ya that article showed me the light on where that darn little triangle cover was it aint very big lol

 

why is the 87 motor special

 

This was written at a time when 1/2 stud kits were as of yet unavailable.

Then, there were only 6.9 -7/16" head stud kits for sale, meaning then, you could clamp down a 6.9 head down more tightly, because 7.3 head studs didn't exist yet.

85, 86, 87 years have the advantages of, while not a true "performance" issue, but they never suffered from the 82-84 weaker blocks, or the 88-later potential cavitation issues.

Because of that you don't have to be careful with the coolant system in these model years.

The only disadvantage, besides the 10hp left on the table from less displacement, were weak rocker arm pivot pads. On 6.9 they are wear items and will and do wear out, if you replace the 6.9 rocker arms with a set from a 7.3, then it is as good as any, especially if you go spend the money on high dollar studs.

But another advantage of the 6.9, is that though they are smaller, the 7/16" bolts are more forgiving of stretch, and therefore can be reused when doing a head gasket job. I reused the stock bolts and tightened them cold to 92 lbs.

The 7.3 stock head bolts, I think they aren't as good for reuse, if I had the 7.3 I would probably get bew bolts or studs when time for replacement.

I just got a new snap on power drive 7/16" 1/2 drive socket, gonna get my engine hot and retorque the heads and all the top end bolts, as it's been about 30,000 miles - give or take, since top end rebuild.

Latest years, like the last 2 years of the IDI, had real internal upgrades probably over stock, with forged and wider internals and different balancing, so perhaps for highest performance build, the last few years would be able to hold more boost, though you should boost these motors very modestly if your wanting to do that, I like my diesel naturally aspirated, because I like simplicity over efficiency or speed. But you would find nobody that agrees, everyone on the planet is in agreement that a diesel without a turbo is a boat anchor, so, get a turbo and boost it less than 10 psi if you want and watch your egts and fuel and such.

 

Classic Diesel Design is selling stud kits for the 7.3L IDI nowadays.

https://classicdieseldesigns.com/col...-head-stud-kit

 

Banks also still sells their sidewinder turbo kit for the IDIs.

https://bankspower.com/products/turb...-f350-6-9-7-3l

 

If I remember correctly, the 6.9 blocks are thicker than the 7.3s. So first off it’s going to be more robust. But it’s also the last year of the 6.9 so they had worked out most of the kinks by that point.

 

Sorry guys, I didn’t realize that some of these posts were going all the way back to 2010.

 

7.3 is a bored 6.9/ blocks are the same. difference is cylinder wall thickness.