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'54 Dominator (iron head)

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'54 Dominator (iron head)

Posted by John Shorter at January 19. 2017

I have just removed  the head from my Dommy, for a rather overdue overhaul.  The valve guides need replacement (no big deal), but the top of the valve stems are worn, and indented.  Although these can be ground flat, the metal is obviously not hard enough to resist wear.

Back in the 50's, when I owned my first Dominator, I fitted satellite valve caps, and am considering using these again.  Any thoughts on this solution?

Re: '54 Dominator (iron head)

Posted by robert_tuck at January 20. 2017

If there is enough stem above the collets for security ,why not?.It may be worth checking that the rocker action is centered on the valve .

Re: '54 Dominator (iron head)

Posted by les_howard at January 20. 2017

Hi John...you said above: The valve guides need replacement (no big deal)....Well you might find this more difficult than your first initial thoughts on doing the job. As the head and guides are both cast iron, heating the head to get them out doesn't help as much (if at all) as if the head was made in aluminium. Getting them back in of course is helped by heating the head but the expansion of iron is not that great so the guides can often be extremely tight noting that by the time they are fully driven in they are as hot as the head, heated by conduction. The other worrying thing is that cast iron is brittle and as you thump in the guides there is a very worrying feeling that you might crack the head especially as you try to get the last millimetre of guide to lie flush with the head.

If I was to do the job again I would heat the head to at least 300 deg C in the hope that you get the guide to instantly slide all the way in before the heat difference is lost (it takes only seconds for this to occur)...Good luck.....Les

Re: '54 Dominator (iron head)

Posted by robert_tuck at January 20. 2017

Consider having the Guides linered.

Re: '54 Dominator (iron head)

Posted by John Shorter at January 20. 2017

Thanks Les, you have really cheered me up!   The last time I did this job was back in 1957, on that occasion there was no problem.

Perhaps I was just lucky, and you were not.   The new guides are on their way, so, I will find out next week.  I think it may be a good idea to put them in the freezer on arrival (didn´t even have a fridge in ´57!).

 

Re: '54 Dominator (iron head)

Posted by les_howard at January 20. 2017

Let us know how the job goes John please...Smile

By the way, for what its worth maybe you should replace the valves anyway as the stems must be worn too and you would be losing the improvement that the new guides will give you plus you won't need the valve caps then....spend a bit of that state pension...it's only money...

One would imagine that freezing items to gain extra temperature difference is a good idea but what are we looking at in reality? possibly an extra 20-30 Deg C.....This extra temperature difference and more can be dialled in by raising the oven temperature and because it's cast iron can take a very high temperature in safety. Secondly does ice cold cast iron tend to shatter more easily when hammered?

Les

Re: '54 Dominator (iron head)

Posted by jonathan_newton at January 20. 2017

Fit bronze; and use liquid Nitrogen to chill, then press them in with a GLOVED hand.  

J

Re: '54 Dominator (iron head)

Posted by les_howard at January 20. 2017

Previously jonathan_newton wrote:

Fit bronze; and use liquid Nitrogen to chill, then press them in with a GLOVED hand.

___________________________________________________

Yes that would be a neat and easy method. What I would mention is that bronze guides fitted into a cast iron head might create a problem due to the near double coefficient of expansion rate of the bronze (18 vs 10) If the bronze can't expand outwards there must be a squeezing inwards which would tighten on the valve stem and lead to it seizing for sure especially the exhaust guide. To avoid this you would have to set a large clearance by reaming the new guide. I would stick with cast iron guides in a cast iron head. Cast iron also wears well too.


Les

Re: '54 Dominator (iron head)

Posted by jonathan_newton at January 20. 2017

Previously les_howard wrote:

Previously jonathan_newton wrote:

Fit bronze; and use liquid Nitrogen to chill, then press them in with a GLOVED hand.

___________________________________________________

Yes that would be a neat and easy method. What I would mention is that bronze guides fitted into a cast iron head might create a problem due to the near double coefficient of expansion rate of the bronze (18 vs 10) If the bronze can't expand outwards there must be a squeezing inwards which would tighten on the valve stem and lead to it seizing for sure especially the exhaust guide. To avoid this you would have to set a large clearance by reaming the new guide. I would stick with cast iron guides in a cast iron head. Cast iron also wears well too.

 

Les

Agree; you adjust your clearance to suit.  Thats why my M7 engine smoked a bit on startup but was clean after warming.  As i remember the  cast iron head had no guide insert so you can machine out to suit any dimension.  Therefore any guide with a corrcet internal dim would work, bronze or cast, or sintered.

Cheers

Jon 

Re: '54 Dominator (iron head)

Posted by anna jeannette Dixon at January 20. 2017

Hello Here is me thinking Cast iron  Heads were only fit for a door stops  alloy heads are better painted with VTH  Black  Matt or gloss  paint  and I world fit Bronze Valve guides  Cast ones in our days are not very good and brake in the head So if anyone its doing the same exercise do your self a favour and fit Bronze valve guides   yours  anna j     PS SEE RGM MOTORS    

Re: '54 Dominator (iron head)

Posted by John Shorter at January 20. 2017

Anna, what was the point of your post? I have not GOT an alloy head, and neither should the '54 model, you boast of owning, have one. If you can't say anything useful, say nothing!

