Head re-assembly prep and ought-to's

The head with the burned exhaust valve is off to to shop be checked out and re-built....new springs, valves, guides, etc.

What is prep for re-assembly?

New studs all around? What hardness? Best source?

What about preparing the deck (block)? Since I don't have it out of car machining it flat seems out of the question.

Thanks in advance, guys/gals.

JTB

John,

I'm just finishing up replacing the head on my 74.

I popped a rocker bracket stud while torquing the rocker back down. After close look at the other three studs, I noticed that for some reason, the top threads on all 4 studs were worn pretty badly.

So...that's one place I would advise you to go with all new studs, washers, and nuts.

Also...my 74 didn't have the shims under the center two rocker brackets. I bought and installed them...Haynes says older cars should have the shims when rebuilding.

ARP is good for studs. I use my old ones without failures.
Best you can do with the block in is to check with a straight edge; hold in one corner and swing it in an arc. Probably fine anyway.

Since you are doing just the head forget about the block. If you are flush with cash you might replace all of the head studs but that isn't really necessary for most street application. If you just have to do something to it pull the studs and clean the stud bosses after chasing the threads.

The head should be stripped fully and cleaned to a spotless condition after making sure that all oil passages are completely clear. If you are doing the assembly at home cut a square of plywood and use it as a working surface. Placing the face of the head down on a steel table top is inviting trouble. Pulling all of the studs and chasing the threads is at your option. I hardly ever pull the manifold studs and do only the top side ones if they seem in the least bit loose.

Other than that and keeping everything really clean as you assemble the jump the rest of the stuff should be done by the machine shop. Oh, you might ask them to NOT assemble the valves and springs. This will allow you to go behind them and positively make sure that the stems and guides and ports are as clean as you would like.

Jack

Thanks, guys.

All the head work is being done by the shop...a Brit Car guy of 40 years experience and impeccable reputation locally....so it will come back completely restored. I am not the most precise type around so that is best left to him.

Point of ignorance here. What do you use to chase the block threads? I understand the concept but haven't done it. Are you using the same tool you use to cut new threads or
something different?

Yup. A tap.

Ditto on the tap, a "bottoming" tap if you have it. You also need some compressed air and eye protection to get the bad stuff out of the hole. Jack

OK...last question about it...

How do I know what thread/size that is so I don't muck it up? Assume they are listed someplace in the usual sources...Bentley, Haynes...but thought I would ask.

Any cautions or instructions about it? Don't assume I know anything about it. Do have compressed air source to clean out. Do you use anything on the tap like oil or water to facilitate it. Seems like you wouldn't but want to be clear.

Machining work ain't exactly my strength.

I never remember and just stick what looks close. If it doesn't go easy, it's wrong. Do it dry. If you were cutting new threads you would use oil. In this case, oil would hold anything you cut off, not a good thing.

Buy an inexpensive thread gauge set, probably WAY less than ten bucks. They come in several styles, and check the stud itself against the diameter broaches and the thread pitch sections.

If you do the chasing routine dry as Chris suggests, do it slowly and with care for jamming by picking up too much scale or other mess. If you get resistance to any real degree back the tap out with the same car. If it tries to jamb coming back out go back and forth with light pressure until you can withdraw it and clean out the bore.

I personally like to use a light machine oil or a specialty cutting oil when cutting new threads or chasing old ones. It does make a bit more of a mess as Chris points out but doing so just feels a little better to me.

Jack

John, if you do decide to go with a new ARP stud kit. I noticed that they are now available at summitracing.com. $102.88.

John, I would recommend using a lubricant of some sort, WD40, even 3in1 if you must but some sort of liquid, petroleum based lube should be used. It will lessen the risk of breaking off the tap even if you are just cleaning out an existing thread. Like Jack mentioned, go slowly and do not use 'brute force' to turn the tap, rotating the tap one or two turns further into the hole and backing it out of the hole until you reach the bottom, also helps to clear out any scaling that may be present. This procedure, though not done many times when head work is performed, truely does make a huge difference as it allows the studs to retain their torque settings longer and further inhibits rust build-up in the hole. Also be sure that the bottom of the hole does not have any lube in it when you go to replace the stud, otherwise you are opening another can of worms.

I should start using oil too!

Sounds like a trip to Harbor Freight is in order.

FWIW, The size tap you need is 3/8" 16 threads/inch.

Clifton

ARP sells a "thread chasing tap"

Definitely worth having a look at their website and downloading their PDF catalog. (www.arp-bolts.com)