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Repairing head bolt threads

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Apr/03/2012 at 7:41am
I've used the long helicoil, but then I also set up a jig to drill perfectly straight..........  I've big on templates, jigs, etc. (as noted in my thread on hinge repair - I use good measuring tools, and make sure it's going to be just right even if it means spending an hour on setup just for a 1 minute drill job.)

The insert would be better for the reasons mentioned.... I guess it sort of depends on your goals for the engine, etc. It also depends on your skill, confidence, and tools available to you. Those things only you can judge.

I personally would do and have done the helicoil thing - and never had any problems.
Re-torques always checked out fine.
OTOH, I'm so busy now, I might just say the heck with it and let someone else deal with that less than fun part.
It will not be expensive at all - seriously, I bet it will be super cheap to have a shop install an insert compared to your time and hassle and running around.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bvpotash1 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/03/2012 at 7:06pm
I stripped out the threads in a block once.  I used 2 helicoils end to end to give  thread 

engagement equal to factory lenght. No problems even after changing the head gaskets many times.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote SportaboutX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/03/2012 at 7:24pm
Well, this will be a stock, lower compression engine, but I'd like things to just go right the first time. The big issue for me is finding any shop in the area that doesn't charge a ton just to do this. Billd mentioned it should be cheap to get it done, can anyone give me an estimated range? Around here, I'd guess I'd have to pay $300-400 to get the thread fixed, but possibly there are other machine shops known in SoCal that actually charge rates in line with the rest of the nation? BTW I am seriously questioning the quality of the rebuild at this point, so I most likely will get the shop to balance the rotating assy at the same time, as well as have them suggest a good brand of head studs, resurface the heads, and I assume basic FelPro's are fine for the headgaskets on a low comp engine?

Essentially, what should I expect to pay to balance the engine with flywheel/balancer, resurface heads, and fix ruined thread? Shop near me that would be about a $1000 bill, but what do real shops charge?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Apr/03/2012 at 10:58pm
My local shop would probably do all that you mentioned for about half that, $500.  The thing about the insert installation is what kind of equipment the shop has.  If they have one of the later variable speed high force mag base drills, it's no big deal drilling and tapping the hole as everything is based off the block deck.  If they don't and have to jig it up in a mill, then the costs go nuts. 
Still buying parts for the Machines. It's a disease.

Roger

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Post Options Post Options   Thanks (0) Thanks(0)   Quote gtoman_us Quote  Post ReplyReply Direct Link To This Post Posted: Apr/03/2012 at 11:00pm
Not that it is the same as a block but I had a heli coil installed in a bell housing for $25 by the machine shop that surfaced my flywheel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/04/2012 at 12:35am
Should not be any more than $50 for the helicoil and no more than $100 for the insert and not much more than an hour or two to do either.  Balancing prices vary by a wide range from $180 (at the shop I use in Mesa, AZ) to $450 in some other parts of the country.  Likewise, head resurfacing should be in the $50-$100 range depending on the shop you use. 
 
If you are coming to the Cactus Cruisers AMC meet in Phoenix this month or know someone else who is coming (weekend of April 21st) bring the stuff with you and we can get it done for you at a very reasonable cost.
Dan Curtis, AZ AMC collector quality Restorations, Parts & Engines - amcmusclecars.com

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Apr/04/2012 at 10:04am
Dude they SLEEVE engines here for 80 bucks a hole - so putting in that insert should not be much different - probably less in this part of the country.

If I could borrow a friend's equipment, I'd put the insert in for well under that.

I'll have to drag out my last machine shop tickets...... can't recall the balance job cost on my 390.

There's also a really great fellow close to me that runs a hi-perf machine shop in his huge garage (he built an Indy racer replica he tools around in now and then) and he's not expensive but he's sure got the respect of the rat rod crowd around here.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote SportaboutX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/05/2012 at 1:27pm
WOw you guys sure are lucky to get rates like that. A sleeve for $90!! You are talking 500+ here. Dan I have to say I am extremely tempted to utilize your shop . That amazingly low balancing price alone would save me hundreds. I have to figure gas costs for 2 round trips to the Phoenix area but I still just might come out ahead. I really want to get the 360 in the hornet this summer, as much of a pipe dream as that may be.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Apr/05/2012 at 1:50pm
The 390 that was in my 69 AMX when I got it had all the holes in one bank drilled to 1/2", then heli-coiled back to 7/16".  Best I can tell is they once had dog leg heads on it, and then went back to square ports.  The 69 cast manifold was also slotted.  The block seemed OK when I disassembled it.  I didn't re-use it, but sold it to someone who may have.

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RamblinMan Quote  Post ReplyReply Direct Link To This Post Posted: Apr/05/2012 at 6:02pm
Metallurgy: Helicoils are stainless. Engine blocks are cast iron. Anyone who's drilled both will tell you that cast iron cuts like butter compared to stainless steel. I know some machine shopps that won't drill and tap heads for screw-in studs without helicoils. In other words: the helicoil is WAY stronger than the iron around it. A helicoiled head bolt hole will be the strongest of all the bolt holes.
As for straightness, you have to be pretty far off (visibly so) to really cause a problem. Pay close attention and take your time. If you have an old head, bolt it on and use it as a guide if your drill bit is long enough. If the motor is on the stand, I rotate it to the point that the bolt hole is in the vertical position. I too, have done many (not thousands, or even hundreds, but certainly dozens) of bolt hole repairs, most of which were head bolt holes.
 
I'm a pretty cautious engine builder, but I am not afraid of sleeves or helicoils (even home-installed). Just my opinion.
Ed
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