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.
(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
