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Sam is having problems with his engine rebuild. Has anyone some advice?
The liners have welded themselves in place quite effectively, perhaps helped by the aluminium/coolant cement in the water jacket. I’ll consult a chap with better apparatus.
A further question: I assume it’s safe to ‘deck’ the head gasket faces of the crankcase and liners by a few thou (taking note of the correct protrusion of the liners, naturally)? The problem is that oil feed pipe in the centre, which looks like it’d be a tit to remove and refabricate. If the job’s done on a milling machine, I wonder if it can be delicately skimmed around?
Our previous conversation:
Hi Sam we have both Opel and Triumph aftermarket pistons machined to suit the Javelin. We also have tons of secondhand liners, but we found that most of the s/h liners either do not clean up at plus 0.020 or have damage on the gasket face. Cylinder liner/gasket sealing is challenging on the Jav. New liners are only a little over 100GBP each. You can soon waste this on gaskets and wasted machining. We learnt that lesson the hard way and sponsored the manufacture of new centrifugally cast, plateau honed new ones. The choice is yours. I will gladly send you a set of Triumph pistons for the machine shop to match to and if it goes pear shaped we'll credit them against an engine set of pistons and liners. Happy new year ! Paul
Cool. Yes – let’s give the Triumph pistons a whirl, as I think there’s a decent chance the liners will go again. I reduced my Volvo Amazon’s engine to the same state over Christmas – a rather foolish move as it was serving perfectly well as a daily hack with four cracked pistons – so I’ll be re-establishing a relationship with Coventry Boring momentarily. I can hand over some Jowett bits when I retrieve the Volvo bits.
I’ve just discovered that Jowett crankcase halves are perfectly designed to not fit in my press. How much pressing out do the liners generally take? I can try rigging something up involving a forklift… but if they tend to be stubborn, maybe I should just ask a grownup to press them out for me?
Cheers,
Sam
I will post pictures of my liner extraction tool tomorrow.
Basically it is a disk that locates at the bottom of each liner. Then a long 40cm stud . a strong bridge the width of the head. And a couple of blocks that raise the bridge above the block. The two pullers are tightened together to raise the liners and gasket support together.
Already in Gallery
Ah. Usually the studs are a challenge and the liner locator on the stud will not come out. Two types of locator. 1 piece aluminium or 2 piece iron or in your case rust. Use aluminium!
Why not carry on the conversation on JT?
Sometimes liners are tight then heating the block helps. Note liners are brittle.
As I said previously try heating it always works in my experience . I put one recalcitrant set a couple of months ago on the wood burner and they came out easily. Sometimes a hearty bang on the end of the removal tool stud also coaxes them into action. You may also try a soak in diesel for a week.
Last edited by Keith Clements on Thu Jan 04, 2018 12:25 pm, edited 1 time in total.
Skimming the block IMHO is not something I would normally undertake except to create a smooth surface after welding which I have done. Reducing the height would require careful measuring to make sure pistons do not hit head whilst maintain gasket pinch. My guess is you would probably be OK at 20 thou. as it can be adjusted with the copper liner shims.
Note that any skimming should be done after gas flowing and balancing the combustion chambers, working out your desired compression ratio, deciding the amount and slope (you can adjust difference between two chambers by sloping the cut) of head skimming in conjunction with the block skimming.
One other issue is the water transfer castings which may need adjustment to locate after skimming. I took serious amounts off in the race engine but some heads are better than others at not exposing cracks into the waterways. You should also make sure after skimming you open up the waterways with a 1/4inch drill.
Removing the head bolts is usually the hardest task as often they break off and need to be drilled out and replaced. The oil feed bolt is usually the easiest to remove, the hardest are the ones that go through the water inlets. Once again heat is your saviour. You might even try some spray can coolant, as used by plumbers, on the bolt after heating the block to say 230C.
Last edited by Keith Clements on Mon Jan 08, 2018 12:22 am, edited 1 time in total.
