6.9 vs 7.3n idi
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
The 7.3L is a 6.9L bored out.
1987 saw a better glow plug system for the 6.9L that was carried over for the 7.3L.
Head bolts on the 6.9L are 7/16", while the 7.3L has 1/2". The length of the head bolts are also different, so the machining of the heads are different to match the different bolt lengths (not sure if there are any other differences between the two types of heads). Prechamber design is also said to be slightly different between the two engines.
Valve stem seals are designed to leak small amounts of oil in the 6.9L to lube the guides. 7.3L seals do not leak, this has been known to cause premature guide failure
Injector pump calibration is different between the two engines, but they are basically interchangable. The 7.3L turbo has a special pump (and injectors) on its own that should not be used on a N/A engine (unless you like making black smoke).
6.9L has seperated fuel filter and water separator. The 7.3L has an integrated filter/separator in the location of the 6.9 fuel filter.
1987 saw a better glow plug system for the 6.9L that was carried over for the 7.3L.
Head bolts on the 6.9L are 7/16", while the 7.3L has 1/2". The length of the head bolts are also different, so the machining of the heads are different to match the different bolt lengths (not sure if there are any other differences between the two types of heads). Prechamber design is also said to be slightly different between the two engines.
Valve stem seals are designed to leak small amounts of oil in the 6.9L to lube the guides. 7.3L seals do not leak, this has been known to cause premature guide failure
Injector pump calibration is different between the two engines, but they are basically interchangable. The 7.3L turbo has a special pump (and injectors) on its own that should not be used on a N/A engine (unless you like making black smoke).
6.9L has seperated fuel filter and water separator. The 7.3L has an integrated filter/separator in the location of the 6.9 fuel filter.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
. But to your question, I have never heard of any size differnence between any of the cylinders in these engines.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Actually there were some engines that used select fit pistons.
And the rear cylinders were larger, more piston clearance was OK in the rear cylinders.
I don't have my book here, and off the top of my head I can't remember what codes the select fit pistons used except the S piston was OK in any of the cylinders.
And the rear cylinders were larger, more piston clearance was OK in the rear cylinders.
I don't have my book here, and off the top of my head I can't remember what codes the select fit pistons used except the S piston was OK in any of the cylinders.
