Orig virgin 5.0 block need machining?

[OX1]

Did Ford machine each cylinder after measuring pistons
during assembly of each original 80's 5.0 HO (like you would
during a typical, correctly done, engine rebuild)?

I'm guessing no, so just curious if one had one of those virgin blocks ( I do) and was
slapping together a relatively low performance (<300 HP), would you
have to machine block to assemble?

I would check piston to cyl clearance to see if it was in spec,
but otherwise, what else might be out? I'd guess you can't buy orig
forged pistons anymore.

BTW, engine would be for an early bronco street rig, so very little high RPM
and really would not be beating it very hard at all.

[wraithracing]

I seriously doubt Ford would machine the cylinders to the pistons. I can see Ford matching piston sizes to bore sizing maybe, but again doubtful. With everything being massed produced. The cylinders are all bored to a tolerance and the pistons are all made to a tolerance. That allows everything to go together without issue in most cases.

If your cylinder bores are in good shape with no ridge or lip at the top of the cylinder and no taper from top to bottom, then YES you could probably use standard piston and rings for a rebuild. You will want to make sure you have a good cross hatch hone on the cylinder walls for the rings. You would also probably want to fit each piston to each cylinder to try and maximize your fit and tolerance. Same for your rings.

You may be able to find some original Ford pistons on Ebay, Green Sales, or others. Although you can order aftermarket Forged pistons in standard bore too. You could go with a used set of OEM Forged pistons if they are in good shape too. I know I have some as I am sure do others. Good Luck!

[BMW Rider]

I recall seeing many years ago the engine building process they used. The blocks were bored and honed to the tolerance range and then pistons selected to fit each bore within the tolerances. Only once the full number of pistons were chosen for a particular block did they become a full set. Building hundreds of engines gave them the luxury of having pistons at various sizing to select from, thus, no actual need to match a single piston to a bore in the machining step.

[OX1]

If your cylinder bores are in good shape with no ridge or lip at the top of the cylinder and no taper from top to bottom, then YES you could probably use standard piston and rings for a rebuild. You will want to make sure you have a good cross hatch hone on the cylinder walls for the rings. You would also probably want to fit each piston to each cylinder to try and maximize your fit and tolerance. Same for your rings.

You may be able to find some original Ford pistons on Ebay, Green Sales, or others. Although you can order aftermarket Forged pistons in standard bore too. You could go with a used set of OEM Forged pistons if they are in good shape too. I know I have some as I am sure do others. Good Luck!

It's a brand new, never assembled factory block, not sure how it could have any ridges.
Maybe it tapers, but that is why I was curious how Ford sold these blocks back in the day
(did they advertise ready to go).

I do have 2 used shortblocks also, but they are well used, so not sure it's worth
looking at those pistons. Probably just better off getting a new set and see how
they mic out.

I recall seeing many years ago the engine building process they used. The blocks were bored and honed to the tolerance range and then pistons selected to fit each bore within the tolerances. Only once the full number of pistons were chosen for a particular block did they become a full set. Building hundreds of engines gave them the luxury of having pistons at various sizing to select from, thus, no actual need to match a single piston to a bore in the machining step.

That makes sense, and probably eliminates the odds that I'd be able to do the same thing.
I guess I really would not have to do anything else on a brand new block, so just the bore machining
might not be bad pricewise.

[wraithracing]

It's a brand new, never assembled factory block, not sure how it could have any ridges.
Maybe it tapers, but that is why I was curious how Ford sold these blocks back in the day
(did they advertise ready to go).

That makes sense, and probably eliminates the odds that I'd be able to do the same thing.
I guess I really would not have to do anything else on a brand new block, so just the bore machining
might not be bad pricewise.

Generally machining is to bore the block to rough size and then hone to final size. I believe the standard Ford production blocks are the same way. I doubt you would need to do much if anything other than clean and prep for assembly.

I know some of the performance blocks were rough bored and the final bore size was to be honed by the purchaser for their specific requirements.

[gr79]

Back in the 70's, worked Ford DEP, a FT engine plant at the time.
They had a piston machining area in house.
Looked like a bottling plant with the large spiral conveyors.
Now pistons arrive already machined off site.
Blocks and pistons are both machined to match each other.
Block family bores can be machined to produce different displacements within limits.

[FB71]

blocks were machined, then checked for tolerance and 'coded'. Three different size pistons were matched to the coded blocks, each varying about 0.0005". Codes were colors, red/blue/yellow. An inspector would measure and paint daub the block, the next station would install matching color coded piston assemblies. Typically, all bores needed to meet one code spec, and all eight pistons would match. If a block varied too much, requiring more than one color spec, it was rejected. Some were reworked, most were scrapped.

[OX1]

Appreciate all the replies.

I guess the only question left is can I economically order pistons
that will fit my block, after I mic the block?

[dynodon64]

If it's a stock bore new block, just order stock size replacement pistons. You are over thinking this. The clearances for the piston to wall has a range limit to it. Stock replacement pistons will not be a problem for a stock block build. You do not need to order special pistons for a stock block. If you intend to build a $10k motor, it won't happen with a stock Ford block, so you don't need custom pistons. It isn't worth the cost.

[OX1]

They really still sell stock forged pistons, or are they hypers??

[martin0660]

They really still sell stock forged pistons, or are they hypers??

That's the question that came to mind reading this, not so much about buying them, but more what was the block intended for?

Bore size and finish should be different by cast / hyper / forged pistons (piston to wall clearance) and the bore finish is typically ring type specific.

[dynodon64]

An engine block is bored to as close as it can to a standard size. The pistons are machine to have the correct sidewall clearance for it's material, cast, forged,hyper. It's not the other way around.

[wraithracing]

An engine block is bored to as close as it can to a standard size. The pistons are machine to have the correct sidewall clearance for it's material, cast, forged,hyper. It's not the other way around.

Are you referring to Ford OEM production blocks, rebuilding process, or all engine blocks?

[STL79Coupe]

They really still sell stock forged pistons, or are they hypers??

No, the only way you'll get the factory OEM forged pistons "new" is if you find some New Old Stock pistons that someone has on the shelf. You can buy aftermarket forged pistons and sometimes at really good prices on ebay. Just make sure you fully read the desription on the listing as some might not have piston pins or are for certain type heads.

[dynodon64]

Are you referring to Ford OEM production blocks, rebuilding process, or all engine blocks?

I'm talking any new factory stock block. No high production manufacturing company like Ford, Chevy, Chrysler will take the time to size a blocks bore match to a piston size. The blocks are bored to the designed size and so are the piston. I'm not talking aftermarket race motors here.

The block this post is talking about is a stock production Ford block.

If you buy custom pistons and are having a block bored over size, then the machine shop can hone a block to match a given piston.

I can't see a high production car company doing that, US based ones at least. Not talking high end cars like BMW and the likes.

[gr79]

Production new pistons, new blocks, etc are machined to match each other per std oe factory blueprint specs.
Pretty much mass produced factory blueprinted engines. Millions of dollars of tooling, robots, camera inspection.
One at a time machine shop rebuild/reman block bores are machined to specs for oversize piston/ring assy.
Sleeves, inserts, liners commonly used now.

http://www.trucktrend.com/cool-truck...gine/#photo-01

One size piston they say:
https://www.pentastars.com/engines/production.php

[OX1]

That's the question that came to mind reading this, not so much about buying them, but more what was the block intended for?

Bore size and finish should be different by cast / hyper / forged pistons (piston to wall clearance) and the bore finish is typically ring type specific.

I believe the block was made (or at least bought) in 93, so if it was production ready, that would have been hypers I guess.