Re: '54 Dominator (iron head)

Posted by Gordon Johnston at January 21. 2017

I have been replacing valve guides in iron heads since 1972... I drift out the old ones cold. I pre heat the head and put the new guides and drift in the freezer and and then, not hanging about, drift the new guides in. The only problem I had was with a pattern guide which was bored off centre. It had to come out and be replaced. Not the fault of the methodology. Always use a drift, don't just batter the valve guide.

I would never put a bronze guide in an iron head.

Re: '54 Dominator (iron head)

Posted by les_howard at January 21. 2017

Hi Anna....If you DO have an old iron head lying around, please let me know...I'll buy it off you...You can PM me or get in touch on Facebook....Best regards....Les

PS...I agree bronze guides are probably better in alloy heads as they expand nearly as much as the aluminium and therefore are much less likely to loosen.

Re: '54 Dominator (iron head)

Posted by anna jeannette Dixon at January 23. 2017
Previously les_howard wrote:

Hi Anna....If you DO have an old iron head lying around, please let me know...I'll buy it off you...You can PM me or get in touch on Facebook....Best regards....Les

PS...I agree bronze guides are probably better in alloy heads as they expand nearly as much as the aluminium and therefore are much less likely to loosen.

Hello Les  NO I do not have any old iron cylinder heads laying around  they went in the scrap bin years ago   I do not use dodgy parts  they get scrapped or put to one side  marked  pattern part use only Do not put other riders lives in danger by sell on dodgy parts or unfit for use   , but I see other have not these feelings  and sell most dodgy parts or worn out parts on eBay  so be careful what your buying  on eBay     AND yes  I did Mean Bronze  Valve guides  to fit in Alloy Cylinder heads  and NOT Cast Iron ones                       yours anna j   

Re: '54 Dominator (iron head)

Posted by paul_webb at January 23. 2017

Previously les_howard wrote:

Hi Anna....If you DO have an old iron head lying around, please let me know...I'll buy it off you...You can PM me or get in touch on Facebook....Best regards....Les

PS...I agree bronze guides are probably better in alloy heads as they expand nearly as much as the aluminium and therefore are much less likely to loosen.

Hi Les,

I have a spare iron head that you can have which I swapped on my 1954 '88'. It has one small part of fin missing.(easily repaired).

PM me and let me know?

Paul.

Re: '54 Dominator (iron head)

Posted by John Shorter at February 02. 2017

Job done.  Replacing guides was, just as I thought, "no big deal".

My original post was not about guides, but the whether using valve caps was I good idea.  To this question, there was only one reply!

The caps are still available (although very expensive, for such a small item).   They should  make for more accurate tappet adjustment.  The old valves were a snug fit in the new guides, and will not be replaced.

Having bought a new Indian fuel tank (excellent value), the silencers looked rather shabby, so are being re chromed (not a lot cheaper than pattern replacements, but the original ones sound right!).

Hopefully the bike will be back on the road soon, with little else to do before the Belgium rally.

Re: '54 Dominator (iron head)

Posted by jonathan_newton at February 03. 2017

Previously John Shorter wrote:

Job done.  Replacing guides was, just as I thought, "no big deal".

My original post was not about guides, but the whether using valve caps was I good idea.  To this question, there was only one reply!

The caps are still available (although very expensive, for such a small item).   They should  make for more accurate tappet adjustment.  The old valves were a snug fit in the new guides, and will not be replaced.

Having bought a new Indian fuel tank (excellent value), the silencers looked rather shabby, so are being re chromed (not a lot cheaper than pattern replacements, but the original ones sound right!).

Hopefully the bike will be back on the road soon, with little else to do before the Belgium rally.

Sorry John; Caps are a good idea if you have wear damage or loss of valve / rocker angle.  They also offer a larger surface area for the rocker to operate on and in my experience have lowered the noise output from valve clatter.  My triumph riding buddys try it too; as I love to rib them about the din those  things produce.

Exhaust;  Always keep with the originals if they can be resurected,  I bought a Norton pattern silencer for my single to brighten its appearance but it sounded flat,  the  mounting bracket was weak, and the finish didnt last long so I reverted to the "goldstar" pipe that its been on since the 70's  

Re: '54 Dominator (iron head)

Posted by John Shorter at February 03. 2017

Thanks Jonathan,  your views mirror my own.  I used valve caps, back in the 50´s, with no problems.   Just can´t think why I didn´t use them when the engine was rebuilt, back in ´98.   I think I was advised that the valves were hardened, and they were not needed, wrong!   The silencers are original Norton items.  They were so well made that it was worth chroming them, for the third time in their life.  Maybe, this is partly due to using the original breathing system, and, they get a light oil mist (also, the rear chain never needs oiling).   My view is that, if a ´50s bike doesn´t drip a little oil, the tank is empty! 

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