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Username Post: Headbolt threads pulled out        (Topic#349560)
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-07-18 05:10 PM - Post#2723681    

Gen VI 454 block JUST bored,decked,tanked,magge d,etc.went to bolt left bank/1-7 head on,using #12367779 head bolt kit from GM (I think these are tty bolts-have a + mark on top of the head) torquing in stages of 30-50-75 for long bolts/65lbs for the short bolts.At 75lbs #6 and #9 threads pulled out of block.Went on through with torqueing,then removed head,helicoiled said holes,remounted head,using ARP headbolt kit,got to the last figure (75lbs long bolts/65lbs short) in torqueing then #12 and #3 threads pulled out.But at #3 hole block is cracked now,pretty much rendering my freshly machined block useless.The other bank/2-8 mounted fine with ZERO issues.WTH....So I stripped the block back down and took it back to the machinist,who says he's never seen anything like this.....I'm pissed and lost.What would have caused this?

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 




Shepherd 
Frequent Contributor
Posts: 1252

Loc: Lake George, NY
Reg: 11-11-15
02-07-18 05:52 PM - Post#2723685    
    In response to Am4wag

Silly question, but is your torque wrench accurate? Without seeing the details tough to offer a meaningful cause. Your machinist is your best source in this case.



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-07-18 06:05 PM - Post#2723687    
    In response to Shepherd

Torque wrench is new and accurate.Checked it at the machine shop.Machinist is stumped as well.

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


Edited by Am4wag on 02-07-18 06:06 PM. Reason for edit: No reason given.

 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-07-18 06:14 PM - Post#2723689    
    In response to Am4wag

OK, I have what will sound like a stupid question, but, WHAT TYPE/DESIGN thread tap was used to "clean" the threads?

I do believe I already know, and have posted about them not too long ago. Just ask the shop what design tap was used, betcha it is the one that severely weakens the threads. BETCHA.

This is NOT a funny situation, neither is using the WRONG design tap in a specifically different type of thread.



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-07-18 06:28 PM - Post#2723690    
    In response to IgnitionMan

I used a thread chaser,not a tap on everything ....lets keep in mind that on the other side/bank,the head torqued down fine.I want to add that this block had been reman'd.and in a boat that sank,but had low hours,std.bore and std.bearings AND was a freshwater /antifreeze cooled engine-so no corrosive erosion around the holes that I can see.I put it in the m/c to get the block freshened as I have a balanced and forged crank,rods,and .030 over pistons I'm just wondering if somehow electrolysis broke down the alloy composition in that area.Strange,as this is the only problem area.

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-07-18 06:38 PM - Post#2723691    
    In response to Am4wag

"I used a thread chaser,not a tap on everything"

Please outline to me just what the EDGES of the "thread chaser" you used, look like. Does each flute of the thread come to a sharp point?



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-07-18 06:54 PM - Post#2723693    
    In response to IgnitionMan

Well,they're not rounded,but not sharp like a tap either.The chaser kit is Snap-On RTD48.I actually remember running the chaser in every bolt hole using only my fingers.But ofcourse that's not to say a tap was not used in the past...But how would that explain the cracked block at hole #3?

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-07-18 07:08 PM - Post#2723698    
    In response to Am4wag

I am NOT trying to bust your chops on this, only that more than a few people have used a lot of different things that caused more problems than they were worth when doing this sort of thread "cleaning".

The actual thread type used is called a "roll" thread, and there are other thread types that are close, but can remove metal if used.

The taps most people erroneously use is the "standard" cut thread taps, flutes come to a point on their ends. the roll tap is what you mentioned, flat on the flute ends. Same as the bolts are threaded.

I use a simple round wire brush in an electric drill down the threads to clean the holes, works well.

Another question, this engine was sunk in water for a period of time, not a dumb question or two, how long, and salt or fresh water, makes a difference in metallurgy attack.



