TR3 engine & box re-build

[Ralph Whitaker]

There is much talk of the FO8s corroding away, but surely if the car cooling system is filled with an appropriate coolant this would be prevented as most if not all contain corrosion inhibitors.

Ralph

[roy53]

If the plastic figure 8s are used would we need to go as far as 105lbs ???????

Roy

[Hamish]

On the plastic coated versions couldn’t you remove the plastic and welseal them to reduce the compression. 

[stuart]

You do know that some engineering shops are now glueing the liners down with no FO8s and everything decked to suit.

Stuart.

[Mr Blue Sky]

Hi all,

really interesting thread that I have been following avidly.  I anticipate doing this to my 3 in the next few years to remedy a number of oil leaks so this is a 'how to' guide of significant interest. 

I was also interested to read about the potential to use plastic for the FO8  seals.  I would caution against that based on my experience of using High Temperature Polyethylene in an engineering application some years ago.  HTPE 'creeps' due to temperature and stress - the combination of both in our engines being much higher than that in the Citroen engine would, I suspect, be very detrimental to a plastic FO8 seal.  I would expect the seal to 'stress relieve' itself quite quickly given the combination of the load applied by the head bolts and ca. 85 deg C operating temp and then offer limited resistance to the 4-20lb pressure exerted by the coolant system.

Just my two-pennorth.

Best wishes, Laurence

 

[Motorsport Mickey]

Some interesting thoughts here,

"Both Revington and Moss list copper FO8 seals, but only in the one size 18thou. I expect the idea is that the copper will compress slightly and end up at the same as steel 15thou."

No...as posted by myself earlier in the thread and confirmed later by Bob The copper Fo8 gaskets don't compress...at all

"

There is much talk of the FO8s corroding away, but surely if the car cooling system is filled with an appropriate coolant this would be prevented as most if not all contain corrosion inhibitors."

 

I've rebuilt many engines where the steel Fo8s have been fitted and they have been in a variety of conditions, varying from OK (normally with Wellseal remains upon them) to corroded thin barely existing lace like versions where if they haven't been leaking they would do in the near years ahead.

This probably shows evidence of earlier less effective antifreeze mixes or owners following the 50s/60s practice of only using antifreeze in winter. I have used steel Fo8 gaskets myself previously and my practice when fitting both steel and copper is to coat EVERY mating surface in Wellseal...top of block Fo8 fitting shelf, underneath of Fo8, top of Fo8, and then the liner Fo8 fitting shelf. The coatings are "tacky" when left to go off slightly and messy to handle but when the heads torqued to 105 almost all residue of the Wellseal is squeezed out with the inconsistencies in the block Fo8 shelf filled with it 

 

"If the plastic figure 8s are used would we need to go as far as 105lbs ???????"

 

Yes...the 105 figure presumably was found to be the figure required to match up the 2 requirements of the engine

1) giving a water tight seal around the liners and bottom of block.

2) Allowing the stiffening of the block with 4 columns of cast steel (the liners) which are then torqued down hard enough to put stiffening stresses through them into the engine casting.

A lesser torque on the liners would likely allow them to "fret" (shuffle about, they are in slide fit holes in the casting) under a low torque loading, which won't add a stiffening to the block and allow water ingress into the sump. 

 

"On the plastic coated versions couldn’t you remove the plastic and welseal them to reduce the compression."

You'd have to strip the plastic chemically from the Fo8s which would reduce the thickness by maybe a thou or two and then make absolutely sure that the Wellseal covers all the surfaces AND THE EDGES to prevent corrosion. Bearing in mind that the 105 applied will squeeze out all but a micron covering on the Fo8 and given that owners have difficulty in covering plastic coated steel Fo8s in Wellseal correctly I think the likelihood is stripping the plastic would just lead to unprotected bare steel Fo8s in points which would rust even quicker.   

"You do know that some engineering shops are now gluing the liners down with no FO8s and everything decked to suit."

