Richard
Looks great!! Nothing like working on shiny bits and pieces with time available. Gonna make for some really satisfying …and really frustrating days…!!!.No doubt you’ll have beer/wine on hand???..just got 1300kms on my rebuilt engine. Still can’t help smiling when the big starter motor kicks all the whirley bits into action!!!
Matt,
It was Don’s engine looked shiny, mine somewhat more tarnished.
Today checked over the 2 2nd hand liners which came with 2nd hand pistons and conrods.
I tried the compression ring from one of the 2nd hand pistons in a 2nd hand liner, and in one of the original liners, it gapped at 33 thou both times.
I have a new set of rings made in U.S.A. by Grant. They gapped around 14 thou.
These new rings are noticeably much less “springy” than the old ones which I guess were OEM.
I will look up the recommended gap later, but it looks in the ball park for liners with a bit of wear in them.
To make sure the firing rings at the top of the liners were spot on, I put them in the lathe and touched up the firing ring with fine emery cloth. They all look good to use, although the original liners have some corrosion on the outer edges but not seriously compromising anything. The 2 2nd hand ones have perfect firing rings, and they were already honed.
Dropped all the liners into the block for a trial fit. Looks like they all seated well and the firing rings are all in the same plane. I might fit the crank next before finally fitting the liners with 518.
I bough the Loctite 518 and 242 threadlocker from China via Ebay. Cheaper source, more choice and easier to find than anywhere near me. The products are actually made in China by Henkel. The 242 has a breakaway torque of 11.5Nm, compared with 26Nm in the popular 243. That means you can use it on highly torqued fasteners and not burst your boiler trying to undo them later. It has a temp range to 150deg C, and 243 goes to 180deg C, but I see no problem there.
Richard…thinking in the reverse to heating the block… try chilling the liner with a bag of ice hoping the liner will shrink a little. One might imagine that parts of the aluminum block will eventually shrink a little also and thinking about the construction of an Al block, the bore for the liner should get bigger. Some might think the opposite but as it is the mass of the material that is shrinking, all cavities in the block should get a little bigger if the block is chilled.
I have used this chilling technique on ceased nuts (in Al housings) to good. effect.
Trev
I was always told that holes in a block of metal expand or contract at
the same rate as the metal itself. Other wise if you cut a cylinder out
of a block of metal, it wouldn’t fit at a different temperature.
Jim 1984 XJSC
Jim. I take your point however I think this would require the metal mass to be similar to the spaces with in it … eg replacing a ring gear on a 49 Ford requires the ring gear (very little mass compared to the huge hole) being heated to slip it on to the flywheel and as it cools it contracts… but if you heat a metal plate the same size of the ring gear with a small hole in the middle the hole will get smaller. It’s all about mass vs space.
However there is no need to calculate the mass of a V12 block Vs spaces, just block the bottom of the sleeve with a rag and fill it with crushed ice and if it frees up you have your answer.
Trev
That’s incorrect. Jimandhelen was correct, a hole in metal expands with temp exactly as a solid piece of metal the size of the hole. Mass is not a factor.
2 Likes
My local Safeway supermarket sells dry ice. Makes ice cubes look pathetic. Valve guides and bearings drop into warmed castings under gravity, never mind a BFH.
1 Like
Years back, I had to replace a ring gear on a 289 Ford. The instructions were to heat up the ring gear and press it on. It was so thin, I couldn’t figure out how you’d press it on fast enough before it cooled with contact with the flywheel. And I didn’t have any good way to heat it anyway. So I put the flywheel in the freezer and left it there for a coupla days, and then I stuck the ring gear in the oven at 400F. Pulled it out of the oven and set it onto the flywheel and it dropped into place, not even any tapping required.
Only way I ever did it: works great!
I installed my EDIS trigger wheel the same way, on Tweety: because I believe in belts and suspenders, though, I put small welds around the periphery, JIC.
Making progress. After spending at least one hundred hours stripping and cleaning up this filthy dirty V12, now is time to start assembly which will take nowhere near that much time. First up is to size the rope seal without the fancy jag tool. I wrapped two layers of polyester electrical tape around the crank to give 4 thou radial clearance.
The plan was to drop the crank in for a trial fit using the engine crane, a single handed operation.
