[whitehillbilly]

Thanks Paul.
What year was your Enfield ?
I know the head had work done by PO's mate who was a head specialist. I will try and contact PO and see if exhaust insert was done.

Whitehillbilly

[Paul W]

My 350 is a 2004 model.

[stinkwheel]

Probably a QC issue with materials and fitting more than a spec. issue. Steel seats should be fine with unleaded and Pauls 2004 model ought to be designed to run on unleaded. You have to wonder what grade of steel they used or if it was heat treated properly. The exhaust valve seat on my original 2008 350 head fell out.

[Paul W]

The engine shop who fixed my cylinder head told me that it wasn't unknown for replacement valve seats in alloy heads to be troublesome and be difficult to keep them in. To ensure that mine stayed in, they fitted a narrow ring insert inside the outer part of the old one!

Seemed a bit strange to me, but in the words of Eric Morecombe, you couldn't see the join and it's worked very well, especially since I gas flowed the head.

[stinkwheel]

Mine aren't going anywhere now after the engine repeatedly hammered the bottom half of a valve into them for me and peened the alloy over the edges nicely. (yes, I did have them re-cut).

[AndyMcP]

I had the same issue with valve seat recession.  One shop flatly refused to take on the job.  Another was very reluctant, until I assured him there would be no come back from me if it went wrong.  I just wanted a replacement valve seat fitted and a useable bike!  They did a great job in the end, but I had to wait a while and they weren't cheap...  I had them fit the oversize valve at the same time (as identified by Bullet Whisperer).

I suspect the rough state of the cylinder head alloy casting might put some machine shops off working on these.

[whitehillbilly]

Afternoon.
What process would you use for Re Torquing the Head Gasket.
I read somewhere by ACE ? you only need to Torque to 20 lbft.
Thanks for commets.

whitehillbilly

[AzCal Retred]

With soft Indian case alloy, you need to use a cross-pattern & sneak up on it. Hand wrenches and feel are OK, you aren't dealing with tremendous cylinder pressures. Most leakage is usually oil from around the pushrod tube passages. You can lap in the spigot to the head for metal-to-metal sealing and use O-rings to seal the pushrod passages, obviating the need for a head gasket.

[Raymond]

OK, I'll bite. Given that spigot, how do you lap in the cylinder head joint? I've cleaned up gasket surfaces in the past, using a sheet of plate glass and a rotary motion - can be done on fine wet or dry paper, or I suppose with fine grinding past. But for this joint, what procedure do you recommend?

[AzCal Retred]

I'd do all this off the bike when you pull the top end. Run a flat mill file over the iron spigot top just enough to get it flat. Use lapping compound on the spigot/head joint, manually rotating either the head or barrel back & forth, lifting periodically & rotating a bit to try to keep the lapping process even. Check progress often with bluing or similar to see what the sealing/mating surface looks like. Clean compound off thoroughly when done lapping. Some "Indian Head gasket shellac" on the sealing surfaces for luck and snug down progressively. Gives a slight bump in compression and stops the spigot from coking up and bonding into the head recess.

The pushrod tube sealing is then a separate issue. O-rings have been used, but even rubberized cork gasketing should work. It needs to be compressed when the head bottoms on the spigot. Pretty lo-tek stuff.

[tooseevee]

I'd do all this off the bike when you pull the top end. Run a flat mill file over the iron spigot top just enough to get it flat. Use lapping compound on the spigot/head joint, manually rotating either the head or barrel back & forth, lifting periodically & rotating a bit to try to keep the lapping process even. Check progress often with bluing or similar to see what the sealing/mating surface looks like. Clean compound off thoroughly when done lapping. Some "Indian Head gasket shellac" on the sealing surfaces for luck and snug down progressively. Gives a slight bump in compression and stops the spigot from coking up and bonding into the head recess.

The pushrod tube sealing is then a separate issue. O-rings have been used, but even rubberized cork gasketing should work. It needs to be compressed when the head bottoms on the spigot. Pretty lo-tek stuff.

           +1 to AzCal. Who was that Reply to? You never quote anybody. Confusing some times.

            This is good advice, Raymond, if the Reply was to you.

            The 2CV engine seals this way with metal to metal sealing only - no head gasket - & these engines, rebuilt carefully as I did mine, go for thousands & thousands of trouble-free miles.

            Aside: I did much of my engine rebuild (& a lot of other restoration details) up here in the house (many times it was just too damn cold down in my garage) which is a credit to my long-suffering wife. That restoration stretched out to almost 4 years; my own lifesize Mattel kit. Ended up with a show car that was not my original intention. Oh, well   

[AzCal Retred]

The "Home-Growed Fix-It" was to Raymond's query at Reply #68.

The metal-to-metal seems to me to be a better method. My Can-Am 175 & 250 used it and they made quite a lot of HP for their displacement. Coking around the spigot top can really complicate disassembly. Using the spigot/head joint as a sealing surface precludes this. Your own high performance example proves that it'll work just fine on my 6.5/1 CR machines, assuming I pay appropriate attention to spigot top flatness.

[Adrian II]

Ditching the gasket on an iron barrel is a good idea, my big head Bullet's engine was built without the gasket using the spigot to seal, and O-rings to seal the push-rod tunnels (that needed circular slots cutting into the old gasket joint face on top of the cylinder with a hole saw).



Photo: B.W.

I've also had this done for my 350, it has a low mileage cylinder head which I managed to buy cheap because a blown head gasket joint actually burnt part of the joint face away into the hole for the cylinder stud.



Using the cylinder spigot to seal the join meant that I didn't have to get the head welded!

A.





Photo: B.W.