Thread: 327 and 350 Blocks Interchangable?

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Hello again! Since my last post about my 'water problem' I've discovererd a crack in my block. I know where I can get a GM Goodwrench 327 block and I've been told that a 327 is the same as a 350 except for the crank and the harmonic balancer "More or Less". I was raised around Oval engines so you can see why this seems too good to be true. Any thoughts?

Thanks for the help!

~Jim

All 350's and a few of the last 327's were produced with large journal cranks (2.450" mains, 2.100" rods). The earlier 327's were produced with small journal cranks (2.300" mains, 2.000" rods). The change was made around 1968. Hope this helps.

if they were the same then they would be called 350's.joking aside yes they had different cranks and the bore's are diff good luck

Externally, and accessory wise, yes; internally, no-o-o! Cranks, bore, depending on the year of manufacture, and provisions for venting and smog.

327 and 350 engines both have a 4" bore. The 350 has a 3.48" stroke vs the 3.25" stroke of the 327. All 350s have 2.45" mains, but 327s had 2.3" mains until 1968 when the mains were enlarged to the same size as the 350. So, if you've got a '68 or newer 327 block, the crank will fit. If earlier, it won't.

Bob

I second what Bob said. He is absolutely correct. 68 and newer 327's used the same block as the 350's. Some were even 4-bolts.

I had a 327 for several years that was built from a 69 crank , rods and pistons and a 70 something 4 bolt block, It ran so nice that I am going to do it again for my 55 Willys PU

A few years back I built up this one using late model 327 crank and rods and a 350 block, never had any issues putting it together and it ran great for years.

Good luck with your project...

Dave Brisco

Most crank grinders would turn the mains on the 350 crank down to 2.300 if that is what you want. In the early 383 days i used to get the 400 cranks turned down. Now with Eagle, scat and various other companies making new ones its almost not worth the hassle.