88 Ford
Full Access Member
I have heard you cannot machine or deck the heads or groove them for rings. Why?
Question on machining or decking an idi head?
- Thread starter 88 Ford
- Start date
DragRag
Registered User
I'm only good at multiple choice questions......
bike-maker
Full Access Member
The precups are really frickin hard, they can be surfaced, but not grooved for an o-ring.
you *can* mill the heads a tad, but be prepared to have to do a little something to your intake manifold as well or you are going to have fit issues. Just make sure to bring the intake in with you when you have the heads cut and they will do what is needed to the intake so you can get the bolts in and torqued down properly I'mm too tired to think that hard at the moment 
bike-maker
Full Access Member
I've decked lots of blocks and heads - some of them alot; the only time I had issues with intakes fitting, it could be remedied with elongating the intake's bolt holes (good bye port match). This was only a couple of times. The more common issue was having to mill the faces of the intake because the angles of them were off.
Never put together a IDI after surfacing the block and heads, though...
Never put together a IDI after surfacing the block and heads, though...
88 Ford
Full Access Member
I just wanted you guys all to know that I have been informed otherwise by machinists that the heads can be cut. The inconel is not a big deal to cut a groove into with the right tooling.
I also have a line on a legitmate source to get fire ringed gaskets, More info to come...
I also have a line on a legitmate source to get fire ringed gaskets, More info to come...
bike-maker
Full Access Member
I used to oring heads and blocks. I'm not saying it's impossible. But it would be a complete pain in the ass that and something that most machine shops wouldn't care to try.
On the fancy BHJ setup I used (which makes lining up the grooves on the block and heads WAY easier), the cutter is a pretty standard little triangular insert, and is done by hand; there's just a foot long handle that you spin around until you reach the desired depth. In order to make a clean transition between the dissimilar metals, I would think that this would have to be done on a milling machine.
On the fancy BHJ setup I used (which makes lining up the grooves on the block and heads WAY easier), the cutter is a pretty standard little triangular insert, and is done by hand; there's just a foot long handle that you spin around until you reach the desired depth. In order to make a clean transition between the dissimilar metals, I would think that this would have to be done on a milling machine.
88 Ford
Full Access Member
The heads will be cut on a CNC mill.
IIRC it was because the precups can/will hammer down on them and cut them.
ON EDIT:
That was towards the rings part.
icanfixall
Official GMM hand model
The act os simple machining cast iron is really simple. A sharp tool and slow speeds. Cast iron actually chips rather than cuts and is abrasive to tool steel at high speeds. Now add some hard inconel to the mix and you really have some issues. Machining two differant metals and getting the same surface finish on both is tuff. Not all machinists can do it correctly. I have herad of some shops removing the precups and machining them seperatly because their tools can't cut them on the surfacer they have. It breaks the tool steel bits... Then they do a really bad job of "Fen" up your heads. The heads can be cut about 4 thousands and so can the block but.. They have a factory tolerance that must be kept too. I still am trying to find out the reason for the minimum deck and head height we all talk about. It can't be the lifter function but it may just be the intake to heads joint matchup. On my build I needed to machine the intake manifold about 15 thousands off both sides. My block was decked twice
And the heads were not touched... So the crappy shop told me... I don't recall if I measured the finished head thickness or not. The were new offshore heads too.
And the heads were not touched... So the crappy shop told me... I don't recall if I measured the finished head thickness or not. The were new offshore heads too.
rhkcommander
Full Access Member
Are there still new offshores available? All of these new gasket possibilities are exciting
towtruckdave
Resident Nutcase
A mechanical direct injected head would be exciting, IMO. O-ring that.
rhkcommander
Full Access Member
X2. With better injector placement and larger injectors
icanfixall
Official GMM hand model
Yes... The new heads can be bought at many locations. My last set of bare heads cost me $52.50 each with free shipping....
Nobody bit on them and I had family driving by the sellers lacation so they picked them up for me. The new heads are thicker than the oem heads are and thought to be a much better head. Nobody makes a new 6.9 head nor are any new blocks being made either. But everything else is still available new. Or mostly everything else. New cams, gears, cranks and I think new rods are out there too. If not well we still have the rebuilts available. From all I have determined I feel sure we can use a 7.3 head on a 6.9 block but using a 6.9 head on a 7.3 block will require you to drill out the bolt holes in the 6.9 heads to fit the 7.3 bolts. That has been done with a 1/2 inch hand drill too...
Nobody bit on them and I had family driving by the sellers lacation so they picked them up for me. The new heads are thicker than the oem heads are and thought to be a much better head. Nobody makes a new 6.9 head nor are any new blocks being made either. But everything else is still available new. Or mostly everything else. New cams, gears, cranks and I think new rods are out there too. If not well we still have the rebuilts available. From all I have determined I feel sure we can use a 7.3 head on a 6.9 block but using a 6.9 head on a 7.3 block will require you to drill out the bolt holes in the 6.9 heads to fit the 7.3 bolts. That has been done with a 1/2 inch hand drill too...
rhkcommander
Full Access Member
I must be blind or something... I cannot find em' anywhere for a 6.9 or 7.3 
