userbmx1315
NAXJA Forum User
- Location
- Dallas, NC
is the bottom of the block square (90*) with the pistons?
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block square
- Thread starter userbmx1315
- Start date
5-90
NAXJA Forum User
- Location
- Hammerspace
I have yet to find blueprints of the block, but it would stand to reason that the axes of the cylinder bores are normal to both the deck (upper surface, where the cylinder head attaches) and the sump rails - barring core shift or mis-machining.
Why for do you ask? Typically, the "normality" (perpendicularity) of the cylinder bores to the sump rails is variable and non-critical, since it's not a combustion seal. However, cylinder bores are almost invariably normal (at the axis) to the block deck - even on engines like the slant six (where the deck is normal to the bore axes, while the sump rail plane is 30* off of normal due to the designed-in tilt of the engine.) And, on V8 engines, the sump rails are typically 45* off of normal. V10 engines are around 36* off, and V12 engines around 30*. V6 engines can be 30* off or 45* off, depending on design. (In case you hadn't noticed by now, the sump rails are off of horizontal by half of the included angle betwen cylinder banks.)
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userbmx1315
NAXJA Forum User
- Location
- Dallas, NC
i'm going to see if i can bore my block myself at work on a saturday off the clock.
and if the bores where perp. then it will be easier to set it up. that'll save me 200 at the shop.
and if the bores where perp. then it will be easier to set it up. that'll save me 200 at the shop.
winterbeater
NAXJA Forum User
- Location
- Royal Oak, Michigan
You can set up on the pan rail. Then indicate in the crank bore halves (front and rear) from the machine table. Shim to make them equal. The important thing is to have the cylinder bores perpendicular to the crank. IIRC, we had .005" perpendicularity tolerance on the cyl bore crank to the crankshaft bore. Make sure to tram in the machine table to verify that your spindle is square before you set up. Also tram the side of the cylinder bore to see that you are square the other way. That doesn't matter as much, but you want to make sure your bores clean up. It would also be a good time to dust off the head deck for parallel to the crank to get compression the same in all cylinders. At least check that. Some production blocks had a lot of variation.
