The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: snowbeard on 27.03. 2009 20:56

Title: having the head redone-ouch?
Post by: snowbeard on 27.03. 2009 20:56
so I just got my estimate from the shop, she needs all four valves, all four guides, and all four seats bored and replaced. 

I've noticed a few folk here have had the seats upgraded for modern fuels, etc. so I just thought I'd ask for some round figures for costs?  I already gave the fellow the go ahead, but I have a whole 'nother Super Rocket head to be done with probably all this plus some broken fins to fix.  I can take my time with that one and would be willing to ship it within the states if there are more affordable folk to go to.

so my tally was parts $246 USD, labor $268 USD.  is this a "very reasonable" quote, or really high? or really low?!

I know we don't do this for the return on investment, I am doing it because I love my Spitfire. here's my newest viddy to prove I love her (or maybe I hate her the way I ran it, but it was the last day out...)

thanks for the moral support!!

Title: Re: having the head redone-ouch?
Post by: bsa-bill on 27.03. 2009 21:11
Nice ride I enjoyed it, great sound too

All the best - Bill
Title: Re: having the head redone-ouch?
Post by: a101960 on 27.03. 2009 21:32
I'm not sure what the current U.S. dollar/British pound exchange rate is at this time, but it cost £375 a year ago to have my ally head fitted with new seats and guides. There is a school of thought that says the valve seats in the ally heads are hard enough anyway and should only be replaced if they are recessed. Having said that the head was transformed there is no smoke at all now. What is interesting is the fact that one of the guides was so loose that when the springs were removed it dropped out. No wonder the engine was burning oil!
Title: Re: having the head redone-ouch?
Post by: beezalex on 27.03. 2009 21:51
I agree that replacement of seats that are undamaged and not recessed is totally unnecessary.  Otherwise, the price quote seems reasonable.  I'm not sure I'd do all that work for that price.  OTOH, I tend to re-use what's still good and not just throw everything out and start fresh.  I can typically salvage valves by re-facing seats, too, particularly intake valves.  It all depends on whether you want to do things on a budget or I-don't-care-I-want-it-new. 
Title: Re: having the head redone-ouch?
Post by: BSA_54A10 on 27.03. 2009 22:36
Firstly a couple of photos of the head would be a good help if you really want us to asess the quote.

It would be really rare for a head to actually need all of that work on a BSA.

If it is an alloy head then I would not replace the guides unless they were split ( in the inlet  or more commonly the exhaust tract )
Otherwise get them shimmed.

Seats rarely need to be replaced as they are a lot harder than the valves and when they start to get thin you can always fit an oversized valve to compensate for an over machined seat.

Start with buying a new set of valves.
Pop them in the head then have a look at how they sit in the seats.
More than once an owner has been shown a pocket in the head caused by his old valves which have been ground down past their limit, in the head to justify replacing the seats which were well within their wear limits.

A set of valves should set you back $40 to $ 100 depending what you buy & where you get them from.
Domi Racer have NOS valves for around $ 20 each  Black diamond ( supposed to be the best ) are around $40 each.
Shimming the guides should cost about $ 40 per guide including the shim.

Hazet or New Way both do a really good set of seat cutters which will cost you around $ 150 to $ 200 which will pay for themselves in 3 uses or keep your beer fridge full in perpetuity from your grateful friends.

OTOH if your hear really needs all that work I think that the quote is a bit high on the labour side.
The parts are about right if they are going to fit top line replacements but the labour seems a tad on the excessive side for a shop with all the gear on hand set up to do the job.

At home with hand tools I can swap all 4 guides in less than an hour ( excluding oven time to heat the head twice) , grind all 4 seats in about 15 minutes ( no lapping required with new grinds ) so I am miffed as to where they can find 4 hours work. ( @ $ 60/hr )   
Title: Re: having the head redone-ouch?
Post by: snowbeard on 28.03. 2009 05:19
thanks for the replies, by the conversion rates, £375 would be 536 usd today.  pretty comparable sounds like, not taking into account new valves or inflation?

but on the other hand, you're scarin' me 54!  the fellow took the piece, did a full cleaning without blasting, took it all apart and measured it by the specs they have.  he said only one valve might be usable, but that the seats had all been recessed so much they were beyond using again.  I didn't know about possible oversize valves, but it sounds reasonable.

the head was working for me, but people kept telling me with concern that I was blowing a lot of smoke on the right side, and I knew that pipe was dripping oil from the silencer and joint. I also knew that that valve stem was rough, rusted at some point, but was hoping to avoid the work.  someone finally scared me enough to make this decision.

I am not one to throw money at a problem or throw away good parts as a general rule.  I may have gotten carried away, but at the same time I want to keep this bike reliable for years to come. I figured this would be a good step.  I also don't want to insult these guys by balking at a fair price for what they suggest when I don't know my idiot from a hole in the ground...

here's the best shot I got of the underside, kinda hard to tell what's what, and since I personally have no reference...


I am not ready to take on the risk of screwing it up, so I didn't even think to take on this project myself. and I do respect these guys, tho they have no good reason not to milk me for anything they can get out of me...

