Ford 401 666T TW15 Engine Rebuild

Joe Pro

Member
Hello guys. I am an MM guy to the bone, but I am working on a Ford TW15 for a friend. Evidently I am the only person in the world who didn't know about the pourus Ford blocks.
I am now up to speed and have disassembled this engine and found a hole in cylinder 6.
The hole is at the bottom of the bore and I'm not sure, boring and sleeving it will repair it.

I have found a block from a 7810 but am not sure this block can be used for my TW build. The parts book shows the oil pump different on the 7810 it looks like it drives different. I wondered if the block was cast different for the 7810. I see there is a large hole under the oil filter on the 7810 that isn't present on the 401 block that I have.

What are the differences between the 7810 block and the TW?
The number on the 7810 block I want to use is 87840645.

Thanks for any info you can offer.
 
Sleeves normally extend low enough to take care of any holes from the water jacket. If it were me, I'd plan on using the original
block unless the machine shop said otherwise.
 
Yes, the porous Ford blocks are well known. The 401 in the TWx5 series was the worst of the worst.

Is the hole truly at the bottom of the block? In other words, is the hole vertical or horizontal? If it's horizontal, a sleeve should repair it. If it's vertical, that would be a rust-out issue, which is not likely. I've sleeved more 401 blocks than I care to recall, and every one was a successful repair.

I'm pretty sure that the 7810 block would work just fine. The only snag would be plugging the hole where the pump drive goes through, otherwise you'd end up with a massive internal oil leak and no pressure.
 

The hole is at the very bottom of the cylinder, where almost to the taper at the bottom of the bore.


Could you elaborate on this?
I would prefer to use the 7810 block if possible.
It appears there is also a half dollar size hold under the oil filter on the 7810 block where there isn't on the TW block.
 
mvphoto26789.jpg
 
I would consult with a competent machinist regarding the hole in the cylinder wall. Without looking at it myself, I can't
say for sure, other than to say that I have rarely seen a Ford block that could not be repaired with sleeves.

As for the hole below the oil filter on the 7810, that is for the cam driven oil pump used on that model. To use that block
on a TW, my thinking is that you'd have to at least plug the hole that the driveshaft goes through to avoid a major internal
oil leak. You would also put a cap and plug on the top, as shown in the parts diagram.

I'm thinking you would need part numbers 46, 47, & 48 in the diagram shown below, with #48 being used to plug the internal
leak.

All that said, I've never used a 7810 block on a TW, so my advice is potentially worth exactly what it cost you.
Oil pump stuff
 
I have done dozens. 3 -4 and 6 cylinder. Some as many as 20 years ago and I have never had one come back. Get a good machinist that knows what he is doing and bore, press thick sleeves in it, bore it back to standard and use new pistons and rings. One of my customers has a 9700 that has close to 8000 hard hours on it since I rebuilt it and still uses it every day. If you do get the other block what is to say it is not in the same shape? If I rebuild one of these engines, it gets sleeved or I don't rebuild it, period.
 
Awesome info guys.
I do have a machine shop that I trust.
They did feel they could repair it, but
I haven't taken them the block yet for
them to personally assess the repair.

The reason that I'm so keen on using the
7810 block is that it is a new block.
( new old stock ).
 
I'd trust a sleeved block before I trusted a new one. Something about the iron that Ford used back in the day that made some of them not go a year before they sprung a leak.
 
I agree that the original block should be sleeved. Don't get a different block, since the same defect may appear in short order.
 

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