Yes, this sort of mod has been done for some years now, normally by competition racers who wish to put in even larger liners (I think they've stopped at 92 mm... at present) where the liner spigot skirt at the bottom is removed entirely (the 89mm skirts are pretty thin as it is) and the liner shoulder machined and prepared before the new shorter liner is put in place upon a "glue" substance. I don't know how permanent this makes the liners fitted into the block, presumably they can't be easily removed unless machined out. If so it makes the rebuilding in future more difficult for the home restorer and removes the flexibility of the engine. If you damage a liner or suffer with a gasket blow normally you dissemble to component parts, remachine or replace and you're back on the road.

I'd like to gain more experience of the substances used and what can or can't be done with them, it's possbily the way ahead. 

Mick Richards

   

 

Edited December 5, 2020 by Motorsport Mickey

[Ian Vincent]

2 hours ago, Ralph Whitaker said:

Both Revington and Moss list copper FO8 seals, but only in the one size 18thou. I expect the idea is that the copper will compress slightly and end up at the same as steel 15thou.

Ralph

Or possibly the idea is that if you are dealing with a leak and replacing a set of worn steel FO8s you have the option of a slightly thicker copper one to use so that you only have to ask your machine shop to lightly skim your liners and you are good to go again.  In other words you have a small margin for repairing the engine without having to go through the major process of removing the block to get that machined.

You would even have the option of regrinding the liner seats with valve paste as per the Citroen Traction Avant article posted earlier in this thread.  All without taking the engine out.

Rgds Ian

[iain]

These later posts do demonstrate  the need for an engineering shop that attend to all the detail. This is not a criticism but our experience between us  has shown some avoidable issues.

Issues that have come to light in this thread...,
Liner seats,  check and machine if necessary, block for parallel face to crank, liners tested with the figure of 8 to be used, to give an even 0.003” to 0.005” upstanding,  in 4 planes on all bores.( with no variance between bores) Pistons machined to deck height. Remove crank plugs, camshaft plugs for thorough cleaning. Check for cracks that are increasingly common around some of the stud holes in the block.

I am sure I have missed some points, let’s get them listed for the benefit of all?

As MIck has said more than once we must not assume that machine shops will know and do what is required.

Iain

 

Edited December 5, 2020 by iain

[stuart]

3 hours ago, Motorsport Mickey said:

Yes, this sort of mod has been done for some years now, normally by competition racers who wish to put in even larger liners (I think they've stopped at 92 mm... at present) where the liner spigot skirt at the bottom is removed entirely (the 89mm skirts are pretty thin as it is) and the liner shoulder machined and prepared before the new shorter liner is put in place upon a "glue" substance. I don't know how permanent this makes the liners fitted into the block, presumably they can't be easily removed unless machined out. If so it makes the rebuilding in future more difficult for the home restorer and removes the flexibility of the engine. If you damage a liner or suffer with a gasket blow normally you dissemble to component parts, remachine or replace and you're back on the road.

I'd like to gain more experience of the substances used and what can or can't be done with them, it's possbily the way ahead. 

Mick Richards

   

 

FWIW Stanwoods in Bawtry use this method apparently it is possible to remove them should the need arise but I dont know how. I know Racetorations use that method of sealing too.

Stuart.

[Lebro]

Camshaft core plug knocked in using Wellseal under it, then block hung back on the engine stand.

Trial fit of the seal centralising mandril. Spent rest of the day checking the crank for clear, clean oilways, & then cleaning up the NOS shells ready for a trial crankshaft fit tomorrow.

Bob.

Edited January 16, 2021 by Lebro

[ntc]

10 hours ago, stuart said:

You do know that some engineering shops are now glueing the liners down with no FO8s and everything decked to suit.

Stuart.

Yep and also machine tapered so no fo8 needed 

[alanwcoote]

I’m glued

[Motorsport Mickey]

Can't see any image Alan, how is the engine going, still good. ?

Mick Richards

[alanwcoote]

All ok so far mick

Your help and input was outstanding and I’m forever greatfull

[Motorsport Mickey]

You are welcome Alan, thankyou.

Mick Richards

[BlueTR3A-5EKT]

Bob Before you fit the crank check the protrusion of the flywheel bolts through the crank rear flange as they might hit the Marx seal.

