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Re: [GMCnet] 403 Crankshaft Needed [message #323426 is a reply to message #323423] Tue, 05 September 2017 21:03 Go to previous messageGo to previous message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
Senior Member
Yeah, I've found several references to 403 & 350 cranks of several
different casting numbers and one mention of at least a 200 gram difference
in the 403 & 350 pistons -- no mention of the rods. Another mention of
having to add heavier metal weights to the counterbalances. All-in-all,
too darned much trouble.

I think John's biggest objection to cranks turned at all is that the
bearings he prefers are only available in std. size. We'll have to talk
more.

Ken H.


On Tue, Sep 5, 2017 at 9:57 PM, Gary Kosier wrote:

> Ken,
>
> The 403 is a part # all on its own. While the dimensions are all probably
> the same, the 403 has a slightly heftier connecting rod an a much heavier
> piston by virtue of it's larger diameter. So the balance would be
> different.
> John could probably rebalance the 350 crank, but that adds to the expense.
> Now I'm looking in the 76-81 parts book(the last printed book) and they
> list 3 different cranks for a 350 gas engine. I didn't root long enough to
> find out the difference.
>
> Gary Kosier
> 77 PB w/500 Cad
> Newark, Ohio
>
> --------------------------------------------------
> From: "Ken Henderson"
> Sent: Tuesday, September 05, 2017 8:11 PM
> To: "GMC Mail List"
> Subject: [GMCnet] 403 Crankshaft Needed
>
> Another parts request: Does anyone one have, or know a source for, a 403
>> crankshaft. Local engine builder John Beaver wants to build a standby
>> 403. He has a core from a recent rebuild, but #7&8 rod bearings spun and
>> #1&2 were about to. He doesn't want to build an engine with undersized
>> journals, so he needs a good crankshaft.
>>
>> That's not a problem with 455's since NEW crankshafts are available (like
>> in Rick Denny's new engine); but, AFAIK, no new 403 cranks yet. I THINK
>> the Olds 350 crank is the same as that for the 403, but need authoritative
>> confirmation of that.
>>
>> Let me know & I'll pass the word to non-internet-active John B.
>>
>> Ken H.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
 
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