Wendy Dawes Posted February 16 Share Posted February 16 (edited) So we suspect Mabel spun a big end a couple of weeks ago, so tomorrow begins the engine strip down ready for reconditioning . She will be transported to my stable yard on Sunday where there’s a bigger place to work on her and plenty of room to store all the bits we remove I’ll keep a picture diary of the process and keep the progress updated Edited February 16 by Wendy Dawes 5 Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted February 16 Share Posted February 16 Good luck, hopefully it's not too nasty inside the engine. 🤞 1 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted February 16 Author Share Posted February 16 (edited) Going for a full top to bottom rebuild, head with hardened stem seals, rebore and crank grind, no points in messing around might as well go the whole hog 🐷 she is a pig lol Edited February 16 by Wendy Dawes 2 Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted February 16 Share Posted February 16 It's for the best, get the OD box & the new carbs fitted at the same time & there will be hardly anything left that hasn't been done. She should (hopefully) be a good girl for a few years. 2 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted February 16 Author Share Posted February 16 Yea Amy that’s the plan, I’ll get the diff overhauled too, that should cover everything mechanically xx 2 Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted February 17 Share Posted February 17 If you're getting a new timing chain, I would recommend buying a duplex chain kit. With the sub standard materials everything seems to be made from it will hopefully be as good as an original single chain. 3 1 Quote Link to comment Share on other sites More sharing options...
RobPearce Posted February 18 Share Posted February 18 I disagree. That is fine. Quote Link to comment Share on other sites More sharing options...
Darren Sharp Posted March 28 Share Posted March 28 Video of the head coming off IMG_0563.MOV Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted April 14 Author Share Posted April 14 Engine out today and investigative surgery, end shells just started to wear but more intriguing was finding that a piston ring had broken on piston No. 3 and had erupted through the side of the piston Explains the metal deposit on the piston crown 1 Quote Link to comment Share on other sites More sharing options...
65redspit Posted April 14 Share Posted April 14 Ouch !!! 1 Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted April 15 Share Posted April 15 16 hours ago, Wendy Dawes said: Engine out today and investigative surgery, end shells just started to wear but more intriguing was finding that a piston ring had broken on piston No. 3 and had erupted through the side of the piston Explains the metal deposit on the piston crown It's good to find the fault & know the crank is fine. A rebore and matching pistons will get the bottom end sorted. You'll be back behind the wheel in no time. 😊 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted April 15 Author Share Posted April 15 (edited) What do you think caused the piston ring to shatter like that Any , it’s been suggested overheating but I haven’t had an overheat issue with the car since I’ve owned it Edited April 15 by Wendy Dawes Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted April 15 Share Posted April 15 3 hours ago, Wendy Dawes said: What do you think caused the piston ring to shatter like that Any , it’s been suggested overheating but I haven’t had an overheat issue with the car since I’ve owned it There's multiple reasons it could have been, reading the various posts by yourself and Darren, the most likely cause was just wear and tear, I suspect the ring groove would have been excessively worn & the ring was chattering in the piston. Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted April 15 Author Share Posted April 15 Thanks Amy that’s the conclusion we reached, suspect it caught in the rather pronounced ‘lip’ at the top of the bore on the stroke and tore a chunk off the top ring. engine recondition being sorted in next couple of weeks 1 Quote Link to comment Share on other sites More sharing options...
Amy Wade Posted April 15 Share Posted April 15 Every time it went up & down the bore it would have been expanding and contracting as it went in & out of the worn area of the bore. The rebore & new pistons will fix it & it should be good for another 100k. 1 1 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted April 22 Author Share Posted April 22 Cleaned up one of the pistons today looks to be original and Std. Not oversize so the engine hasn’t had any machining in the past 3 Quote Link to comment Share on other sites More sharing options...
65redspit Posted April 23 Share Posted April 23 Hi Wendy, I used JE pistons in my rebuild. They were light and balanced up really well 👍🏻 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted April 23 Author Share Posted April 23 Thanks for the tip I’m just waiting to hear from the engine reconditioner to know when he can do it 1 Quote Link to comment Share on other sites More sharing options...
Darren Sharp Posted May 6 Share Posted May 6 Ok post cleaning update ladies and gents … all the engine components have now been dismantled and checked for damage and wear within our ability to assess them . There are small areas of wear on the ends and mains with small areas of copper showing on the main and big end bearings / journals but no scoring . The piston ring in no3 which can be seen above, fractured and passed the piston crown embedding in the crown and putting small marks on the cylinder head . This has clearly happened previously to no4 bore as there is greater damage of an identical nature to no4 piston crown even though its rings were unbroken . There is no damage to the mating surfaces of the head and the gasket remained intact . Greater wisdom seems to confirm that the head will be fine providing their are no cracks or other damage . It cleaned up nicely but I will leave any machining to the experts . Wendy will take the opportunity to have all new valves and hardened exhaust valve seats fitted . She has already amassed new valves , and guides . The cylinder walls are standard size currently and have a small ridge at the top which will need boring/ honing with new pistons and rings to match . Mabel being an early 12/50 has the smaller diameter cam followers from the 948 engine , they all needed a gentle tap to remove and one had a small amount of damage on its face . They will also be replaced . The cam gear appeared to be in good order with no hooking on the sprockets and the tensioner in good condition, the cam looks ok to an untrained eye with wear on the fuel pump lobe . It too will be checked over . In all it has been a very interesting learning experience and although it’s going to get expensive from now on it has been very rewarding .. my thanks to Colin Wake and Kevin Hagger for pouring over the pictures and giving advice . Quote Link to comment Share on other sites More sharing options...
Clive Posted May 6 Share Posted May 6 Darren, I think there is a pair of spitfire SU's being fitted? Would it be wise to get a spitfire cam and get the head skimmed to get the CR te same as a spitfire, so you get the better performance? (I will be doing the head and cam on my vitesse 1600 later in the year, the std head is ridicously low CR and the cam is very very mild) Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted May 6 Author Share Posted May 6 Hi Clive iMabel is a 12/50 so has a mk2 spitfire cam shaft . I’m having the engine completely machined top to bottom oversize pistons to suit and also crank bearings and thrust washers to suit, , new valves, guides springs, hardened seals, new cam followers, oil pump, timing gear, and anything else which need replacing so should get her sorted Thanks Clive 😊 1 Quote Link to comment Share on other sites More sharing options...
Clive Posted May 6 Share Posted May 6 Aha, I have consilted the oracle, and yes, the 1250 has the 18 58 cam (late mk2 and mk3 spit had a sportier cam, which I had assumed was used far all mk2 spits, every day is a schoolday) Definately worth looking at the compression ratio though, I know my 1600 vitesse needs about a 40thou skim to get things a bit perkier with a MK2 vitesse cam. Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted May 6 Author Share Posted May 6 It’s being done by a friend of Pete Jackson who’s a very highly regarded engine builder so it’ll be in good hands, I might ask if it’s worth porting a little 🫢 2 Quote Link to comment Share on other sites More sharing options...
Clive Posted May 6 Share Posted May 6 3 angle valve seats are cheap (or were) and help. I might even do that on the vitesse! 1 Quote Link to comment Share on other sites More sharing options...
Wendy Dawes Posted May 20 Author Share Posted May 20 Arrived today shiny new spitfire camshaft, engine being packed up ready to go for machining late next week, the expense goes on 😳 2 Quote Link to comment Share on other sites More sharing options...
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