As above.. need to bolt head down now. It has not occurred to me as yet how I clean the bolt holes sufficiently?

Best way is to soak in gunk and if you have access to an air line blow them out.

have you got any old bolts, you will also need a nut that fits, screw nut onto the thread all the way down, take a hacksaw and cut a slot down the middle of the bolt for about 12mm, unscrew the nut - this will remake the thread were the saws chewed it up a bit, put some grease in the slot and screw the bolt in the thread in the block, mark the bolt with a pencil level with the top of the block, once the holes clear take a pencil or similar, thats thinner than the hole, push it in the hole and again mark it level with the block, compare the measurements, or if you have one use a depth gauge off a vernier to get the hole depth

A thin screwdriver and a strip of rag should suffice as the holes should have clearance at the bottom of around 3 times the bolt Radius, if my memory serves me ( and I know its going 'cos I'm old ). I hear a lot of talk of the bolt 'bottoming' and not tightening the head down enough, but in reality, there would have to be a serious amount of shyte to stop the bolt tightening right up.
At worst, loosen anything in the bottom of the hole with a long thin screwdriver and then grease the screwdriver and get it back in the hole. ( The shyte will stick to the grease and come out on the screwdriver).

Edit in green , I said diameter instead of radius.

So the idea being the grease picks up all the dirt etc and holds it to the bolt? Then you compare the depths so that you know it's gone deep enough?

That'll be the trick of it, but as I said, I very much doubt there will be any in there and they'll be plenty deep enough.

thats how i do it yes, though if i need i also have a set of taps here, only thing using taps is its very easy to cut a new thread !!!

Well, they're looking pretty good now. Some cack came out with the grease when using the screw driver. Sticking a torch down there I can only see grease particles.

hope you have covered the bores ?? dont want any shite in there when she fires up

Yep covered that!

Ok, not a great day progress wise. Just want some clarification here, figured it is better to be safe than sorry. 17 of the bolt holes will insert a bolt, hand driven, to the same depth before feeling resistance. The remaining hole will not allow a bolt to go as far down. The difference is only 2 spins by hand, NOT full turns. Just two partial rotations with your hand as you would when screwing a bolt down. That is the only difference with this remaining bolt.

I tried and tried to clean the hole out every way mentioned. All the other holes feel open smooth and circular when you insert a small screw driver and rotate it around. This hole feels rough at the bottom like it has ridges or divets. It almost seems to have a raised side and a lower side at the base of the hole. Whatever it is, it is NOT moving. No more dirt is coming out either. I can only assume it is an irregularity in the manufacture of the block and nothing to worry about as it must have been like this before? Also you wouldn't hit rock bottom when tightening the head anyway, right? I'm probably being over the top here but I just would rather be safe than sorry after this hole saga.

I ran an old head bolt in and out a few times with mine to clean things up once i'd got the worst out. Seemed to torque down ok after that. Will find out soon enough when i fire it up!

Bolts will be around 15mm from the bottom of the hole, they would never have been made to end up anywhere near the bottom

if your worried then ideally use a vernier to measure the depth of the head were the bolts pass through, then compare that to the bolts, measure the bolt length left and then compare that measurement to the holes depth, dont forget to add the thickness of the gasket

in engineering its not easy to thread a blind hole which is exactly what your bolts are going into, so you will not be able to screw to the exact bottom of the hole anyway

Given the distance difference we are talking about, and how far Lez has just said the bolt will be from the bottom, then I'm fine. All good. cheers guys. Think I'll be donating to the forum after all the help everyone has given me on this.

As Said, Ideally I would insert all the bolts into the block, do them all finger tight (I do them to 2.5nm but only because I use a power screwdriver and that's what it's set to).

Put a ruler over the tops and see if they are all the same height.
If there is one standing proud, Measure the lenght of bolt sticking out, from the top of the block to the underside of the bolt head.

You then want to take the depth of the head, if you do not have a vernier you can put the head down on a flat surface and put a pencil or something into the bolt hole, scribe a line at the top surface then take a measurement off that.
You also want the thickness of the gasket (compressed/installed thickness), the thickness of the bolt washers (should be 3.2mm for new ones I think) and the 'stretch amount' of the bolt.


Do the following sum:
Installed bolt length, minus head depth, minus washer thickness, minus gasket thickness, plus bolt stretch. You should end up with a negitive number which is the clearance you will be left with under the bolt threads after bolting down.

ps, 'stretch' is worked out as so, the bolts are a 1.25mm pitch. That means for every 360deg turn the bolt will climb down by 1.25mm.
The initial 29nm torque will preload the bolt and that will be (should be) the point before stretch starts.
You then tighten by 120deg so 1.25/360x120=0.42 so add that in above.
Worth checking as the blocks (and aftermarket heads!!) vary and yours may be closer than you think.
Do it on one hole first and if you have 15mm spare then you can forget the others as your safe enough!

Or to do it easy, take the amount of the one bolt you were having trouble with then put the ruler to the head. If it's 15mm or more you are plenty safe enough.

Could you re explain the short version? I got you on the long one.