover has a threaded boss below the distributor which I think is also for the bracket. I think that you can mount the compressor down there on a Weber S2 if you have those parts.

Ed Prytherch
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A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #5 of 6 (permalink) Old 02-23-2018, 09:09 AM
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I've mounted compressors two ways, on two different 105/115 Alfas that weren't originally A/C equipped. The first time I did it by buying a universal "York to Sanden" bracket and attaching it to the studs where the SPICA pump was originally mounted. This worked but was a major pain, and required lots of head scratching and measuring to figure out exactly where I'd need to drill holes in the bracket to place the compressor in the right location. Even then it sat further outboard of the engine than the S3 Spider method and required some "clearancing" to keep it from hitting the passenger side of the engine bay. Plus with the limited belt adjustment provided by the shimmed pulley I then had to figure out what size belt would be needed by trial and error.

You could possibly try something similar with the fuel pump studs but I would recommend against it. You'd be using half as many studs as I did with the SPICA pump mount and it was a major pain in the butt anyway.

The second time around (on my current '74 Spider project) I got smart and used an all Alfa-engineered solution. S3 front cover, S3 oil pan, S3 pulley, S3 bracket. Far easier and much more stable.

My suggestion is that if you aren't willing to do it right - meaning swap over the correct front cover and oil pan - you're probably better off doing without air conditioning.

Jason Arrington
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post #6 of 6 (permalink) Old 02-23-2018, 03:01 PM Thread Starter
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My suggestion is that if you aren't willing to do it right - meaning swap over the correct front cover and oil pan - you're probably better off doing without air conditioning.
I agree. Until I have to remove the front cover, I'm going without.

1986 Spider Grad (one owner) converted to 1973 2L w/dual Webers in 2018, 2007 Honda Spirit VT1100C, 1980 Honda CX500 Custom, 2017 Triumph Tiger Explorer XRt, 1971 VW Beetle Convertible (complete restoration in progress for the wife)
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