Tim Butler Posted January 2 Report Share Posted January 2 Hello, hoping some engine buffs can assist. I bought a mk3 gt6 a while ago and the further I dig the more I think Mary Shelley could write a novel about it. I recently noticed the head gasket was blowing coolant, so I whipped the head off today. Transpires that it's an early vitesse head I believe, I'm curious as to whether this will throw up compression ratio issues... The block appears to be a mk3, the number is KE011446HE, flat top pistons, whereas the head is 515440 with the in line ports. Should I just throw it back together with a new gasket or should I make some alterations? It ran OK, but I did notice that a few rocker clearances were tight even with them fully wound in. I don't much fancy buying a new head and manifolds, but don't know if the earlier head will be giving me poor performance. Any advice would be appreciated... Link to comment Share on other sites More sharing options...
Wagger Posted January 3 Report Share Posted January 3 There are different lengths of pushrods I believe. Plus you can fit spacers under the rocker pedestals. Just do some measuring and select as required. Link to comment Share on other sites More sharing options...
johny Posted January 3 Report Share Posted January 3 The earlier head had smaller valves than the later one so power reduced somewhat. Also larger head bolts were used so your earlier head may have had the holes machined. Link to comment Share on other sites More sharing options...
JohnD Posted January 3 Report Share Posted January 3 The later GT6s had domed pistons because they were fitted with cylinder heads identical to those fitted to 2.5L engines! The dome occupied extra space in the chamber to maintain the compression ratio, but made no difference to the swept volume. Vitesses never had this, so any 2L, but not 1600, head would be fine on your non-domed GT6 engine. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 3 Report Share Posted January 3 this may give some clues head_applications_chart.pdf (chriswitor.com) what makes you think you have an early head surley its not been fitted with a stepped Mk1 head worrying as you say may change manifolds ??? can you check the casting numbers from the chart and maybe load a photo Pete Link to comment Share on other sites More sharing options...
johny Posted January 3 Report Share Posted January 3 Unfortunately that list is all mk2 heads so the inline ports head Tim has wont appear in it.... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted January 3 Report Share Posted January 3 A pair of GT6 heads (all 2 litre) for reference: Mk1 above, MK2 below. The Mk1 is stepped back from the manifold, and has a visible lip; the later ones all attach to the straight face. Link to comment Share on other sites More sharing options...
Tim Butler Posted January 3 Author Report Share Posted January 3 Thanks for the feedback. It's definately a mk1 stepped head, have added a photo as below. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 3 Report Share Posted January 3 (edited) with domed pistons i guess this head will increase the compression ratio has 34mm inlets vs mk2 36mm so what carburation is fitted ??? and i wonder how a MK1 head will suit the head gasket with recessed bores should work so its been drilled to take the 7/16 studs with the higher nut torque Pete Edited January 3 by Pete Lewis Link to comment Share on other sites More sharing options...
Nigel Clark Posted January 3 Report Share Posted January 3 A KE engine number means the block is from a Mk3 GT6, which I would expect to have domed pistons. Is it possible that someone has fitted an early Mk1 engine and fraudulently re-stamped the engine number? Measuring the diameter of the cylinder head studs should throw more light on the situation. 7/16" studs for the Mk1 engine and 3/8" for the Mk2 and Mk3. Nigel Link to comment Share on other sites More sharing options...
DanMi Posted January 3 Report Share Posted January 3 20 minutes ago, Nigel Clark said: A KE engine number means the block is from a Mk3 GT6, which I would expect to have domed pistons. Wasn't it only the late GT6s ie the non rotoflex ones that had the domed pistons. Of course any block could have been fitted with any pistons, crank and cylinder head over the years. Link to comment Share on other sites More sharing options...
johny Posted January 3 Report Share Posted January 3 According to Canley its from KE10001 that got dome pistons so making Tims engine originally one of these😳 Link to comment Share on other sites More sharing options...
Tim Butler Posted January 4 Author Report Share Posted January 4 I shall check the pistons for markings, but they are definately flat topped. And I've got new head gasket, studs and nuts on order so I can check the diameter of the existing. It only really flagged up to me when I realised that I've ordered studs for the mk3 engine, which are all long, and when removing I realised that half of the studs are short... It doesn't look like the block has been re-stamped. Carbs are dual stromberg, with the crank breather hose going into the inlet manifold... Certainly a frankenstein's monster as it has a d type overdrive. I bought the car as the bodywork was in good nick with no rust and I don't mind mechanical tinkering, however when rewiring to accommodate more fuses and re-veneering the dash I discovered the body was originally a LHD 🙄 It's also supposed to be a rotoflex by the model year, but is now a swing spring 🤷♂️ Link to comment Share on other sites More sharing options...
johny Posted January 4 Report Share Posted January 4 Ah a US re-import might change the story as Triumph did different things across the pond. Even so mixing blocks and heads seems extreme... Link to comment Share on other sites More sharing options...
johny Posted January 4 Report Share Posted January 4 (edited) Yes Canley says dome pistons fitted from KE10001 except US market... It probably would have come with emissions type carbs so maybe someone just installed another head complete with carbs and manifolds? Edited January 4 by johny Link to comment Share on other sites More sharing options...
