How do the figure out the correct shims at the factory?

[Crash Cash]

Here's a thought for you... we all know how time consuming & labor intensive it is to adjust valves when you have shim-under-bucket.

So how do they do it in the factory when they're rolling an engine off the line every 5 minutes? How do they figure out the clearances for that particular new engine and put in the right shims? It would be neat to see whatever weird gadget/method they use...

 

[johnny80s]

I'll second that...

 

[exskibum]

Great question. Looking forward to a reliable answer.

 

[BlackStar]

My guess would be a few key measurements from the manufacturing process (i.e. installed valve height, bucket thickness, cam base circle from spring deck, etc...) and some statistics. Or you could just throw in a statistically std shim, measure the clearance, calculate the delta, select your shim and install it and be done with it.

 

[chrisflock]

Here's a thought for you... we all know how time consuming & labor intensive it is to adjust valves when you have shim-under-bucket.
So how do they do it in the factory when they're rolling an engine off the line every 5 minutes? How do they figure out the clearances for that particular new engine and put in the right shims? It would be neat to see whatever weird gadget/method they use...

Magic?

A set of 'go no-go' feeler gauges?

 

[lnewlf]

Perhaps they have a department with extra workers and special equipment that just does heads.

 

[Geezer]

It would be pretty simple and quick to do before the valve cover and plumbing are even installed, and the engine is on a bench.

The valve adjustment is not difficult, the hard part is getting all the stuff out of the way.

 

[Silent]

It would be pretty simple and quick to do before the valve cover and plumbing are even installed, and the engine is on a bench.
The valve adjustment is not difficult, the hard part is getting all the stuff out of the way.

My thoughts exactly. I'm sure they have a special tool that makes it a snap to pop the shims in and out. Especially for those little hands that have done the same task a million times already.

 

[radman]

My thoughts exactly. I'm sure they have a special tool that makes it a snap to pop the shims in and out. Especially for those little hands that have done the same task a million times already.

Little hands?

 

[Patriot]

Here's a thought for you... we all know how time consuming & labor intensive it is to adjust valves when you have shim-under-bucket.
So how do they do it in the factory when they're rolling an engine off the line every 5 minutes? How do they figure out the clearances for that particular new engine and put in the right shims? It would be neat to see whatever weird gadget/method they use...

Magic?

A set of 'go no-go' feeler gauges?

yep, FM... :yahoo:

 

[mattster31]

So how do they do it in the factory when they're rolling an engine off the line every 5 minutes? How do they figure out the clearances for that particular new engine and put in the right shims? It would be neat to see whatever weird gadget/method they use...

I think the engines come pre-assembled from mexico...........

 

[charismaticmegafauna]

My guess would be a few key measurements from the manufacturing process (i.e. installed valve height, bucket thickness, cam base circle from spring deck, etc...) and some statistics. Or you could just throw in a statistically std shim, measure the clearance, calculate the delta, select your shim and install it and be done with it.

Best answer (guess).

I've had valve work done at very professional automotive (race) machine shops where, when done, the machinist said, "I've altered the valve length so that you should be able to use all the shims in the places they were." I brought in the bare head with valves removed and stuck in a numbered board. Sure enough, almost all of the original shims could be used in their same places.

I think they do that work so often and it needs to be so precise that they know (or have a very good idea) of the amount of metal they're working with?

 

[radman]

My guess would be a few key measurements from the manufacturing process (i.e. installed valve height, bucket thickness, cam base circle from spring deck, etc...) and some statistics. Or you could just throw in a statistically std shim, measure the clearance, calculate the delta, select your shim and install it and be done with it.

Best answer (guess).

I've had valve work done at very professional automotive (race) machine shops where, when done, the machinist said, "I've altered the valve length so that you should be able to use all the shims in the places they were." I brought in the bare head with valves removed and stuck in a numbered board. Sure enough, almost all of the original shims could be used in their same places.

I think they do that work so often and it needs to be so precise that they know (or have a very good idea) of the amount of metal they're working with?

You almost always grind a bit off the valve stem tip to compensate for seat and valve face material removed in the regrind process.

 

[wfooshee]

Nothing to do with valve shims, but everything to do with industrial manufacturing processes.

I toured the Taurus factory in Atlanta several years ago when a friend of mine was working there as a contractor developing software to model soft goods, like upholstery, rubber, and interior panels. Computers were great with fitting solids, but not so good with squishy stuff. Anyway, he walked me through the line, from the first plate being laid down to become the front crossmember to cars being driven out the door.

I came away most impressed by two items:

Early in the line, when the roof panel is welded onto the pillars, is another automatic process. The body shell is placed so, and the roof drops down and is placed here, and the robots with zapper fingers go to town. There was one body shell set aside in the aisle that the roof got turned sideway somehow, but the welder arms didn't know or care. It was smashed all to hell and back where the arms went through what was supposed to be empty space.

But what the valve adjust question made me think of is this: the last step on the line is a 4-wheel alignment. It's automatic, robot arms reaching up from under the car, and takes about 15 seconds.

BTW, time from those first two plates becoming the start of the front crossmember to the car driving out the door was about 17 hours.

 

[charismaticmegafauna]

You almost always grind a bit off the valve stem tip to compensate for seat and valve face material removed in the regrind process.

Yes, true -- and to 'dress' the valve lash end of the valve stem (which can be pocketed in some systems).

But, in this instance, he specifically mentioned my (probably) being able to use the original shims.

I remain impressed....

 

[charismaticmegafauna]

Nothing to do with valve shims, but everything to do with industrial manufacturing processes.I toured the Taurus factory in Atlanta several years ago

And (trying not to thread-drift too far away...), I was asked over dinner a couple decades ago by a retired mechanical engineer what new car I was partial to.

I told him that I thought only Ford had a new car. They had to build a complete new factory, for the Taurus, with a completely new way of building cars. The rest is history -- Taurus being a best-selling car for many years.

BTW, the engineer owned 3 successive Mercury Sables (Taurus derivatives) since then...

 

[Crash Cash]

It seems Triumph motorcycles uses Mitutoyo Coordinate Measuring Machines, and they put the head on a jig, and measure the height of each valve stem with a computer controlled digitizing probe. A program calculates the shim sizes and prints it out. See https://www.engineeringtalk.com/news/mto/mto124.html They say it's not much faster, but it's always right the first time.

Apparently before, yes, they did have someone temporarily install the cams and do it the "old-fashioned way" with feeler gauges!

I was thinking about this because I saw a TV show on P-51 fighters, and they showed the Allison engines being built at Rolls-Royce. There was an enormous machine that simultaneously honed all 12 cylinders, and another that put the head on and torqued all 48-odd bolts down as a single operation.