Which block for mild build 6.9 or 7.3

[Sawyerroos]

Hello Iam new here but have researched the forums for years i recently just picked up a 1992 single cab f350 7.3 5spd 4x4 for a reasonable price from friend truck runs but brake system needs attention before on the road in my process of getting her going I did a compression test my high pressure was only 280psi and had a few cylinders with a fair bit of discrepancie I have faith the old girl has some life in her but Iam going to pick up another motor to build and replace mine my question for you all is that I can get a good deal on a later block 6.9 and with the cavitation issues with the 7.3 and seeing as the blocks are over 30 years old now and I don’t have the budget to re sleeve one should I just build a 6.9 with head studs and 7.3 rockers and not half to worry about cavitation thanks in advance?

 

[IDIBRONCO]

I don't think that there's any scientific proof, but the overall feeling is that most of the cavitation prone blocks have been recycled into Hondas by now. The ironic part here is that they no longer make new 6.9 pistons. The solution is to bore the cylinders out to use standard 7.3 pistons so the cylinder walls will be the same thickness. Will this cause a new round of cavitating blocks? Only time will tell. Either way, I feel like the cavitation issues is overblown (although it can still happen) and I wouldn't be worried about using either block. As long as you're not planning to get carried away with boost, you won't have any problems with a studded 6.9 block.

 

[Old Goat]

Just keep the cavitation coolant additive at the propper level.

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Goat

 

[Austin86250]

Use what ever is easier for you. I Run upwards of 20 psi of boost in my studded 6.9 reliably
I second Idi Bronco on cavitation

 

[onetonjohn]

I had no idea 6.9 pistons were not available. What are 7.3 relative to 6.9 20 tho over? Sad. I always tought I would put some 10 tho over pistons in the brown truck someday and it would outlast me. I suppose the heads are problematic too - I have in my mind no- decking the heads unless machinist is old and familiar with 6.9 (most probably aren't).

 

[IDIBRONCO]

IIRC, standard bore for a 6.9 is 4.00" while a 7.3 is 4.11". That is a large overbore, but it can be done. Once in a while, you can find a set of 6.9 pistons lurking around in the shadows, but, sadly, they're mostly unavailable.
I have to admit that about a year ago, I was thinking of buying a set or two of 6.9 pistons while they were still available, but the extra money wasn't there. I guess that's life. At least we can use the 7.3 pistons and keep our engines going.

 

[jwalterus]

IIRC, standard bore for a 6.9 is 4.00" while a 7.3 is 4.11". That is a large overbore, but it can be done. Once in a while, you can find a set of 6.9 pistons lurking around in the shadows, but, sadly, they're mostly unavailable.
I have to admit that about a year ago, I was thinking of buying a set or two of 6.9 pistons while they were still available, but the extra money wasn't there. I guess that's life. At least we can use the 7.3 pistons and keep our engines going.

Mahle 224-2190.040

Mahle 224-2190.040

frsport.com

I might just to add them to the shelf o' parts.....
My idi isn't on the road anymore, it pushes snow a few times a year but that's it.
All 3 of my boys have said they want it eventually.....

 

[IDIBRONCO]

I might just to add them to the shelf o' parts.....

My only question is this. Is this for one piston or all 8? I couldn't find the answer. I know it's listed as a set, but I still want to know. The same place also lists Sealed Power piston sets too. If these really are prices for a set of 8 pistons, I WILL be buying at least one set. The price just seems too cheap to be for 8 pistons.

 

[Nero]

My only question is this. Is this for one piston or all 8? I couldn't find the answer. I know it's listed as a set, but I still want to know. The same place also lists Sealed Power piston sets too. If these really are prices for a set of 8 pistons, I WILL be buying at least one set. The price just seems too cheap to be for 8 pistons.

This is how much it cost for rockauto mahle pistons for my old mans truck, so I assume cost is per piston;

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[IDIBRONCO]

This is how much it cost for rockauto mahle pistons for my old mans truck, so I assume cost is per piston;

You must be registered for see images attach

That's exactly what I was thinking. It seemed way too cheap for a set.

 

[jwalterus]

That's exactly what I was thinking. It seemed way too cheap for a set.

[email protected]

I sent them an email asking, I pulled this email off of their facebook page.
At least the site seems legit for once