helicoil in heads

[68 A]

hi,

I had a intake manifold leak and took the intake off. Also, each head has one set of threads that have stripped out that hold the valve covers on. I was planning on taking the heads off as well to put the heli coils in, but now i see that the holes do have a bottom to them. Is it safe to drill and tap these holes with a couple magnets close by to pick up the metal coming out? or is the chance of getting metal filings into the engine too high?

I ordered new head gaskets and will have them if i need them, i am just trying to save some work.

Laziness never pays off does it?

Anyway, here are some pictures

Thanks,

Steve

 

[street demon]

Not too sure what holes your talking about. The three closest to the headers should be no problem. The two closest to the intake have extra meat on the bottom that are visible in the intake port. If you drill and tapp these to a larger size for the heli coil you might break threw then you need to putty(moroso) up the area so you don't suck oil in. It would be best to do with the heads off but I've had great luck with someone holding a shop vac right next to the bit and tapp. Hope this helps.

 

[LM23P9B]

I've got a set of heads just like that too. Those are junk. Send them to me along with the rocker arms and shafts and I'll throw them away for you. I'll send you some nice 587's. Oh, I'll need the pushrods to throw away also. J/K
Helicoil shouldn't be to hard to do. Just be clean about it. Ray

 

[Dart-swinger]

I'd just use a shop vac while drilling,like street demon sugested

 

[abodybill]

Use heavy wheel bearing grease on the drill bit and tap.

chips will stick to it.

Thanks,

 

[D-mailman]

Yes easy repair. Tap out with grease and use vacuum and you will be fine. Also if you do break thru..use a stud instead of bolt and there will be no vacuum leak and no oil sucked into port. Good luck and keep us informed as to your progress.
Terry.

 

[fishy68]

I've got a set of heads just like that too. Those are junk. Send them to me along with the rocker arms and shafts and I'll throw them away for you. I'll send you some nice 587's. Oh, I'll need the pushrods to throw away also. J/K Ray

Yeah right!! I could be mistaken but they look like TA heads to me.

 

[68 A]

LM23P9B, I can send you some pushrods that don't work!! Or send you the heads off of my 273, i'll need scrap price plus shipping!

Yeah right!! I could be mistaken but they look like TA heads to me.

You are good!!

I knew they were 915, but checked the entire number 3418915 and checked it on moparts . They were used on '70 340 6 bbl. T/A, '71 360 and '72 340/360.

Thanks for the tips, it will save me some time tommorow.

Steve

 

[LM23P9B]

I'd like to find some spare 3577076, 3577077, 3577078, 3577086, and some 3577121's. What are the chances. Good luck with your repair, it should be easy.

 

[fishy68]

You are good!!

I knew they were 915, but checked the entire number 3418915 and checked it on moparts . They were used on '70 340 6 bbl. T/A, '71 360 and '72 340/360.

Thanks for the tips, it will save me some time tommorow.

Steve

Steve the 915 casting number is used for the 1970 TA head and non TA heads made from 70-72 (don't ask me why Ma Mopar used the same # for different heads) but the TA heads are different because they have offset intake pushrods to allow more intake port opening. The other 915 heads are the same casting design as any other small block LA head. I noticed yours have the offset pushrods and rockers which makes them the TA heads.

Your a lucky man. The TA heads are worth a small fortune.

 

[68 A]

Steve the 915 casting number is used for the 1970 TA head and non TA heads made from 70-72 (don't ask me why Ma Mopar used the same # for different heads) but the TA heads are different because they have offset intake pushrods to allow more intake port opening. The other 915 heads are the same casting design as any other small block LA head. I noticed yours have the offset pushrods and rockers which makes them the TA heads.

Your a lucky man. The TA heads are worth a small fortune.

Thats good info. I never really looked into what they were too much. I also haven't seen too many other heads or the rockers to notice a difference in mine.

And you know what else makes me lucky?! They were given to me.

I took another picture, you can see 360 cast into the head on the opposite end of the casting number. What is that there for?

