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Thanks Ian. I used a piece of glass over the chamber, sealed with a dab of grease, covering all of the "hole" bar a slight gap at one end. I used a 10mL syringe to add water till it took no more. I will re-do this today on a different chamber just to double check.

Did you fit the guides yourself, or get the machine shop to do it?

I was going to use the original springs for now as I wont be changing the cam yet. when do a full engine re-build I will probably go for the newman cam, so may have to reconsider. 

I will look at Moss offerings today, & possibly order.  I presume the machine shop will supply the seats ?

Bob.

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Hi Bob,

 I was living in W Devon at the time so I used a machine shop recommended by Stuart Edwards. I supplied the valves and guides, they supplied the seats, faced them to match the valves and fitted the new guides. Oh, and then skimmed the head. 

Rgds Ian

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I’m following Bob’s posts closely as I have recently gone through this exercise - at least partially. I have had a 4A engine with 87mm pistons in my  3A for 20 years ( the original one is under the bench) and late last summer had a head gasket start leaking coolant into n°4 cylinder. The head, which came off fairly easily, was checked and lightly skimmed and pressure tested locally and pronounced OK in spite of some battle scars and cracks in and around the usual places.

I have always had some minor angst with pinking particularly when running on 95 octane. 98 has always been fairly available here in France but less so recently and trips elsewhere in Europe reveal that it is virtually unobtainable in many countries. So I decided reduce the CR a bit.

The combustion chambers were measured at 52ml - big difference from Bob’s 65ml on his apparently virgin cylinder head. I have replaced the composite head gasket with a 2mm copper one, at great expense, which should give a 9.5 CR. Heaven knows what the CR was before, my thanks to Carl at Revington TR for his help and advice on this.

Although it is all hung together and running now I haven’t been able to try it out in anger yet.

james

 

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OK, firstly I measured a different chamber this morning, & got 60mL, I did so because I had a feeling that I wrote yesterdays result down wrong, and added the last syringe full of 5mL when it did not actually go in !  so 60mL is the figure for a standard early high port head.

20200410_093804.jpg.70d693751828c01c87f9403541998759.jpg

I have measured the stems of all the inlet valves to see whether I can re-use them (the seat contact area looks perfect)

measured at top, middle, & bottom of the stem in two orientations, worst case was:  top 2 thou under,  middle 1.9 thou under, bottom 2.5 thou under.

My exhaust valves are already the 5/16" ones in "conversion" guides. all the guides a pretty worn

oddly I only found 2 of the collars which fit under the valve springs ??  should there be 4 or 8 ? the ones I have fit over the exhaust guides, which are bigger then the inlet

& Moss only seem to sell one size.20200410_101342.jpg.79c4e3149e26b3f269aff95151597142.jpg

I am happy to buy all the bits from either Moss, or Rimmer bros (or even the TR shop) moss do not say that their exhaust valves are unleaded compatible

Rimmers do.

This is the shape I will be aiming for:  20200410_121353.thumb.jpg.43ac2bce2f8f14e750cef983c98e0e93.jpg

 

Bob.

 

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AFAIR there are four collars that sit under the exhaust valve springs and locate the third spring. If you are going with the triple springs on the exhausts and need a couple of collars drop me a pm. I think I still have them in the garage somewhere. 

Rgds Ian 

PS they will date from before we moved so they may take a bit of finding!

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Don't worry Ian, they are only £3.55 each. I guess without them there is a bit less strain on the cam as the inner spring will drop down a bit.

Bob.

 

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Just done some compression calculations based on my measured chamber volume, & known displacement (1991cc) & nominal Triumph quoted ratio of 8.5:1

Result is a total non swept volume (chamber + gasket) of 66.3mL.

Using that figure I then calculated what the CR would be with my head as it is but with 86, 87, & 89mm bores  9.05:1   9.2:1  &  9.6:1

I then used the CR calculator, Peter mentioned above, & got this:   not spot on. but pretty close.

I now have to decide whether (in the future) to go for 87mm or 89 when I strip & rebuild the whole engine.

If I go for 87, (cheaper & less hassle) then I need to end up (after chamber mods & skimming) with a chamber volume of around 61mL to get 9:1 CR

Bob.

