Cylinder Head Work Concern

[bl**dydrivers]

I’m ready to send my cylinder head out to get vapor blasted, get valve guides replaced, mating surfaces skimmed,  unleaded conversion and rebuilt using all new parts collected.

Just don’t know of anyone here in Florida that can perform it well!
Know Wes Scott Cycles in Fort Lauderdale and is about a 20 minute ride away! However, he doesn’t have a machine shop and wouldn’t tell me who he uses.

Just don’t want to have to send it out to SRM as postage will be a killer


And my concern is a step on the right side inner edge combustion chamber.
Going to be using 8.25:1 pistons and hope they won’t hit the lip!

[Rex]

If I was going to get a top-notch job done by a top company I'd swallow the postage/shipping, as it's not much particularly when compared to the cost and value of the finished item.
A happoth  of tar...and all that?

[bl**dydrivers]

If I was going to get a top-notch job done by a top company I'd swallow the postage/shipping, as it's not much particularly when compared to the cost and value of the finished item.
A happoth  of tar...and all that?

That’s what my gut is telling me

[Radlan2]

I am with Rex on this one, you need to find a specialist in Britbikes with alloy heads. Among other things one problem that can arise through inexperience is if the guides are knocked out cold which you could perhaps get away with on an iron head.
 With triples some people go to the trouble of drilling out the old guide leaving a thin wall which can then be collapsed to avoid the possibility of hard carbon and corrosion tearing up the hole in the casting. Think of the amount of heat cycles that head has been through during its 60+ years lifetime, if there is alloy on the old guide after it has been removed that's your interference fit gone. Then after a season of hoping it will repair itself and wiping the oil off the head you will be taking it apart and sending it to SRM, choose wisely.....
          DAMHIKT
               Best Regards
                             Chris

[limeyrob]

I've had very similar work done recently here in the UK.
Guides - you need them out with the head hot then you can measure the bores and see whether you can get standard guides or need oversize.  I needed oversize the the only ones available are 0.016 over so they have to be trued to fit after the bore in the head has been trued. The oversize guides come with an undersized bore for line honing (not boring) so you need that done.  Then seats skimmed to line up.
With the pistons at TDC you can measure them and see it they will hit that step or not, my bet is not.  If it worries you take a Dremel to it.
Go steady on skimming the joint surfaces, there's only so much metal and you want it to last!
I shopped around and found a machine shop that did general engine machining. The head work - both inlet guides, turned, fitted honed, 4 seats re-cut, £220.  I run the original seats with unleaded.  They did need exact instructions and did just what was agreed but i was happy with the work and the engine runs well.

[sean]

any competent  automotive machine shop can do the work I ordered colisbro guides, G and S valves and springs from SRM 
I heated the head in the oven when the wife was out  *smiley4*removed the original cast guides the new guides I ordered at .020 over size and measured each guide hole and had a friend with a lathe turn each guide to proper od then heated the head and fitted the guides , ordered diamond hones from Brush Research in USA and honed [ you cant ream colisbro } the guides id to spec from SRM I believe the intake clearance was .001  and exh was .0015 but SRM will give you the specs .
I took the head  and valves to an automotive machine shop that also does bikes and got them to cut the seats ....I believe the cost for that was $175.00 CDN .
send an e mail to Bob Gross in Florida he used to have a shop specializing in BSA closed now but he would give you info on where to go he runs a fb site " bsa owners of North America only "
on a side note check everything is functioning as it should the springs I got from SRM 3 were fine although close to being coil bound and 1 was coil bound so I didnt use the ones they shipped and too expensive to return .

good luck

[bl**dydrivers]

Everything I ordered from SRM (other than valve collets).
What I’m concerned about is the guides I ordered std and the valve springs I got from them are MCA (never had luck with MCA!).

I contacted SRM

Bead blast                                   £59.08
Set of 4 Colsibro guides                £87.96
Fit & hone 4 guides                        £49.64
Cut both inlet seats                        £25.60
Leadfree exhaust seats                  £120.00
Skim head face                                £49.50
4 valves                                             £94.60
Spring set                                          £32.99
Re-profile combustion chamber   £52.88
Lap & assemble head                      £49.57

Sure adds up

[sean]

plus shipping both ways

[Klaus]

Lead free valveseats are only mony making from SRM. The original seats will last forever, there is no need to convert.

cheers Klaus

[BagONails]

Lead free valve seats are only money making from SRM. The original seats will last forever, there is no need to convert.

cheers Klaus

That's my understanding too so unless the originals are worn/recessed so far they can't be recut then not strictly necessary. Although if you call SRM I'm sure they will give you a convincing reason to do it all...

You know; "while its all apart / you only want to do this once / for us to guarantee the work we always recommend this" etc.

and you are sending it half way around the world and back...

[Klaus]

Lead free valve seats are only money making from SRM. The original seats will last forever, there is no need to convert.

cheers Klaus

That's my understanding too so unless the originals are worn/recessed so far they can't be recut then not strictly necessary. Although if you call SRM I'm sure they will give you a convincing reason to do it all...

You know; "while its all apart / you only want to do this once / for us to guarantee the work we always recommend this"
etc.


Original Valveseats are cast in and very hard to machine off complete, worst case is to discover a blowhole.
If the seats are to deep you can convert to an 1.5 inch inletvalve I had done three times.
I have not the best experience with SRM, they had done my first engine for a high price and it last only one year or 10 thousend kilometres. One piston split parallel to the piston bolt, one loop from the cam has gone and a valveguide come loose. So no more missions to SRM.

cheers Klaus

and you are sending it half way around the world and back...

[Swarfcut]

 All these jobs are surely well within the expertise of a local machine shop, when us Limeys see the work carried out on your custom car and bike shows, nothing is impossible.
 
  Original seats are best left, as stated, unless really too far gone to recut. Even then, local fitment gives a greater chance of getting exactly what you want. 

 Swarfy.

[BagONails]

Had another look at your photos. The combustion chamber is a bit strange looking on the one side isn't it. Have you accurately measured the volumes with a pipette and some kerosene? I think I would, just to be sure you're getting even compression, never mind piston clearances etc.

[berger]

those seats look shot to me .as for compression mine has been running erm thrashed for ages with one piston 10thou lower than the other after having the big end re done when some fool had shaved off the cap to stop an engine knocking , i only found this out when putting the engine together years ago with different rods. i was saving the original polished rods for the berger build but put thunder rods in, polished rods have now been sold.

[Joolstacho]

I agree with BagoNails... Measure the swept volume and compression space volume correctly before you do anything. You just don't know what has been done to it in the past, the compression ratio might be WAY out. When I got my engine, it had been used as a grasstrack racer and had been skimmed to about 12:1 to run on Methanol. Easy to get back to correct 8.75:1 using a compression plate under the cylinder base. But it could have been messy if I hadn't checked it. Your head 'looks' unskimmed, but check the cylinders too they could have been skimmed. (Or maybe I'm just being a paranoid alarmist!)