650ss cylinder barrel front studs

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Hello,
650ss rebuild.
On attempting to fit the cylinder head I cannot seem to align the front cylinder barrel studs with the cylinder head. The other studs align, and the push rods are free but these two studs are just out of alignment and will not engage. I dare not be too heavy handed as the pushrods will foul the sides with the resultant nasty damage.
Has anyone experienced this if so what was the solution.
Thank you.

Odd problem..did the parts…

Odd problem..did the parts fit before you took them apart? Are the stud threads simply catching on undersized or out of place holes in a copper head gasket? The contact faces must of course be parallel as they are brought together

Head Ache

Did the cylinder head fit before the engine was dismantled???
Are you, for example, now trying to fit an Atlas head on a 650 barrel???

I once took a 650 barrel to a workshop to have the studs replaced and the clown of an engineer fitted 3/8" all round.

Have the tapped holes in the…

Have the tapped holes in the head been helicoiled? or some other inserts fitted? Are they truely perpendicular? If they have been done by hand there is a good chance they are on the piss so to speak.

Try.....

Try fitting the head without head gasket and without pushrods, this will hopefully show up the issue. But there is no tapped holes in the head. Nor do you have to be 'assertive'. Without pushrods the head should just drop on.

Not quite correct Al. What…

Not quite correct Al. What about the 3/8"BSF tapped holes that the three studs screw into (the sleeve nut studs and the middle stud at the rear of the head) If those have been inserted badly that can cause loads of problems.

Ongoing...

Thanks for your input guys, more info as follows:

It is a spiggoted Head and barrel. The cylinder barrel is probably a late model 99 barrel ( 9 fins, V cut out at the front) the cylinder liner clearance cut outs were a bodge-it and scarper affair, so a couple of hours with a Dremel brought them back to a better looking finish. The cylinder head has BMC 23166 number on the lower face.

The cylinder head came off ok, there is no evidence of helicoils or oversize studs etc. The studs at the front of the barrel are 5/16" with BSF 26 TPI.

l have fitted the head to cylinder with and without the copper gasket. Incidentally the old copper gasket was quite large ( with evidence of blowing). No composite head gasket will fit and I have also bought two copper head gaskets which also do not fit. I have had to gently open the stud/bolt holes and the cylinder spigot openings so that it will fit. The two 5/16 studs are not long enough and the nut is only engaging half its threads, (not good practice). New studs on the away.

So, all fits together nicely until the push rods are inserted then I cannot locate the front two cylinder 5/16 studs, they are just enough out of alignment not to fit. That is with trying all angles (including keeping it parallel) I have also tried inserting the pushrods into the head first to assemble it that way but my hands are not big enough to hold it altogether.
There is a way that I can locate the cylinder head and pushrods initially without the 5/16 studs, then put them in after the head is located (This I know, is not sound engineering practice).

Have you got the pushrods…

Have you got the pushrods the right way round? Longest in the middle. I bet you are tangling the pushrods up with the rockers, try taking the rocker adjusters out and getting the rockers to touch the valve collars. this will give you maximum wiggle room with the pushrods.

Yes, longest pushrods…

Yes, longest pushrods inboard, short pushrods outboard. Adjusters out of the way and rockers held in position with elastic bands Mick Hemmings style.... :)

I'm still confused. On mine…

I'm still confused. On mine (which is an 88, so has shorter barrel and probably easier to fit), it is impossible to get the head in place unless the pushrods are up inside the head. You say you can't hold them up. But you'll never get the head on unless you do hold them up. If you do, you'll bend the pushrods. I use rubber bands and cut them off as I lower the head. It's the worst job on the bike (apart from clutch rubbers).
Then it's keyhole surgery with bits of bent wire or a magnet on a telescopic rod to make sure the rods are in the bottom cups and rocker balls are in the rods.
I widened the bolt holes in my copper gasket to make it a bit easier. And anneal it.

Practice

Thanks for your advice and coaching.
Maybe it's just the practice I need :)
Once I have replaced the front 5/16 studs I will try the "pushrods in the head technique" again.

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