Dear Slant Six Sages,

I need to grind a mid-80s cast crank and put new main and rod bearings into my 64 Dart engine.

#2 and #3 mains have significant wear due to some questionable oil control and high rev issues (note to self: check oil and top off before running autoX, and get a rev limiter...). Rod bearings and #1 and 4 mains are almost all fine, with only a touch of wear. Crank has some small scratches on #2 and #3 main journals.

Do folks here have opinions about bearing materials and clearances on such a motor? I set the mains up at 0.0023 - 0.0025" clearance and I don't recall what kind of bearing but I believe NORS Clevite/Michigan 77s.

ACL, FM, Mich77 and Clevite77 can all be bought now. ACL appears to use aluminium facing and others may have the older and softer tri-metal. It seems the tri-metal may be better for hipo applications, but maybe aluminium is OK too? Is aluminium better for cast vs. forged cranks?

It appears that ACL makes bearings with "3/4 groove", but I have not ordered a set to see. I don't usually trust pics online as they can be too general. I may do "full groove" mains as the groove width is not large on the cast crank bearings, and I've never tried it. The bearing sets are cheap these days.

I would especially like to hear from Dennis, Greg, Ron H, Seymour, and Will, if you guys have opinions or experience (cast or forged crank motors). Anyone should feel free to chime in! I plan to call Mike J as well.

Let me know your thoughts and many thanks!

Lou

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Home of Slant6-powered fun machines since 1988

I really have no cast crank experience, but you can't go wrong with just a set of Clevite 77s. Aluminum has always been considered drag race high rpm stick stuff.

If you can get full groove you will be better off, but it's not super critical.

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Official Cookie and Mater Tormentor.

Whether or not you buy bearings there, you might very well want to take a swing by Old Car Parts Northwest since you're in the neighborhood.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Have a read thru the Mahle/Clevite catalogue,they have a good rundown of comparisons of 1/2...3/4 and full groove bearings,pretty much proved that half groove was the best option.

I believe in Clevite 77 half grove. That being said i think Clevite has dropped our bearing. After I stopped messing with full grove I stopped tearing up rod bearings. I have used both 2 sets to get a full grove and ground one in my self.
.0025 clearance, or a little more for me.
All this has been on a forged crank.
Will

Thanks, Will! All info is much appreciated. I have never tried full groove and it sounds like that probably is not the way to go. I have done 0.002" on the mains for forged crank, but it sounds like I can go bigger. I ran bigger on the cast crank due to the higher factory specs.

Best,
Lou

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Home of Slant6-powered fun machines since 1988

1/2 groove as mentioned.

use oil with at least 1200 ppm of zddp.

.002" is really enough on a stock engine if good oil is used, especially with 1/2 grooved bearings.