Question for you guys: Is the bolt pattern on the rear of a 348/409 W block, the same as the later BBC 396/427/454 ? For transmission bolt on, or just attaching to an engine stand ? Thanks Jim
Yep, that's one thing I do like about Chevy over Ford, one transmission bolt pattern instead of 3 or 4....
Exactly. What about Cadillac V8's, and Pontiacs, and Buicks, and GMC 6's, and oh yeah, kind of starting to look like Ford now isn't it???
not really, the non Chevy GM V8 and V6 engines all converged on the BOP design by 1967. The small V6 and 4 cyl bolt pattern which was first used around 1980 also was a standard, used on many different engines, both front and rear wheel drive.
True, but most HAMB'ers like to play with the pre '67 Caddy and Olds motors. All sorts of bellhousing fun can be had with those things. I never had to find a starter cross over for a Ford motor.
If you include Merc, Edsel, and Lincoln, you get a few more bellhousings in the Ford family.... and since OP was talking about Chevy, not GM, we probably should not include those when comparing Chevys to Fords.
Wonder what kindof Mickey Mouse design standards (get it?) Chevy had for powertrain bending moment if they kept that small bolt pattern for everything from a low power six up to their largest v8? There’s a reason other people use a larger bolt circle for larger, higher torque engines.
What they did was use the large bolt pattern for everything, and it worked out pretty well. Until they got around to putting automatic transmissions in 4x4 trucks, that is...then they had to add some bracing. And that was with the small blocks, not big blocks.
If you run and automatic, the flexplate attachment is a little different on the 348/409. The flange on the end of the crank is larger on these engines so a shim is needed to make the correct fitment. Company called Sho-Cars sells the shims or they also sell a direct fit flexplate. The pic below is from the 348/409 forum. Pic is property of owner
I’m not a Chevy guy, even though I have a couple in the Fleet, but I thought the bop transmissions had a bigger pattern (or more bolts) than the traditional Chevy pattern. If true, then the Chevy is, indeed, the small pattern in the GM world. The larger pattern gives a stiffer structure, which improves strength and reduces NVH, which is probably why the BOP cars use it.
It always seemed strange to me that the only people that complain about Chevrolet’s single bellhousing pattern are Chevy haters. Sent from my iPhone using The H.A.M.B. mobile app
No, not really bigger. Just different. The bottom two and the dowels are the same. A dual pattern case will illustrate this. In fact , wasn't it Chevy that had the 7th hole drilled and tapped at the top of some truck engines?
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