7.1 IDI???

[IDIoit]

evidently, theres a shop in WA that is taking 6.9's
sleeving and boring them to a 7.1
using 1/2 studs and using 7.3 heads.....

anyone heard of this?

 

[Thewespaul]

Sounds expensive I would just use a idit block instead, do you know who’s doing this?

 

[IDIoit]

I chalked it off as BS
but heard about it again lastnight..
even with expenses sounds like a great way to detune by a few CI's lol

 

[Thewespaul]

No replacement for displacement. I’m building a 7.4 right now.

 

[Macrobb]

I've seen that shop and what they offer, haven't talked to them.
I did talk to a guy who looked into them, and said he had several people tell him that their quality control wasn't the best, issues with whatever motor that person had built.

This seems to be a common theme with IDIs - people seem to have trouble building them correctly for some reason. Of course, second hand info is still second hand... who knows.

Either way, the guy I originally talked to ended up deciding on a 6.9, rebuilt by a shop local to me(who I had issues with, but seems more reliable overall and is a one-man shop currently), with headstuds.

 

[chillman88]

What's the point? Is it a wall thickness thing? Seems the 7.3 block is plenty strong from the abuse I've seen on here. I'm not knocking it I'm just curious?

 

[franklin2]

Did they finally figure out how to keep the sleeves in the block? I remember a long time ago they were press fitting the sleeves, and then the fire ring on the head gaskets sat right down on top of the sleeve and tended to push the sleeve down in the block.

 

[Thewespaul]

Did they finally figure out how to keep the sleeves in the block? I remember a long time ago they were press fitting the sleeves, and then the fire ring on the head gaskets sat right down on top of the sleeve and tended to push the sleeve down in the block.

If that’s the issue they were having someone does not know what they are doing. You don’t machine for sleeves like you do boring out for larger pistons, you leave a lip at the bottom of the bore to stop against, you press in the sleeve till it’s flush, then deck the whole surface. The sleeve won’t have any room to move down and it will be flush with the deck height, the cylinder head keeps it down as long as the clamping force is sufficient for the cylinder pressure

 

[Macrobb]

If that’s the issue they were having someone does not know what they are doing. You don’t machine for sleeves like you do boring out for larger pistons, you leave a lip at the bottom of the bore to stop against, you press in the sleeve till it’s flush, then deck the whole surface. The sleeve won’t have any room to move down and it will be flush with the deck height, the cylinder head keeps it down as long as the clamping force is sufficient for the cylinder pressure

I know that's the reason a lot of cheap rebuilds fail - because they don't leave that lip, just Locktite it in. Which is why they fail.

 

[jaluhn83]

6.9 with 1/2 studs is not realistically possible. Not enough meat to drill and rethread the block.

Sleeving and bore to a different diameter is not hard, and easy to make reliable. Hard part would be finding pistons. 7.3 block sleeved to 6.9 would make some sense, although I’m not sure it’s worth the effort. Might also have issues having enough of a lip to retain the sleeve - 0.120 over is the normal sleeve od iirc, so a 4” bore sleeve would need a 4.117 ish bore - maybe possible with a stock bore, but if it’s been bored or badly worn forget it. You may be able to get thicker sleeves and compensate that way, but not sure.

 

[Randy Bush]

If that’s the issue they were having someone does not know what they are doing. You don’t machine for sleeves like you do boring out for larger pistons, you leave a lip at the bottom of the bore to stop against, you press in the sleeve till it’s flush, then deck the whole surface. The sleeve won’t have any room to move down and it will be flush with the deck height, the cylinder head keeps it down as long as the clamping force is sufficient for the cylinder pressure

If an sleeve is put in correct it takes a lot to get one to move. In all the ones my dad did I don't ever remember one coming back because it moved, 50 yrs of doing them. Although on a lot of them he did leave a lip at the bottom.

 

[Macrobb]

6.9 with 1/2 studs is not realistically possible. Not enough meat to drill and rethread the block.

I disagree. Justin @ R&D did it - just drilled and threaded. You do lose a bit of thread form, but there is plenty of meat - I recall that he tested to failure a stud in that hole - the stud stretched before the block threads gave way.

He, however, gave up because he couldn't get the threads "straight enough" for his liking - that he could have the whole set of studs sticking out of the block, and then slide the head down over it. He was more than able to use two studs as a guide, then install the rest with the head seated.
(I personally think this is good enough - a slight slight angle difference isn't going to affect anything as long as the studs go through their respective holes and thread in correctly).

 

[jaluhn83]

I disagree. Justin @ R&D did it - just drilled and threaded. You do lose a bit of thread form, but there is plenty of meat - I recall that he tested to failure a stud in that hole - the stud stretched before the block threads gave way.

He, however, gave up because he couldn't get the threads "straight enough" for his liking - that he could have the whole set of studs sticking out of the block, and then slide the head down over it. He was more than able to use two studs as a guide, then install the rest with the head seated.
(I personally think this is good enough - a slight slight angle difference isn't going to affect anything as long as the studs go through their respective holes and thread in correctly).

1/2 is 13 threads/inch, 7/16 is 14..... so you could drill it partially out and retap with 1/2-13 tap, but it will be a ugly messy thread that's not right and not as strong. Only way around that would be an insert/heli-coil which probably requires drilling out enough to overly weaken the structure or plug weld and redrill (if it's even possible on a block).

So yes, you *could* do it.... but it's going to be a half ass mess and not worth the effort.

 

[Macrobb]

1/2 is 13 threads/inch, 7/16 is 14..... so you could drill it partially out and retap with 1/2-13 tap, but it will be a ugly messy thread that's not right and not as strong. Only way around that would be an insert/heli-coil which probably requires drilling out enough to overly weaken the structure or plug weld and redrill (if it's even possible on a block).

So yes, you *could* do it.... but it's going to be a half ass mess and not worth the effort.

OD on 7/16-14 is .4375. Basic minor diameter(the peak of the thread on the inside) is .4167.
So, by drilling to .4375(which will remove all existing threads), and then tapping with a 1/2-13 tap, you still end up with most of the thread - you are only losing ~.0105" per side of thread form. We should still have ~62% thread form left, which is sufficient.
See: http://www.carbidedepot.com/formulas-tap-standard.htm for reference.
http://www.harveytool.com/secure/Content/Documents/Tap_Drill_Chart.pdf

 

[hce]

The 62% thread engagement is not bad when considering target thread formation is around 75%. Also at 50% the threads, the bolt should fail before the threads.