Re installing th e head

[Lou Earle]

I am planning on chasing the threads on then original bolts and adding one from a junk engine I have. What should I use on the stud threads? I have used # 2 gasket sealer in the past - that OK or what is better?

Lou

[bob westphal]

I always run a thread chaser and/or tap over all threaded surfaces before assembly of all parts. A clean thread should give a good seal against leakage of fluids. I usually use antiseize on head bolt threads. This give plenty of lube to allow a correct torque setting. It also allows easy removal if the occasion arises.

[Guest dave_in_carlsbad]

FWIW, I was advised against doing much of anything to the theads by a couple of very knowlegable builders. I had already run a tap through the threaded holes in the block (as was my custom to clean out the accumulated crud); they winced and advised against ever doing this again. (I don't see why this is bad, but they have done this more than I have ...)

I cleaned the stud threads on a wire wheel and coated the stud/block threads with Permatex sealant. The nuts on the head were lubed with anti-sieze.

YMMV

Dave

[Young Ed]

I've read using a tap is bad because it can remove more material from the threads. As with any thing you want to use the proper tool and that is a thread chaser. Tap is for cutting new threads and a chaser for cleaning existing ones. You probably didnt hurt anything but there is always the chance of damaging the threads so they wont hold the torque.

[Guest dave_in_carlsbad]

Hmmmm... This is in line with what the boys were saying. I always thought you 'chased threads' by gently working a tap/die over the piece. This did not result in bright metal showing (except where there had been damage); I did not consider this 'removing metal'.

A little Googling showed things like: "A thread chaser is essentially a slightly undersized tap that will clean threads without removing any metal. It should be used on any old parts where bolt ..."

Anyhow, I learn something new every day. But I think I'm likely to get a set of bottoming taps before I buy a set of thread chasers. <g>

Dave

[Tim Frank]

I was fortunate enough to have worked a few years with a superb old machinist/tool and die maker.

His two best tips on taps and dies (I think) :

1) As you build up your tooling, add full sets of taps and the correct tap drill for each size rather than buying a full range of lead, plug, and bottoming taps and drills. This concentrates your $$ in sizes that you use often, and gives you full utility in each size. Make a small wooden block to hold all 3 taps and the tap drill. Then there is no searching through drill charts etc. when you need to drill and tap something.

2) If you are near a machine shop, see if you can get some of their throwaway tools...too worn for production. Work brilliantly as thread chasers.

Too worn to cut but will clean threads beautifully.

[greg g]

Dad taught me to take a bolt the size of the of the ones you will be using. Take a triangle file or nowadays a dremel, cut a line perpendicular to the threads along the length of the bolt. Then spray in some penetrating oil and work the bolt in like you would a tap. Two turns in one turn out till it bottoms out. Then spray in some more penetrant, and back it out. The groove in the threads gives the crud someplace to accumulate, and you can clean the hole and thread lans without cutting any metal.

[PatS....]

Greg, that's the best idea I've heard today.

Sometimes Dad's are pretty smart.

Sometimes sons listen to Dads and that's even better!

Now I have to find my Dremel...

Gotta chase the threads in the block to put the head back on this week.

Thanks Greg

[grey beard]

What Y'all do not want to lose sight of with all this talk of thread cleaning is the fact that most head bolt threads go into the water jacket, and for this reason need some appropriate sealer applied to them. Nice, clean head bolts and threads can and will leak antifreeze past themselves unless some kind of sealer is used. I would not wish to count on anti-sieze for this sealing. JMHO:)

[Guest dave_in_carlsbad]

IIRC, some of the intake/exhaust manifold bolts also connect into the water jacket on the MOPAR flatheads, so sealant is in order here as well.

[teardrop puller]

I put cast iron headers and an Offy intake on, now when I run the engine there is a littleakage that drips on the headers. What is the sealing stuff I should buy when I go to the States next week.

thanks

kai

[Thomas Russom]

Just a thought here. Anti-seize does make the bolts thread less effortly but would that not also cause a change in the torque readings. Could the bolts be actually overtorqued at the proper reading?