Plug a smog hole

[Snake]

Looking for some ideas,what to use to plug the smog holes on my 360 head.Could a self taping screw work than grind of the head to get a flat finish.Or whats your thought JB weld fill that hole and be done with it.Looking for a cheep long lasting fix.I have the 340 exhaust manifolds,that don't cover those holes.Thanks in advance.

 

[Bad Sport]

Tap them and use a hex head plug, the kind that you put in with an Allen Wrench.

 

[JBurch]

Go to the hardware store, get 8 1/4-20 set screws 1/4 to 3/8 long, buy a 1/4-20 tap while you are there unless you already have a tap and die set. Tap the holes not quite the full length of the set screw, if you like you could use a little J-B Weld on the set screws, run them in and make them tight. Grind or flat file anything that sticks up till it's smooth. Done!

 

[Treblig]

Go to the hardware store, get 8 1/4-20 set screws 1/4 to 3/8 long, buy a 1/4-20 tap while you are there unless you already have a tap and die set. Tap the holes not quite the full length of the set screw, if you like you could use a little J-B Weld on the set screws, run them in and make them tight. Grind or flat file anything that sticks up till it's smooth. Done!

That's what I did. Be sure to "NOT" tap all the way through. You want the set screw to bottom out in the threads so that it locks itself against the last thread in the hole. I don't think any kind of epoxy or JB weld will help because all those two part epoxies melt at higher temps. If you torque the set screws down hard against the last thread in the hole it really can't go anywhere. I tightened the hell out of mine knowing that I would never have to remove them.
Self tapping screws are usually meant of for thinner sheet metal or other (less than 3/16") metals. I've never tried using self tapping screws in cast iron.
Cast iron is pretty easy to tap because of it's metallic properties. Just do your best to keep the tap square and straight (use a "starter" tap as opposed to a "bottom" tap), but even it you get the hole a little crooked the screw will still lock in there if you go deep enough. It will also help if you get a larger drill bit and cut a slight taper at the entrance of the hole, this will make it easier to start the tap in the hole. I use a 45 degree chamfering tool to make the taper but a drill bit will work.
I can post pics of a "bottom" and "starter tap" if you need to see the difference.

treblig

 

[mopowers]

You can also braze them shut.

 

[JBurch]

A trick for keeping the tap "straight" into the hole is to take a piece of aluminum, steel, even a block of hardwood, that is 1 to 1 1/2 inch thick, drill a hole thru it that is just the OD of the tap. That will hold the tap so it goes straight into the hole.

I suggest this on the assumption you have a drill press; if you don't don't worry about it, just start the tap as square as you can.

Good luck!

 

[Snake]

Kind of nerves of the tap thing,never done it befor,any videos or there on how to.I guess i could U TUBE.

 

[Treblig]

Here's one for you. As you can see it's not hard at all if you take your time. Also, if you chamfer the hole with a drill bit it makes it easier to start the tap straight. If you lived nearby I go over and do it for you and make sure it's done right. You can't really mess it up> Well .....you could mess it up if you go too fast and break the tap in the hole but there are ways to remove a broken tap as well, done it numerous times.

Treblig

 

[TrailBeast]

You can also tap a ball bearing in the hole and slightly peen the edge of the hole like they do in transmission castings where something need to be drilled but where the drill went in needs plugged like the green circle on this pump stator.

 

[Treblig]

You can also tap a ball bearing in the hole and slightly peen the edge of the hole like they do in transmission castings where something need to be drilled but where the drill went in needs plugged like the green circle on this pump stator.

View attachment 1714982555

I was going to suggest the same thing but was not sure if the cast iron head (area around a hole) would crack or break off (malleability). Cast iron is somewhat brittle and when you get near an edge it can sometime chip/break off. Of course it wouldn't hurt to try. He could also get a straight rod that's a 2 or 3 thousandths of an inch larger than the smog hole, grind a very slight taper on the short piece of rod and hammer it in till it gets stuck then grind off anything that's still protruding. But since the OP hasn't ever tapped a hole I figured that he wouldn't have the instruments to measure the hole or measure a piece of rod (as far as thousandths of an inch goes).

