Don Terrill’s Speed-Talk

I am looking for the bolt and dowel locations for a 1965, 5 bolt 289. I have to make an adaptor to bolt on to the dyno bellhousing. I can mount the block in the cnc machine and pick up the locations but it would be better to have the real numbers. This older stuff is not very accurate. Thanks, Kaase

https://www.fordmuscleforums.com/attach ... -jpg.1140/

https://www.fordmuscleforums.com/attach ... -jpg.5367/

Hope that's what you need Jon

Edit: Sorry just seen 5 bolt block, so assume it's different. MY BAD

One thing to remember, is the 5-bolt block/bells only used 3/8" bolts instead of 7/16" like the 6-bolt variety. Would be a shame to find all the dimensions, then use the wrong bolt size.

Every try finding an old 5-bolt bell housing, and using that for a pattern?

Good Luck

I am convinced that Ford had one engineer that made himself important by changing the bellhousing pattern every year. I would bet there are 15 different patterns for all the V-8’s. The 5 bolt was 62 to 64 1/2, 221, 260, 289”. 3/8” bolts and 3/8” dowels

---this might be what you are looking for

http://vb.foureyedpride.com/showthread. ... -fox/page2

JonKaase wrote: ↑Sun Mar 22, 2020 8:57 pm I am convinced that Ford had one engineer that made himself important by changing the bellhousing pattern every year. I would bet there are 15 different patterns for all the V-8’s. The 5 bolt was 62 to 64 1/2, 221, 260, 289”. 3/8” bolts and 3/8” dowels

If you reverse engineer the pattern, be aware that Ford typically used only two decimal places for their block dimensions. If something measures 3.378", it's likely meant to be 3.38", not 3.375".

Also, did you get my PM with the Ford engineer's contact info? He's pretty good, if that info is still in the archives at Ford, he will likely find it.

Charliesauto wrote: ↑Sun Mar 22, 2020 10:08 pm
If you reverse engineer the pattern, be aware that Ford typically used only two decimal places for their block dimensions. If something measures 3.378", it's likely meant to be 3.38", not 3.375".

Also, did you get my PM with the Ford engineer's contact info? He's pretty good, if that info is still in the archives at Ford, he will likely find it.

Many of those dimensions were fractions... and just reported to two decimal places.
For example, a 289 has a 4" bore and a 2-7/8" stroke. 7/8 is 0.875, but in books it is listed as 2.87".
Rod lengths are the same. When Ford stroked the 289 by 1/8" to make the 302, the rod length got shortened by 1/16". In books, it's all truncated/rounded decimals.

n2omike wrote: ↑Sun Mar 22, 2020 11:35 pm

Charliesauto wrote: ↑Sun Mar 22, 2020 10:08 pm
If you reverse engineer the pattern, be aware that Ford typically used only two decimal places for their block dimensions. If something measures 3.378", it's likely meant to be 3.38", not 3.375".

Also, did you get my PM with the Ford engineer's contact info? He's pretty good, if that info is still in the archives at Ford, he will likely find it.

Many of those dimensions were fractions... and just reported to two decimal places.
For example, a 289 has a 4" bore and a 2-7/8" stroke. 7/8 is 0.875, but in books it is listed as 2.87".
Rod lengths are the same. When Ford stroked the 289 by 1/8" to make the 302, the rod length got shortened by 1/16". In books, it's all truncated/rounded decimals.

Block dimensions are two place decimals on the blueprints. For example bore spacing on a SBF is spec'd as 4.380" and is actually that, not 4-3/8" .

https://files.eric.ed.gov/fulltext/ED368987.pdf

With blueprints made in fractional inches you need to know the tolerances as this will guide the number of decimal places. See page 45.

When you are using a CMM to reverse engineer a part you need to know the units used to design that part. You need to make the assumption that the machinists were trying to replicate a blueprint and to use that knowledge to work backwards to the intended point in two-space or three-space.

Most of the Ford machining I've seen has been consistent enough per any given fixture. Now to say the bellhousing end is dead nuts with the timing cover end or the cylinder head deck might be a stretch. We had to surface the timing cover end of a block once, stood it up on the bellhousing end clamped it down. .025" out of whack , we shimmed about half of it out and said its better than it was.
I think I would build as accurate as possible to the block you are going to use. It will still work fine for other projects that probably won't get the level of attention this one will.

n2omike wrote: ↑Sun Mar 22, 2020 11:35 pmMany of those dimensions were fractions...

Lots of engineering and machining in the USA operated in fractional inches until WWI, when several Detroit automakers and other prime contractors petitioned the War Department to standardize on decimal inches to make dealing with subcontractors easier. Most everyone went to decimal engines and stayed with that. Ford stayed with fractions internally at least through the Y-block; I've seen old Y-block stuff dimensioned in 64ths and 128ths.

Ford engineers, thought like most people, born before ~1980, think in fractions. The USA was suppose to convert to MM, around 1970 but, that didn't happen until much later.

I'm a machinist and even though I know millimeters, I think in factions and decimals and convert with 25.4. I'm posting a Ford drawing, from ~1933, it does not have any fractions on it but, only decimal equivalents of fractions, as well as rounded off fractions and whole decimals. You will see drawings that have fractions but, other than a fraction, here and there, it will be 90% decimal, if it comes from a engineer.

I can't speak for machines, made before 1900 (I have a machinist book dated ~1902) but, all the machines that I have seen back to ~1920, have lead screws that give movement in 1/10 (.100) and more commonly, 1/5 (.200). To make a movement of 1 1/16", you count 5 revolutions (1.0"), then go to 62 and 1/2 divisions. So, a machinist only works in decimals, whether fractions or MM. But, today, we have DRO's you can switch it to MM but, NOT fractions.

Drumroll...

ANNUAL MEETING OF THE
SOCIETY OF AUTOMOTIVE
ENGINEERS
Held at
Engineering Societies Building
New York
January 10 and 11, 1917
MEETING OF THE STANDARDS COMMITTEE

https://www.jstor.org/stable/pdf/44716140.pdf
I will leave it to the mathematically inclined members to determine which of the following MM/inch ratios belong to which fractional (and/or decimal !!) blueprint specifications in Fig. 1.

Yes !!! They are all different but "almost the same."

25.173333
25.369369
25.396825
25.428571
25.263157

We settled on 1 in. for the short diameter of the hex; this should
be 25 millimeters. There was a discussion whether it should be 25 or
26 mm. but as I remember, we decided on 25 mm. as being almost the
same as an inch

Since 1933, the official length of 1" in MM, is 25.4. At that time, it was 25.400051. Even so, most of those conversions are wrong.

The post drawing was a part, designed in MM and someone did a very soppy job converting the dimensions to inch.

The British Standards Institute defined the inch as 25.4mm in 1930 in the document "Metric Units in Engineering: Going SI". In March 1932 the American Standards Association were asked to rule on whether to adopt the same value (at the time the American inch was 1/.03937 mm which approximated to 25.400051 mm). Because the values were so close, and because Britain has already settled on that value, the ASA adopted this value on March 13, 1933.

During the two WW's, we also dealt in "Points", the Russian standard of measurement. 1 "Point" = .1 inch.

Most all ball bearings are MM (there is a series of inch bearings but, they are not widely used). The reason that, that came to be, is that they where designed and patented in France (as I remember) and the sizes never change.

Of course if your building a Ark, you have to deal with Cubits