JohnD Posted January 4 Report Share Posted January 4 Even if the block originally had dome top pistons, it doesn't now (see original post). It also has a Mk1 head which would match those pistons in terms of chamber size. In effect a DPO has made up a Mk1 engine from parts! Tim Butler, this discussion is turning into a beard pulling competition as minutiae of production are discussed, so to return to your original Q, yes, you can reassemble this bitsa engine and expect it to run! But you found a leaking head gasket - the later GT6 engines had a groove machined in the block face around each bore and used a special head gasket with a 'fire-ring' that went into the groove. If this groove is there in your later block, but you used an early style gasket, then I'm not surprised the gasket failed! Refit the head with the later style gasket, it has a tab at the back, that may be marked "TOP". Good luck! JOhn Link to comment Share on other sites More sharing options...
Gully Posted January 4 Report Share Posted January 4 Irrespective of the engine number, flat top pistons with that head should be correct. Both may have been changed from its original build... It sounds right that the crank case breather goes to the inlet manifold - hopefully via the Smiths valve. As for the D-type overdrive, a D-type is correct for a GT6. Gully Link to comment Share on other sites More sharing options...
DanMi Posted January 4 Report Share Posted January 4 lets face it very few of our cars are as they left the factory after 50 years plus of use, abuse and rebuilds, engine numbers etc really aren't a guide to what you have, as anything could have been changed, just because you have a 2500 saloon block, doesn't mean that it is of that spec, it could easily have been built to GT6 spec. I have a spare Herald 1147cc block which was built by the factory as a recon to mk2 spit standard (bar no cam bearings). Bodies shells get replaced etc etc. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4 Report Share Posted January 4 is there a fire ring support groove machined around the top of the bore to support the gaskets fire ring ??? if it has the gasket must be the tabbed one hopefully not then its the std non tabbed gasket the small rectangular Tab is on the rear edge to identify the type . can you confirm the head stud diameter ???? Pete Link to comment Share on other sites More sharing options...
johny Posted January 4 Report Share Posted January 4 16 hours ago, Nigel Clark said: Measuring the diameter of the cylinder head studs should throw more light on the situation. 7/16" studs for the Mk1 engine and 3/8" for the Mk2 and Mk3. Nigel Is this the right way round? I thought the later engine had the thicker studs. Reckon Tim must have custom made short studs for a mk1 with the diameter to suit the later block😳 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted January 4 Report Share Posted January 4 1 hour ago, johny said: Is this the right way round? I thought the later engine had the thicker studs. Reckon Tim must have custom made short studs for a mk1 with the diameter to suit the later block😳 Later heads had thicker studs, so the thick ones won't be a straight fit through the early head. I can assume it was easier to drill out the early head than rethread the block, but maybe varicoil inserts were used? Link to comment Share on other sites More sharing options...
johny Posted January 4 Report Share Posted January 4 Id be worried about using an insert for a head bolt🤔 Link to comment Share on other sites More sharing options...
Nigel Clark Posted January 4 Report Share Posted January 4 11 hours ago, johny said: Is this the right way round? I thought the later engine had the thicker studs. Reckon Tim must have custom made short studs for a mk1 with the diameter to suit the later block😳 You're right of course, my mistake, bigger studs on the later engines. Nigel Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 5 Report Share Posted January 5 unless ive missed something we still dont know what stud diameter is actually fitted Pete Link to comment Share on other sites More sharing options...
Tim Butler Posted January 5 Author Report Share Posted January 5 So the studs are definately the smaller diameter. Having said that I don't think the block has been re-stamped, it looks like that's exactly what has happened. Had a closer inspection and removed a metal plate that someone has stamped up from where the block number should be. No stamped numbers underneath sadly, guess the block could have been skimmed in the past so no way to ID what it was in a past life. So I guess I've a LHD mk3 body, converted to RHD. With a MK1 engine fitted and a MK3 OD. Like the world's shittest puzzle... Best re-order parts for a mk1 engine... Link to comment Share on other sites More sharing options...
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