Newbie Darksider

[V6 JOSE]

Hi John,

I recommend helicoiling ALL the threaded holes in the manifold, but the only ones I would change to the metric thread, are the ones for the rocker cover bolts. All the rest can stay the same.

Jose

Thanks Jose,
Just to clarify, you recommend helicoiling all of the threaded holes in the manifold, right?

 

[SoCalpine]

YouTube makes installing inserts look easy enough. I'd just as soon buy tools as give my machinist another task. Now to find the dimensions on the manifold, other than 6mm 1.0 that is.

 

[kmathis]

Hi, John:

Check those threads on the Offy; I believe they are all SAE and not metric.

 

[SoCalpine]

Hi, John:

Check those threads on the Offy; I believe they are all SAE and not metric.

I'm guessing the right way to do that is to find a bolt that fits then use a thread gauge (first tool on the shopping list) For the larger ones I might be able to fit the gauge inside. My motor is still in line behind a Buick motor so I probably have some time to sort out the intake before it's time to bolt it on. Did you helicoil your manifold?

BTW the M10x1.75 33 wasn't available at McF&D. They had 1.5 thread only. Most of the rest were there though.

 

[kmathis]

Hi, John:

I didn't helicoil my manifold; I would though, on the next one.

 

[gordonra]

Hey John,

Where are you needing the M10-1.75x33?

I didnt see that in Kelly's list. Did I miss a post?

Standard course thread is 1.5, fine thread is 0.75, 1.0, and 1.25.

Rich

I'm guessing the right way to do that is to find a bolt that fits then use a thread gauge (first tool on the shopping list) For the larger ones I might be able to fit the gauge inside. My motor is still in line behind a Buick motor so I probably have some time to sort out the intake before it's time to bolt it on. Did you helicoil your manifold?

BTW the M10x1.75 33 wasn't available at McF&D. They had 1.5 thread only. Most of the rest were there though.

 

[SoCalpine]

Hey John,

Where are you needing the M10-1.75x33?

I have a list with M10 1.75 x35 but I could only find M10 1.5 x35 or M12 1.75x35 so I went home without either figuring it was another hen's tooth available only at the Pinto Bellhousings and '74 Heads Emporium or some online rare bolt broker.

 

[kmathis]

Hi, John:

That was a 12mm x 1.75 x 35mm.

 

[SoCalpine]

I made it to McFadden-Dale's in time to get screw gauges and calipers, but I didn't make it back in time to get the helicoiling stuff. Anyway here are the measurements:

12@ 5/16 x18 x 3/32
1@ 13/16 x16 x3/8
1@ 1/2 x18 x 1/2
2@ 5/8 x18 x 5/8
2@ 3/8 x 24 x 9/32
8@ M6x1.0 x 6mm

Next week.....................

 

[SoCalpine]

Now then there is the new question. Since the manifold is in two parts, it came attached from the factory, should I disassemble it and helicoil that as well?

 

[Series6]

Hi John,

I recommend helicoiling all the bolt holes, because any of them can strip and then you have a problem.

Jose

p.s. I am at Nicks place this week end and he graciously allowed me to use his computer.

Now then there is the new question. Since the manifold is in two parts, it came attached from the factory, should I disassemble it and helicoil that as well?

 

[SoCalpine]

Hi Jose,

I trust Arizona is finding you well. While I've got the manifold apart and all I'm wondering what it would take to dress up the aluminum. The casting is kind of rough and I'm willing to bet the heads aren't even started getting ported yet so I could always spend a few hours with a drill or Dremel for a bit more shine.

Today I'm after cleaning up the engine compartment, maybe a bit of wiring, or something.

Actually, i will probably be doing nothing related to the car as my wife has discovered that I have "free time" and has given me extra homework.

 

[SoCalpine]

Now I'm screwed!

