2.2 case savers - what outside diameter?

[RobFrost]

The studs in my 2.2 case all look sound but I've been advised by it's best to put case savers in the four short studs around the intermediate shaft and the big long stud too. I'm pretty sure the studs are M8 and 1.25 thread pitch. But what outside diameter case savers are normally used here? RS components have ones you drill 9mm and others you drill 11.5mm.

Logic dictates larger will have the stronger thread, but smaller will leave more strength in the residual magnesium flange. I'm inclined to go with the smaller because it leaves future rebuilders somewhere to go. Anybody have experience?

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[Dpmulvan]

Originally Posted by RobFrost

The studs in my 2.2 case all look sound but I've been advised by it's best to put case savers in the four short studs around the intermediate shaft and the big long stud too. I'm pretty sure the studs are M8 and 1.25 thread pitch. But what outside diameter case savers are normally used here? RS components have ones you drill 9mm and others you drill 11.5mm.

Logic dictates larger will have the stronger thread, but smaller will leave more strength in the residual magnesium flange. I'm inclined to go with the smaller because it leaves future rebuilders somewhere to go. Anybody have experience?

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Use the smallest ones that will fit.

[Flat6pac]

8mm casesaver is 10 mm on the thread outside.
You need that on intermediate shaft long bolt as it will pull with torque.
4 bell housing bolts need case savers on the 10mm studs. 60 years of tight, too tight wears threads.
Bruce

[Dpmulvan]

Highly suggest using a mill or at least a good drill press.

[stownsen914]

Yes, assumed no freehand for such procedures

[RobFrost]

In order to drill the case savers by hand, I'm considering making a jig comprising a flat plate with a steel sleeve attached at right angles whose inside diameter matches the drill bit, and another sleeve attached at right angles, to place over another case stud, to hold the jig in place.

Then drill through the sleeve by hand with the drill on high speed and very gentle pressure, to ensure it doesn't pull through the hole suddenly.

The sleeve will keep the drill bit central and perpendicular.

Is that unwise? The only risk I see is the bit pulling through suddenly and breaking off the case. Is that likely to happen, and is my plan a bad one?

I also have a 13.2mm reamer to run through the cylinder heads ready for oversize valve guides. Is doing that by hand also unwise?


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[stownsen914]

With a jig it might be ok. The challenge is getting them perfectly straight, which is important to ensure proper loading of the fastener not to mention getting the case halves to mate correctly. It’s easy to be off by a few degrees when doing by hand.

[Dpmulvan]

Originally Posted by RobFrost

In order to drill the case savers by hand, I'm considering making a jig comprising a flat plate with a steel sleeve attached at right angles whose inside diameter matches the drill bit, and another sleeve attached at right angles, to place over another case stud, to hold the jig in place.

Then drill through the sleeve by hand with the drill on high speed and very gentle pressure, to ensure it doesn't pull through the hole suddenly.

The sleeve will keep the drill bit central and perpendicular.

Is that unwise? The only risk I see is the bit pulling through suddenly and breaking off the case. Is that likely to happen, and is my plan a bad one?

I also have a 13.2mm reamer to run through the cylinder heads ready for oversize valve guides. Is doing that by hand also unwise?


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What kind of reamer? You’ll need two reamers and a hone to do valve guides. You’ll need to ream cylinder to accept oversized guide, then install and ream guide to accept valve and then finish inside of guide with hone.
You can run into issues hand reaming especially dulling the reamer when reaming inside of guides. On occasion a reamer isn’t enough and you might have to drill to enlarge a hole enough to ream ( impossible by hand). If anything is off ( talking thousandths) valve won’t seat properly and heat won’t dissipate properly.

[RobFrost]

The 13.2mm reamer is to ream the 13mm bore in the aluminium head to accept the 13.26mm 1st oversize guides. That leaves one hundredth of a mm to hone, leaving 0.05mm interference.

I have good seat cutters.

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[Dpmulvan]

Originally Posted by RobFrost

The 13.2mm reamer is to ream the 13mm bore in the aluminium head to accept the 13.26mm 1st oversize guides. That leaves one hundredth of a mm to hone, leaving 0.05mm interference.

I have good seat cutters.

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If your going to ream by hand use this kind of reamer, also measure the OD of the guides don’t assume they’re all the same size. After the guides are installed they will also need to reamed due to compression.

[RobFrost]

Thank-you for the advice, especially re measuring the guides.

My valves are a little narrower than their original spec so if I'm lucky the guides will come in a bit.

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[RobFrost]

Just following up with my experience how your advice played out. I didn't get your message in time re the hand reamer, and screwed one head up using a machine reamer by hand. That one will have to go out to 14mm or 15mm now and I've an oversize generic guide in hand which will have to be turned down on a lathe

The others I reamed the bores by hand and results were good - straight and to size. The guides came consistently sized and all drove in nicely with consistent force.

I note your comment re dulling the ream on the bronze. Upon driving in, the insides have all come in to the vicinity of 8.98mm which is almost perfect for my ever so slightly worn valve stems. I'm going to ream them all to 8.98mm (more to ensure straightness than for diameter) and hone, and hopefull I'm taking such a tiny amount off the reamer will be okay.

A couple of valve stems are a hundredth or two of a mm narrower at the very valve end (due to wear), however once they're in, there is next to no play. Assuming the guide is tight enough to allow it, would you polish the rest of the stem down to a consistent diameter or leave them with a narrow end? Or replace? This isn't a "throw money at it" build, but I do want it to last.