Hey guys wondering a few things

I personally like the 6.9L better

But its hard around where I am to get a good running 6.9L the 7.3L are far more abundant

So what's the benefits of a 7.3L idi over a 6.9L idi ??

Thanks Aaron

Also if someone who knows can include engine physical measurements I wAnt an idi for a swap

 

Easier to find.
The only thing I really like better is the rocker arms, and the bigger head bolts.

 

I'm assuming u mean on the 7.3 L

 

Yep That is how I understood the question. I personally like the 6.9 better,as I feel it is more rebuildable, and I can always use the later rockers.
There are some more upgrades, but those two are the ones I feel were the most important.

 

Late 6.9s have the upgraded rockers and I think the head bolts too

 

Just the rockers in the 87 models, the last year.

 

these engines have pretty low hp.the 7.3l is bored out of course which leads to more power.if you maintain your coolant (easy as pie) then it doesn't really matter if you can rebuild the engine or not,cus odds are it's going to outlast your truck anyway.
mid year '92 you get a serp belt and 130a 3g alt which are each nice (despite what the old timers will tell ya lol. )
of course the updated '87 + glow plug system is more advanced and overall much better.i wouldn't even run the old system,id update or push button mod.
keep decent care of either one,and this old debate becomes so tedious im surprised it's brought up still lol.
a many truck have rotted around a 7.3l.

 

They both have their pros and cons.

For example :

Good -
6.9 is more rebuildable as it can be safely bored over.
Most better 7.3 can be swaped over

Bad -
Harder to find
Glow plugs system 1983-1986 sucks (converting to manual plugs is best thing to do and easiest solution)
Weak block 1983-1985.5

7.3 good -
Easier to find
Better glow plug system (solid state)
Bigger head bolts
Stronger rocker arms

Bad -
Not many bad points, just one huge issue is cavitation, BUT if previous owner kepted that in check, no problems!


So when buying a 6.9, theres alot of "little" things to check for, when buying a 7.3, not as much, but just that big one, if you ask the previous owner about SCA's or coolant additives, and he gives you a deer in road look, walk away from it if it's around 150k miles.

 

Some do and some don't, and if you are buying one nowadays, unless you knew the owner, you have no clue haw it was taken care of. When the 7.3 first came out virtually nobody knew anything about the sca's so they were never checked.

There are lot's of 6.9's and 7.3's that have not outlasted the trucks, as we see here on this forum. We also see and I have bought several that did outlast the truck too though.

 

My dad put DCA4 (well back there it was the older DCA2 stuff) in the 7.3 first thing when he drove it home in May of 1990. Cause his brother had bought the same setup truck in 1988 as an F350 though, and he suffered cavitation in cylinder #2 a few months before my dad buying his. He had that cylinder sleeved, and started adding DCA2 after that, no problems after that. He had the truck till 2003. A IH diesel mechanic told them both about that, so my dad knew about that before even buying the truck.


But good luck finding another 7.3 that was treated with coolant additives since brand new!

That's one good reason why I won't let this 7.3 out of my sight! It may have a ton of mileage, but damn it still runs great, and no worries about Cavitation at all!


It's just to bad he didn't care about the body as he did the mechanical end of it, or else this thing might still be in top shape today!



And even though 6.9's don't suffer from Cavitation, we been maintaining that in the motorhome as well since we have it.

 

Not that it matters too much because the 7.3 rocker style is better, it is not because they are stronger, and I didn't see the advantage listed.

The way the tips where they contact the valve is the difference. The 6.9 style rockers beat the crap out of the valve tips and break them, the 7.3 style doesn't do this nearly as bad.

Another thing that nobody mentioned is the heads. 7.3 heads/blocks don't have the lower corner cooling jackets, thus, they don't stay nearly as cool pulling loads as the 6.9 does. There is plugs that are put into place in these corners on the 7.3, but even if you were to pull them out, and drill the gasket to accommodate them, they are still only about 1/4 the size of the 6.9 jackets. This coupled with the thin cylinder walls just makes for a much hotter running engine.

Also, the early blocks being called weak is a generalization and kind of a misconception. They are known to crack around the block heater location by the dipstick tube due to an error in casting. If you don't use the factory block heater, there is said to never be an issue. There is no other weak points.

From a performance standpoint, 6.9 heads are also more desirable castings because the injectors sit over .060" further into the pre-cup. The 7.3's were pulled out to appease the tree huggers in reducing black smoke. 6.9 pre-cups are also smaller displacement which is better for performance. Again, 7.3 cups were enlarged for emissions.

The only real advantage to N/A 7.3's is the larger head bolts, but with overtorqued studs and prepped surfaces you will never seen an issue with the 6.9.

Also, the factory turbo 7.3 IDI's have 32mm wrist pins vs 28mm, and they are factory anodized topped pistons. There is also rumor that the main webs are larger, I looked at a turbo block and didn't observe this, so I think its just the larger wrist pins.

 

^^^^^ X2 excellent mostly overlook points!

 

All great answers I appreciate the feed back and diesel john I'm happy to hear from you again !!!

 

As I said I like the 6.9 better and I might just wait out for a 6.9L that was my first diesel truck ! And I still miss it

 

Can you just switch to ELVES and not worry about coolant with the 7.3 L?