advice for drilling/tapping PS mounting location holes

[mcbrat]

I'm going to be installing a ea81 from '83 that only has 1 of the 3 holes tapped for the PS pump mounts.

 

anyone have a motor out that can check the depth of the holes

 

this motor only has 86k on it, so I don't want to mess it up

[TomRhere]

Could just put drill bit into the one tapped hole, and wrap tape around it to mark depth. Then drill out other 2 holes, stopping at the tape.

[WJM]

I think this EA81 block i have had PS...i will check it out and measure tomorrow morn.

[mcbrat]

I think this EA81 block i have had PS...i will check it out and measure tomorrow morn.

 

I got the holes drilled, and tapped, but because of the space of the tip of the tap, the threads don't go all the way back in....

 

I drilled the holes to the depth the bolt would need. nervous to go any further. the one hole I already had there was a through hole, so I couldn't measure it.

 

need to find a tap with less "non threading tip" on it

 

I probably have about a 1/2" of threads to work with.....

[92LoyaleSW]

You can grind the tip of your tap down and then use a thread file to fix the first thread. I have had good luck doing that in the past. What you need is called a blind tap (at least that's what we call them).

[mcbrat]

You can grind the tip of your tap down and then use a thread file to fix the first thread. I have had good luck doing that in the past. What you need is called a blind tap (at least that's what we call them).

 

I thought about grinding the tip down, but will go find a spare for that operation

or look for a blind tap.....

 

thanks.

[NorthWet]

I thought about grinding the tip down, but will go find a spare for that operation

or look for a blind tap.....

 

thanks.

I believe that the name that I have heard it called is a "bottoming tap". Might try that if tool man looks at you funny. :-\

 

Grinding a high-quality tap can be a PITA. Probably ruin the hardness. Another option is to use a regular bolt and run it down the hole and let its threads "cut" the last bit. Works better on a bolt that has had its threads cut rather than rolled. Maybe make your own bottoming tap from a bolt that has had some waste slots cut into them. Just be sure to have a couple extra bolts in case you waste a couple.

[mcbrat]

I believe that the name that I have heard it called is a "bottoming tap". Might try that if tool man looks at you funny. :-\

 

Grinding a high-quality tap can be a PITA. Probably ruin the hardness. Another option is to use a regular bolt and run it down the hole and let its threads "cut" the last bit. Works better on a bolt that has had its threads cut rather than rolled. Maybe make your own bottoming tap from a bolt that has had some waste slots cut into them. Just be sure to have a couple extra bolts in case you waste a couple.

 

I bought a spare tap, and ground it down with the bench grinder. piece of cake. didn't even have to clean up the cutters afterward. had to use the coarse wheel though. the fine wheel was too soft as it started to peel on the tap...

 

tapped the hole all the way to the bottom, and bracket snugged up great...

 

as a side note... wow. that head aluminum is soft!!!!