Well, that plan needed the crane boom out to max and a right hand to steady and locate the crank with the left hand releasing the valve on the hydraulic cylinder. If I were 10 feet tall my hands would stretch that far, but I do not fit the plan. Plan B would be if i were a mountain gorilla I could just pick the crank up and drop it in.
Waiting for my pal to turn up and give me a hand.
Curiously, there was one item in this V12 that was pristine, needed only a wipe with a rag to make it look almost brand new. This is it.
There is only the slightest impression where the chain ran on the track. Looks as if this tensioner was a brand new item fitted when the engine was rebuilt. When I say rebuilt it would be more accurate to say all the engine parts were just roughly bolted back in a big hurry. The tensioner evidence is that it did not run for long.
It had crossed my mind to make some more steel backed tensioners like the batch made 15 years ago.
The 25 made were all sold to forum members and a couple of parts shops, but I only used one to rebuild the V12 HE engine in the coupe. I never saved one for myself - bad move.
However the OEM tensioner out of this engine, ( on Ebay for A$400 ), is too good to waste. It will be used.
What I should have said was there is a new tensioner on Ebay for A$400.
WHY would you do that?
I set many, many rope seals, w/o the fancy tool, and just used the crank, no tape. Jags, Minis, Triumphs…all worked well.
I always had a good result. But I am confused about the tape for clearancing…
There is an urban myth that if you just bolt down the caps on the crank without “sizing” the rope seal first, it might be a tight fit and cause excess friction and overheat the crank.
You just exploded that myth. Alternative explanation is you just been lucky.
For relatively little effort I played it safe.
Have Jaguar always recommended “sizing” rope seals on their engines ? Perhaps they once had a bad experience with warranty claims and then played cautious.
I just put in the block half, seated the crank in it, oiled it, tapped the crank down with a large soft mallet, then slightly trimmed it, to being just proud of the bolting face.
Repeat with main bearing cap, on the crank, outside the block, repeat trim.
Then, I would use the slightest bit of silicone, to seal the chamfer of the main cap, torque in the crank, rotate through. Never a burn, and pretty darn leakproof.
I have seen rope seals that looked a bit charred, as though they got too hot for some reason. Perhaps not presized properly? Dunno. Whatever, they still seemed to be doing the job! In fact, the reason I was in there on my '83 was because the main bearing right next to the seal had seized. Could THAT have been because the rope seal was heating up the journal too much? Dunno. Whatever, I’d recommend presizing if possible. Can’t hurt.
It’s been my feeling for some time that the timing chain tensioner is quite durable indeed if the engine hasn’t been overheated. Once overheated, the plastic becomes brittle. The incidence of overheating in Jaguar V12’s is so common that I dunno if anyone has any reliable data on how long the tensioner will last if it’s never overheated. Perhaps, though, that’s the case with yours! The first ever never-overheated Jaguar V12!
I kinda think you should presize the rope seal if you can, but I’m not sure I’d use tape. I’d suggest using shim stock. If you do use tape, you might want to use just one layer; presizing a bit on the tight side would be better than too loose.
Are you using Jaguar rope seals or Ford 460? The Ford 460 seals are graphite impregnated, probably far less sensitive to being too tight.
If you’re lowering that crank into position for sizing, I think you need to have a couple of main bearing shells in place.
Remember to apply a narrow bead of Loctite 518 across the top surface of that mating face in a line from the rope seal to the hockey stick groove when bolting on the main bearing cap.
" Perhaps, though, that’s the case with yours! The first ever never-overheated Jaguar V12! "
There was so much crud around the top of liners in 6A and 6b those cylinders would be warmish.
Apart from that no obvious sign of overheating. The tensioner is in such good condition simply because it is not the OEM one, and had a very short operational life in this engine.
I think the tape is OK, I know it gave me 4 thou radial clearance in theory. Probably the tape compressed a bit and maybe the seal bounced back a bit too. This is not exactly a scientific way to do it.
They came in a Jag packet.
Yes, had 3 main bearing shells.
You bet.
I thought that would go without saying…but thanks for saying it!
On a few rare ocassions—none my fault—I had reasons to tear a couple engines apart, and not ever found a rope seal “burned.”
Likely a case of just having been taught by an old-school mechanic, in the fine tradition of Rolls-Royce, whose service manuals state, “This operation should be undertaken by an experienced fitter.”