Quote from: 427John on March 26, 2021, 05:35:58 PM

Gaugster,many years ago I was inspecting a 69 Cylcone GT R code for possible purchase.I noticed that it had the mirror image 105 block and asked about it,the owner who claimed to be the original owner and had receipts dating back to 1969 though I never saw the original registration with his name,claimed that the engine had been replaced under warranty in 1974 and that D3TE and D4TE 391 truck blocks were being used as service replacements by then according to what he dealership service manager had told him.I don't know how much truth there was in this fairy tale but am relating what he told me,I do know some 391 truck blocks were cast with thicker walls by using the 428 jacket cores,I have personally seen a couple that had the the 428 cast in the bottom of the water jacket,so its something to keep in mind when you tear down and inspect.If by chance you do find the 428 cast in the bottom of the water jackets and get the block sonic checked please post the results.The way I remove core plugs is I have a tire iron that has the lug wrench end cut off and I use that as a punch at the edge of the plug to drive one side in as it starts turning grab the edge with channel locks and pull it out.

Never seen a MCC 105 block with 428 water jacket cores.  Considering that MCC could not use the DIF cores and had to make all new ones I would tend to believe those who were there and have said all they made was 390 type blocks.  Many of them came with the large distributor hole and the oil return drilled.  If going into a light duty truck they would use a bushing in the distributor hole and plug the oil return.

I know some say you can bore the MCC blocks out to 428 size.  If you get a block with no core shift may be safe, but I would not believe for a minute that it was cast with 428 cores.  There are a few 391 blocks that had the 428 water jacket cores, but all I've seen or heard of came for DIF and seems a 1968 casting date is common.  Also have heard of some passenger car 390's that turned out to be a 428 block with a 4.05" bore.  They all have had the C scratch.  Considering Ford had a strike in 1968 that screwed up production may have something to do with it, but who knows...

One nice thing about the 105 MCC blocks is they all have the crows foot main webbing.  Bad thing is they tend to crack at the oil passage to oil the heads. Something to check for.  If cracked can be sleeved with a piece of tubing.

Removing core plugs, I just knock them in with a hammer and chisel, grab the lip with vise grips and pry them out.

I had a multi year,multi seal rear main leak. The “fix” came after a refresh due to a broken cam.
I can only tell you what I did and going on 3 years I’m just now getting oil on the outside of the pan,but no drips yet.
My feeling was the leak is from the three surface block/head/intake junction . My last head install right at the junction I put a dab of sealant on both sides of the head gasket at all four corners as well as top and bottom of the intake manifold gasket then of course the front and rear “China wall”. This is only right at the junction to the China wall.

Also when I installed the intake I did the same at the valve cover rail,both sides of gasket.

For 2 year the outside of the engine was oil free,like I said it’s come back a bit.

I’ve had valve cover gaskets leak too with oil around the plugs and around the back of the heads.