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Jul 21st, 2025 | | | | Joined: May 2008 Posts: 114 Shop Shark | | Shop Shark Joined: May 2008 Posts: 114 | Can anyone tell me if the main bearing caps on a 409 truck engine are the same as on a 348 truck? Both types look the same and have the same casting number (938). Are the crankshafts the same or are they of a diff. stroke? Thanks
James | | | | | Joined: Nov 2005 Posts: 6,061 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,061 | Hy oldiron57, according to my parts book, all the main caps listed are the same for 348 and 409, but there is no rear main cap listed in my book, rear main caps are listed for all the others but not for the 348/409. As far as crankshafts go, they are not the same stroke, the 348 has a stroke of 3.250, and the 409 has a stroke of 3.50, hope that helps | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | You cannot interchange the main caps without haveing it line bored.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: May 2008 Posts: 114 Shop Shark | | Shop Shark Joined: May 2008 Posts: 114 | I appreciate your quick reply, it confirms what I thought would be true about the main caps. I have several 409 and 348 truck engines (VERY RUSTY) that I'm pulling parts off before disposing of. Many thanks for the info!!
JAMES | | | | | Joined: Dec 2001 Posts: 14,522 Moderator: Welcome Centre, Southern Bolters, Legion Hall | | Moderator: Welcome Centre, Southern Bolters, Legion Hall Joined: Dec 2001 Posts: 14,522 | James, after you get what you need don't send the parts to the salvage yard..... put them on the swap meet... especially if you have a complete motor. I wish I'd never sold mine  | | | | | Joined: May 2008 Posts: 114 Shop Shark | | Shop Shark Joined: May 2008 Posts: 114 | Anything of any value that I don't need will certainly go to the swap meet. Many of the motor parts are too far gone due to rust so I know they would only be worth scrap value.
Appreciate your interest! JAMES | | | | | Joined: Feb 2004 Posts: 110 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2004 Posts: 110 | On main bearing caps, I know that line-bore is very critical, but many years ago I had one break and I went through six or seven sets of caps from junk engines using plasti-gauge at three points until I had one that read in the specs. I built that engine and it ran for years. Just a personal experiment that might save someone's engine block.
Truck Tinker | | |
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