An M16x2 thread chaser/cleaner is very hard to find...

 

Can you post another pic of that bolt, say looking more onto the end of it...

 

Amen to that brother! I'm going crazy trying to chase one down. And when you do find them they're super expensive!

I don't have a picture of the end of the bolt but can get one later. To be honest it doesn't look too distorted. It's only the end of the threads that are eaten up.

 

GM list there 12557840 Bolt for a standard LS1 at M16 X 2.0 X 103mm
GM list there 11570046 Bolt for the LSA application at M16 X 2.0 X 110.5mm

ARP list there 234-2503 LS1 Crank Bolt as M16 X 2.0 X 4.330 in. 4.330 in = 109.982mm

That being said. Since they made thousands of these cranks, I am sure the bottom few threads in these cranks are likely crap as mentioned. For a machine shop/ engine builder. It would be wise to buy a bottoming tap and verify you can get down far enough without damaging a new bolt.

The average garage enthusiast won't spend the money on one long enough. As mentioned there very expensive. Especially for a 1 time use. New, these taps can be around $100 or more. A standard length tap is not long enough. It needs to be at least 5 inches or longer. In metric look for one 120mm or longer.

You can find some nice used ones occasionally on Ebay for around $20 or sometimes less. The used ones will work more like a chase on the existing threads as they won't be as sharp as a brand new one.

 

FWIW, for a new one, this isn't priced too bad and it's 10 inches long too! You could probally rent it out or re-sale it afterwards.

http://www.ebay.com/itm/M16-X-2-0-D7...YAAMXQ9u1RFSsD

 

Is that a tap or a chaser...?

 

It's a tap. Similar to a bottoming tap. That's probably a $200 tap if I had to guess. It's nearly 10 inches long.

 

If the thread is not cut all the way at the bottom of the crank, a thread chase will not fix it.

 

So are the ARP bolts too long, or are the GM cranks not tapped sufficiently deep...?

 

You could make a thread chaser with a stock bolt like this

I've done it multiple times, pretty quick with a cut off wheel and grinder. Works great

 

I would suspect that the issue is with the machine work. I have seen/ heard of a few people pulling the OEM bolt only to have similar issues.

That works with old head bolts. The old crank bolt is not long enough to get the last few threads in the crank. Especially if you're replacing with an ARP bolt. Thus the need for a special tap.

I am not sure anyone makes an actual thread chase that will go deep enough as well as a chase only cleans threads, it does not cut new threads. If there heavily damaged or non existent near the bottom you will need a tap.

 

Tar Heel Follow ARP Tech Supports recommendations as there is a Huge Difference between an Chase and A Tap, Taps remove material from the Threads and can cause the thread pitch to change slightly even with the "correct" size causing the bolt to back out much easier or even pull through the threads when you are torqueing it down. If you have a bench grinder grind a flat shank on the messed up threads then take a thread chaser to establish a new starter thread on the old bolt and like they said use some anti-seize and run thread it in to the crank snout by hand in and out several times then use brake clean to clear the threads of any debris and when you install the new bolt use some blue loc-tite.

 

Not sure if I missed it, how was the balancer previously installed prior to installation of the ARP bolt?

 

I used a balancer installation kit. Everything went together fine on cam change #1 and it's run without an issue for almost 3 years.

I did find a 16mm x 2.0 tap ($$$) but it was too short to use. I used my old ARP bolt and made a "chase" like in post #30 but the threads wouldn't clean up. Worked on it for about 90 minutes ... run it in a few turns with cutting oil, took it out, cleaned up the threads on the bolt with some grade 8 nuts, blew out the crank with air, sprayed lubricant in, repeated the process ... This didn't get me anywhere so I'm assuming the crank threads are shot.

I called ARP and they said GM crank threads are crude at best and they see it happen all the time. Called some reputable machine shops and engine builders and they said ARP bolts do that all the time and they won't use them. So in summary ... who knows? Just one of things that happens.

I ordered a time sert kit ($200) and am going to give that a try. In doing online research as well as my conversations with some engine builders they've used this method before and it's worked fine. I'll just use red loctite on the time sert and check the balancer bolt often. I do not wish to pull the engine if necessary because when I do it won't be a 346 cubic inch LS1 going back in.

Scott

 

Tar heel, Do you feel a Tap that is long enough will work in your situation so you don't have to Time sert ?

I am willing to loan you one is why I ask.

 

Thank you for the offer; that is very kind of you. I have a tap that is long enough to start (if it would) but would only allow me to go in about 0.25" or so if it would get going. However, it won't even bite and get started which is weird since my homemade "chase" will thread in some. Even when I do get the "chase" in part way it just doesn't feel right if you know what I mean.

I sincerely appreciate the offer but a time sert would make me feel better. I'll keep an eye on it. We don't drive or race the car much but do like to have it all together when we do want to go out. Our youngest daughter is in college now so hopefully when she graduates in a few years we can do an iron block and big cubic inch forged nitrous engine. We're so thankful and blessed that we can afford college and that she is doing well and working hard but for what we spend on tuition we could build a NICE motor every year! I wouldn't have it any other way though.

Scott

 

No worries! I ran into a similar situation and had a hell of a time finding a long enough tap. Eventually I found one just barely long enough. I actually had to use a 12pt socket to drive it into the crank. I have since acquired some nice used longer ones and thought if it would help I would offer it up.

 

Thank you. Let me see how this time sert kit looks when it arrives later this week and I may take you up on your offer. I know the larger tap in the kit to install the time sert won't be long enough but I'm going to weld a deep socket on the end of it in order to be able to get the depth I want as well as use a 3/8" or 1/2" drive to install new threads.

Scott

 

Update: Well, after walking away from my cam change for a few weeks to do some summer around-the-house projects and keep from burning the car to the ground from frustration I went back at it this week. Order a Time-Sert kit as well as 29/32" drill bit and long story short I got the balancer back on today and the bolt seemed to bite and torque down. Kit was pretty slick and worked perfectly as long as you take your time and stay patient. It held during installation; let's see if it lives at 7,000 rpm now.

BTW: the Time-Sert kit is for sale is the classified section if anyone is interested or facing the same problem.

Scott

 

Glad you got it fixed and thanks for the feedback. With the number of guys who bugger up their crank threads by following ls1howto.com for removal and installation, I think someone is going to need that kit