289 HiPo Fan Spacer Variations

[s2ms]

I've been taking notes over the years on the variations in 1963-1966 289 HiPo fan spacers and figured I better post my observations for discussion before I forget about it or lose the notes. All spacers are 2.36" in total length. The differences are based on four criteria:

A) Presence of either an engineering number or a "blank-out pad"
B) Dorman logo style (number present or not)
C) Location of Dorman logo relative to the engineering number or "blank-out" casting number pad
D) Weight which presumably is an indication of material differences (aluminum vs. magnesium alloy?)

I have seen the following 5 variations, photos are of variations 1-4.

1. C3OE engineering number, Dorman #(blank), number to right of logo, 5.10 oz,
2. Blank-out pad, Dorman #(blank), pad to right of logo, 5.00 oz
3. Blank-out pad, Dorman #1, pad to left of logo, 5.10 oz
4. Blank-out pad, Dorman #3, pad to left of logo, 7.80 oz
5. Blank-out pad, Dorman #4, pad to right of logo, weight unknown, (6S1757 original, on car)

Anyone with additional info on the variations or where they may fit into production sequence, if at all, please post. I assume there are more variations, like a Dorman logo with #2, but I haven't personally seen it. Also, anyone know why the engineering number would be blanked out?

Thanks,
Dave

[Bob Gaines]

Very interesting .I never had that many at one time to make a comparison like that  . Thanks for posting.

[Karguy]

Amazing, very detailed observations. I'll have to look at the spacer I have for 6S281 and see which one it is.  Thanks for sharing.
Karl
6s281

[JD]

I had some that were on very early '67 GT350's (San Jose build dates late '66)
A Dorman 4, nose damaged
A Dorman 2
and one no markings of any kind and no "blank pad"

The overall height of the D2 was 2.74"

Did not weigh any of them.

[Bob Gaines]

I have had both 65/66 and 67 hipo spacers over the years that I thought were magnesium because they were so much lighter in comparison. They were also coincidently a darker shade of silver which also made me think that they were a different material other then aluminum.

[s2ms]

Magnesium is about 1/3 lighter than aluminum so it makes sense those are the two materials, the weight differences I observed match perfectly. From what I have read magnesium is also more prone to corrosion which also matches what I've seen.

[Don Johnston]

There is also a different spacer for use with a Paxton unit. Maybe someone has the specs.

[J_Speegle]

......... From what I have read magnesium is also more prone to corrosion which also matches what I've seen.

Yes it is. It gets a chalky flat finish to the exposed surface fairly quickly as well as expands and contracts this the temp/weather also. Of course allot more visible with higher percentages of magnesium in the finished product.  Have a set of wheels on one car that I have to remove and repolish just about every ting it goes out and have to check the lugnuts every time also

[gt350hr]

There is also a different spacer for use with a Paxton unit. Maybe someone has the specs.

     There wasn't a "Paxton specific" spacer. I ran the stock hi po fan and spacer on 6S240 during the many years I had a Paxton on it. Yes fan clearance was a bit tight but it worked fine.
   Randy

[6R07mi]

Magnesium is about 1/3 lighter than aluminum so it makes sense those are the two materials, the weight differences I observed match perfectly. From what I have read magnesium is also more prone to corrosion which also matches what I've seen.

Magnesium is quite expensive, this part wouldn't require that material's unique properties,
is it possible the non-aluminum material is a die-cast zinc ??

jim p

[gt350hr]

   Zinc is heavy.  Early parts were an aluminum / magnesium alloy. They are die cast which is lighter than sand mold castings.
       Randy

[Dan Case]

   Zinc is heavy.  Early parts were an aluminum / magnesium alloy. They are die cast which is lighter than sand mold castings.
       Randy

Long ago I wanted to reduce the "height" of a used one from a salvage yard. We thought it was just aluminum but as the lathe cutting bit started removing material each chip burst into a bright flame and the chips completely burned up before getting about half way to the floor......magnesium or magnesium rich. The machinist was upset because the shop protocol for machining magnesium and its alloys required different safety equipment close to the work station. He stopped until he could get better prepared for an unintended fire.

[Bossbill]

I had some that were on very early '67 GT350's (San Jose build dates late '66)
A Dorman 4, nose damaged
A Dorman 2
and one no markings of any kind and no "blank pad"

The overall height of the D2 was 2.74"

Did not weigh any of them.

The 2.74" of the D2 is measured is measured how exactly? I can't tell for sure from the picture if it's machined surface to machined surface or from water pump pulley face to tip of pilot (incl Ford logo). The drawing looks like the later.

[JD]

I had some that were on very early '67 GT350's (San Jose build dates late '66)
A Dorman 4, nose damaged
A Dorman 2
and one no markings of any kind and no "blank pad"

The overall height of the D2 was 2.74"

Did not weigh any of them.

The 2.74" of the D2 is measured is measured how exactly? I can't tell for sure from the picture if it's machined surface to machined surface or from water pump pulley face to tip of pilot (incl Ford logo). The drawing looks like the later.