AWSOME news and Questions....

[Olb Blue Beast]

Ok, Some of you may have read my thread bout swapping a 6.9l into a 77' F350, well..... Stage 1 is Complete! I got the green light from the family and will be buying my new truck sometime early next month! I would post pics, but im kind of a retard, so i dont know how.

Now for a question. I know i may start a war, but here it goes. Which is better, the 6.9l IDI or the 7.3l IDI? I know the 6.9l has weak head studs, but doesnt cavitate. On the other hand, the 7.3l has stong head studa but is prone to cavitation. One option is to sleeve a 7.3l to 6.9l. What are your opinions????

 

[The Warden]

Now for a question. I know i may start a war, but here it goes. Which is better, the 6.9l IDI or the 7.3l IDI? I know the 6.9l has weak head studs, but doesnt cavitate. On the other hand, the 7.3l has stong head studa but is prone to cavitation. One option is to sleeve a 7.3l to 6.9l. What are your opinions????

IMHO there's your best best, although it won't be cheap...take a 7.3l block and resleeve it to hold 6.9l pistons. That'll give you the bigger head studs and you'll considerably reduce (although not eliminate altogether) the risk of cavitation.

 

[Agnem]

I have both, and I like both. I feel much safer buying a used 6.9, then I do a 7.3, but if you get a good 7.3, you've got what is technically the better engine. The weaknesses of both you have already identified, but I the 87' 6.9 is probably my ultimate choice. It truely was the best of both worlds.

 

[Olb Blue Beast]

What about boring a 6.9l to a 7.3l? Isnt that basically replicating a 87' 6.9l?

 

[The Warden]

What about boring a 6.9l to a 7.3l? Isnt that basically replicating a 87' 6.9l?

IMHO that would be the worst of both worlds...you'll end up with the 7/16" head bolts/studs and you'll have the thinner cylinder side walls that tend to flex more, which is a big part of why cavitation's such a serious problem on the 7.3l.

IMHO the only real advantage to the 7.3l block over the late 6.9l block is that the 7.3l's head bolts are bigger (1/2" instead of 7/16"). With that said, there are some good reasons to avoid an early (pre-mid-'85) 6.9l block...early 6.9l blocks have a nasty habit of cracking near the block heater, and the early piston oil cooler jets have to be pressed in and IIRC aren't available new anymore.

The '87 6.9l has all of the improvements made to the 6.9l block (strengthened block near the block heater, bolt-on piston oil-cooling jets, etc) along with external improvements such as the 7.3l style glow plug system. A general rule of thumb is to try and buy an engine (or a vehicle) that's close to the end of that specific model's run, because all of the mistakes made in the earlier models have been recognized and (hopefully) corrected.

 

[Olb Blue Beast]

ya, sorry, that was a stupid thing of me to say. I meant somethin else, but relized my mistake

 

[hairyboxnoogle]

Ok, Some of you may have read my thread bout swapping a 6.9l into a 77' F350, well..... Stage 1 is Complete! I got the green light from the family and will be buying my new truck sometime early next month! I would post pics, but im kind of a retard, so i dont know how.

Now for a question. I know i may start a war, but here it goes. Which is better, the 6.9l IDI or the 7.3l IDI? I know the 6.9l has weak head studs, but doesnt cavitate. On the other hand, the 7.3l has stong head studa but is prone to cavitation. One option is to sleeve a 7.3l to 6.9l. What are your opinions????

Go with a factory turbo engine if you want the best imo. Bigger wrist pins, stronger rods, heavier block, bigger oil cooler, 1/2" head bolts, serp. belt etc. If its not pinhole'd run SCAs and it wont, or if youre skiddish sleeve it and forget about it, not to a 6.9, as you cant run the turbo rods/wrist pins.