I have a older 2-piece seal 350 4-bolt block..3970010. It was used in a race car. Just above each of the lifter bores there is some kind of machining. It looks like for clearence or something. Not sure. Were these for special lifeters? Rollers or offset? I have never seen this done before. Any ideas?

Is there 3 threaded bosses in the center? Maybe someone machined it to use a new style roller cam, they take special retainers to hold the lifters from turning. Was wondering about the 3 bosses cause that would need a way to hold the spyder bracket down(that holds the lifter retainers)

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Confucius says " he who uses small, crimped exhaust, gets short of breath"

[This message has been edited by Bruce Sherman (edited January 16, 2005).]

No holes drilled or tapped for the roller lifter spiders.... this machining is similar to what you would do to the bottom of the cylinders if you were building a 383.looks like they were making clearance for big block lifter or tall rollers... very strange.... they machined out a valley over top of each lifter bore. Thee machining is where the cylinders are... and they are deep..about 1/4 to 1/2 inches and about 2 inches tall. I'll try to get a photo of it. Theres 16 of them in the valley of the block...

Could either be clearance for the horizontal bar on a roller lifter or someone was cleaning up the valley for better oil control.

Some machine shops do that to "ensure the bores are square to the valve train". I think its a bit of overkill but I have seen it done just "to be sure" about the lifter bores. Agree with comments to the effect thats its a strange idea.

This block was a pro-race engine. It has been bored and sleeved, the drain holes above the cam have been drilled, tapped and plugged, the oil holes at the end of the block have been tapped and plugged, screens were epoxied into the drain holes above the cam, all the flashing was ground down, the block was clearenced for a stroker crank etc... I'll try to get a photo....