engine block preparation question

[70MCx2]

I'm in the process of building a big block engine to drop into my '70, and have a question.

 

I got a 1/2 NC bottom hole tap and cleaned out the threads for the main cap bolts; got to the bottom of the hole with no problem.

 

Switched to a 7/16 NC bottom tap and started cleaning out the threads for the head bolts, and the holes are different. I never did bottom out with these, just kept going. Are these "pass through" holes, or are they much deeper and I just didn't get to the bottom?

[Sam (Bones)]

they are bottomless into the water jacket

[70MCx2]

thanks, that was what I was thinking, just wanted to make sure. It's a '79 block, and I'm planning on using ARP studs on top and bottom to try to prevent pulling any threads out. I know early '70s blocks were stronger, but couldn't turn this one down - did some yard work for a guy one day in exchange for a complete engine to rebuild.

[Sam (Bones)]

make sure you seal the threads when you install them, head studs aren't really necessary unless you are planning to make big power, like well over 600hp

[stangeba]

As an aside FYI, I used Teflon tape on my stock iron 4BBL intake to stop the oil that was leaking up through them.

Bruce

[wallaby]

Thread sealer for sure.

An interesing aside, is that you can't pull the heads with the engine in the car if you use studs.

[Mike 57]

I never use a new tap to clean threads on a block. I use a thread chasing tool or a old worn tap. You just want to clean the threads not cut into them.