Chasing a knock at idle, # 1 main bearing, I found that the threads were stripped out of the block so the bolt couldn't be torqued down. I know heli-coil won't stand up in this situation. A friend suggested taking it to a machine shop and have a"thread zerk"installed. Anyone familiar with this or have other suggestions.
drill and tap to the next sized bolt???? that is the cheapest fix maybe the strongest too
Plus if you were to use the Heli-Coil you'd have to up the thread size anyways, and might as well go with the next size up. That being said I'm not 100% sure of the room around there to go with the bigger bolt. It's been a few years since I've had my bottom end apart.
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05:57 PM
Snacktime Member
Posts: 13 From: Pittsburgh, PA Registered: Sep 2010
I think your friend meant "Time-sert", and if so, I have used them before, but only once before on a cylinder head.
But more often than not, I have center-punched and drilled the middle of the bolt and used an easy-out. Seems like I get a lot of bolts unstuck that way.
-Snacktime
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05:58 PM
2farnorth Member
Posts: 3402 From: Leonard, Tx. USA Registered: Feb 2001
I think your friend meant "Time-sert", and if so, I have used them before, but only once before on a cylinder head.
But more often than not, I have center-punched and drilled the middle of the bolt and used an easy-out. Seems like I get a lot of bolts unstuck that way.
-Snacktime
The bolt is out... The threads in the block fell out in small pieces when the bolt came out. When it was reman'd they apparently over torqued that bolt an stripped the threads. It was an end of production deal so there's no warranty.
I thought about drilling and tapping to next size up but I'm not sure if I can yet. Either way I'd have to take it to a machine shop and have them do it. They'd have to drill the bearing cap also. I need to make sure there would be enough metal left around the cap hole.
[This message has been edited by 2farnorth (edited 10-18-2010).]
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06:46 PM
KurtAKX Member
Posts: 4008 From: West Bloomfield, MI Registered: Feb 2002
How about drilling & tapping the hole DEEPER, instead of bigger? As long as you have the same length of threads as original, & a grade 8 bolt MADE IN THE USA (so you can be sure of the grade), you should be fine. Of course, I don't have a block in front of me to check if that's possible... HTH, ~ Paul aka "Tha Driver"
Congress and babies should be changed often for the same reason.
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01:24 AM
TONY_C Member
Posts: 2747 From: North Bellmore, NY 11710 Registered: May 2001
You can use a Helicoil insert. The insert is actually stronger than the surrounding cast iron. I'd contact Helicoil directly, you might be able to get samples, they offer helicoils in a wide range of materials, from steel to titanium. Helicoils are used in far more stressful applications than holding a Duke main cap. http://emhartamericas.com/products/helicoil.asp
Want Tony said... Call Helicoil first. They can tell you want part # to use. (Assuming there is enough metal in the block for drill and tap...)
Use a bigger bolt is not a good idea... Problem is the Cap section... Usually not enough metal in Cap. It doesn't hold up very long.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
I had the same problem on hole for a head bolt on the 455 in my Trans Am. I used a time-sert and was able to pull the full 90 ft. lb. of torque once the repair was done. Highly reccommend the time-sert.
The bolt is out... The threads in the block fell out in small pieces when the bolt came out. When it was reman'd they apparently over torqued that bolt an stripped the threads. It was an end of production deal so there's no warranty.
I thought about drilling and tapping to next size up but I'm not sure if I can yet. Either way I'd have to take it to a machine shop and have them do it. They'd have to drill the bearing cap also. I need to make sure there would be enough metal left around the cap hole.
If you're going to be taking this into a machine shop to have them fix it you're going to exceed the value of the duke engine in labor expenses very quickly. I hate to say it but it's most likely more cost effective to just get another duke
If you're going to be taking this into a machine shop to have them fix it you're going to exceed the value of the duke engine in labor expenses very quickly. I hate to say it but it's most likely more cost effective to just get another duke
Installing a helicoil is easy and can be done yourself if done carefully. It's key to make sure the drilling is done so that the new hole is perpendicular to the block and not drilled at an angle. Drill out the hole to the proper size, tap with the proper helicoil tap and install insert. The Helicoil kit will cost about $25 or so. You can buy the helicoil kit at msc.com or mcmastercarr.com
Edited to add: I just looked at the web page for Time-serts, I doubt you have enough rib thickness to use a Time-sert, it requires a much larger hole be drilled to install it than it does for a Helicoil.
[This message has been edited by TONY_C (edited 10-19-2010).]
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01:14 PM
2farnorth Member
Posts: 3402 From: Leonard, Tx. USA Registered: Feb 2001
Well, this duke is already rebuilt and broken in. I will end up replacing the mains, but the rings, rod bearings, new pistons, cam and cam bearings can't be transferred to my other block without significant additional expense, plus all the gaskets. If I can,t make this work, then I'll do something with the very worn longblock I have sitting in the garage.
I guess I'll try the helicoil set up as soon as I get enough time to take the engine out of the car. Likely this weekend. Meantime I'll contact helicoil and see what they recommend. I sure appreciate all the responses and suggestions
Well I ended up doing a heli coil. The biggest problem was the "odd size" of the bolt 11mm. Required a special order set that cost $43. 6 coils in it , but I only needed one. Got it back together and running. Sounds okay so far. Haven't got it back on the road yet. Still need to double check everything and put the dogbone, cradle skirts, and tires on.
