egret Posted January 14, 2014 Share Posted January 14, 2014 Thought I'd say hi. I got a spitfire recently and it ran OK, but i was chasing electrical gremlins and trying to sort the mixture and timing until I realised the head gasket had gone. I'm working through what I actually have and aiming for a bit of preventative maintenance while is apart, but hope to have it running again soon. Future job list includes sorting the suspension and tackling the decidedly diy paint job. Thought I'd attach a pic of the gasket. Link to comment Share on other sites More sharing options...
Nick Jones Posted January 14, 2014 Share Posted January 14, 2014 Hi, This is presumably from the engine you mentioned in the other post, originally from a Dolomite? Doesn't look like a great quality gasket, but it is so well blown I wonder what else is amiss. You need to get a straight edge across the block and head to make sure the faces are flat, paying special attention to the areas between the cylinders. Wouldn't be a bad idea to CC the chambers, or at least check that the head is close to it's original thickness as the +.60 bore already means the compression ratio is up a bit. Could just be ignition timing or fuelling though. If you have a tubular manifold, sports exhaust and/or free flowing air filters you need different carn needles otherwise there will be a tendency to run lean when pushing on - which can lead to scenes like that. Did you have any overheating or pinking issues before it let go? Cheers Nick Link to comment Share on other sites More sharing options...
egret Posted January 14, 2014 Author Share Posted January 14, 2014 The car wasn't really running well enough to be driven hard. I think the head gasket failure was due to a combination of poor head torque and residue on the bore recesses preventing the previous gasket from seating properly. I've cleaned it up and have a better (payern?) gasket and will borrow a calibrated torque wrench when re-assembling so I'm hoping that there wont be a problem when it goes back together. There didn't appear to be any temperature problems and no pinking, but the timing and fuelling was probably way out. I've measured the head thickness and between machined surfaces its 77.4mm so I don't think it's been skimmed, the head looks standard to my eyes and in good condition. Cylinders look to have been re-bored to +60 thou pretty recently. This starts to makes sense of whats written on the pistons: ,060 and 75,141 which matches up to a 60thou overbore and a 75.14 piston diameter. The only thing that I don't know what it means is that pistons 1&2 have S1 written on them and 3&4 have s7. Anyone got any idea what that could mean? Cheers Link to comment Share on other sites More sharing options...
egret Posted January 14, 2014 Author Share Posted January 14, 2014 If I assume everything else is stock then the addition of a 60thou overbore will bring the original 1493cc up to 1555cc and the compression ratio from 9:1 up to 9.33:1 If properly set up I think this should run fine on 95ron without pinking? Cheers Link to comment Share on other sites More sharing options...
Nick Jones Posted January 14, 2014 Share Posted January 14, 2014 Yes, the recesses need to be very clean for a reliable seal so that is likely correct. Payen gaskets are excellent. Mk2 Vitesse / GT6 Mk2 have 9.5:1, but slightly different chamber shape and longer cam timing. 9.33:1 should be just about ok, but might be a little close to the edge with a standard cam - assuming that is what it has of course. Just makes the ignition and fueling setup a bit more critical. If it does pink then either better fuel, octane booster or a good excuse for a slightly wilder cam! Don't know what the S1 & S7 mean. Don't recall having anything but +0.20 and an arrow on the County pistons I fitted in my PI last year. Cheers Nick Link to comment Share on other sites More sharing options...
egret Posted January 15, 2014 Author Share Posted January 15, 2014 Thanks Nick. It's great to get a second opinion from someone with experience! I'll hopefully have it back together in a week or so and as I have to re-do the timing and fuelling I'll make sure I take the time to do it properly. As I'm not doing loads of miles having to use better fuel isn't the end of the world. Link to comment Share on other sites More sharing options...
egret Posted February 1, 2014 Author Share Posted February 1, 2014 Got some pictures today during the brief amount of sunshine we had. You can see the area of primer that needs dealing with, but the pictures are of a low enough quality to mask the poor paint job on the rest of the car! Link to comment Share on other sites More sharing options...
Nick Jones Posted February 1, 2014 Share Posted February 1, 2014 Looks presentable in the pics at least. Does seem a bit high at the back though not hugely so. I'd say long shafts are fitted from the way the wheels sit in the arches - bit of a flyer though. Nick Link to comment Share on other sites More sharing options...
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