Drill and Tap block?

[saxart]

I'm in the process of adding Power Steering to a 350 SBC which has bosses that are not drilled to accept the power steering bracket that goes with the short water pump.



While I could just go with a long water pump, I'd really like to stick with the short water pump. I'm curious to hear from anyone who has had to drill and tap these holes in a block. I think I've learned that the hardware that holds the pump bracket to the engine are 3/8" diameter. Anybody know how deep the holes in these bosses need to be?

I'd hate to "drill through" a completely good engine block...

I'm familiar with drilling holes in cast iron as well as using taps, but just a little shy of messing up a good running engine. Any thoughts or experience you guys have is greatly appreciated.

[richard2717]

If no one gets it to you tonight I will grab a picture and measurement of one of my spares in the morning and post it for you

[toolboxchev]

That must be a real early V-8 block, I would have thought most all in our model years have been drilled and tapped prior to factory install.

[VetteVet]

Originally Posted by toolboxchev

That must be a real early V-8 block, I would have thought most all in our model years have been drilled and tapped prior to factory install.

It seems to me that those holes were drilled on some blocks for a front motor mount on some models.I found these two pics on my computer that show the PS bracket and pump mounted there.

[saxart]

Originally Posted by toolboxchev

That must be a real early V-8 block, I would have thought most all in our model years have been drilled and tapped prior to factory install.

Based on the numbers that are stamped into it, I believe the block is a 1974 vintage. From what I've learned recently, the '73 on up (truck) engine blocks had the long water pump which used a threaded boss on the water pump as the mounting point for the power steering pump instead of the block like most 67-72 models.

[CaptRMW]

VetteVet your picture is of a long water pump with the long water pump style power steering bracket that has been jury rigged to bolt up to the short water pump style mounting position. The pump bracket shown should have one bolt about 2 1/2" long through the upper mounting hole and pass through the boss on the water pump that is just below the lower water pump mounting bolt. I will try to post pictures of the correct style power steering pump for the SWP.

[richard2717]

Here are pictures of two different motors I have. Notice the holes are not in the center of the bosses but also dont appear to be in the exact same place on both engines. I would think as long as you have them centered with each other the rest of the adjustment will come from the belt tensioner.

I measured 1 5/8" center to center on the bolt holes and they all averaged 3/4" deep. I am also assuming them to be fine thread bolts (didn't have any handy) because the 3/8 coarse thread would not go in.

Hope this helps


.

[VetteVet]

Originally Posted by CaptRMW

VetteVet your picture is of a long water pump with the long water pump style power steering bracket that has been jury rigged to bolt up to the short water pump style mounting position. The pump bracket shown should have one bolt about 2 1/2" long through the upper mounting hole and pass through the boss on the water pump that is just below the lower water pump mounting bolt. I will try to post pictures of the correct style power steering pump for the SWP.

Yes you are correct, when I was looking at the pictures I was just looking for a pump mounted in those holes. As soon as I looked again this morning I knew it was a long pump bracket. I also saw the frayed belt and knew the alignment was off. I used the long water pump on my engine and the correct brackets so everything fits. I just have to get busy and finish it.

[100%Chevy]

GM introduced the small block v/8 in 1955.
At the same time GM also drilled and tapped the front bosses to accept the front motor mounts in use then.
They are 3/8-16 coarse thread and 1" deep.You will have to find center before drilling.
Most of the older small blocks are drilled and tapped already.My original 75,350 is from a truck and it's done.
A lot of later engines aren't.Probably because the holes weren't needed.
Mike.

[saxart]

Originally Posted by 100%Chevy

GM introduced the small block v/8 in 1955.
At the same time GM also drilled and tapped the front bosses to accept the front motor mounts in use then.
They are 3/8-16 coarse thread and 1" deep.You will have to find center before drilling.
Most of the older small blocks are drilled and tapped already.My original 75,350 is from a truck and it's done.
A lot of later engines aren't.Probably because the holes weren't needed.
Mike.

Wow, this ENTIRE thread has been full of great info and pics. Thanks for all of the help guys. I can't tell you how much I appreciate it.

Looks like I get to order some parts tonight after work and start drilling some holes once things show up.