TR3 engine & box re-build

[Motorsport Mickey]

That's the difference between engine builders and engineers Ian. 

The engineer doesn't know that the unspecified difference between components which would take the engineer another hour to equalise, will be an essential part of the engine build, he just knows it's another £70 off the profit line and will leave it.

If Bob was building engines on a regular basis and throwing back discrepancies in machined quality, the machine shop would realise...no short cuts. If there's a problem (if they pick it up) talk to the engine builder because it's easier to carry out the rework even if it's an extra cost, earlier than later, and sometimes essential in preventing costly mistakes and p***ing off an income stream who will come back with further work. 

I may have mentioned this, NEVER trust a machinist, always check the work they've done straight away.

Mick Richards

PS: Nice little Boxford Bob, wish it was mine.

[Lebro]

Thanks Mick, I couldn't live without it !.

Have proved a setup which allows me to accurately turn the liners, if I cock up the cutting of new FO8 seals I can always take 3 thou off all the liners & then use the stock 19 thou seals.

Bob.

[Motorsport Mickey]

1 minute ago, Lebro said:

Thanks Mick, I couldn't live without it !.

Have proved a setup which allows me to accurately turn the liners, if I cock up the cutting of new FO8 seals I can always take 3 thou off all the liners & then use the stock 19 thou seals.

Bob.

A man...with a plan, I love it.

Mick Richards

[Lebro]

Checking piston height again today after reducing them all yesterday, 1 & 2 were 12 thou, 3,& 4 were a bit less, so re-mounted those, & took a bit more off, nor all 12 thou below liner tops. I was aiming for 10, but happy with 12. then check the weight of them (again) & took a bit more off the base to get them all the same at 654 grams (including gudgeon pin)

  

Check the ring gaps, all were >16 thou so no action required, fitted to pistons. now waiting for copper sheet to arrive so I can make the FO8 seals.

Bob

Edited January 16, 2021 by Lebro

[Lebro]

Copper sheet arrived, together with a sheet of MDF to keep it flat. I used this to make a sandwich in which the copper could be cut.

     

Cut the copper into 4 squares, & positioned them centrally between the two MDF pieces, drilled 4 holes through, & bolted the whole thing to a lathe faceplate.

Then cut a reasonable size circle out of the copper, & then slowly increased the diameter to 92.5mm

Results:

I popped them (one at a time) over a liner base, & scribed around the outside on the liner seat to mark where the needed to be trimmed to.

  

Finally annealed them, which made them a lot softer.

Trial fit tomorrow.

Bob.

Edited January 16, 2021 by Lebro

[Hamish]

Great job Bob. Just love all the attention to detail - knowledge and work rounds. 

but what are you going to call them ? Can’t be f-o-8

 

[Lebro]

F-o-0 !

[Lebro]

Getting really p1zzed off with trying to get liner height right.  Fitted the new (home made) 16 thou (0.4mm) rings today, followed by the head, torqued down to 105 fl lb, removed head, & re-clamped the liners, liner height now varies between 2 & 3 thou.  Bugger.

It was reading 3 thou all over when last measured using the steel 15 thou seals, so it should have gone up by a thou today. I wondered if annealing had allowed the rings to compress, but on removal, they were still 16 thou.  I decided to clean up the copper fo8's I removed from the engine when stripping, they are in perfect condition, but also measure 16 thou. I tried them anyway, repeated the head fitting & removing. still 2 to 3 thou.

Lastly, I annealed the new copper 19.4thou FO8's, and fitted those. torqued up the head, removed and got between 6 & 7 thou all over.

It seems the thickness I need is 17.5 thou to put the readings in the middle of the required range. but copper only comes in decimal metric sizes which equate to 19.7 thou (0.5mm) or 16 thou (0.4mm)

So, question - is 2 to 3 thou,  or 6 to 7 thou acceptable ?  if not I will have to take  2¼ thou off each liner, which is a real pain.

Bob.

[iain]

Bob, I feel your pain. I can’t  help feeling C and M should have sorted this for you. I think the answer is to adjust the liners to the correct height with your “ o”rings  or choice of figure of 8 rings numbered and marked for front etc as you have been doing. Will this then impact on you piston deck heights? I think you had 10 thou, so will the reduction be of consequence?
Good luck

Iain

[Lebro]

Thanks Iain.

Yes, I suspect the only proper answer is to take 2¼ thou (or as near as I can get) off the base seat of each liner, I have already shortened one by 1½ thou to get them all the same, so I know how to do it, just need to very careful to get it all running true in the lathe, which takes time. Then use the 19.4 thou FO8 seals.

