Head & head gasket questions [Archive]

hayd3n

1st May 2013, 18:50

ok so im drilling out my 10mm threads on my POS xl250 and fitting 12mm head bolts

what is the safest way to make the head gasket holes bigger to fit the bigger bolts??

the head gasket is made of 3 layers of some kind of steel with a teflon?? coating,
i have had a play with the old gasket and tried using a die grinder to make the hole bigger but it just makes a mess of the hole :(

also i will have to remove the locating pins between the head and barrel to fit the bigger bolts will this be a problem as they wont be going back on??

there must be a way with out damaging the gasket, other wise can i make my own gasket out of something???

Drew

1st May 2013, 18:54

The two head stud holes in the gasket, that used to have dowels should accept M12 bolts. Drill and tap those two first, then bolt the head to the barrel, and do the other two.

Not putting dowels in with the new bolts, will be an interesting way to fuck a motor. Good luck with that.

FJRider

1st May 2013, 18:54

Have you actually tried putting a 12 mm bolt through the bolt hole in the gasket ??

Akzle

1st May 2013, 18:55

hole pnch dude. with a short taper, and probably on hard wood.

else if you were gang$ta with a twist drill...

hayd3n

1st May 2013, 18:59

the head and barrel will accept the new bolts but the gasket wont yet

bogan

1st May 2013, 19:00

Step drill would be my first try; anything else is going to be tricky to line up right.

Dowels, I agree with Drew on that one.

hayd3n

1st May 2013, 19:01

if i have to i can make new dowels just a little more work to do with the radial drill

scumdog

1st May 2013, 19:07

if i have to i can make new dowels just a little more work to do with the radial drill

Check your PMs

Virago

1st May 2013, 19:13

hayd3n

1st May 2013, 19:20

will have a play tomorrow :niceone::niceone::niceone:

FJRider

1st May 2013, 19:23

hayd3n

1st May 2013, 19:28

Pre-drilled with 10 mm holes in the wood .. would be easier to center the holes.

Or get stepped 12 / 10 mm stud bolts.
cant see how this would work ??

bogan

1st May 2013, 19:36

I regularly drill perfectly neat holes in paper, using a standard twist bit in a drill press. I would think it should work okay on a gasket.

Sandwich it between two bits of wood, the top piece pre-drilled with your 12mm hole. This will provide perfect support under and around the hole as you drill it.

That'll work cos the paper is softer than the wood, try it with steel between wood and I expect you'll make a mess. Sandwiching it between steel or aluminium is more likely to work I think. ut bear in mind a twist dril from 10-12mm is going to have a lot of 'bite' you might want to adjust the cutting angle a bit first.

Drew

1st May 2013, 19:39

Do the studs not go right into the casings?

Virago

1st May 2013, 19:46

...bear in mind a twist dril from 10-12mm is going to have a lot of 'bite'....

Yup. That's why it's important to use a drill press - that way you can finely control the feed. Do it with a hand-drill and it will rip things to shreds.

hayd3n

1st May 2013, 23:22

Do the studs not go right into the casings?

the cylinder bolts to the crankcase via 4x 10mm headbolts and the head bolts to the cylinder via 4x 10mm headbolts,
the threads in the cylinder head are stripped and 2x have already been previously helicoiled (last year ) by a engine reconditioner
which lasted 10 kms

Drew

2nd May 2013, 07:02

the cylinder bolts to the crankcase via 4x 10mm headbolts and the head bolts to the cylinder via 4x 10mm headbolts,
the threads in the cylinder head are stripped and 2x have already been previously helicoiled (last year ) by a engine reconditioner
which lasted 10 kmsSweet. Clearer picture now.

The important thing is to sandwich the gasket between two things to drill it. I would use the head and barrel for the sake of making sure it all lines up in the end.

Things to remember. Without dowels, the head and gasket might twist. Piston hitting either of those will fuck it and maybe bend a rod and fuck a big end.

The holes on the barrel need to be smaller than the holes in the head, so there's material for the tap to cut away. If you do it my way, don't go too deep with the drill when going through the gasket. Drill press for the win.

If it had already been helicoiled and they stripped, those holes might already be oversize to cut a 12mm thread into. Check that out first methinks.

Others will come up with more warnings, wrap your head around it all before you start work. Many a workable solution has been botched, by impatience and eagerness.

Akzle

2nd May 2013, 07:43

stepped bolt= shoulder bolt,
tap head *block for m12, have m12 stud turned down to m10 just below *mating* surface. Save fucking arnd with gasket.
Damn. Hate agreeing with figgy.