 

[fishy68]

Wow you are lucky to have had them given to you. I just saw a set sell for $2000 awhile back on E-bay. I have to say that it surprises me to see the 360 on them since 360's didn't come out until 71 and the TA head was only made in 70. All the 915's I've seen have 360 cast onto them even when used on 340's I guess because the 915 casting was originally designed for the 360 engine. I have never actually seen a set of TA heads in person, only pics on the web, and assumed they would have 340 on them. Guess Ma Mopar used all the same casting stamps on all 915 heads. The tell tale sign of them being TA heads is the offset rockers and the pushrods don't go through the edge of the intake runner, their offset to clear it.

 

[D-mailman]

68A,
the TA heads are the 'J' 915 castings and are the same as any of the 915 castings. The only difference was in the machining of the heads for the TA (six-pac) engines. As Fishy68 said, the push rod 'tubes' have been machined outboard for offset rockers to allow for additional porting to widen the port more than is possible with the std. 915 castings. In the as cast form they flow the same as all the other 915's, because they are the same. But they can be made much better. Given to you...WOW what a friend. You should do something for his birthday.
Terry.

 

[68 A]

$2,000! wow. i think i have $3,300 in the rest of the engine. The entire engine was given to me about 6 years ago for my Barracuda. My dads John Deere dealer had a '68 fastback and had a 340 for it. He gave this engine to me for my barracuda. It was at someone elses house that had rebuilt it in the early 80's and never ran it. The valve covers were off, so you could see the offset rockers. He may not have known what they were either.

So maybe next winter i will take these off and get them ported and get the full value out of them!! If they are specail i should treat them that way.

Thanks for the info! And i did get the helicoils in with no problems, it was easy. Now i just gotta put everything back together, get it to my neighbors house and take the tranny out again.

Thanks!

STeve

 

[69 Valiant Kid]

easy breezy beautiful cover girl, drill, tap and thread away....

 

[fishy68]

So maybe next winter i will take these off and get them ported and get the full value out of them!! If they are specail i should treat them that way.
Thanks!

STeve

Steve your best bet is to leave them stock and sell them for a good profit and buy a set of Edelbrock's ready to go and pocket the extra cash. If you have them ported that'll cost you upwards of $600-700 and the heads aren't worth as much ported as they are stock being what they are.

 

[krazykuda]

fishy68

You actually answered your own question and then headsbikesmopars gave the answer, also.

the question is:

(don't ask me why Ma Mopar used the same # for different heads)

The answer is:

The only difference was in the machining of the heads for the TA engines.

The reason is:

They didn't have to change the castings to make the T/A heads because the difference was in the machining. Castings are expensive and it is not worth spending the money for new molds if you don't need to - especially when you are only making 5,200 x 2 of the parts.

You just use the existing (already paid for casting) and machine them different. **You don't need new castings.**

It's the simple cost/effort issue we make everyday. Why spend the time and money do something if you don't have to?? It also makes it possible for the working man to afford.

Another question I see asked alot and have an answer for is:

**Why is 360 casted on my 340 head?**

The answer is:

After they made the 340 castings and ran them in production, they probably found some things they wanted to change. Either for improved performance, manufacturability, problems that weren't caught before production started, or changes needed for new products. It is not possible to make these changes to the parts because you need to use them to make parts every day and don't have time to send them out.

So when the new product comes along (ie. 360), you get the opportunity to make a new tool/casting and change the parts without stopping production. (This means time to make the tool and the money allocated to do it.)

You can make the changes to the new tooling without taking the current tooling out of production and bring it into production early so your current product can benefit from the changes also.

** In short, they made changes to the head casting for the 360 and released them early on the 340. So they changed the number cast on the head because it was paid for with money allocated for the 360 program. It keeps the company executives and accountants and the government off each other's backs. **


Steve the 915 casting number is used for the 1970 TA head and non TA heads made from 70-72 (don't ask me why Ma Mopar used the same # for different heads) but the TA heads are different because they have offset intake pushrods to allow more intake port opening. The other 915 heads are the same casting design as any other small block LA head. I noticed yours have the offset pushrods and rockers which makes them the TA heads.

Quoted by fishy68 *-


the TA heads are the 'J' 915 castings and are the same as any of the 915 castings. The only difference was in the machining of the heads for the TA (six-pac) engines.

Quoted by headsbikesmopars *-

 

[krazykuda]

Tips for Helicoils in heads:

I remove the rocker arms and pushrods and lay shop towels/rags in the valley to catch any chips that may fall. Then carefully remove them when you are done.

