Yep, I thought the tapering may be some innovation, unfortunately not. I agree this is just type 1 engine fitting. Yeh, I’ll do a measurement comparison with a micrometer when I pull the old tubes back out. I strongly suspect diameter of tube where orings wrap around will be the culprit.
Billet pushrod tubes – nice as there are – won’t cure the problem unless there is a fault with all the tubes you have. You’ve got a standard Type 4 engine and standard Type 4 parts will fit. You’re using O-rings that have been forced into place with a broom handle and tubes that you have no idea what size they are. Slow down; measure the parts, compare old with new, and inspect everything, if there is a scratch in the head or crankcase or the O-ring has a nick it will leak. If there is nothing wrong with the old tubes reuse them, but if they have been battered into place the O-ring groove could be distorted. If the new tubes don’t fit tell us what the difference is – and send them back to the supplier telling them why they won’t fit. Oil drips onto heat exchangers are messy but probably not particularly dangerous. It takes quite a lot to set fire to oil – but it can be done.
The Billet ones are machined and so are round and correct size .. the few sets of repo steel type 4 ones I’ve had were all poor quality, out of round and just plain poor . Source a second hand original set
Sanity! Hopefully a result here. I removed the seals from the new pushrod tubes and fed the tube through the head, guess what, wouldn’t fit in. Measured them and the external lips on both ends were 0.6 to 1.0mm wider. Kind of explains the fitting issue. Knowing this it could have filed of the excess, but shouldn’t have to do this. Strangely I’m happy now. Hopefully the new JK ones should be ok when they arrive. Maybe s message the to check any new ones fit without seals Thanks for your advice!
A problem you may now have is that the lands where the O-rings slide may have been damaged during the attempts to force the tubes into position. And check the new tubes very carefully; they are at least as likely to be wrong from JK as any other supplier.