IDI Rebuild Do's and Dont's - Diesel Forum

metrojd · 09-21-2007, 04:39 PM

I am tring to get input on the do's and dont's on the rebuild.
I have a 88 7.3 I am about to rebuild.
I an looking foe any suggestions and or proven tricks.
ie: cam, pistons head work ect...

Has anyone tried Copper Head Gaskets???

How about lowering the compression???

Thanks
John

hesutton · 09-21-2007, 05:46 PM

DO'S
-Felpro gaskets. Copper head gaskets are not for daily drivers and will leak if used that way. They are more for toys than drivers. Don't know if you can get them for the IDI anyway.
-New bearings (cam, crank, and rod)
-Have the heads magnafluxed and pressure tested for cracks
-New valve guides, have the seats checked/reground
-Hot tank the block and have it honed (not bored....it will increase the risk of cavitation). It the cylinders are out of spec, sleeving is much better than boring.
-You can get ceramic top pistons if you desire, not needed though
-Guys have found low compression pistons, but I don't know where you can get them. If you lower compression, expect hard starting, especially in cold weather.

DON'Ts
-DO NOT BORD THE CYLINDERS - as stated above, too much risk for cavitation.
-Don't reuse the old head bolts, They can stretch. It is not as much of a problem on the 7.3 as it is on the 6.9, but I would recommend new head bolts or studs if you are planning on getting crazy with the boost.
-There are no cams available for the IDI that I'm aware of. There are a few guys out there who have had custom grinds done by crane (I think that's the company) but there is little to gain with increased duration/lift with these motors. The cost vs. benifit is not good.
-Don't get impatient and just bolt stuff down. Torque the heads, rods, main caps to spec.
-Don't use a wimpy engine stand. This sucker is heavy and will need a stand that can hold at least 1000 lbs.

There is a ton of other stuff I'm forgeting. Others will be along to help fill in the blanks. Are you building this thing for big HP? If so, you might try looking for IDI turbo rods/pistions. Also, talk to Ken at DPS. He has build some 400HP IDI's.

Heath

yaric008 · 09-21-2007, 06:55 PM

My tip would be to use at least medium locktite on everything except head bolts and exhaust manifold bolts. Defintley use some on the valve covers. Those bolts always come loose. I've also had some bolts on accessories come loose a few times from all the vibration.

icanfixall · 09-21-2007, 09:55 PM

The low comp pistons can be bought from Mahle. They machine the pin bore 10 thousands higher in the piston. They come with a hard anadized top that is similar to ceramic. You can also mill another 12 to 15 thousands off those pistons but don't go more than that. It exposes the top ring to more heat and damage. Aligne honing or line boreing the crank webs in the block is a must. When you pull the main bearing caps look at the wear on them. If its worn on one side more than the other you know "things" are not straight. The same with the rod bearings. Balance it and make it no more than 1/2 gram differance between pistons. Felpro gaskets are a must.

typefour · 09-21-2007, 10:27 PM

Delta cams in washington state has a very nice grind they put on that picks the torque up some. They have a website not to expensive for the benefit.

metrojd · 09-21-2007, 11:07 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: icanfixall</div><div class="ubbcode-body">The low comp pistons can be bought from Mahle. They machine the pin bore 10 thousands higher in the piston. They come with a hard anadized top that is similar to ceramic. You can also mill another 12 to 15 thousands off those pistons but don't go more than that. It exposes the top ring to more heat and damage. Aligne honing or line boreing the crank webs in the block is a must. When you pull the main bearing caps look at the wear on them. If its worn on one side more than the other you know "things" are not straight. The same with the rod bearings. Balance it and make it no more than 1/2 gram differance between pistons. Felpro gaskets are a must. </div></div>
What pistons did you get?
Do you know what the 10 thousands pin differance would put the compression ratio at??
Thanks
John

metrojd · 09-21-2007, 11:11 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: typ_4</div><div class="ubbcode-body"> Delta cams in washington state has a very nice grind they put on that picks the torque up some. They have a website not to expensive for the benefit. </div></div>
Thanks
The only other one I found was Summit Has a Melling Cam.
Thanks
John

88beast · 09-22-2007, 12:26 AM

if in doght wear a coat well sleeve it at least, it will bring back like new proformance
i like rubber idr who makes them
dont use silicone use rubber or felt gaskets no cork
no fancy super seal or whatever they have now it will still leak but if you do it right first you will be happy without leaks just needs right trq per bolt kinda a feel thing

i would recomend alloy rockers if they make them
it will give better proformance and will not have as much flex in the rocker (could be like bad timing)

typefour · 09-22-2007, 01:25 AM

They dont make any roller type rockers yet for these, If they did I would have them, I am working on fitting some to an old head I have to see what will fit, Dont know the ratio of the stockers yet, just gotta measure it. I hope it is close to 1.73 then a bb ford rocker might work.

Greg77 · 09-22-2007, 08:42 PM

If your going to spend the time and money going thru the motor at least sleeve the back four pistons. The rest of it just use good quality components and you'll be fine. I don't see any of the fads helping you much as far as performance, unless your going to rebuild it into a turbo motor.