Building a high output idi

[idiabuse]

I have a set of 6.9 heads I used for 120,000 miles on my 7.3 IDI they are still worthy of service!
They had good guides when I found them in a field in the bed of a dead FORD

guides are still in perfect shape! well one head deck surface is .017 past the limit, and the other is .022 past the deck suface limit.

They did work great and always fired up with no GP always, I keep them just in case

Javier

 

[icanfixall]

How did you get a 6.9 head to fit the 7.3 motor??? Just wondering because the 7.3 head bolts are 1/2 inch and the 6.9 head bolts are 7/16... I don't understand how a stock 6.9 head fits on a stock 7.3 block.... Got any pictures....

 

[idiabuse]

How did you get a 6.9 head to fit the 7.3 motor??? Just wondering because the 7.3 head bolts are 1/2 inch and the 6.9 head bolts are 7/16... I don't understand how a stock 6.9 head fits on a stock 7.3 block.... Got any pictures....

I used a drill press and drilled the holes out and made spacers for the bottom row of bolts. here is one pic I have

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Javier

 

[tuckerd1]

I went the DPS route on IP and injectors and wish I hadn't. The injectors are junk. I always had a fuel knock with them. I put Delphi BBs in and was way more satisfied. Wish I had the Moose Misters and Moose pump.

 

[Agnem]

Let's make sure we understand you correctly. You're saying you used 6.9 heads on a 7.3? What did you do exactly to put this together?

 

[idiabuse]

Let's make sure we understand you correctly. You're saying you used 6.9 heads on a 7.3? What did you do exactly to put this together?

I used a drill press and drilled the holes out and made spacers for the bottom row of head bolts.

look closely you will see why they are 6.9 heads, you can see in my previous picture the casting numbers clearly.

I was told over and over by the experts years ago you cant do it

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Javier

 

[rhkcommander]

I used a drill press and drilled the holes out and made spacers for the bottom row of head bolts.

look closely you will see why they are 6.9 heads, you can see in my previous picture the casting numbers clearly.

I was told over and over by the experts years ago you cant do it

Javier

I saw this thread late or else I was going to say 6.9 heads on a 7.3 sure, but not vise versa. I've seen a few drill out the 6.9 heads to throw em on a 7.3.

 

[icanfixall]

Well... Thats kinda where I was going with my posting but didn't think anyone would go as far as drilling out the 6.9 heads to accept the 7.3 bolts.... I gotta give it to you for attempting this. It takes courage doing this type of work... Plus one for you.... Now did you use a 6.9 or 7.3 head gasket.....

 

[88beast]

i wouldn't recommend drilling out the holes
if not perfect you can ruin a head

 

[idiabuse]

The holes are perfectly drilled from the factory 7/16 OD, when you throw a head on a drill press and start drilling the 7/16 holes out to 1/2 the drill bit centers itself.
I did it with a small 110volt sears drill press cause everyone said they wouldn't do it for me. screw em! been there done that bought the t-shirt...

there is a difference in head gaskets for the 6.9 and 7.3? I used a 7.3 gasket Fel Pro

Javier

 

[Abull78]

The holes are perfectly drilled from the factory 7/16 OD, when you throw a head on a drill press and start drilling the 7/16 holes out to 1/2 the drill bit centers itself.
I did it with a small 110volt sears drill press cause everyone said they wouldn't do it for me. screw em! been there done that bought the t-shirt...

there is a difference in head gaskets for the 6.9 and 7.3? I used a 7.3 gasket Fel Pro

Javier

Way to go man. it's always nice to see people doing what others say cant be done!

 

[subway]

The holes are perfectly drilled from the factory 7/16 OD, when you throw a head on a drill press and start drilling the 7/16 holes out to 1/2 the drill bit centers itself.
I did it with a small 110volt sears drill press cause everyone said they wouldn't do it for me. screw em! been there done that bought the t-shirt...

there is a difference in head gaskets for the 6.9 and 7.3? I used a 7.3 gasket Fel Pro

Javier

wow, i would tend to agree though. the holes through the heads are really clearance to a degree. the dowels (i assume they have them, i cant remember if the engine i parted had them) should be doing all the fine alinging.

i suppose in theory you could use the heads as an alignement hole to upgrade the size of stud in the block. the head could be used to keep the drill bit and tap in a straight line going into the block. such as taking the smaller 1/2 6.9 bolt to a 7/16 or 5/8 if the meat is there and you dont punch into a water jacket.

i have not done any of this just thinking out loud here.

 

[93_444idi]

i heard that to put a 7.3 head on a 6.9 block you'd just have to drill out the holes in the block, but i think it'd be a lot less of a hassle (assuming everything else is the same) to just put 7.3 valves and rocker arms in a 6.9 head. you have all the parts at that point anyways. maybe a bigger stud would be more reliable than a 1/2" stud though. but.. ARP has 6.9 head studs on their site for under 300... i think i'll go that route.


gonna start with just getting the turbo and intercooler first and throwing them on my current motor. get better mileage = more money a week to spend on this project. can a hx-40 be toned down to just run with a stock 7.3 for the time being? limited to 12 psi i guess. not sure how thats done (i assume with the wastegate?) or if it can be done. can break it in on this motor before being put on the built one.

 

[icanfixall]

All idi non turbo valves are the same in the 6.9 and 7.3 motors. The only differance is the turbo exhaust valves are made from an inconel material. They cost around $35.00 each too.....

 

[Agnem]

I'm going to propose that 6.9 and 7.3 blocks start out as the same chunk of metal, and the only thing that happens different is the machining. It's not my belief that the water jacket arrangement is any different between the two motors. If it were, then they would not have had to block off the lower coolant passages in the 7.3 with a head gasket. They would have just made that adjustment in the block. I'm also going to suggest that the same is true wtih the heads. Only the changes to the molds were made that allowed the 7.3 heads to have those nifty head bolt bosses that the 6.9 heads don't. To keep manufacturing costs down, as much tooling from the 6.9 would have been used as possible. Consequently, I feel any machining operation you could do on a 7.3 head or block, you should be able to get away with on a 6.9 head or block. The only problem with fitting a 6.9 with 7.3 head bolts is the question of not using the correct size pilot hole to start the tapping operation. If you could get a pre-machined 6.9 block (which clearly isn't going to exist, unless you worked at the IH foundry and took one home as a paper weight, then you would have no problems tapping it for 7.3 head bolts.