461 head Question

[Clem Z.]

Re: 461 head Question

i understand that these heads were located from the dowl pin holes for machining and if the head was cast a "little" short then the machined ends of the casting were missed when the cut the ends. JMHO i have head blueprints here somewhere and i will see if i can find them but they are for CI bow tie heads.

[John H.]

Re: 461 head Question

Is there any logical reason for that machining process..

Tim -

As Clem noted, the two master gage holes for all machining operations were the two dowel holes; normal casting variations due to large numbers of multiple patterns would result in the external finished surface differences you noted at the ends of the heads.

[Jim S.]

Re: 461 head Question

i understand that these heads were located from the dowl pin holes for machining and if the head was cast a "little" short then the machined ends of the casting were missed when the cut the ends. JMHO i have head blueprints here somewhere and i will see if i can find them but they are for CI bow tie heads.

Clem ,

If you could locate those blueprints I would love to see them . I am still not clear on why they look that way. Maybe I am just slow and a drawing is just what I need to "get it " .

JIm

Ps, those are indeed Red Wing Slippers with the steel reinforced toe !

[Jim S.]

Re: 461 head Question

Jim,

I wanted to post back that both my 67 with 462 heads and 63 coupe with 461x heads are exactly as you describe.

Is there any logical reason for that machining process..

Tim,

Thanks for looking and reporting back . It seems like a pattern is developing here . I just looked at two more heads and they match ours as well .

Jim

[Jim S.]

Re: 461 head Question

Tim -

As Clem noted, the two master gage holes for all machining operations were the two dowel holes; normal casting variations due to large numbers of multiple patterns would result in the external finished surface differences you noted at the ends of the heads.

Hi John ,

Thanks for the reply . I know what you and Clem and Culp are trying to say , but I am still having difficulty understanding it . From the results so far , it appears that most look all the same . One side is all machined on both ends , the other side just has the double hump machined.

The reason I am having a problem is because it doesn't seem to have anything to do with allignment. I am posting two new pictures to demonstrate my confusion.

The "Both Ends Machined " side is indeed milled to the same height . (see pic #2)However the "double hump only machined " side is way off .(see pic # 1) .That is to say the double hump is machined way below the single hump depth , assuring it could not "line up " with anything.

Maybe It will all make sense if Clem can post those blueprints, And I can get on to more important matters.

Jim

[Clem Z.]

Re: 461 head Question

Clem ,

If you could locate those blueprints I would love to see them . I am still not clear on why they look that way. Maybe I am just slow and a drawing is just what I need to "get it " .

JIm

i will look but the blueprints i have are for the bow tie cast iron performance heads that were over the counter only and they are fully machined on the ends for accessory bolt on

[John H.]

Re: 461 head Question

The reason I am having a problem is because it doesn't seem to have anything to do with allignment. I am posting two new pictures to demonstrate my confusion.

The "Both Ends Machined " side is indeed milled to the same height . (see pic #2)However the "double hump only machined " side is way off .(see pic # 1) .That is to say the double hump is machined way below the single hump depth , assuring it could not "line up " with anything.

Jim

Jim -

The machining reference drawing is shown below. You'll note the two dowel holes at 0.000 and 18.000; everything is dimensionally referenced from the primary dowel hole at 0.000, and there are no references to anything on the external as-cast surfaces - they simply weren't that important (until later, when the ends of the heads were finish-machined for accessory drive attachments starting in 1969).

Flint V-8 apparently used one end of the head as a locator for some subsequent operation (probably in the automated head assembly line), and Tonawanda didn't.

[Jim S.]

Re: 461 head Question

Jim -

The machining reference drawing is shown below. You'll note the two dowel holes at 0.000 and 18.000; everything is dimensionally referenced from the primary dowel hole at 0.000, and there are no references to anything on the external as-cast surfaces - they simply weren't that important (until later, when the ends of the heads were finish-machined for accessory drive attachments starting in 1969).

Flint V-8 apparently used one end of the head as a locator for some subsequent operation (probably in the automated head assembly line), and Tonawanda didn't.

Hi John,

Thanks for that drawing .

Like you said , and I suspected , they probably used the "both sides machined" as a locator and or a flat plane , and did not care about the other side . Which begs the question however , why did they bother machining half of it ? Seems like a giant waste of time.

I guess some things we will never know . It is curious though !

Jim

[Timothy B.]

Re: 461 head Question

Thanks John for the blueprint.

I agree with Jim and question the reason for machining the humps only on the other side. I never noticed this before believing the complete side would be broched.. I don't know if we will ever know the reasoning for this.

[Jerry W.]

Re: 461 head Question

John...Thanks for the pic but there must also be another up stream pre-drilling print to account for the horizontal and verticle facing of the cast surfaces....the first cut ref. of the (machined complete) double hump end would be a starting point for other facing operations and i suspect the the other end machining would only be required on one of the bosses for subsequent ( soft jaw clamping ) to hold the part for drilling .....using the dowel hole for datum location.

i'm not familar with the GM machining line but i once got to see an automated head machining line for Caterpiller engines. It was a very long unmanned sequenced machining line and the part was untouched by human hands from beginning to end. It also included automated quality check stations that stopped the line for faults found and rang a bell for operator investigation and resolution.

Conceded :The facing operation could have been either up stream or down stream of drilling.

[Jim S.]

Re: 461 head Question

John...Thanks for the pic but there must also be another up stream pre-drilling print to account for the horizontal and verticle facing of the cast surfaces....the first cut ref. of the (machined complete) double hump end would be a starting point for other facing operations and i suspect the the other end machining would only be required on one of the bosses for subsequent ( soft jaw clamping ) to hold the part for drilling .....using the dowel hole for datum location.

i'm not familar with the GM machining line but i once got to see an automated head machining line for Caterpiller engines. It was a very long unmanned sequenced machining line and the part was untouched by human hands from beginning to end. It also included automated quality check stations that stopped the line for faults found and rang a bell for operator investigation and resolution.

Conceded :The facing operation could have been either up stream or down stream of drilling.

Jerry,

Now that makes sense . A three point set up of sorts . Line up the front (complete machining), and either than , or later , hold from at least one flat point on the rear. In fact it is the only thing that makes any sense at all.

Now I can Sleep ! Even if it is not what really happened , it's a very plausible explanation !

Thanks,

Jim