My piston decking exercise took the liner height error into account, & it will be correct when I get the liner height correct, so at least I will not have to re-visit that one !

I cannot start re-assembling the engine yet anyway, as I am waiting for the new spring washers to arrive.  Also still waiting fro the 4A valve springs from Revingtons to arrive, they were posted on the 1st Dec, 1st class !

Bob.

Edited December 11, 2020 by Lebro

[Hamish]

Bob 

looks like you are over coming issues that you shouldn’t have had to face as iain suggests.
 

can I ask if this is usual to run into these issues when building an engine ?

or is it a case that you only had “certain” jobs commissioned with a view you would be engineering the final jigsaw. 
rather than an assembly task. 
 

I would like to “assemble” an engine but I couldn’t even dream of attempting what you are having to do. 
 

and sending an engine away to be done in total doesn’t give you “ownership” in the work. Even if it does come back right. 
 

but if I consider an upgrade I would have to fund the latter ?!??? Given this thread. 
 

with you all the way on this one Bob.

 

mickey perhaps you could do my engine when the time comes. 

[David Owen]

43 minutes ago, iain said:

Bob, I feel your pain. I can’t  help feeling C and M should have sorted this for you. I think the answer is to adjust the liners to the correct height with your “ o”rings  or choice of figure of 8 rings numbered and marked for front etc as you have been doing. Will this then impact on you piston deck heights? I think you had 10 thou, so will the reduction be of consequence?
Good luck

Iain

 

 

Either way you should let them know.  Without feedback they can't correct things like this in the future.

[Motorsport Mickey]

2 hours ago, Lebro said:

Getting really p1zzed off with trying to get liner height right.  Fitted the new (home made) 16 thou (0.4mm) rings today, followed by the head, torqued down to 105 fl lb, removed head, & re-clamped the liners, liner height now varies between 2 & 3 thou.  Bugger.

It was reading 3 thou all over when last measured using the steel 15 thou seals, so it should have gone up by a thou today. I wondered if annealing had allowed the rings to compress, but on removal, they were still 16 thou.  I decided to clean up the copper fo8's I removed from the engine when stripping, they are in perfect condition, but also measure 16 thou. I tried them anyway, repeated the head fitting & removing. still 2 to 3 thou.

Lastly, I annealed the new copper 19.4thou FO8's, and fitted those. torqued up the head, removed and got between 6 & 7 thou all over.

It seems the thickness I need is 17.5 thou to put the readings in the middle of the required range. but copper only comes in decimal metric sizes which equate to 19.7 thou (0.5mm) or 16 thou (0.4mm)

So, question - is 2 to 3 thou,  or 6 to 7 thou acceptable ?  if not I will have to take  2¼ thou off each liner, which is a real pain.

Bob.

I fear I would regard the 2-3 thou as being too close to the bottom datum Bob, over time (2-3-10 years) the block will continue moving and compromise the clamping force, your methodology is proven go for a 4 thou height by skimming the liners on the bigger Fo8 gaskets.

Mick Richards

PS: you could act all aggrieved and return them to C+M and tell them their machining is off,...please resolve (but that would mean trusting them) Hhhmmm.

Edited December 11, 2020 by Motorsport Mickey

[Ian Vincent]

Not very helpful I know, but I gave my engineering shop the FO8s I was Intending to use and asked them to sort it including decking the pistons to the correct height. (5thou below block height) 

when I assembled it all they had got it right but my total bill inc. VAT was over £1,000.

Rgds Ian

[iain]

......exactly Ian, we used the same machine shop I believe.

[Motorsport Mickey]

B...M...S...M - Repeat  - Repeat - Repeat = hours = cost.

Mick Richards  

[Ian Vincent]

Bob,

 I wouldn’t take more than 1.5 thou off your liners. Then clamp them down and measure them. I had a conversation with Pete Cox on this a couple of years ago and his view was that 6 thou wasn’t a problem. 

Rgds Ian

[Motorsport Mickey]

13 minutes ago, Ian Vincent said:

Bob,

 I wouldn’t take more than 1.5 thou off your liners. Then clamp them down and measure them. I had a conversation with Pete Cox on this a couple of years ago and his view was that 6 thou wasn’t a problem. 

Rgds Ian

Depends upon head gasket being used.

Mick Richards

[Lebro]

Mick.

I am using a standard "86mm" composite gasket from the TR shop, was told it was ok up to 87mm, laying on the block the inside of the compression rings is level with the liners edge, or just outside near the valves.

Bob.