I’m only thinking of the lightest of passes to clean up the gasket faces of the crankcase. I’ll see what it looks like when it’s clean.
I’m going to cheat on the liner front. There’s a chap five minutes from me with a large hydraulic press, which’ll make fast work of extracting them without risking damage or soiling my oven.
The head studs succumbed to butane and oscillation, with – as you predicted – the exception of the rear ones. Both pretended convincingly to start moving, then snapped in the hole they pass through in the block deck, which looks ideally designed to attract coolant through capillary action and foster electrolytic corrosion. I figure I can extract them by cutting them and welding nuts to the lower bits once the liners are out of the way.
I’ll take specific photographs as I achieve/ruin stuff. In the meantime, here’s a colourful shot taken shortly after head removal.
Sam, that looks like ‘jointing compound’ used on top of the liners, not recommended on the Jowett engine. You
may be aware that the liners are assembled dry at the head gasket.
Good luck with the studs, before doing too much work I would check the crankcase for cracks!
Regards. Alf.
Sam, Reference your made to the 'oil feed pipe'. This is probably the balance pipe that stands proud of the decking face. I have ground off this material level to provide better access for checking the fit, head to the block and have had no problem with the engine in my Javelin after 20k plus miles with this modification.
The rear stud hole is threaded both sides of the water passage. The original design where the stud only passed through the section into the water passage proved to to be a weakness, if over tightened it resulted in a crack in the casting running near parallel to the block face. A late mod. introduced the longer stud that bridged the water passage to try and improve the strength in this area. The longer stud is available from JCS. To clean up the thread or to add the thread to take the longer stud you need a tap that is long enough to engage either side of the water passage. Is there a Helicoil tap long enough to refurb. these holes?
Alfs advice is very sound you need to pressure test the castings to start with, saves a lot of heart break further down the refurb. path. Looking at you photo the casting looks promising with very little corrosion along the bottom flange.
I have always maintained that the Javelin/Jupiter crankcase cylinder head gasket face must never be skimmed. My reason for this self-applied imposition has been the balance pipe nip flange protrusion. Also, as has been mentioned, there is the dreaded piston protrusion at TDC. The valve gear oil feed pipe should not be a concern, because the No. 1 head stud is threaded against its flare.
another point to watch for, if the faces are skimmed, is the head stud shank counter-bore depth in the crankcase.
I have had weld repairs locally skimmed in a milling machine, however, in the case of the PB engine I rebuilt three times recently, ALL FOUR CRANKCASE faces had been skimmed by our local (and very respected) engine machinist before I became involved with the subsequent rebuilding of the engine. I called in on the machinist and asked about the reasons for skimming all four faces. The explanation was that, due to their (and previous) welding activities, the main bearing tunnels and cylinder head faces were that distorted, something had to be done. Just looking at the amount of weld, made me believe their explanation! I would not have touched that engine with a double-length barge-pole.
My reasoning about the balance pipe protrusion was that, with nature's welding, the steel pipe section and the crankcase parent metal would by now be 'one' and gas leak-proof. So far, that appears to be the case. I was going to get a pair of brass 'thimbles' machined, but thought the 0.008" lip might be a bit dicey. I also considered gluing-on a brass shim washer, but thought of others going in there in years to come. So, I stuck with nature at its best!
The photo of the crankcase above, is fairly frightening and, to me, furthers explicitly the case for manufacture of new crankcases. Could the liners be wound out with a long piece of 0.625" UNF all-thread rod (with liberal application of anti-galling compound), through a thick walled tube and some pieces of suitable 10 mm abutment plate and a 12 mm thick disc to pull the liner through the bore in the crankcase? I agree that the centre head gasket support could hold up proceedings quite a lot.
Cylinder head stud removal could provide quite a challenge. Someone once suggested soaking the whole assembly in hot vinegar, but I have never tried it, and Sue would probably be embarrassed if I wheeled out two trolleys loaded to the gills with vinegar at the supermarket during Friday shopping!
