Tap head bolt / intake bolt holes on rebuild?

[GXPWeasel]

Hey guys. I couldn't find exactly what I needed in the search, and I'm not positive this is the correct place to put this thread, but I figured it's at lease relevant to the topic sub-section.

I am getting my block / heads / pistons / rods / crank / cam back today from the machine shop. In reading the Haynes manual, they recommend tapping the head bolt locations with a tap. Probably recommend for the intake bolt holes as well, just to be safe.
I have no problem getting a tap and die set for this, but I want some opinions on what would be a sufficient kit.

I may end up doing this again, but it's not going to be something I use daily, or probably even annually. But I don't want ****** tools either. Most times I have found that the middle of the road "specialty" tools do the job for the average joe who tinkers in his garage once in a while.

So, here are my 2 questions.
When purchasing a tap and die set, would you purchase one for an engine build, with no real plans to use it again in the future, from a place like Amazon or Harbor Freight?
Second question, am I correct in that a stock Gen 1 small block (1982 GM 305 cid) uses a 7/16" - 14 bolt for the heads, and therefore that is the tap I need be most concerned about receiving in a kit?

Thanks in advance.

 

[Paladin]

Hmmmm..... I know that when I had my 454 block and heads machined the shop took care of all that, I just had to check and make sure it had been done, which it was! So I didn't have this problem but if I needed to do this my self I would buy a mid-road set and be sure to use way plenty Tap Magic while I chased the threads! JM2

 

[SDJunkMan]

I've always heard that you should run a tap down all the holes just to clean them out and clean up any problems. I doubt if you would need a complete tap set, just one of each the main sized taps and a tap handle, much cheaper than a whole set. You might want bottoming taps if they are dead end holes, a regular tap has the threads taper towards the end and will not do a real good job of cleaning out the bottom threads.

I bought a HF set one time, and was very disapointed in it.

I use some stuff called Mistic Metal Mover that I get at NAPA, works great with taps and drilling.

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[Ricko1966]

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Buy 2 stainless bolts the correct diameter and thread pitch. Stainless is harder than mild steel but not as brittle as a tap. Grind a flat spot on 1 side from the tip to about an inch up. Great thread chasers cheap and less chance of breaking of in the hole. I've seen it happen especially with someone unfamiliar with taps and dies. I've got 1 or 2 in my box I'll try to get a pic up in the homemade tools thread today.

Do not skimp when buying taps a cheap tap is worse than no tap! A tap is harder than a drill bit if you break one off it cannot be drilled out. Yes there are ways of getting broken taps out sometimes NBD sometimes it's a b#+ch. So use thread chasers or buy good taps the sizes you need go slow and carefully if it gets tough to turn take it back out clean it blow out the chips and start again.

 

[MikeB]

I've used these thread chasers for years. They don't cut the threads, they simply clean and restore them.

https://www.summitracing.com/parts/sum-900200

Just found this:

A cutting tap is designed to create new threads, whereas a chaser tap is designed to clean, re-form and restore existing threads. If you want to clean-up existing female threads (maybe the threaded hole has burrs or a bit of corrosion, etc.), it's best to use a chaser, or follower tap instead of a common cutting tap.

 

[Ricko1966]

Funny I have that same set. The bolt I pictured is one I made to replace one ,that one of my employees broke off in an assembled short block. I was not happy.It was user error for sure not a bad tool. Try a stainless bolt with a flat spot sometime, you'll thank me.

 

[GXPWeasel]

Wow guys! great info.
You probably saved me $50, and possibly some (or a lot) of cussing.
@Ricko1966 I'm going to give that a try. I've got a great hardware store close that has a good selection of stainless bolts. S/b easy to find in the 2 or 3 sizes I need for sure.

 

[Turbo Dog]

I've used these thread chasers for years. They don't cut the threads, they simply clean and restore them.

https://www.summitracing.com/parts/sum-900200

Just found this:

A cutting tap is designed to create new threads, whereas a chaser tap is designed to clean, re-form and restore existing threads. If you want to clean-up existing female threads (maybe the threaded hole has burrs or a bit of corrosion, etc.), it's best to use a chaser, or follower tap instead of a common cutting tap.

You are right, don't chase threads with taps. I have a full set that I've been using for years just like this one:
https://www.tooltopia.com/Lang-Tool...zl2Ffn_ZsYQ9khk7xHHIKCC0fZVgutLxoC1xQQAvD_BwE

 

[J-Bob]

Chasers clean and taps cut. The Summit ones for $10 worked great for me.

 

[GXPWeasel]

Got the 2 sizes of stainless bolts needed today, and going to chase them tomorrow before a quick assembly for primer. I like the chaser kit linked above too...

 

[MikeB]

Got the 2 sizes of stainless bolts needed today, and going to chase them tomorrow before a quick assembly for primer. I like the chaser kit linked above too...

I don't understand what the stainless bolts will do. They are not designed to clean and restore the threads.

 

[SirRobyn0]

Honestly if your going to do it chasers would be better. If you already had a tap set, you could use them, but! I've never done any of that. When you get your parts back from the machine shop they are going to be, or should be extremely clean, like the kind of clean you see on new parts. It won't hurt at all to run chasers though them, but it does take time, and I would just skip it personally.

 

[Ricko1966]

I don't understand what the stainless bolts will do. They are not designed to clean and restore the threads.

Did you read where I said and pictured to grind a flat to collect chips? Stainless is harder than mild steel or the scrap in the threads and will chase them just fine. Try it sometime.I have a full set of taps and chasers and still use a stainless bolt when I don't have what I need handy and have replaced my broken or missing chasers with stainless bolts with a notch ground in them.

All he's doing is cleaning some dirt that may or may not be in some threads. He's not building a space shuttle.

 

[Ricko1966]

These were just the taps dies and chasers not in my kennedy box.Its not like I'm too cheap to by taps or chasers. Notice the one ground stainless bolt in the chaser box.That takes the place of the one an employee broke off in a block. See the other stainless bolt another one I made don't remember why. See I stood up a couple of taps that I welded nuts too so I could use them where I needed to.Put up pics so when I tell someone to do this 10 people don't tell them , oh that'll ruin the tap, they're heat treated blah blah blah 30 + years of doing this for a living, not a hobby has taught me some things.One of those things is that for what the O.P. is doing S.S. bolts are more than adequate he could have ground an angle on an old head bolt for this deal.

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[Turbo Dog]

My tool box has pretty much the same assortment, a chase set and two various parts still remaining tap sets. It's rare that I need to put threads into a virgin hole, but I have needed to clean up plenty of other ones.