The cheapest way would be to drill the threaded holes out to 5/16 then tap them to 3/8,buy 10 of 3/8 x 2 1/4 unc socket allen head cap screws, a bolt shop should be around a $1 a bolt the ebay ones are about a $1 each but postage makes them not worth getting.
Drill the cylinder head out to 3/8. That's what I would do.
[img]http://[/img]https://photos.app.goo.gl/53bDapT3qVZLktrK9 Ok guys. No work 2morrow due to rain. The lady of the house gonna be out all day. Got my kit from from a man that was selling one. I'll keep you all updated.
Hate chime in late but had make sure brain was in gear before opening mouth.
IF 5/16 course thread you can drill with a 5/16 bit and re-tap at 9mm-1.25. Make sure to use rubbing alcohol on the drill and tap for smoother finish and to prevent the tap from sticking in the aluminum. Of course assumes that you can drill straight with no wobble and the same when tapping. Plus you would need open up the hole(s) in the head slightly.
I still feel that the Helicoil is the best way to go as it'll be stronger than straight alloy thread. Just don't go too silly with the tightening of the head bolts as you only have the short Helicoil threads and not the longer variants.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
The tap chamfer is the tapering of the threads to distribute cutting action over several teeth. The type of hole to be tapped has much to do with the chamfer style of that tap that's best suited. Some holes go all the way through; some, while not through-holes, are relatively deep; some are quite shallow (a little deeper than diameter). Each of these three kinds of holes - through, deep-bottoming blind, and shallow bottoming - has a tap chamfer best suited to threading requirements.
Taper Taps - This style, with a 8-10 thread chamfer, has the longest chamfer of the three to distribute action over the maximum number of teeth; and the taper also acts as a guide in starting the cutting action in the hole. Taper style taps start the thread square with the workpiece. Taper taps are commonly used in through holes and in materials where a tapered guide is necessary.
Plug Taps ( Seconding Tap) - This style, with a 4-6 thread chamfer, is most widely used in through holes and where there is sufficient room at the bottom in blind holes.
Bottoming Taps ( Finishing Tap) - This style, with a 1-2 thread chamfer, is made with just enough chamfer for starting in the hole; as the name implies, it is designed to thread blind holes to the bottom.
That should get all of us on the same page when it comes to the basic threading taps. Now the UK/OZ terminology makes a little more sense. I think it would make more sense to be Starting, Intermediate, and Finishing but that's probably just me.
The terminology between countries does make it more difficult to be same page when it comes to repairs or anything at times. This is why I posted what I understood were the three basic threading taps. Of course there are numerous other specialised versions of taps.
Eventhough there are different types of threads, here I mainly deal with SAE and Metric but have come across an engine with British threading.
What a pain to get taps and dies for an one time project. Even with both SAE and Metric die and tap sets I finding the need to buy even more of the more non common sizes as manufactures try to propriety some of the screws and threads that are more common to their part of the world.
Here when I was in school in the 1970's the teachers were making out that the world was switching to metric. Boy were they wrong. LOL !
That would be a great idea wouldn't it ?, well that's what most of the world thought apart from one particular country that thinks it is the world and continually throws a spanner into the works.
Just look at the stupidity and arrogance regarding Gun control, while this mentality exists the world can't move forward.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
Totally agree it is those that want to stay in the dinosaur age that are a problem.
Personally being an Amateur Radio Operator I deal with metric daily and it is so much easier to convert. I have to pull out the cheat sheet every time I turn around to figure out the next size in inch fractions.
As gun owner and hunter I subscribe one shot one kill rule. I don't seen any reason to use an AK-47 to rabbit hunt. Those military type weapons has no place in the general population. Too many hair brains out there.
I started thinking about this metric thing, all of Europe/Asia would be/was metric, guessing Russia would be, not sure what the UK is so that is a big chunk of the world. One problem we here have is that a lot of us work on old machines that predate the general world swapping to metric.When I really think about it how many countries were not metric, probably British Commonwealth countries and the US.
Metric works on the base of 10 and that makes it just so easy opposed to imperial and then which imperial ?
I know we have to deal with the old stuff but most of that has come to the point of being turfed out now and being replaced with a metric equivalent. There's plenty of old tooling still left around to deal with tat stuff but honestly metric is far easier to work with and having a common playing field all around the smaller world would be far better in the long term I feel.
Now if we could just apply that theory to shoes and clothes we'd be on top of it wouldn't we ?
Cheers, BB
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
I know we kinda got off the subject at hand, but I am wondering if Dave107 has got around to trying to one of methods we all discussed? Be it re-tapping or helix coiling.
Sorry for taking so long respond guys. Yes I did go the helix coiling option. Bought a kit that included a 21/64" drill bit with a tap and handle and 10 coils. Heads back on and going strong.
