No, I don't think the position of the dowels changed.  It is simply that the reduced thread engagement caused by the counterbore caused issues, which a longer bolt fixed.

Now that makes sense. Reduced bore thread as a result of the dowel insertion.


THANX!

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No, I don't think the position of the dowels changed.  It is simply that the reduced thread engagement caused by the counterbore caused issues, which a longer bolt fixed.



Lawrenceville, GA

So of what Charlie posted, the dowels were moved further into the block (machining protocols - both early and late used the same dowels according to the MPC), for whatever reason and the added depth required longer bolts at the dowel locations?

This change came on the first run 1956 production? Wonder if FORD had gasket sealing problem(s) on the 54 and 55 block?

Learn something new everyday.

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I have had no issues using the four longer bolts at the top end holes in the heads on the ’54-55 Y engines.  As Charlie and the Ford Bulletin mentions, thread retention on those four particular holes (two per side) is improved when using the longer bolts.  When using the ARP head bolts, I will install the bolts first without the washers to ensure that the bolts do fully seat against the bolt heads before removing to install the washers and then torquing the bolts.  When milling the heads and blocks, the head bolt thread lengths do get dicey.

Lorena, Texas (South of Waco)

The bulletin does not explicitely say, but I guess it was ok to use the longer bolt in the 54's and 55's since there was no warning about not using the longer bolts in the 54 and 55 engines.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

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71% of original size (was 709x19) - Click to enlarge

64F100 57FAIRLANE500

The Upper end holes loose some thread length because of the counterbore for the dowels.  I would guess that there were some problems as a result of the reduced thread engagement that caused them to lengthen the end bolts.  Another possibility is simple human error.  Maybe the original intent was to use longer bolts but somehow the documentation had an error.  I would expect bulletins to exist for either of these.



Lawrenceville, GA

That agrees with what I have seen.  My ’55 272 had all the same length bolts on the top row.  When I rebuilt the engine, I installed the longer 1957-up bolts in the end top row holes.

I am trying to figure out the why of FORD going to different length head bolts in the mid/late 1956 production year. There were several changes also made (valve-train) along with this.

Rhyme or reason? Is the difference(s) in the head or block casting?
 
I would think a SERVICE LETTER was released regarding this.

- CORNFUSED IN W(BY GOD)V ...

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