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Any machinists want to tackle the forged crank into the cast crank block?
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Author:  hyper_pak [ Thu Feb 29, 2024 2:44 pm ]
Post subject:  Any machinists want to tackle the forged crank into the cast crank block?
1st, please don't ask why you would want to do that questions!

The trick is 4 spacers inserted on the sides of the thrust bearing and using a forged crank thrust bearing.
Second, it looks pretty simple.
2 spacers made from aluminum, thrust bearing location, one on either side.
One .060, one .090.
They look like this, but need 4 spacers total, top and bottom.

????
Dave, Mark, others???

Attachments:
Crank Spacer 2.JPG
Crank Spacer 2.JPG [ 34.69 KiB | Viewed 710 times ]
Crank Spacer 1.JPG
Crank Spacer 1.JPG [ 54.17 KiB | Viewed 710 times ]
Author:  ProCycle [ Thu Feb 29, 2024 3:04 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Any specific reason to make the spacers out of aluminum?
They would be easier to make in steel.
Author:  hyper_pak [ Thu Feb 29, 2024 3:24 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
No steel is fine also.
The pictures are from youtube, they used aluminum.
Author:  Charrlie_S [ Thu Feb 29, 2024 3:52 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
1st, please don't ask why you would want to do that questions!
I'm going to ask Why. To me it doesn't make any sense. I could see trying to put a cast crank into the forged crank block. Narrower bearing for less drag, and lighter crank for faster/higher revving.
Please splain your reasoning to me.
Author:  volaredon [ Thu Feb 29, 2024 4:59 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
Quote:
1st, please don't ask why you would want to do that questions!
I'm going to ask Why. To me it doesn't make any sense. I could see trying to put a cast crank into the forged crank block. Narrower bearing for less drag, and lighter crank for faster/higher revving.
Please splain your reasoning to me.
I second that
Author:  Rick Covalt [ Thu Feb 29, 2024 5:07 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
Please splain your reasoning to me.
You know he could tell you but you know he'd have to kill you, so it is better that you don't know! :mrgreen:
Author:  Jimmy [ Thu Feb 29, 2024 5:10 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
Any specific reason to make the spacers out of aluminum?
They would be easier to make in steel.

I would disagree. Aluminum is much easier to turn but steel would be better.

It will cost more to make these than a crank or different block. I know you didn't ask for this info but thought I would put it out there. 30+ years of manufacturing here.
Author:  ProCycle [ Thu Feb 29, 2024 6:06 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
I would disagree. Aluminum is much easier to turn but steel would be better.

It will cost more to make these than a crank or different block. I know you didn't ask for this info but thought I would put it out there. 30+ years of manufacturing here.
If you used steel they can be made very precisely flat and parallel on a surface grinder. That would yield a much better finished product and the machine work would be very straightforward even for an unsophisticated machine shop. It would not take any special skill or luck to make them very accurately. It would even be easy to 'adjust' the fit if it was a little too tight.


@hyper_pak - Instead of shims did you consider having the thrust surfaces on the crank welded and re-ground to fit the cast block thrust bearing?
Author:  hyper_pak [ Thu Feb 29, 2024 6:09 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
All they have to do is locate the trust bearings in the correct location.
I like the steel idea, it's would take the trust loads better.
Author:  hyper_pak [ Thu Feb 29, 2024 6:10 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
No don't want to weld and machine.
I just want a drop in solution.
If I had a design document I could get a shop to make them.
If.
Author:  volaredon [ Thu Feb 29, 2024 6:39 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
I seen a YouTube showing a magazine that did a forged crank into a cast crank block not long ago. And since, there has been questions as to why. I haven't seen anything answering that so far.
Author:  Jimmy [ Thu Feb 29, 2024 6:48 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
Quote:
Quote:
I would disagree. Aluminum is much easier to turn but steel would be better.

It will cost more to make these than a crank or different block. I know you didn't ask for this info but thought I would put it out there. 30+ years of manufacturing here.
If you used steel they can be made very precisely flat and parallel on a surface grinder. That would yield a much better finished product and the machine work would be very straightforward even for an unsophisticated machine shop. It would not take any special skill or luck to make them very accurately. It would even be easy to 'adjust' the fit if it was a little too tight.


@hyper_pak - Instead of shims did you consider having the thrust surfaces on the crank welded and re-ground to fit the cast block thrust bearing?

Thinking I didn't know what he was asking for. If it is flat I agree. My bad.
Author:  hyper_pak [ Thu Feb 29, 2024 6:50 pm ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
The Engine Power program used either a turbo or blower, don't remember right now.
So their reason was they wanted the strength of the forged crank for the higher power levels.
So there is one possible answer.
Author:  Dart270 [ Fri Mar 01, 2024 2:31 am ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
80s cast crank block weighs typically 22-28 lbs less than a forged crank block. Both cranks are plenty strong unless you go beyond about 400 HP, then forged is your deal.

Lou
Author:  volaredon [ Fri Mar 01, 2024 4:59 am ]
Post subject:  Re: Any machinists want to tackle the forged crank into the cast crank block?
The cast crank is also lighter than the forged, and though I never could afford to have a toy that I could just let sit around and have to be trailered everywhere it went, only to come out a handful of weekends a year, it's been said that the cast crank is actually pretty robust also. If you're at power levels that you don't think the cast crank made for the cast block will work you're probably better off with a block made for the forged crank as well with it's wider bearing for more support.
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