-edit-
sent from cellphone. you shoulda got whut i meant. (hell, he did...)

hayd3n

2nd May 2013, 17:45

stepped bolt= shoulder bolt,
tap head for m12, have m12 stud turned down to m10 just below head surface. Save fucking arnd with gasket.
Damn. Hate agreeing with figgy.

i have to tap the barrel not the head
THE HEAD isint tapped

FJRider

2nd May 2013, 17:57

i have to tap the barrel not the head
THE HEAD isint tapped

Do we have to draw you a picture .. ???

The stud has two different sized threads.

The 12 mm thread goes into the newly enlarged tapped holes in the barrel.

The 10 mm portion of the stud is what the head bolts attach to.

ANY half decent engineering workshop could make up the required number in less than an hour. You give them the required length of each thread ... and no issues.

hayd3n

2nd May 2013, 18:15

Do we have to draw you a picture .. ???
.
would be a lot fuking easier lmao
is this what your referring to??

http://tnt-power.com/images/A1_STUDS.jpg

the ones i have look alot like this

http://www.peninsulardiesel.com/WP-PENTEST/wp-content/uploads/wpsc/product_images/6250504.jpg

FJRider

2nd May 2013, 18:29

the ones i have look alot like this

And a reason not to change to the double sized studs would be ... ???

Quick and easy and you don't fuck gaskets.

hayd3n

2nd May 2013, 18:36

And a reason not to change to the double sized studs would be ... ???

Quick and easy and you don't fuck gaskets.

hardened bolts are not that easy to thread
, and ive managed to sucessfully drill out the gasket now :)

hayd3n

2nd May 2013, 18:45

Sweet. Clearer picture now.

Things to remember. Without dowels, the head and gasket might twist. Piston hitting either of those will fuck it and maybe bend a rod and fuck a big end.

.

the barrel dowels that attach to the crank will still be there :),
i cant see the head (with out dowels ) moving causing any piston problems apart from loss of compression,
+ the new bolts / holes have only slight clearance,
my foreman (engineer) is quite content that i should be fine with out the dowels in the head,
but i am looking into making new ones :)

Akzle

2nd May 2013, 19:07

hardened bolts are not that easy to thread
, and ive managed to sucessfully drill out the gasket now :)

unharden them, machine them, re-harden them. sheeesh. blowtorch and lathe.

bogan

2nd May 2013, 19:18

the barrel dowels that attach to the crank will still be there :),
i cant see the head (with out dowels ) moving causing any piston problems apart from loss of compression,
+ the new bolts / holes have only slight clearance,
my foreman (engineer) is quite content that i should be fine with out the dowels in the head,
but i am looking into making new ones :)

It won't be sliding around, but thermal expansion forces etc may cause bits to move. If you can get it lined up properly and dowels sized right there is not reason not to do it.

Akzle

2nd May 2013, 19:29

It won't be sliding around, but thermal expansion forces etc may cause bits to move. If you can get it lined up properly and dowels sized right there is not reason not to do it.

stainless roll pin?

Drew

2nd May 2013, 19:37

I've never pulled a motor down that didn't have locator dowells. I suspect the good folk who design motors all agree they should be there for some reason.

hayd3n

2nd May 2013, 19:43

I've never pulled a motor down that didn't have locator dowells. I suspect the good folk who design motors all agree they should be there for some reason.

:):niceone::niceone:

FJRider

2nd May 2013, 20:03

If it had already been helicoiled and they stripped, those holes might already be oversize to cut a 12mm thread into. Check that out first methinks.

The difference between a 10 and 12 mm bolt is an extra one mm in the bolts radius.

Is that extra one mm enough safe steel to thread a bolt hole .. after a helicoil has been stripped from the same location ... ???

jellywrestler

2nd May 2013, 20:06

the threads in the cylinder head are stripped and 2x have already been previously helicoiled (last year ) by a engine reconditioner
which lasted 10 kms
so why did they fail, did you torque them correctly?

Grumph

2nd May 2013, 20:09

The difference between a 10 and 12 mm bolt is an extra one mm in the bolts radius.

Is that extra one mm enough safe steel to thread a bolt hole .. after a helicoil has been stripped from the same location ... ???

No - but I'd put a 12mm helicoil in there anyway - and the tap drill size for a 12mm thread helicoil is 12mm....

