Technical > Matt Shaff's Engine Shop
Pulled threads on #3 main
wideopen231:
it can be done. Use grease or vasaline on tap to catch trash.Carb clean the heck out of it .Loctite the time cert using medium grade. As said its not ideal but will work. Not sure why getting it done would keep you from making race at end of month.Heck we had chassis repaired old body mounted and was racing 3 weeks after tearing car in half at Bristol in 91,might have seen the video,Most coverage we ever got. But you got to do what you got to do in this sport.
H.G. Wells:
Delay would be if I disassembled it and waited on machine shop. This was the motor in the car in my avitar, but planned to power a flat bottom drag boat 8hrs away. Still alot to do besides just the motor so 3 weeks is pushing it.
I am leaning toward pull it apart, buy the time sert kit and try it myself. With some soapy water and bottle brush clean it all up then re assemble. It is in my brothers shop and not the cleanest environment.
The bottom of the bolt hole is where the oil passage to the crank intersects with the passage running the length of the block. Not sure grease is an option as it will just push into the passages, really no place to screw around with crumbly little bits of cast iron.
I am afraid this is not the only hole that will need repair, and that is why I would want to get a machinist involved.
Thanks for all the input guys.
LZ:
--- Quote from: H.G. Wells on May 04, 2014, 12:50:27 PM ---Looking for some guidance from those that have experience with this.
Putting new bearings in a cast iron block BBC. Has ARP studs and when I went to torque #3 main one of the outer studs pulled the threads out. Looks like some of them were already rusty and on their way out. Thought I would helicoil it till I realized that one went into an oil passage and I did not trust myself to get all the little crunchy parts out if I drilled and tapped it. I have not disassembled the motor yet. Thought about stuffing a piece of hose thru the outer galley plug and making sure not to drill into it, but wonder how many other threads are about to go.
Will a heli coil hold or do I go with a timesert or one of the better pieces?
Pull the whole thing apart and take it to a machine shop and have them check all the holes? One of the inner holes thread did not look so hot either.
This is on a blown 496.
--- End quote ---
(disclaimer)This post is not meant to be condescending or anything so please anyone do not read that tone into this. I am just going to offer up some humble experience that I hope can be of use to you.
HG
H coils get a bad name because in many instances they are not installed correctly. I see this quite frequently. In most instances they give you a superior connection then just parent material.
We are at the beginning of the season and am sure you don't want to here this but she should come out IMO. A field repair no mater how careful will not guarantee gunk not getting into the galley. That would be a risk for you to decide.
The other thing is you mention that another hole does not look good. They all should get a good looking at and the head holes too. Was this block new to you?? It may have seen a hard life.
Part of successful H coil install is the the hole is tapped drilled to the correct size and its quality. It has to be decided that the H coil fix will give you a clean hole by taking out all the bad. It needs to be sized correctly and straight , or not oblong-out of round. Pistol drilling a fix is fine but you need extreme care and work a plan of drilling and or reaming the hole to get it correct. A pistol drill is going to be subject to how the hole is when you start. face angle , tooling, the operator etc. You would have a different approach pistol drilling to being in a machine. A hole can be pulled , distorted etc that it needs to be fixed in a machine to get the hole on location and on its position. This is why personally I like a mill for most repairs as you have the ease, rigidity and control, to get the hole -tapped correct.
Am I getting to wordy sorry.. :-[
Its so easy to tap the hole off and the h coil is relying on this to get the correct thread fit.
Keenserts, twinserts, locknstitch, etc. They all are great and have there uses. Especially sparkler thread repair.
So in a word you should have no concerns about H coiling the holes. But check them all.
Ricardo:
Yes you have a hardened thread going into stainless steel, compared to Cast iron. The threads need to be lubricated with a good quality lube to prevent galling. Also if the insert was installed in an oversize tapped hole it will give you a grabby mushy feel. Its so easy to tap the hole a little over such as if hole was power tapped or incorrect tap hole and using correct lube etc.
I apoligize for my sentancing etc.. Not good at putting thoughts to print.
If I can be of some support please give a shout out. I am sure you have much experience but just wanted to get some info out for any to use.
thanks and good luck
Luke
H.G. Wells:
Luke, thanks... I came here to bounce ideas and think outloud with some feedback. If I was sure it was only one I would be fine with the heli coil and a good cleaning of the bare block. (no it was not new to me) but since I am worried about there being others putting it in a mill and being able to drill square and in line to do several is the best solution. Won't know if others are bad till I blow it apart anyway, so might as well. Sad part is there is a Bridgeport and a knock off copy sitting a few feet from this motor and neither are set up and ready to run. (they belong to the other brother)
Several of the head bolts have heli coils done by me from the last build, and all of the intakes have heli coils, but none of those torque to 110lbs. I believe the time serts or other none wound inserts may be a touch better (I could be wrong, I have been wrong before, even today) this hole also only has about a half inch of threads because of the oil passage at the bottom. I believe I knew the answer when I started, just needed convincing. Will find out tomorrow if one of the local machine shops can get to it anytime soon. If not I will run up next weekend and get dirty.
Not to prolong the drama, but just to complicate things, I am in San Antonio TX. The motor is in OKC. My brother blew up the motor in his boat and I am letting him use mine since I bent my chassis and am out till I decide what I want to be when I grow up. I trust him to take it apart and take the block to the machinist, but I want to be the one that screws it back together. If it blows up in his boat after I put it together I am ok. If if blows up after he puts it together I may not be so forgiving.
ricardo1967:
--- Quote from: LZ on May 04, 2014, 06:56:22 PM ---Ricardo:
Yes you have a hardened thread going into stainless steel, compared to Cast iron. The threads need to be lubricated with a good quality lube to prevent galling.
--- End quote ---
Luke,
Thanks for sharing your experience, we appreciate it. I agree with you, a well installed Helicoil will be stronger that the parent metal thread (considering parent metal aluminum or cast iron, not alloy steels). In my case, both the original and the repaired threads were lubbed with ARP assy lube, but the cast iron thread is still smoother.
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