Barrel Shims for 2.7 Engine

[DanCoffman]

Hi everyone,

I ned a little advice. I got my engine case back from Ollies and they included a packet of what are labelled as "Barrel Shims". As part of their work on the case, Ollies faced the spigots so they are all the same height. I assume that these shims are to make up for the material they removed during the facing. My question --- and please forgive an obvious newbie question! --- is what the correct position of these shims should be. I am guessing that the correct order of things would be: engine case, shim, gasket, cylinder. Is that correct? Or should the gasket be closest to the case?

Thanks!
Dan Coffma

[Lapkritis]

What material is the shim made from? A picture might help.

[304065]

Originally Posted by DanCoffman

Hi everyone,

I ned a little advice. I got my engine case back from Ollies and they included a packet of what are labelled as "Barrel Shims". As part of their work on the case, Ollies faced the spigots so they are all the same height. I assume that these shims are to make up for the material they removed during the facing. My question --- and please forgive an obvious newbie question! --- is what the correct position of these shims should be. I am guessing that the correct order of things would be: engine case, shim, gasket, cylinder. Is that correct? Or should the gasket be closest to the case?

Thanks!
Dan Coffma

Dan, if Ollies cut the case spigots then if you use standard 0.25mm cylinder base gaskets you will end up with reduced deck height, reduced piston-to-head clearance and reduced valve clearance. So they may have faced everything off to the same spigot height, then given you a package of thicker base gaskets to compensate. You should call them and speak with George or Ike and ask, that is the easiest route.

I bet if you take your micrometer and measure them they are all the same and thicker than 0.25mm. In any event, it's customary to use only one base gasket, not to stack them. Case, gasket, cylinder, that's it for the bottom side.

[Henry Schmidt]

All 2.7 engine cases have twist issues. It is customary to deck the case halves and bore the mains back to standard.
It is also customary to deck the cylinder spigots after installing case savers.
In order to bring the case dimensions back to standard, shims are required.
I would assume that the shims correspond to the accumulative amount removed from both location.

[wndsnd]

Don't, mean to hijack this but I measured my 2.7 case spigot height today and found about .0065 to .0075 variance.

Couldn't I adjust for variance with base shims or gaskets rather than have the case machined and come out OK ?

John

[Lapkritis]

That's pretty close. How confident are you in the margin of error? Did you repeat the measurement consistently with good tools?

[wndsnd]

I used a macninists straight edge ground to .001"" across all the spigots. I cut a 24" straight edge down to fit accross all spigot surfaces 1-3, 4-6.

Then I used precicely ground feeler guages under the edge on the center spigot and the center edges of the inner and outer spigots.

one side I got .0065 and the other I got .0075. 90% of the distortion was at the center bore.

I think it is pretty acurate, unless my process is totally out of wack.

John

[304065]

I would measure spigot height with a mandrel (a piece of tubing turned to the bearing diameter) mounted in the main bearings with the through-bolts torqued, then use a depth micrometer on the spigot against the mandrel. Subtract half the mandrel diameter to get the height above the crank centerline. I can't remember who had a photo of this on their website, maybe Vic Skirmants?

Craig Garr (here) made such a mandrel out of bar stock. . . I think it weighed 50 pounds. . .