I'll call them again tomorrow and see if they think that oversized valves would be a good idea, but I was strongly advised to do the hardened seats already. do the oversized valves change performance also? require carb tuning? 

thanks again!  I'll be away the next few days, but I'm still very interested to hear any thoughts!!!

Title: Re: having the head redone-ouch?
Post by: a101960 on 28.03. 2009 09:26
It is always difficult to know what to do for the best, but before you commit yourself to new guides read this. I am sure that if your valves are worn and are still a good tight fit in the head that this may well be a scheme that is worth investigating.I think that in the U.S. there is a company called Colisboro ( or something like that) that do these inserts. What ever solution you opt for the seats will need to be machined to ensure perfect alignment. Here are some  pictures of my head before it was refurbished you can see just how bad it was.
Title: Re: having the head redone-ouch?
Post by: a101960 on 28.03. 2009 09:35
You can clearly see how the timing side cylinder was burning oil. Apart form the smoke once the engine warmed up there was a constant ting, ting noise generated by the guide bouncing about. I naively kept checking and resetting the tappets. Ah well you live and learn.
Title: Re: having the head redone-ouch?
Post by: BSA_54A10 on 28.03. 2009 10:14
I for one try very hard not to denegrate any one who I do not personal contact with or at least very reliable knowledge of.
They might be trying to milk you for the largest amount of work that they can get or just trying to cover their own back sides by replacing every thing ( belt & braces approach with added rope just to be sure ).
OTOH when a shop starts to sprout the "unleaded Valve seat recession" line I do smell some thing fishy.
The only recession you are likely to suffer from will be your wallet ( and possibly your hairline ).
It is real, but only manifest itself in very high performance engines doing very high revs for a very long time.
Our bikes are more likely to rust than receede .
You really should check the archives on this one, it is a topic that has been done to death both here and over on Britbike ( check all of the forums, not just the BSA one) , I know of several riders ( all Notrun owners ) who ended up with scrap heads after the seat replacement was botched but not a single owner who has had the seats receede and we do ride a lot down here in OZ as there is only 2 or 3 months a year when the weather is too foul.

Just about every pocketed valve I have seen over the years was the result of excessive lapping or grinding not ULP.

OTOH if the seats are well beyond their limit then by all means get them replaced with new harder ones , that is good advice.
From your photo they did not seem to be all that deep but this is assuming that the valves have had a few grinds .
As stated before you really need to see what they look like with new valves in there before you make a decision.
AS for oversized valves we are talking in terms of 1/64" to 1/16" max  which should not demand much in the way of jetting modifications.

A10 1960 has posted the link to K line and I strongly suggest that if the guides are gone ( and your right dose look suspect  ) then get these fitted instead of replacing the guides unless they are cracked , burnt or loose in the head.
Title: Re: having the head redone-ouch?
Post by: MikeN on 28.03. 2009 20:13
Regarding the reference to "The Cylinder head Shop", I have had 3 heads worked on by them over the years with  good results. The bikes were a Sunbeam S7,Triumph T110 and My current A10.
  On running these bikes after rebuilding I found that on all 3 m/c's , I benefitted from a significant improvement in fuel economy.On the S7 , a bike not known for fuel efficiency I could easily attain 60-62 mile per (Imperial) Gallon. They often struggle to attain 50.The Triumph would do  70 -75 on a run and I see from my log that My A10 will do an indicated 80-82 although the speedo is at present reading approx 10% "fast".Even so this makes it 72mpg which I believe is quite good for this bike.
  I think this improvement comes about by the use of the special valve guide liners he fits which allows you to run with almost zero clearance in conjunction with the competition valves. With minimal clearance you can get an  improvement in carburation because the carb is now drawing more air through the intake and less down the valve stems.Your head is returned with instructions on the very simple alteration that you should make to obtain this improvement.
  He will also fit new v/guides complete if for example your guides are loose and have worn the head.The advantage of this is that you can now have guides fitted that incorporate a modern stem seal which I imagine improves things even more
   The competition  valves that are supplied by the CH shop are not much more expensive than std valves and I believe  approx 25% lighter and to a more modern streamlined profile.It must all help towards improved efficiency.
 Incidently I change my oil every 1000 miles and never have to top up in between. So none is going down the guides (or anywhere else).
 Hope this is of interest to someone.
Title: Re: having the head redone-ouch?
Post by: snowbeard on 31.03. 2009 19:43
thanks 54, I hear you on the fishyness of recessing seats, but I wouldn't be surprised if they have been overly lapped.  I do trust these guys to do the best work possible, and to stand behind it.  they may well be covering their own behinds, but better that than beg them to "half-behind" it and have it fail with no recourse.  I do believe them when they say it needs to be done, so I'll just continue and be happy.  apparently the parts are ordered and on their way, so I'll let them finish and get my bike running again for the season.

that looks very much like my head, 1960, they also said they will return all the old parts too, so it will be interesting to see just how bad things were!

very nice looking bits those guide liners, maybe I'll be able to use those on my super rocket head when I get to it. 