Cheers

Peter W

 

 

[Lebro]

Funny you should say that Peter, that was one of todays tasks:

Only two needed to be shortened, & not by much.

Also finished cleaning the crank oilways, & fitting the plugs back in, plus temporary fit of crank to block to re-check end float, 10 thou measured. my existing thrust washers although very slightly worn measure up at standard on one side & +5 thou on the other, so if I order a set at +5 all round the float should end up spot on at 5 thou.

Have ordered a shed load of new spring washers to fit the various sizes of bolts used in the engine.

Bob

Edited January 16, 2021 by Lebro

[Lebro]

Regarding crankshaft thrust washers, if I order from say Moss, or Rimmers etc, the +5 thou set, do I get 4 parts, each 5 thou thicker than standard, which would decrease end float by 10 thou, or do I get two parts at 5 thou each, & 2 parts at standard, or 4 parts at 2.5 thou each ?

Thanks

Bob.

[Ian Vincent]

47 minutes ago, Lebro said:

Regarding crankshaft thrust washers, if I order from say Moss, or Rimmers etc, the +5 thou set, do I get 4 parts, each 5 thou thicker than standard, which would decrease end float by 10 thou, or do I get two parts at 5 thou each, & 2 parts at standard, or 4 parts at 2.5 thou each ?

Thanks

Bob.

When I bought them Bob, I got four parts at +.005".  I had to mix and match with a standard set that I already had.

Rgds Ian

[Lebro]

Hmm that's what I thought, so it's either re-use part of what I have, or buy a standard set & a +5 set. Not ideal. Shame they don't sell them in pairs, perhaps I will suggest it !

[Lebro]

So today I put the crank back in the block, & added the pistons & conrods in order to measure the piston height.

They were above the liner top by approx 30 thou, (measurements below) Since only 15 thou was machined from the block, they would have been 15 thou above liner height even if I had done nothing to the block.

Don't know if this is due to the Maxspeedingrods being a bit longer than they should be ? of if the pistons were too tall (TR shop 87mm liner / piston set) only other possibility is that the block had been machined before, but by 25 + thou ?

Anyway, there is lots of meat on the piston crowns ¼" at least, so machining off 40 thou to get -10 thou deck height should be fine. 

These are my measurements, thou above liner. Note liner no 3 is about 1 thou higher than the others, so you might expect the +ve deck figure to be lower - but it's not  it's higher !      variations in pistons I guess

              1                       2                      3                    4 

            31                      29                   34                  32

    30          33       32          32      35        34      32        34

           31                       29                   35                  32

So with 16 thou FO8 gaskets (15 thou in at present)

40 thou off No 1,   41 off No.2,   43 off No.3   42 off No.4

Then re- balance them.

Ready for machining

Bob.

Edited January 16, 2021 by Lebro

[Lebro]

Compared old & new con rods for length - exactly the same. Also new & old pistons ( using small end as reference) exactly the same. Compared old & new liners, new one was 7 thou shorter than old. Still does not account for the 31 thou above liner deck. Top of block must have been machined a fair bit more that the 15 thou I was told. Unless my maths is wrong.

3 of 4 pistons now reduced in height, I may take 1 thou of liner No. 3 to make them all the Same height.

[iain]

Great attention to detail Bob. Now we know why a rebuild is the price it is.

The materials are relatively cheap, the hours of labour required to get everything spot on seriously add to the total if going with a specialist for all the machining and build.

[Lebro]

REduced height of pistons to get required -10 thou deck all approx 40 thou off.

    

DEcided to take 1.5 thou off the base of the 1 liner which was 1.5 thou higher than the others, first had to make a support plate for the tailstock end, used a bit of scrap ali.

     

Finally centered the liner up on lathe, & turned 1.5 thou from bottom .

put back in the block, & now protrudes the same as the others, I will still have to make some 16thou FO8 seals & then the protrusion should be 4 thou all over. 

Bob.

Edited January 16, 2021 by Lebro

[Ian Vincent]

Very impressive Bob but I'm surprised that you had to do this, I would have expected C&M to get them all the same.

Rgds Ian