Chief Z metal flywheels

[tfburke3]

Since there did not seem to be a definitive answer to my question as to when the first Chief Z metal flywheels appeared,I will add the following new to me info.
There is an ebay listing for a 1939 parts catalog(that I cant afford).
The book show a pic of the flywheel section,listing 36-38 74 and below a listing for 1939 74 Z
Based on this I would conclude that 1939 was the first year of the Z metal wheels.Maybe late 1938
Any info on this appreciated,
Thanks
Tom

[tfburke3]

Cdf is I believe correct.
Earlier round hole gusseted have less material than later as the gusseted area is all filled in and rounded out.If you had both in your hand its pretty obvious.
I thought the Z wheels would be an easy question.
Thanks
Tom

[fillibuster]

The slot tops are the later rods. The 80" rods are also slot tops. I'm 100% sure that even though Indian didn't assign a different part number, that the slot tops are mid 40's to the 53's.

yer giving me doubts, on my theory: that as time went on castings left more material (the gussets in top) in the work, as with more cooling fins, beafier bases, trans cases with more material in the later years at mounting surfaces, larger fins on heads, ... as if the molds were simply chisel'd out in previously weak areas. Have to study those gusset and slot-tops some more.
Still no answer on the Z timing.

[cdf6333]

The slot tops are the later rods. The 80" rods are also slot tops. I'm 100% sure that even though Indian didn't assign a different part number, that the slot tops are mid 40's to the 53's.

[tfburke3]

If I recall, the round-hole tops also have a "gusset" on each side under the wrist pin boss. These are the last run of rods, I was once told, good for 80" work. Figures they would be heavier up there. ... I always thought the round hole rods were 1948+.

The round hole rods with gussets are I believe weaker as the gusset area is all filled in and rounded covering up the gusset area in the slot top rods.80 rods are beefed up in the lower female rod end.
And Z metal wheels were first introduced in????

Tom

[fillibuster]

I match the Z flywheels with slot top rods and earlier flywheels with the round hole top rods. So far it has saved a good amount of time static balancing the combos. This week I did slot top rods with Truett and Osborne flywheels and had to remove a lot from the counter weight side of the wheels.

If I recall, the round-hole tops also have a "gusset" on each side under the wrist pin boss. These are the last run of rods, I was once told, good for 80" work. Figures they would be heavier up there. ... I always thought the round hole rods were 1948+.

[cdf6333]

I match the Z flywheels with slot top rods and earlier flywheels with the round hole top rods. So far it has saved a good amount of time static balancing the combos. This week I did slot top rods with Truett and Osborne flywheels and had to remove a lot from the counter weight side of the wheels.

[tfburke3]

Interesting question, I don't know but while on the subject, did the change to Z flywheels and slotted top connecting rods happen at the same time? I'm pretty sure it did, in my years of balancing engines I found the round top hole type rods to be a consistently heavier than the slot tops.

Thanks Red dog and Bob,
I would not guess 33 as I have a 34 that I rebuilt and it had the earlier non z.I thought maybe with the y motors of 35 and later but cant find a reference.
Im building a 35 and have cherry earlier wheels or beat up z metal so was curious.Probably just look for better z wheels.
Thanks
Tom

[cdf6333]

Interesting question, I don't know but while on the subject, did the change to Z flywheels and slotted top connecting rods happen at the same time? I'm pretty sure it did, in my years of balancing engines I found the round top hole type rods to be a consistently heavier than the slot tops.

[fillibuster]

What was the first year Chief to have the later type Z metal flywheels?
Thanks
Tom

Just a guess here: Let's see, DuPont criticizes the "soft" wheels in letter to his quality control dept in 1930. Changes to dry-sump oiling in 33, chain primary in 34...... I'll say 1933.
I'm NOT sifting through the Redskin book until I've seen 5 more guesses.

[tfburke3]

What was the first year Chief to have the later type Z metal flywheels?
Thanks
Tom