 

2048993456_compessionratios.thumb.jpg.62a10f551208c460e7b5380113d20053.jpg

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Bob, i don't know what head gasket you are going to use, but it will need to match your reshaped chamber.....standard head gaskets will sit inside the new chamber and create Hotspots and cannot be reshaped to suit.

I too have the head off at the moment........ruddy steel figure of 8s have all sunk, now flush with the block after 10k miles. I have a suspicion they have too much sealant/varnish sprayed on them when made so give a false impression of height, which when pulled down to full torques just disappears. After all that is the only compressible bit in the operation to my knowledege

Iain

Edited by iain

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TBH Bob I would stick with 86/87mm I have gone to 89mm only because I had an exceptional deal on the piston/liner kit and I cant really tell the difference so not really worth the extra effort and expense.

Stuart.

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Just now, iain said:

 

I too have the head off at the moment........ruddy steel figure of 8s have all sunk, now flush with the block after 10k miles. I have a suspicion they have too much sealant/varnish sprayed on them when made so give a false impression of height, which when pulled down to full torques just disappears. After all that is the only compressible bit in the operation to my knowledege

Iain

Thats why your supposed to put the head back on with the old gasket, pull it down to a good torque then take it off and measure again Iain.

Stuart.

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58 minutes ago, Lebro said:

Don't worry Ian, they are only £3.55 each. I guess without them there is a bit less strain on the cam as the inner spring will drop down a bit.

Bob.

 

Sounds like a set of valves and guides is needed.  For me that would be a company like Sutton Rebore too.  They may need to roller burnish the guide bore after fitting - make sure you let them have the valves to get the valve to guide clearance correct. Dimensions are in the Repair Operation Manual.  The machine shop will also fit and recut the seats to match the new guides.  Reaming guides can leave a less than smooth surface.

Roller Burnishing - https://cogsdill.co.uk/brochures/burnishing-tools/

I think the 3rd spring on the exhausts was to overcome the heavier valve on the early engines, it being a thicker stem.  With 5/16" diameter stem exhaust valves I would probably ditch the 3rd spring. - If you intend to go to the Newman PH1 cam I think the triple springs go coil bound at full lift so you need to go to the later twin springs set from Newman. You will need to fit them with appropriate top retainer caps, which seat the different diameter springs.

With the lathe you could spend a delightful hour making the spacers rather than lashing out money to Moss, if you decide to stay with triple springs on the exhausts.

Cheers

Peter W

PS   Bob  -  You probably know this - removing the shroud over the valve will mean you have to chamfer the top of the liner and cut the gasket to suit. - unless you get a proper gasket from Racetorations.  The thickness of the shroud does not want to go too thin either or it becomes a hot spot, ensuring running on.....  As stated above.

PPS  Bob  - are you sure your deck height is zero?  - Top of piston the top of liner.     Is the gasket thickness given a compressed standard TR copper asbestos one?

PPPS   Iain -  I too had the sinking steel fig 8 scenario - Built the engine, clamped the head on for a week measured again and found the liners had dropped to less than 0.003"  Fitted slightly thicker copper ones, clamped for a week and the are all back where they should be.

 

Cheers

Peter W

Edited by BlueTR3A-5EKT

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Hi Iain,

If you find that your F08 gaskets are already the copper ones and .018" thick you will either need new liners or thicker F08s.

If you go down the latter route, you can buy copper sheet in varying thicknesses from 055mm (.0216") up.  I used a 92mm hole saw in my pillar drill to cut the inside and a pair of tinsnips for the outside.  Dress with a file afterwards to match whatever you take out.  Relatively straightforward if you are careful.

Following a conversation with Pete Cox, I didn't worry too much about going to .006" as long as they are all even (he said even .0065" was ok), the standard gasket can accommodate the extra and you ensure that you get a good seal where it matters.

Rgds Ian

 

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Stuart , I did that about 60 lbft..........they where coated steel, when they come out i will re measure them. 

Cheers

Iain

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1 hour ago, iain said:

Stuart , I did that about 60 lbft..........they where coated steel, when they come out i will re measure them. 

Cheers

Iain

IIRC the steel ones are the thinnest ones anyway, you may find theres not much left of them.

Stuart.

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Was a fair way through a reply to above when my broadband went down (& still is) using 4g on phone for this but too painfully to type full answer!

