When I rebuilt my 540CAD I used a torque plate to bore and hone the
cylinder.
It is amassing how the bolts when torqued will show up on the walls.
I'm now too old to waste time and money on those luxuries.
Still have the Torque plate I will let go for cheap.

On Fri, Oct 16, 2020 at 6:11 PM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:

> A technical instructor at the GM Training Center near Portland, where I got
> much of my Oldsmobile training, demonstrated on a 400 SB Chev block on the
> flimsy bore stability. He took a telescoping gage, set it so it would stay
> in the bore by itself, then, using only his hands, squeezing the bore
> sides. This caused the telescoping gage to fall right out of the bottom. I
> had no idea they were that flimsy. Wouldn't happen on a 455 Olds, I am
> sure. He didn't have much love for the V-6's either. Nor did I.
> Jim Hupy
> Salem, Oregon
>
> On Fri, Oct 16, 2020, 5:56 PM Matt Colie via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> James Hupy wrote on Fri, 16 October 2020 16:08
>>> When cylinders are bored, often times, particularly with non-robust
>> engine blocks, cylinder bore stabilization plates are used. They are
> purpose
>>> built, very thick, very dimensionally stable, plates that simulate a
>> cylinder head. The bores in the engine match bores in the plate that
> allow
>>> boring machinery, (cutters or hones) access to the engine cylinder
> bores
>> for re-machining. The bore plates are torqued down on the cylinder
> blocks,
>>> and cylinders are re-machined. Then after re-machining, the bore plates
>> are removed, and the rest of the machining is completed to the blocks.
> Then,
>>> when the engine is re-assembled, the cylinder head torque matches what
>> the torque plate torque was, and the bore shape supposedly is round.
>>> Engines like the small block 5 litre Ford, and yes, the Olds 403,
>> benefit from this extra step. Like Matt says, overtorquing from
>>> retightening the head bolts, can distort the thin wall engine blocks.
>>> So, It's a crap shoot. In my opinion based upon personal
>> experience in machine shops, it is probably best to not molest it if
>> possible.
>>> Jim Hupy
>>> Salem, Oregon
>>
>> Jim, when we did this, we found three essentials:
>> The plate had to be more than just a solid plate, it had to be machined
> so
>> as to duplicate the flexibility of the cylinder head casting.
>> It (of course) had to be put down at the design fastener tension. We
> used
>> gages that measured the bolt tension.
>> You had to use it with the headgasket that was planned for the final
>> assembly.
>>
>> The Ford 302 was way better than the 2.3l particularly in the SVO
> version,
>> but one of the worse was the Chevy SB 400 and you can guess why.
>> It was a siamese bore (like the 403) but there was no metal left.
>>
>> Great days - those were? We made it all work. A 455 is easy.
>>
>> Matt
>> --
>> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
>> GMCES
>> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
>> Brakes with Applied Control Arms
>> SE Michigan - Near DTW - Twixt A2 and Detroit
>>
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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