JimMueller

iTrader: (9)

I bought a used built block, and it turns out my new crank bolt basically slides in. The owner says he used to have a ATI blower on it and used a bigger bolt (he says it was a 16x2.0 4.5" long). He says he has the bolt he used.

The installer is skeptical of the reason for the longer bolt, and says I need to find a 18mm course thread tap and a matching bolt. Does it matter what material the die is made from? What other details do I need to know? Grade of bolt, 1.5x2.0x2.5 threads, etc.

Any place on the West coast I can still find this to have it overnighted?

Scalpel

iTrader: (4)

They must have stripped the threads and helicoiled it to accept a bigger bolt? I don't know why they'd helicoil a bigger sized diameter thread replacement, though.

This could be a PITA to fix.

Scalpel

iTrader: (4)

If at all possible, try to remove the helicoil and install the stock size threads with a new helicoil.

Also, the easiest thing could be to call up ARP and have them make you a custom bolt to the specs of the threads already in there. They can do it to the correct thread, pitch and depth. That's what I'd do.

JimMueller

iTrader: (9)

I've been reviewing other threads, and someone mentioned that ATI forgot to send him the right size crank bolt, as the stock one didn't work...? The previous owner did say never to buy an ATI blower. I'm gonna check in the FI forum...

JimMueller

iTrader: (9)

Just spoke with a ATI vendor and I was told that some of the ATI pullies need a longer crank bolt, and that this bolt doesn't fit into the stock pulley. He said that the crank gets pinned so it doesn't turn, and then they use some sort of drill mechanism to use a larger bolt in the snout.

Mean anything to anyone?

LordFlux

I've got an ATI D1-SC and am not familiar with using a larger (in reference to diameter) bolt. I've heard of a pinning kit that can be used to install a pin in the crank so that the crank pulley won't spin on the end of the snout, but a larger crank bolt? Never heard of that.

The crank pulley bolt that came with my kit was longer, but the diameter and thread pitch was all the same as stock. The only reason it's longer is to support the width of the extra crank pulley you're adding.

JimMueller

iTrader: (9)

Perhaps by drill he meant notching it. At any rate, I spoke with the installer again to verify. He said normally the stock bolt wants to start threading about an inch into the snout, but the bolt goes in further before wanting to start threading. We've already got the engine back in the car. I haven't been able to get in touch with the seller since earlier today but want to conference him with the installer to get the facts straight.

We put in the old crank bolt to turn the bottom end over to check valve clearance and it didn't have any problem.

So what do you think? Should we tap it? What specific equipment do I need to tap it? I was told to get a 18mm metric tap course thread - does it matter if it's 2 or 2.5 thread pitch so long as I have the matching bolt? What kind of bolt? How do I keep the tap straight so it doesn't angle during operation?

What other options do I have? I've got to get this car back on the road in reliable condition literally ASAP. It's my only vehicle and I've been bumming rides for a month.

JimMueller

iTrader: (9)

t/t/t

Scalpel

iTrader: (4)

Your wording is confusing me.

Let get get this correct, here, the stock crank bolt DOES fit, it just takes more depth of insertion before the threads begin to catch, correct?

This must be the case since you say above that you use the old crank bolt to turn the engine over.

If this is the case, then the crank was not heli-coiled to a different or bigger thread and pitch. The bolt that comes with the ATI kit I assume has more depth to it to allow for the added clearance of the pulley?

JimMueller

iTrader: (9)

Correct. I'm told that they are unable to torque the bolt due to the lack of threads inside the snout.

Paul F

iTrader: (2)

Okay guys lets get this straight. Are we talking about ATI Procharger or are we talking about ATI Dampers???? These are 2 totally different companies. The ATI pulley does not come with a bolt you either reuse a new GM bolt or an ARP bolt. We've installed tons of these pullies and NEVER needed a longer bolt.