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-07-18 07:37 PM - Post#2723700    
    In response to IgnitionMan

Boat had been hauled out same day,engines run and pickled.Sat on shop floor for about a year,I bought it from the boss and only used the block and harmonic balancer.I guess I'll chaulk it up to the heads being removed/installed multiple times in the past.This really "put a wrench in my fan".I went on and bought a NEW block.

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-07-18 09:02 PM - Post#2723708    
    In response to Am4wag

Cast iron "ages" with time, and unlike metals with water between them sure doesn't help that cast iron stay strong.

Sounds like a few small calamities that ganged up and became a giant PITA. We've all had it like that on various projects.

Too bad it took a different block to resolve it.



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-08-18 05:44 PM - Post#2723801    
    In response to IgnitionMan

Just glad it's reveiling now instead of maybe going down the road later and a head lift or be constantly blowing head gaskets.

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-08-18 05:58 PM - Post#2723806    
    In response to Am4wag

I have a hobby I like to work on, all sorts of all aluminum Buick 215 V8 and their descendant Rover 4.6 V8's. I use all sorts of different engine stuff, Leyland truck cranks that stroke them .600, early Chevy rods narrowed, Chevy 305 V8 pistons, aluminum Buick 300 heads with late model Corvair valves, all sorts of weird and unusual combinations.

I have had my share of stropped "cleaned" bolt holes on those engines, and find that the ONLY common sense is to do the cleaning correctly, and use studs where ever one can fit them in.

Yes, studs are a pain in most situations, but, they don't rotate stress the threads when bolts are torqued into stretch. The less you turn a stretched thread, the less it develops problems.

I am glad you got it going, way too much hassles, though.



 
models916 
Valued Contributor
Posts: 4774

Age: 67
Loc: Addison, IL
Reg: 05-28-10
02-09-18 06:21 AM - Post#2723848    
    In response to IgnitionMan

Just regular motor oil for a lube to get torque correct. If you use molly or super lube you have to reduce the torque. ARP has a chart for their bolt lube. Use a stretch gauge for the rod bolts.



 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-09-18 07:00 AM - Post#2723850    
    In response to models916

Excellent info on lubes and bolt stretch. That is what fastener torque is all about,



 
Am4wag 
Contributor
Posts: 102

Reg: 11-19-15
02-09-18 12:45 PM - Post#2723886    
    In response to IgnitionMan

I WAS using engine oil under the bolt head(s) and under the flat washer (only a drop or 2) along with Permatex liquid thread sealer on the threads.I got a new block in today,put it in (a different) machine shop to get 30 over and deck checked.....I know I know,what a shame to bore out a new block but I already have a balanced rotating assy.w/made to order 30 over pistons (GM/Edelbrock dome)...wasn't cheap.

The bearer of gossip is a small untrustworthy person who takes delight in someone else's problems. Avoid them.
Let's all make the day count. - Charlie Daniels


 
mjc1 
Senior Member
Posts: 1458
mjc1
Loc: Burlington Ontario Canada
Reg: 09-15-04
02-09-18 04:00 PM - Post#2723898    
    In response to Am4wag

Use studs.

1967 Grande Parisienne 4DR HT
My Flickr page



 
CNC BLOCKS N/E 
Senior Member
Posts: 974
CNC BLOCKS N/E
Loc: NORTH EAST
Reg: 12-12-03
02-10-18 09:15 AM - Post#2723946    
    In response to mjc1

If the block was plate honed like it should have been why didn't the head bolt holes strip out at the machine shop?



 
IgnitionMan 
Valued Contributor
Posts: 3303

Reg: 04-15-05
02-10-18 11:16 AM - Post#2723955    
    In response to CNC BLOCKS N/E

Might come down to the engine hero guru that did the work on it.



 
raycow 
Honored Member
Posts: 27372
raycow
Loc: San Francisco, CA
Reg: 11-26-02
02-10-18 11:17 AM - Post#2723956    
    In response to CNC BLOCKS N/E

I have never had a block plate honed, so I have to ask....
For plate honing, are the bolts normally tightened to the factory torque spec? Is the thread engagement length the same as when you have a head on the block?

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 




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