Using a shop vac to suck any chips out of the holes and valley is a good idea.

I would not recommend using oil or grease because they tend to attract dust and dirt and hold on to it like a magnet.

I recommend to drill and tap the head dry and then take a can of parts cleaner with a straw and stick the straw down the hole almost to the bottom and give a good blast or three to wash any chips away that may be too deep for the shop vac to suck out (before removing the shop towels, of course).

Then I would change the oil to remove any chips that may have gotten past all of that other stuff.

****
Things to think about with Helicoils.

Make sure that you set them deep enough so your bolt doesn't bottom out on the flat tang on the bottom when putting everything back together.

The flat tang at the bottom is used to drive the Helicoil into the hole and then stake it in when you back out the installation tool. You can sometimes hear it snap when you do.

If you use it on the straight through holes with out a bottom, cut the tang off and use some strong Loctite or equivalent thread locker to keep it from coming out. If you have to cut the tang before installing it, use a thin nut at the top of the installation tool to drive the Helicoil into the hole. Sometimes the end of the bolt has to go past the end of the Helicoil.

If the hole is threaded deeper than one Helicoil, use two to get enough thread depth and cut the tang of the top one as described above.

I know that you are already done, but this can be used for reference for others that need to use them in the future.

Just a few tips from a guy who's "Been there, done that".

Remember: You can't race your house, but you can always sleep in your car.

 

[68 A]

Lots of info! Thanks for the tips, i'm sure that i'll have to put a helicoil in again sometime and the more info the better. It's also nice to learn some history about them and understand what i have.

Fishy68, i think thats a good idea, i'm glad you told me that. I could get better flowing heads for less money, and i wouldn't ruin the purity of the heads i got cause someone out there would like them stock.

Time to go put it back together.

Thanks,

Steve

 

[68 A]

ok, i am still not done with this project.

I put the intake back on, and with 3 bolt left to tighten down, it stripped the thread in the head. Another trip to town to get a 3/8 helicoil pack. Got back and looked at the rest of them, there are quite a few intake threads that already had helicoils in them. One of which was not drilled square and had been a pain to put the intake on the first time. So of course when i am drilling one of the 2 i did tonight, i thought i was drilling square.

Turns out i wasn't and not i cannot get that bolt in because it is angled down too far. I took the rest of the bolts out and moved the intake so that i could get it started, and then tried to put the rest of the bolts in. But, it moved the intake too far and i wasn't even close to starting the bolts on the opposite head.

How do i fix this? Can i redrill the helicoil? or do i have to drill (at the correct angle) and tap it to a 7/16?

Possibly use a dremel tool on the intake to get the bolt to clear with the helicoil i put in?

I need to get this fixed tommorow night and get it all back together to go to a transmission shop on thursday. Hopefully there is a way!

Thanks,

Steve

 

[lilcuda]

Tips for Helicoils in heads:
****
Things to think about with Helicoils.

Make sure that you set them deep enough so your bolt doesn't bottom out on the flat tang on the bottom when putting everything back together.

Since the tang should be broken off when the helicoil is properly installed, this is a moot point. The tang should NEVER be left intact after installation. You leave the helicoil high enough so you can snap off the tang with a small punch. NEVER use the bolt to snap it off. Helicoils are very hard and can damage the threads on a Grade 5 bolt very easily if the tang does not cleanly snap off.

The flat tang at the bottom is used to drive the Helicoil into the hole and then stake it in when you back out the installation tool. You can sometimes hear it snap when you do.

Yes, the tang is used for driving the helicoil in, but you do not stake it in place, you snap it off.

If you use it on the straight through holes with out a bottom, cut the tang off and use some strong Loctite or equivalent thread locker to keep it from coming out. If you have to cut the tang before installing it, use a thin nut at the top of the installation tool to drive the Helicoil into the hole. Sometimes the end of the bolt has to go past the end of the Helicoil.

DO NOT use loctite in helicoils!!! There is so much misinformation about how to install these useful items, I can't beleive it!

You use the tang to install it no matter if the hole is blind or not. Always snap off the tang after installation, then using a small punch, stake the TOP of the helicoil. That, plus the fact that it is stretched lengthwise and compressed in diameter will hold it in place.