I have been wondering what my mileage is for a while now, but it's certainly not 72 mpg!!  I'll try to see what it gets after this work!  thanks Mike, and everyone else for that matter!!

Title: Re: having the head redone-ouch?
Post by: MikeN on 01.04. 2009 08:47
Well Im not a very fast rider and I have other improvements to my bike. It must all help consumption.I have replaced 4 bushes in the engine and 2 in the g/box with needle rollers and fitted tooth belt primary which will help reduce friction.
Title: Re: having the head redone-ouch?
Post by: prewarbsa on 07.04. 2009 11:14
G'Day folks,

I work for Headworks Engineering here in Melbourne, and we do an awful lot of classic bike work. From our viewpoint it is extremely common for an alloy head to need all that work. 54A10 is right in saying you can line the guides (we use K-Lines), then ream them to fit the new valves. It is rare that we don't recommend the owner buy new valves ( again, we highly recommend Black Diamond......just as a quick aside, Black Diamond valves are made by Kibblewhite in the US, they come INDIVIDUALLY packaged and are clearly labelled. We have recently encountered some shiftys trying to pass 'black-coated valves' off as Black Diamond. Worth keeping in mind!)

On the labour issue: giving the head an acid bath, wire-brushing, replacing guides / K-Lining them, reaming, recutting the seat, facing the old valves (too often out of round if we re-use them) lapping them in (we do it by hand, it's the ONLY way!!!) bluing them in, reassemble............personally, I'd want 4 hours to do all that, assuming it's uninterrupted (again, very rare!)

As with other folks, I'm not completely intimate with the exchange rate, and I cant say whether the price you've been quoted is good, bad or indifferent. However, I can say that it's very probable the head does indeed need that much work.

Best regards, Matt

Title: Re: having the head redone-ouch?
Post by: snowbeard on 07.04. 2009 16:50
thanks Matt, I'm feeling better about it these days, altho I don't know that they ordered the black diamond valves, at least they are new.  I think with the exchange rate, and all considered, that this is a fair price for what they are doing, and I do have confidence in their work for sure.

now I'm just excited to get everything else ready for the return!!  changing the seat position, retiming, changing the rear tire, etc etc!!! 

Title: Re: having the head redone-ouch?
Post by: beezalex on 07.04. 2009 18:15
AFAIK, kibblewhite do not make valves for A10's
Title: Re: having the head redone-ouch?
Post by: snowbeard on 20.04. 2009 19:31
just a quick update, not that anyone really needs to know, but I just got off the phone with the shop and they said that with the new valves the head doesn't need the hardened seats after all!  the thickness of the new valves sets them up to a good positioning, so I can wait until the next head job to replace the seats if needed.

I knew there was a reason I trusted these guys! Acme Machine in Ft Collins, CO.  glad to know that they weren't just pushing the seats.

thanks again!, hoping to have 'er all back together by the weekend!!
Title: Re: having the head redone-ouch?
Post by: tombeau on 21.04. 2009 07:09
Jolly good!
Title: Re: having the head redone-ouch?
Post by: snowbeard on 02.05. 2009 04:36
well, got the head back last week, still doing the other little piddly stuff to get ready. Checked my timing and found why she ran best with a little retard, cause I missed the mark on my last attempt at timing even tho I thought I had made it. even double checked, maybe it slipped.

oh well, that will be remedied soon enough!

so it was interesting, the parts returned with my head.  The valves were all sharp on the edges, as explained to me that's why they were so recessed, as well as unusable. one was a maybe, but he figured while we're at it, we might as well do it right with all four.  keep from having to redo it that much sooner.

the valve guides were an interesting situation.  they had been reamed out with a spiral pattern. he said that was often done as a stop-gap fix, as the reaming raised the metal and closed the hole, then they were redrilled to the right size for the valve stem.  it almost looks like the K-liners suggested, but just done to the guides themselves.

anyway, just reminscing already... more to come regarding head gaskets and the like soon, as my wife is leaving town for a week starting sunday, finally! a good bit of time to be wrenching out in the garage!! :)
Title: Re: having the head redone-ouch?
Post by: snowbeard on 07.05. 2009 22:13
well, I know at this point I'm the only one posting to this thread, but I just had to put it to bed!

SHE LIVES!!  fired up first kick even!!!  the head seems happy, and with the timing right about 34 BTDC (I don't trust myself so I tried to err on the side of caution just in case) she purrs like a lion! 

the retard actually changes how she runs and pulls, so I guess I got something put back together better than the first time! 

and just in time for the 7th annual Old Bike Ride, I love it when a plan comes together! *yeah*
Title: Re: having the head redone-ouch?
Post by: bsa-bill on 08.05. 2009 19:40
Nice one, it is nice when an expensive plan goes well.

All the best - Bill
Title: Re: having the head redone-ouch?
Post by: RichardL on 08.05. 2009 20:20

Great news! Now I'm envious of all the Colorado scenery you get to ride around in. It is pretty far from where I live in Illinois to get to places that are hilly, winding and offer a view. If I recall my visit to Golden of many years ago, it should be a nice ride from Boulder.  have a great time.

Richard L.