Helicoiling was going along well enough until I got to the two holes on the side of the upper intake for the brass fittings. A combination of funny angles and the fine threads means that the coils just won't go in without breaking off the tang on the 2nd twist. It looks like I've ruined the manifold. I should have stopped with the mounting holes. Now I'm $200 down for the helicoiling gear and odd size drill bits and whatever a professional solution is going to cost.

 

[Ken Ellis]

I don't know your particular hole size, etc., but is it impossible to go the next size up? Or, I have heard that there are "helicoils for helicoils", than can be placed one in the other. A threaded bushing can also be inserted, then staked, welded, or red-loctited in place. There are usually a few additional options after helicoils. Can you post a pic?

 

[SoCalpine]

The size is 3/8 24 and now that I've calmed down some I'm thinking about other inserts, maybe ones that aren't springs. The thin wire just snaps off almost as soon as it goes into the hole. I've tapped it again to try to get it cleaner and tried it with and without the blue adapter to no avail. Maybe a solid insert is the answer, but I'm not sure how to manage the threaded bushing solution. I will try to get a picture up soon.

I'm using Perma-coil and maybe a different brand of inserts might be an option too. I really wanted to be able to get this part of the project done this weekend and this complication was really the last thing I needed. I've decided to forgo helicoiling any more of the fine thread holes since the course thread ones went in fine and I don't want to create more problems on top of this one.

 

[Ken Ellis]

To be honest, I don't know what your manifold is made of (aluminum, as a guess) or whether the holes in question need to end up "gasket-worthy", or are just mounts for accessories like throttle mechanisms. A few photos would help there.

You might just try another brand of insert, as a first step. Anything fancy, like helicoils whose internal threads match the next smaller size helicoil (instead of a standard bolt size) is not something you're going to get in time to finish this weekend, most likely. Browse places like McMaster-Carr.

A threaded bushing could be made from a bolt of compatible material, drilled and tapped thru the center, and threaded/loctited into a suitable enlarged, tapped hole. Grade 8 is seldom required, and lower grades are much easier to drill and tap accurately, while still being harder than the aluminum.

If there's enough material around the hole to bump up to the next size, just drilled and tapped without the helicoil, you might consider that. Is it something that gets assembled frequently, where stripping out is a real danger? Or is this a preventative exercise?

 

[SoCalpine]

Here is a photo of the holes and the part that goes in it. I don't think there is much room to size up, but you can judge for yourself from the photo. The manifold is aluminum and I was helicoiling it as a preventative measure, but it seems the problems have found me now. So it goes.

 

[V6 JOSE]

Hi John,

If you were trying to helicoil the two large holes where the vacuum fittings go, those are the only ones that don't need helicoiling. What I'd said, was all the bolt holes. If you can get the vacuume fitting to go in, I'd just leave it alone.

This is the reason I said you should take it to a machinist. Even guys with mechanical experience can have trouble doing the procedure, so is best left to the pros.

Jose

 

[SoCalpine]

I guess I'll be taking the whole kit over to Superior and see if they can make good of my mess. Maybe throw a polish on top while the meter's running. Rumor has it my motor will be ready to be picked up this week which is why I was trying to get the manifold ready.

Hi John,

I recommend helicoiling ALL the threaded holes in the manifold

Jose

Hi John,

I recommend helicoiling all the bolt holes, because any of them can strip and then you have a problem.

Jose

p.s. I am at Nicks place this week end and he graciously allowed me to use his computer.

At least I come by my confusion honestly.

 

[V6 JOSE]

Hi John,

I'm sorry you got confused when I said all the threaded holes, but the other quote shows I was talking about the bolt holes. Your confusion comes from the fact that you've never done this before, and was the reason I suggested taking the manifold to a professional. I think you may still be in luck though. Did you already tap both vacuum port holes? If you haven't, you can have the one you did, plugged with JB weld. You only need one vacuum port to work, and that is for the vacuum powered brake booster; the other gets plugged with a pipe plug.

Again, I apologize for your confusion and subsequent problem. Even I, an experienced mechanic, have to sometimes take some parts of the work needed to do this conversion, to a professional.

Jose