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So I tore down my 400 out of my 79 F150 Supercab 4x4 and found this. It seems to be where the valve reliefs would sit on the piston. Every cylinder is different. Some minor and some as bad as the picture above. I didn’t know if this was from previous machine work, factory, or just wear. Any help would be appreciated.
Had to take 3 blocks to the shop before I found one worth building. And of the 3, the block pictured has a cam bearing hole that is 5 thou over. Had to take one cam bearing to a special metal shop that dipped the bearing in a solution for five hours (one hour dipped = added 1 thou metal to the bearing) to get the added 5 thou to the diameter of the bearing to make it fit. Was not easy at all.
Had to take 3 blocks to the shop before I found one worth building. And of the 3, the block pictured has a cam bearing hole that is 5 thou over. Had to take one cam bearing to a special metal shop that dipped the bearing in a solution for five hours (one hour dipped = added 1 thou metal to the bearing) to get the added 5 thou to the diameter of the bearing to make it fit. Was not easy at all.
Hopefully I don’t have to do that. If this one doesn’t work. I’m just going to build a 460 but I would like this to work cause I’m a tight budget
Every 351 M 400 that I have seen is like that, no one can explain to me why. Valve relief maybe, but the valves don't come that close to the cylinder wall AFIK.
Budget is why I am building a 400, if I didn't have a ton of M and Cleveland junk laying around, I would have done either my 429 or 460. Regardless, of the huge pile of 351/m400 and Cleveland junk I have, every one of them ran great when pulled and had hundreds of thousands of miles on them.
I never worried about mine either, until I laid the head gasket over the top and it hung over in those areas! The notches seemed legit on mine and I'd never heard them discussed before. But an edge of metal gasket hanging into the combustion chamber just can't be a good thing in any engine.
So I tried three different brands and all had full circle bands with no accommodation for the notches. So without any confirmation of my suspicions, I installed the heads anyway.
Been crossing my fingers it does not come back to bite me, but I'll know at some point I guess. And since you all have them, and nobody has ever seemingly had an issue, I won't worry quite as much.
But I always wondered why our engines are so sensitive to pinging. Maybe that hot edge of gasket starts the ignition!
I just realized I have my original '79 engine still intact. I should remove a head to see what, if anything, the factory did.
