998cc Short Engine Build

[philthehill]

I take it that you will not be fitting a duplex timing chain set up as you have the lock washer for the 1/4" UNF bolt in place. As you are no doubt aware - if you fit the duplex you dispense with the two 1/4" UNF bolts and lock washer and use two 1/4" UNF countersunk screws instead which are secured with loctite.
As above fit a Helicoil insert.

[Monty-4]

Yes I favour the single chain with tensioner (A+?) setup, I found it was nice and quiet before.

I will investigate and learn to use thread inserts!

[Monty-4]

Doh!

Have been torqueing down the main bearings and big-ends. All moves freely until I torque down big-end #2 and then I can no longer turn it by hand using a socket wrench, fine with 1, 3 and 4 at 35 lb-ft. I'm 80% sure I didn't mix any of the caps up!

[philthehill]

The caps and rods should be marked 1/1, 2/2, 3/3 & 4/4.
Have you got the No: 2 rod the right way round so that the big end offset is placed correctly.

[Monty-4]

The rod offset is correct, looking at it I don't think I'd even be able to get it on the crank the other way.

The caps have no markings I can see, here are what I believe to be #1 (left) and #2 (right), or at least those that match the rods in bore #1 and #2.

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Perhaps I should swap the caps in a logical order I can remember to check if I might have made a mistake earlier, as the bits have been moved around a bit over the last couple of months.

[philthehill]

The caps must be fitted the right way round on the rod.
Have a look at the inside of the cap. The white metal bearing tang locating slot of the cap should be identified as a dirty mark on the rod. Make sure that the cap matches the dirty mark so ensuring that the cap is the right way round.

[Monty-4]

Had a long think about this and came to the conclusion that it's likely caps #2 and #4 got swapped as I switched those pistons over to get the big-end offsets in the right places. Re-tightened and the engine turns over easily now. Phew! Final assembly to take place shortly.

Exited to see how it goes but wish I'd had access to a bigger-bearing Miget 1098 block as that may have negated the need for oversize thrusts.

[Monty-4]

Pretty good bodge no? The big-end doesn't come closer than an inch of the oil pickup bracket although the camera makes it look close.

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Engine is timed in at the cam figure of 106 and assembly is pretty much done other than waiting on a timing cover gasket in the post. Then I just need some engine-fitting friendly weather!

[philthehill]

Very good but I would not have put two 90 degree bends into the support. I have in the past just shortened the support and put a less than 90 degree bend into the bottom of the support and drilled a new hole for the support bolt. Done to compensate for the additional thickness of centre main bearing strengthening bar.
The two 90 degree bends could allow for a resonance/vibration that leads to the support breaking.

[Monty-4]

Life got in the way in between my last posts about this and today - when I found myself unpacking everything in a new storage unit rented in cooperation with some other nutters (MX5 not mine).

The engine has been sitting for some time and has some surface rust on the unpainted areas like where the manifolds mount. Perhaps wet sanding it would avoid getting too much metallic dust around areas where I really don't want it?

A warning... you may need to don sunglasses to gaze upon my exhaust manifold wrap.

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