Thread: Drill accessory holes on sb heads

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Hi
I was wondering if any of you have seen or heard of people drilling and tapping accessory holes on heads such as camel humps or power packs that didnt have them??

I did that once. But it ended in a disaster. Not that I drilled in some water passages but the hole where not aligned.

Why do you not use the brackets for accessories build for that older engeines?

I dont have them for starters lol. I want to put the heads on a 80s truck. How deep could you drill before getting wet?

Put on the brackets, then using them to get the location, weld a 3/8 nut to the head. You may have to grind a bit off whatever the bracket holds to compensate for the thickness of the nut. This has worked for me several times. There isn't enough iron in the front of the heads to hold threads.

Even IF you could drill the things, you face two other problems:

1. Is the casting thickness enough to support the load of the accessories and belt tension?
2. The ends of the old heads are not flat; the new style heads are milled flat on the ends to give a good reference surface for the brackets.

I have never welded cast iron before, what type of welder can this be done with? I only have access to mig and arc.

Nomacast rods work good, use DC current. Another trick I've used is to thread a piece of threaded rod into a spare new-style head, then butt it up to the oldie on the bench with a nut on the rod. With the bottom edges parallel, evrything's lined up, weld the nut on. This way you can grind the face of the nut to match your head.

On just a standard 3/8 nut from the hardware store how much needs to come off with the grinder? Your idea of setting of a "jig" i would call it to get the correct alignment is awesome. I will rememeber that one.

Just angle the face of the nut so it matches the angle of the face of the head. If you grind the flats off round and grind the welds they look pretty good with a coat of engine enamel.

thanks for the info, sounds like it will work!

Originally posted by R Pope
Nomacast rods work good, use DC current. Another trick I've used is to thread a piece of threaded rod into a spare new-style head, then butt it up to the oldie on the bench with a nut on the rod. With the bottom edges parallel, evrything's lined up, weld the nut on. This way you can grind the face of the nut to match your head.

That's one of the slickest tricks I've ever read anywhere. Thanks for that!!!!!

Just the rewards of a mis-spent youth.

Tech...
Isnt the accessory bolt pattern different on a Chevy head for the left side vs the right side? ONE of the bolts line up but the second and third are off quite a bit. Putting the two heads together would get one of the locations.

if the pic in the last post is too small, here is the link to the real pic.

http://www.hotrodlane.cc/ONLINETECH/sbcboltholes.htm

mike in tucson

i drill all the way thru. no different than any other bolt in a water jacket. seal them and run them in. i worried about this too until i drilled thru. head bolts go into water jacket.