And make it a long series one while you're at it.

hayd3n

2nd May 2013, 20:13

so why did they fail, did you torque them correctly?

when i originally removed the head last year the head bolts were so tight it removed a hell of a lot of aluminium :(
, i believe the helicoil diddnt have much to bind to,
the new 12mm threads in the cylinder are a hell of a lot longer than the old one as the threads were recessed down about 25mm, below the dowels , so they only had 20/25 mm of grab

hayd3n

2nd May 2013, 20:17

the heli coil drill size is 10.5 which is also the same size i have used to tap the new 12mm x 1.5 bolts , however i have a lot more depth in the thread now :)

jellywrestler

2nd May 2013, 20:25

the threads in the cylinder head are stripped and 2x have already been previously helicoiled (last year ) by a engine reconditioner
which lasted 10 kms

when i originally removed the head last year the head bolts were so tight it removed a hell of a lot of aluminium :(
, i believe the helicoil diddnt have much to bind to,

seems like you know better than your engine reconditioner, i'd get a better one of the two

hayd3n

2nd May 2013, 20:32

seems like you know better than your engine reconditioner, i'd get a better one of the two

well you dont know unless you try these things / hes a gc and has given me free head bolts :), and brush honed the cylinder

the gasket itself is cheep,

other work i have had done has been fantastic

tigertim20

2nd May 2013, 20:47

And a reason not to change to the double sized studs would be ... ???

Quick and easy and you don't fuck gaskets.
double sided bolts mentioned by fjrider could be a good solution - but with them not having a head on them can make them a right cunt to get out later if you need to do other work for some reason or whatever.

I cant see it being difficult to sort out the locating pins, it doesnt matter where they are really does it? even if you drill new holes and reuses the same pins you have now or swap out for roll pins or similar?

hayd3n

2nd May 2013, 20:50

double sided bolts mentioned by fjrider could be a good solution - but with them not having a head on them can make them a right cunt to get out later if you need to do other work for some reason or whatever.

I cant see it being difficult to sort out the locating pins, it doesnt matter where they are really does it? even if you drill new holes and reuses the same pins you have now or swap out for roll pins or similar?

im thinking if i made studs there may not be enough clearence to refit the head its a tight squeeze already,
the dowels are to small as the headbolts go thru the centre of them.
i am looking at making /buying new ones, most likely make them

FJRider

2nd May 2013, 20:55

double sided bolts mentioned by fjrider could be a good solution - but with them not having a head on them can make them a right cunt to get out later if you need to do other work for some reason or whatever.

I cant see it being difficult to sort out the locating pins, it doesnt matter where they are really does it? even if you drill new holes and reuses the same pins you have now or swap out for roll pins or similar?

In my younger years I rebuilt the top end on an old XL250. The studs were buggered and new ones were helicoiled in. Using nuts on the studs removed the need to endanger the helicoils if head removal was later needed for some reason.

It lasted for years ... until I found a deep water hole. As far as I know ... the bike is still in that same hole.

DrunkenMistake

2nd May 2013, 21:59

im thinking if i made studs there may not be enough clearence to refit the head its a tight squeeze already,
the dowels are to small as the headbolts go thru the centre of them.
i am looking at making /buying new ones, most likely make them

If for whatever reason you do use studs and need to get them back out gimmie a yell we have stud removers at work, shouldnt fuck the studs but sometimes they can.

Akzle

3rd May 2013, 05:47

If for whatever reason you do use studs and need to get them back out gimmie a yell we have stud removers at work, shouldnt fuck the studs but sometimes they can.

wtf.
Just lock two nuts against each other on the threads you've got and wind out using the bottom one.

Drew

3rd May 2013, 06:24

wtf.
Just lock two nuts against each other on the threads you've got and wind out using the bottom one.Doesn't always work on seized studs. Extreem measures, weld a nut to them...Always let it cool down before attempting to wind it out.

Akzle

3rd May 2013, 08:14

Doesn't always work on seized studs. Extreem measures, weld a nut to them...Always let it cool down before attempting to wind it out.

or use heat/oil/impact driver, to unseize it.

(i've yet to meet a bolt i can't fuck up)

hayd3n

3rd May 2013, 20:53

scored some dowels today :) 14mm od

Tarded

4th May 2013, 17:16

I dont like helicoils. Glorified bloody springs.

have a look at Wurth timeserts - a much better product.

I dont work for them by the by but I did years ago.

http://www.wurth.co.nz/

I was a mechanic for years too and timeserts are the shit.

I hate fixing shit twice so would rather spend the coin once.

Up to you.

imdying

6th May 2013, 16:30