Will try later

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Bob 

I believe I have 87mm set up. 
very happy with it

but if I need a rebuild I would like to go to 89mm as I have heard it makes more of a difference to the torque.

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1 hour ago, stuart said:

IIRC the steel ones are the thinnest ones anyway, you may find theres not much left of them.

Stuart.

They are.  .015" and the copper are .018".  The aluminium ones if you can find any are .021"

Rgds Ian

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Peter.

The compressed gasket was original composite, I measured it at 1.3mm.  0 deck height is correct.

All relying on the quoted 8.5 as being correct of course.

I will omit the 3rd spring, but (having just taken a look) the collar does a good job of locating the 2nd spring (which drops over the shoulder) & won't do any harm.

I am not intending to remove metal which goes outside of the gasket / liner edge, the drawing (above) does show a dotted line to the left of the valve, but that is already cut out below the surface of the head, I will only be removing the shaded section. I will need to ensure that the "overhanging" part does not get too thin with skimming.

2046531357_Gasketover.thumb.jpg.23cbbf837ac4c9e00db5be2f22ec4f67.jpg  can afford to lose a bit if I have to to keep a reasonable thickness

Slowly slowly catchy monkey (as they say)  remove a bit, fill with 61mL of water, see how much to come off, repeat till limit reached.

Does mean I will actually be down on compression while I run with 83mm, but not too much.

Any thoughts on standard Moss EX valves being ok for unleaded ?

518779462_Headmarkedout.thumb.jpg.43629a4d14c65aa4e7f8064cf489035a.jpg   Head marked out using template        

Took the cam followers out to see what sort of state they were in after 55 years  Followers.jpg.e3b495c9ddd950d0a508fca8b344ae91.jpg  no defects at all !!

This is the tool I made to remove them - squashed 15mm copper pipe    1735650278_Followerremovaltool.jpg.ed6692edd5abb772d9ec503fad7f2964.jpg  365670323_Followerremovaltool2.thumb.jpg.c6d2424db3bb9b5e8fb6f63a9441c9de.jpg

Bob.

Edited by Lebro

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1 hour ago, Ian Vincent said:

They are.  .015" and the copper are .018".  The aluminium ones if you can find any are .021"

Rgds Ian

Hi Ian

those are the alleged figures for sure. I have a brand new set of copper in front of me that vary from 0.019" to 0.0205"on the same figure of eight.

Fingers crossed these will give me approx 0.004" of clearance if the steel ones were in spec at 0.015". Other wise its back to the machine shop for a block skim to correct the situation. The liners and pistons having been decked.

Iain

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Ouch, have you already got the engine out?  That would be a challenge in my single garage, which is why I made thicker F08s. 

Oh an apologies for not picking up on the fact that you had steel F08s in your original post. Doh!

Rgds Ian 

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Hi Bob,

              I did the Vizzard mod to my 4A head around 20 years ago and have been using standard composite gaskets all that time, the head's been off once or twice during that time for various cam changes and piston/liner changes but there has never been any sign of gasket failure, as you say the metal removed does not compromise the gasket, the mod did however make the SAH 26 cam that I had originally run very much smoother at low revs along with a noticeable torque and power increase throughout the rev range, so in my book it's definitely worth doing.

Cheers Rob

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Thanks Rob.

The gasket seal will only be compromised if too much is skimmed off the surface.   Do you remember how much you took off, & what CR you ended up with, & what chamber volume ?

Bob.

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Hi Bob, I have to be honest here, I just did the whole thing empirically (seat of the pants sort of thing!!, using Mk.1 eyeball), it just worked, as to the CR I suppose the best answer is adequate!, no problems with pinking, ..... I did at a later stage get the head lightly skimmed to clean it up before installing the latest iteration of a brand new crank and 89mm liners, this along with a Piper fast road cam and a pair of Webers works really well.

cheers Rob   

PS, Yes, I am still using composite gaskets with the 89mm liners, no problems here.

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Good luck with your endeavours today 

back to the grind ?

great thread keep the info and pictures coming.

H

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1 done, 3 to go.  I left a slight curve on the profile (Visard profile was a stright line from base to surface) to save have ing to skim too much off.

Will measure capacity after lunch.

Bob.                                20200411_124356.jpg.e9f1f2b1e6243ccbb9e6ad5303bf4450.jpg

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