Early and Late 1959 Cadillac 390 crank???

[NATEUDD]

I recently purchased a 1959 390 engine that had been rebuilt by a machine shop and never picked up.  The Machine shop has had it for a couple of years and sold it to me.
The short block is assembled, heads are off.  It is missing the timing chain.  I was going to use my 1960 390 chain and sprocket set on it but found out the 1960 9/16 crank bolt is too big for this 1959 390 crank.  I have found very little information about this but did find a post on another forum that stated there are early 1959 390's and late 1959 390's .  The early ones used a smaller front crank bolt that is 1/2"-20 x 1-3/8".  The forum also stated that the crank stroke is different on the early 59 390 than it is on the late 390.  Perhaps i am over thinking this but is this true and first question is where can I find a 1/2" crank bolt for the early  390 and will a standard 1959-1962 timing gear and chain set work on this engine?  I looked up part numbers for a 1958 365 and they appear to be different timing gears and chain than what is listed for a 59  390-   Help??  Block casting #1469230 and crank casting # is 1463340 .  Milodon # 84532 shows a crank bolt and washer kit that appears to be the 1/2"-20 x 1 3/8"   does anyone know if this will work??  sorry for all the questions and information but became a little worried about my purchase when I tried to run a 1959/60 bolt into the front of the crank.   Who can tell me if there is truly an early 1959 390 with a 1/2" damper crank bolt that shares the same crank casting number as a 1959 with the standard 9/16" bolt?

[Caddyholic]

rock auto has the chain and sprockets. The 365 crank sprocket and chain are different part Numbers.

[savemy67]

Hello Nate,

You should be able to get a 1/2-20 bolt from any fastener vendor, although you may not find one that is 1 3/8" long.  You can always cut to length a longer bolt, and there is probably not an issue with using a 1 1/4 inch bolt - though I will defer to the 390 experts.

What was the other forum that indicated early and late 390's?  If an early 390 stroke is different, then the bore must be different to maintain a displacement of 390 cubic inches.  I can see a change in the crank bolt, but a change in the bore and stroke within the same model year seems unlikely - although I again defer to the 390 experts.

Since you have the short block with the heads off, measure the bore and stroke and compare the results with the shop manual specifications.

Respectfully submitted,
Christopher Winter