If the hole is threaded deeper than one Helicoil, use two to get enough thread depth and cut the tang of the top one as described above.

Not really necessary. The helicoil is designed for the particular diameter bolt you are working with and should be fine to hold torque with only one if you properly drill , tap & install the helicoil.

Take my advice. I spent 10 years in the automotive machinist business and was ASE ceritified. I installed a lot of helicoils and fixed a lot of improperly installed ones.

 

[68 A]

Hi,

I got my last problem solved. I ended up grinding some aluminum out of the intake to get the stud to go in at the "new" angle of the threads on the helicoil. Also cut the bolt shorter so that it would clear the intake to get it into the hole.

Tonight was much better than last night, but of course, i stripped another set of threads out for the valve covers. That'll be taken care of another day though...

Thanks for the help!

STeve

 

[krazykuda]

I hate to tell you, but I don't think it is a good idea to redrill the Helicoil.

If you do, you should use the same diameter drill that you used before you tapped the hole. If you go any bigger you will be taking metal out of the minor diameter of the threads. Any metal taken away from the minor diameter of the threads reduces the load that the thread can support.

Let me give you some definitions so you will understand what I am talking about.


The major diameter is the diameter from the outside thread from one side to the other.

The minor diameter is the diameter from the inside thread of one side to the inside thread of the other side.


The area that supports the load is the difference between the major diameter
and minor diameter. Or here is the math equation:

(major diameter - minor diameter)/2

This is the area that supports the load on a thread. To reduce the stress on a part, you either have to reduce the force acting on it or increase the surface area that supports it. The opposite is true here, increasing the force or reducing the supporting area of a part increases the stress on a part.

Not to mention that it is very hard to redrill a hole that is not crooked and make it straight. Drills like to follow the existing hole and you can make it worse trying to redo it by hand. You will probably make the hole egg shaped or too big trying to fix it by hand. You need a drill press to do it properly.

In your case I think the best bet is to get out the dremmel and grind what you have now to get the bolt to fit. Still a little risky. Then I would recommend tigntening the bolt an extra 3 - 5 ft-lb to make up for the lost clamp load from the cocked bolt if you think that the helicoil is done properly, it should handle it. You don't want to overcompensate and strip out the threads again.

The proper way to correct this is to have the hole drilled oversized and use a "sleeve or plug". Sleeves are typically flat on the outside and press fit into a hole that is slightly smaller than the outside of the sleeve. This definately should be done by a good machinist and not at home. A plug that is threaded on the outside that fits into a hole that is threaded on the inside would be the best way to do this. A sleeve may tend to creep over time with the heating and cooling of the engine and come out. The hole you press it in would have to be cut with a reamer and not a drill to ensure proper fit. Using threads would be best. Basically a Helicoil for a Helicoil, but much fatter. Definately done at a good machine shop on a drill press or mill.

One possibility worth looking into could be to see if you can find a pipe plug with an internal hex drive (hex key). You would want to make sure that you would be able to drill all of the hex drive out and put in a helicoil. If you can't remove all of the hex drive and have gaps to the outside of the helicoil is not recommended.

This again would have to be done in a machine shop. Drill and tap the thread to put the pipe plug in and secure it with a good loctite. Then maching the gasket surface of the head to make sure it is flat and the plug doesn't go above the sealing face of the head and keep the manifold from seating flat to the head. If there was a way to accurately set or countersink the plug .001" to .002" you might not have to mill it flat first, but this would require accurate depth control to insert the plug. Then clamp it in a drill press or milling machine and redrill and tap for the helicoil. This would make the part as good as new but take alot of time and money. Again the diameter of the hex plut would have to be less than the diameter of the helicoil going into it or it is not worth trying.

You probably can get away with the first idea. It is your decision. I'm just giving you some options to think about. I hate to see a T/A head scrapped.

 

[krazykuda]

lilcuda

You are correct on the tang. I just read the package and never noticed that before. I have been doing them wrong myself. How do you get the tang out of the hole?? Skinny magnet on a stick?

However, there are cases where there is more thread than the standard helicoil is made. The design standard for thread engagement is 1 1/2 x diameter of thread. Look at the head and rocker arm bolts.