who knows this answer
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Elder User
Joined: Sep 2006
Posts: 852
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From: ARIZONA
who knows this answer
ok, how to get better flow from an old 2 valve per cylinder diesel head,
does any one know the intake and exhaust valve size,
any one ever port and polished the heads.
and moved up in valve sizes, this is mostly just wishful thinking on my part as an inquirey.
does any one know the intake and exhaust valve size,
any one ever port and polished the heads.
and moved up in valve sizes, this is mostly just wishful thinking on my part as an inquirey.
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
I hear you bro. I've thought about this too ala old school porting stuff. 
Unfortunately, what I have found thus far is that the setup does not leave too much to be desired, even in the camshaft department. I do not know if this is because IH designed it that well or because the total sum of the parts will not net an appreciable gain. It is a turbocharged engine so flow says only real big problem corrections net big gains.
I do know polishing and porting has never hurt unless you botch it and gains can be had. Just don't think I'm gonna do it but glad you asked because if somone can say that it is a big improvement, I will do it. Also, I believe we have regular hydraulic lifters. I have heard nothing of roller solids or hydraulics in these. Wonder why? Probably nobody makes them. Seems everything with the 7.3 is a bolt on.
Unfortunately, what I have found thus far is that the setup does not leave too much to be desired, even in the camshaft department. I do not know if this is because IH designed it that well or because the total sum of the parts will not net an appreciable gain. It is a turbocharged engine so flow says only real big problem corrections net big gains.
I do know polishing and porting has never hurt unless you botch it and gains can be had. Just don't think I'm gonna do it but glad you asked because if somone can say that it is a big improvement, I will do it. Also, I believe we have regular hydraulic lifters. I have heard nothing of roller solids or hydraulics in these. Wonder why? Probably nobody makes them. Seems everything with the 7.3 is a bolt on.
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
Tenn is right. There hasn't been much luck in the porting department, or cams for that matter. The high HP 7.3's out there seem to be doing better with only very light head work and valve spring replacment. Other than that, not much else is going on up there. There's been a few who have played around with custom grind cams and that has actually caused a loss of power.
Senior User
Joined: Oct 2004
Posts: 374
Likes: 0
From: Ridgecrest, CA
Just food for thought on polishing the intake runners on normally aspirated carburated motors. An old motorhead told me that it's not a good idea on daily drivers, just on Hi-perf motors that you want to keep the revs up. The rough sides help swirl the air/fuel mixture together during low RPM's to provide a better burn pattern in the cylinder. Now on turbo/injector motors, I don't see a lot of gain from doing porting or polishing unless there's a huge mismatch in the pathway.