Treblig

 

[Snake]

Here's one for you. As you can see it's not hard at all if you take your time. Also, if you chamfer the hole with a drill bit it makes it easier to start the tap straight. If you lived nearby I go over and do it for you and make sure it's done right. You can't really mess it up> Well .....you could mess it up if you go too fast and break the tap in the hole but there are ways to remove a broken tap as well, done it numerous times.

Treblig

Well that lookssssssssssss easy the good thing the hole is all ready drilled,thanks a bunch just what the Doctor ordered.Well tomorrow i will get 1/4 starter tap and give it a try,is there a tap to stay away from ,meaning cheep tap.

 

[Snake]

You can also tap a ball bearing in the hole and slightly peen the edge of the hole like they do in transmission castings where something need to be drilled but where the drill went in needs plugged like the green circle on this pump stator.

View attachment 1714982555

Well i will tell you the guy who did the valve springs said the same get a ball bearing,but just what size would fit? stump me.

 

[Treblig]

Well i will tell you the guy who did the valve springs said the same get a ball bearing,but just what size would fit? stump me.

If you use a ball be sure that's it's a good press fit...you wouldn't want the ball to fall through into the combustion chamber#@&^%*#@%&^%$&^%(^%.
Those smog holes are cast into the head, holes (especially long holes) that are in cast iron are sometimes tapered (not straight) so that something will fit tight in one section of the hole and loose in another????
If you use a tap get a 1/4 X 20 thds and set screws of the correct length.

Treblig

 

[Snake]

Someone said to hammer lead weights you know fishing weights.

 

[TrailBeast]

I was going to suggest the same thing but was not sure if the cast iron head (area around a hole) would crack or break off (malleability). Cast iron is somewhat brittle and when you get near an edge it can sometime chip/break off. Of course it wouldn't hurt to try. He could also get a straight rod that's a 2 or 3 thousandths of an inch larger than the smog hole, grind a very slight taper on the short piece of rod and hammer it in till it gets stuck then grind off anything that's still protruding. But since the OP hasn't ever tapped a hole I figured that he wouldn't have the instruments to measure the hole or measure a piece of rod (as far as thousandths of an inch goes).

Treblig

A lot of trans pump housings and stators are also cast iron.
To answer another concern, a ball that fits tight in those holes are in no danger of ever getting into a combustion chamber.
And I would be leary of using something as soft as lead as it could get loose to easy and fall out.

Really the only two ways I would be comfortable with it is tapped and a bolt or plugged with a steel ball, and it sounds like he's going with the tap method.

 

[318willrun]

Go to the hardware store, get 8 1/4-20 set screws 1/4 to 3/8 long, buy a 1/4-20 tap while you are there unless you already have a tap and die set. Tap the holes not quite the full length of the set screw, if you like you could use a little J-B Weld on the set screws, run them in and make them tight. Grind or flat file anything that sticks up till it's smooth. Done!

THIS ^^^^^ I put a drop of oil on the tap, and slowly go back and forth to let is slowly cut the threads and avoid breaking the tap off inside the head. I always go deep enough so that the set screw is just submerged below the surface. That way, no grinding, and your manifold/header will fit flat and seal proper. I've done this way more than I wish to remember, and never had anything go wrong. You'll do fine

 

[Snake]

OK the tap it is, and thanks to badsport, he was the first to offer the same fix as you all have said, the heads are not on now,i am sure it can be done after the heads are on.

 

[JBurch]

Myself, if the heads are off, I'd do it now, it will never get any easier. Think about it, you're leaning over a fender, you come to the area of where the shock towers close up the space to work in, trying to keep the tap square to the hole......why make it hard on yourself. Set them down on the edge of the work bench, sit on a shop stool, they are right in front of you, easy to work on, easy to see, easy-peasy. Just a thought..............