Bob.

[Lebro]

2 hours ago, Ian Vincent said:

Not very helpful I know, but I gave my engineering shop the FO8s I was Intending to use and asked them to sort it including decking the pistons to the correct height. (5thou below block height) 

when I assembled it all they had got it right but my total bill inc. VAT was over £1,000.

Rgds Ian

I also gave the machine shop the FO8's I was going to use (copper) they said they always use steel, & so when setting the liners up they assumed that the copper ones would squash down by 3 - 4 thou, so set the height to be 8 thou. & they do not put any pressure on the liners to check, just do it all from measurements. Ah well I will get there in the end.

Bob.

[Motorsport Mickey]

You are nearly there Bob, I can't see what difference quibbling about leaving a thou or so on the liner makes, once it's set up you can take the amount off to make the liner height what you want, it's just another cut.

The composite gasket will take up extra heights and should be capable of 6 thou height..., I've run the steel twin ring gasket at 6 thou but with very close tolerances with nil difference in any plane on the liners. As said it's not the liner seal that becomes a problem with the higher height, it helps contain higher compressions of a modified engine, but the higher the liner becomes the less gasket deforming and clamp they allow on the surrounding area on water jackets and drillings along the block. I can't see a benefit for road user of a higher liner height unless fortuitously the liners all conformed to 6 thou upon the first build, and it would save any more work to get it there. If you have to machine to achieve 6 thou "I'd not spoil the ship for a halfpence of tar" and take another cut to achieve 5 or even 4 if you wanted, to ensure a safety factor against another cut being needed.

Mick Richards

Edited December 12, 2020 by Motorsport Mickey
Clarity

[Lebro]

Yes I agree, overnight I have come up with a better way of holding the liners in the lathe, rather than set up the 4 jaw chuck every time, I will use the faceplate, bolt 4 bars of aluminium to it, then turn metal off them to produce 4 stepped mounts to fit precisely inside the top of the liners. I already have the corresponding plate to hold the other end central in the tail stock, so once done I can swap liners without any re centering required.

Bob.

Edited December 12, 2020 by Lebro

[Ian Vincent]

10 hours ago, Motorsport Mickey said:

You are nearly there Bob, I can't see what difference quibbling about leaving a thou or so on the liner makes, once it's set up you can take the amount off to make the liner height what you want, it's just another cut.

The composite gasket will take up extra heights and should be capable of 6 thou height..., I've run the steel twin ring gasket at 6 thou but with very close tolerances with nil difference in any plane on the liners. As said it's not the liner seal that becomes a problem with the higher height, it helps contain higher compressions of a modified engine, but the higher the liner becomes the less gasket deforming and clamp they allow on the surrounding area on water jackets and drillings along the block. I can't see a benefit for road user of a higher liner height unless fortuitously the liners all conformed to 6 thou upon the first build, and it would save any more work to get it there. If you have to machine to achieve 6 thou "I'd not spoil the ship for a halfpence of tar" and take another cut to achieve 5 or even 4 if you wanted, to ensure a safety factor against another cut being needed.

Mick Richards

Mick,

My comment was prompted by the fact that you can take metal off fairly easily but you can’t add it back on. I would want to check at least one liner before I trimmed all four. Hence approach it gradually. 

Rgds Ian

[Motorsport Mickey]

22 minutes ago, Ian Vincent said:

Mick,

My comment was prompted by the fact that you can take metal off fairly easily but you can’t add it back on. I would want to check at least one liner before I trimmed all four. Hence approach it gradually. 

Rgds Ian

Thanks Ian, understand now, didn't mean my comment to sound dismissive.

Mick Richards

[Lebro]

New mount to hold liners central on head stock made

    

 

2 thou taken off seal surface all 4 liners

Quick clamp test gave promising results, head was torqued down, & left on overnight, will do final check & record today.

Did some tests comparing the new standard TR4A valve springs (from Revingtons) with my original TR3 ones.

Used the bench vice to compress one of each outer spring in tandem (with a large washer in between) compressed them till the original was at "full valve lift" dimension, then measured the new TR4A one, identical length, so identical spring rate when valve open.

Did the same with the inner springs, & the standard one came out slightly weaker (only by a tiny amount).

None came near to being coil bound.

Th TRouble with using later springs (which are a smaller diameter) on an early head, is that the springs can move around on the head surface, whereas the original springs are constrained within the machined pocket, so cannot move.

There for decided to stick with my originals, & move the new ones on. (See advert in parts for sale / swap section)

Bob

Edited January 16, 2021 by Lebro