Topic: 5 bolt to 6 bolt changeover

[acman63]

is there a definite date that Ford went from 5 bolt 289 blocks to 6 bolt blocks

[J_Speegle]

I don't know Jim. Haven't collected type of block and casting dates for them over the years  

Maybe someone else has an idea.

[jwc66k]

Bob Mannel's book (Mustang and Fords Small Block V8) indicates the change was documented by change lever L5 that ". . occurred at the beginning of 1965 production. ." that extended from July 1964 thru February 1965. Mannel did extensive research into this but apparently did not discover an "absolute" date.
Jim

[acman63]

Im sure they used up the existing inventory until they had full production going on 6 bolts  Thanks for reminding me about Bobs book

[Dan Case]

From Bob Mannel's book, quoting other sources, Monday August 3, 1964 is the earliest known assembly date for any production six bolt 289 engine. (I said production as prototypes and engineering test units were being made as early as 1963 if I recall correctly.)

For whatever reason when Shelby American (SA) required an order of five bolt HP289s in August 1964 Ford built up engines for the purpose. Ford stopped issuing serial numbers to five bolt HP289 engines in July 1964. For whatever reason Ford used some parts just like July 1964 engines and some parts just like late August 1964 engines in a mix to furnish 48 each strange engines to SA, a mixture of 1964 model year parts and 1965 model year parts. The assembly tags indicated 1964 engine assembled during the 1965 model year in a combination Marti could find no Ford documentation of.  Ford master parts lists are not much help with those 48 units.

[Burgundy66]

I know this is an OLD thread, but I thought I'd post here, as I found something interesting today on this very subject.

Concerning changeover from 5-bolt to 6-bolt, I have a July 8, 1964 C5 block casting 289 in a car on my lift right now, and this engine is a 6-bolt.  Engine assembly date was July 24, 1964.  Heads are similar early July castings.  But main point is this July 8 casting is a 6-bolt.  I know there?s no special prize 😁, but that?s ahead of the August 3 date quoted in the book by nearly a month.

We are in the process of pulling the engine and transmission right now, starting a full restoration of the car. So I?ll have some pictures to post in the next few days.

And?.this is not the original engine to the car.  It?s a January 19, 1965 scheduled build for the car, and I need a December ?64  289 if anyone has one.  Last fun point.  In the process of searching for a December ?64 289, I have unearthed a complete D-code 289 that the seller checked and the assembly date is July 23, 1964?..one day before mine. Don?t know if it?s a 5 or 6-bolt, but now I?m gonna check that out!  I may buy it just to find out what it is, lol.

Thanks, Kevin

[jwc66k]

What is the engine code in the VIN? Ford made "change overs" with the general instruction to the assembly line to use old inventory first. In most cases, that was followed, but Ford was in the business of making and selling cars, not being a precise "numbers institution".
Jim

[Dan Case]

In my notes I routinely see weeks between when a raw cylinder block casting was produced and when the completed engine was built and some more time went by before a given engine installation into a vehicle. 1964 Examples:
Block Cast           Engine Assembled
June 4                August 25 (82 days) (1964 five bolt HP289, went to Shelby American for a new Cobra)
August 6            September 4 (29 days) (1965 six bolt HP289 Fairlane automatic transmission engine)

Said another way, if Ford's plan was to start putting six bolt engines in new cars was about the first week of August 1964, six bolt type cylinder block castings made weeks to months before hand makes perfect sense.  What is interesting to me is that July 24 engine assembly date. Ford would have had to have made complete engines in advance of new car 'change over' in new cars.  Bear in mind that not all assembly plants would have stopped old and started new the same day most likely.

The transition from five bolt to six bolt bell housing designs at the engine assembly plant level was not mutually exclusive, i.e. Ford could make either design engine as they wished or needed and they did. It that way last of this and first of that was a fuzzy subject. Ford made five bolt service long block assemblies and new engines for quite a while after no new car still received them.

[jwc66k]

Also, Ford built the majority of its cars to marketing forecasts, known for it vast "hindsight" (in other word, often wrong but close).
My "K" block was cast on 5H11 (Aug 11, 1965 - on block), assembled on 5H23 (Aug 23, 1965 - per stamping on block), scheduled assembly line date of 18K (Oct 18, 1965 - per door data tag) and sold on Oct 28, 1965 (per owners manual).
Jim

[RoyceP]

  In the process of searching for a December 64 289, I have unearthed a complete D-code 289 that the seller checked and the assembly date is July 23, 1964?..one day before mine. Don?t know if it s a 5 or 6-bolt, but now I?m gonna check that out!  I may buy it just to find out what it is, lol.
Thanks, Kevin

I had a D code early 1965 Mustang. It was a 4 speed, generator equipped 5 bolt bellhousing. I would expect any D code to be the same as the D engine would have been installed in cars prior to the official start of the 1965 model year.


I can see both 5 bolt and 6 bolt engines being assembled pretty much simultaneously at the engine plant. Not a lot of difference other than the block casting.

[Burgundy66]

What is the engine code in the VIN? Ford made "change overs" with the general instruction to the assembly line to use old inventory first. In most cases, that was followed, but Ford was in the business of making and selling cars, not being a precise "numbers institution".
Jim

This July 64 six bolt engine came out of a C code coupe, Dearborn built, January 19, 1965 scheduled date. Clearly not the original engine for the car.  Understood, and agreed completely about build outs, not worrying about numbers in production, and using up older inventory. Being in engineering/manufacturing, this is common, no matter what industry.  I just wanted to pass along what I thought was kind of odd. Very early six bolt engine.
Kevin

[Burgundy66]

Couple of pictures.  Block is July 8, 64 casting from what I can tell.  And July 24, 64 assembly. 

[Burgundy66]

Also, I contacted the owner of that D-code that was assembled the day before this engine.  He?s going to check and see if his is 5 or 6 bolt.  And try to get a casting date code.  Just for fun.  I?ll post back what we find.

[krelboyne]

I have worked in Manufacturing a good portion of my life.

There would be too many variables to have an exact change over date between 5 and 6 bolt blocks.
The starting date may have been recorded, when the first block casting, came out of the first mold, at the foundry(s).
Then again, it may have been recorded, when the first 6 bolt engine assembly was assembled.

Do we know if Ford was using both Cleveland and Windsor foundries in this time period? I could not find the information.

Not sure that Ford would have tried to pull off a clean changeover. Scheduling is everything, changeovers need to be done on the fly.
Normally you change over one line at a time.

Ford would have also had to coordinate inventory of manual and automatic bell housings.

[Dan Case]

Couple of pictures.  Block is July 8, 64 casting from what I can tell.  And July 24, 64 assembly.

Interesting. Did the engine have a 1963-64 model year design oil pan or a 1965 model year design oil pan. Was it configured for a generator or alternator (different dip stick tubes and dip sticks) plus hole size in the RH cylinder head for a mounting bracket bolt?