Back in post #7, you stated you've never done stuff like this before, you were kinda nervous...........Just an other thought

 

[Treblig]

OK the tap it is, and thanks to badsport, he was the first to offer the same fix as you all have said, the heads are not on now,i am sure it can be done after the heads are on.

You wrote, "i am sure it can be done after the heads are on.". If you do the tapping with the heads on the engine and the engine in the car it will be more difficult. If the heads are on the engine and the engine is "out" of the car then it's pretty easy. Which scenario are we working with here??
Treblig

 

[Snake]

Myself, if the heads are off, I'd do it now, it will never get any easier. Think about it, you're leaning over a fender, you come to the area of where the shock towers close up the space to work in, trying to keep the tap square to the hole......why make it hard on yourself. Set them down on the edge of the work bench, sit on a shop stool, they are right in front of you, easy to work on, easy to see, easy-peasy. Just a thought..............

Back in post #7, you stated you've never done stuff like this before, you were kinda nervous...........Just an other thought

You wrote, "i am sure it can be done after the heads are on.". If you do the tapping with the heads on the engine and the engine in the car it will be more difficult. If the heads are on the engine and the engine is "out" of the car then it's pretty easy. Which scenario are we working with here??
Treblig

The 360 is on a stand,heads on the bench.

 

[JBurch]

The 360 is on a stand,heads on the bench.

There you go...........It won't get any easier than right now. Just take your time, a little cutting fluid, though no really needed, the graphite in the iron acts as a lubricant, it (cutting fluid) falls under the realm of "it doesn't hurt". "Tap Magic" is an excellent product. If in your search for a tap and "T" handle, if you have a choice 2, 3, or 4 fluted taps (4 is most common) buy a 2 or a 3, they are a little stronger than a 4. If a 4 is all that is available, that's ok also, it will feel a little more "springy" as you turn it.

Good luck.

 

[Treblig]

The 360 is on a stand,heads on the bench.

If the heads are on the bench you might take one more thing into consideration........When you're tapping a hole you have to make sure that the item you're tapping is secure. If the heads are on a smooth (slippery) surface they might tend to move (rotate, shift) when you're applying torque with the tap. If the heads move at all it can cause the you to put uncontrolled force on the tap causing the tap to break. But if the heads are bolted or clamped down securely (or in a large vice) this can't happen. I know that I've tapped items that shifted and caused me to break off a tap. It was one of the smaller taps but still, so be careful and make sure that the heads can not move during the tapping process.
Making the heads secure will also give you a much better feel as the tap cuts the threads. If you noticed in the short video I posted, the guy has the small part in a vice!! The guy in the video also used "Tap Magic", I also use Tap magic when I'm tapping threads. Tap magic allows the tap to cut threads with a much smoother action which decreases the chances of breaking the tap. Once you tap a hole using Tap Magic you'll never want to be without it.
As JBurch wrote, cast iron has properties that can be considered "self lubricating" when it comes to tapping or machining.

treblig

 

[Snake]

OK got the 1/4 tap did 1 hole threads went great,but used a 1/4 bolt but it just felled in,what went wrong.Is it the wrong tap its 1/4 bottoming.

 

[Treblig]

One of three things....either you have the wrong size tap (not likely), You have the wrong size bolt or you weren't putting enough pressure on the tap so that it continually cut threads. If you don't put enough pressure the tap will cut all the material out of the hole as you turn the tap. You didn't say if the tap went in easy or hard or if it was cutting threads. Can you see "good" threads in the hole?? It's not a big deal because there are other options and there's plenty of material around the hole.
PICS OF HOLE?THREADS??
treblig

 

[Snake]

When the tap went in it was hard to turn,when the tap was in it I could not pull it up,so my thought then it has threads,I call my local machine shop they were happy to help to the tune of 30 dollars,the price of the bolts and tap Handel+ 1/4 tap.witch i am returning - the tap.So in short I bailed.