What it sounds like has happened is someone tried to seat the ATI pulley with a bolt instead of the correct tool and has stripped threads out of the end of the crank. I'm not sure what the fix will be other then drilling out the crank and putting in a heli-coil. I'm not sure that they have one that size and I'm not sure they would hold the torque need to seat that pulley. Sorry Jim.

Scalpel

iTrader: (4)

They make that heli coil but it's damn expensive from what I have gathered. A member had to have his helicoiled a few months ago.

I'd drill it out and install the new helicoil. Do it right the first time. It'll save you TONS of aggravation later.

Paul F

iTrader: (2)

Man aint that the truth.


Paul

JimMueller

iTrader: (9)

The seller is sending us the bolt he was using. He said that the bolt which ATI sent him for his ProCharger wasn't quite the right size and it would only grip a few threads when it was put in, and damaged some threads. When they took it back out and put in the replacement bolt from ATI, it further mangled the threads. He said that ATI sent him something to extend the depth of the crank threads inside the snout and he then used a longer bolt. He estimates the bolt was gripping ~1/2" of threads at the back. Still doesn't seem like a lot of threads. The bolt he was using was a 16mm x 2 x 4.75" long bolt.

We're going to take a look at the used bolt and go from there. Why should we heli-coil it instead of tapping it up to 18mm? Let's play devil's advocate and tell me the possible scenarios of both resolutions.

Whistler

iTrader: (46)

The crank threads are stripped as far as a stock bolt will reach. The bolt just pushes in all the way to the shoulder without turning it.

The guy who sold Jim the engine says that there's a few good threads left that a longer bolt can grab onto... we'll try that before moving to the next step, because even if it doesnt work, I'm planning on having to drill and tap it anyway. I'll drill and tap it out to 18MM or 11/16 thread before I helicoil it.

FWIW I assemble engines with Kent-Moore Gen 3 tools, the crankshaft pulley installation tool is a long 16MM bolt with a nut on it to seat the pulley. It went all the way into the crank and pulled out when I attempted to install the pulley.

Nice of the guy to omit this from the description of the engine before selling it... dontcha think?? I also liked how he told me how to bang the balancer on with a mallet.

LordFlux

DANSLS1GTO

Sounds like the threads were stripped even before his problem with the install.
As far as the difference between heli-coil and drill and tap - so long as drilling and tapping isn't going to significantly weaken anything structurally - it's going to be the best bet for the joint.
Dan

Larry

iTrader: (4)

I would check the major diameter of the bolt(thread size) that was used and see if the 16 x 2.0 Heli-Coil drill will remove the damaged thread. Ideally you would like to have 1.5 D of thread. That's .945 bolt length engagement. I would not go to a larger thread if not absolutely necessary as it will weaken the shaft. It may be still strong enough but without calculations who knows.

You can buy an M16 x 2 Heli-Coil kit from Bass Tool & Supply in Houston. Part number 77-5403-16. I have a fairly old catalog but the price listed is $96.01. Their phone number is 1 800 442 0042. Or 713 682 1889

They do have an M18 x 2.5 and an M18 x 1.5 kit if necessary.

Scalpel

iTrader: (4)

Tapping is not the same as heli-coil. A heli-coil inserts new threads. Tapping cuts new threads and if you use a tap on precut threads (like the ones in your crank) you'll shave some of the material on the threads that was already there thus making the threads possibly weaker.

A heli-coil is a new set of threads and are, for the most part, much stronger than the original threads.

If it were my motor I would drill out the remaining threads, cut the new heli-coil threads and insert the OEM dimension heli-coil threads. I know it's not what you want to hear but it is the proper way to fix this situation. As it is you have less thread engagement than OEM = weaker.

It'll be a PITA to do but when done you can rest easily knowing the correct procedure was carried out and not one that is "maybe" or "possibly" type fix.

Phate

iTrader: (2)

Did this guy even tell you that the threads were botched when you were buying the motor? If not, I think that he should be paying for the parts and the labor for this to be done. In fact, I would be trying to get my $$$ back for the motor and start fresh with something else.