Freebird Posted September 7, 2006 Share Posted September 7, 2006 Hi AllI have been offered what I think is a 2.5PI lump to replace the tired 2.5 saloon engine in my Vitesse. The engine number is MG126HE with a 20 thou overbore.My current engine number starts MM, but I can't remember the rest of it.What are the main differences? eg are the heads, cams etc the same or not?CheersGlen. Link to comment Share on other sites More sharing options...
itiejim Posted September 7, 2006 Share Posted September 7, 2006 MG is definately a PI engine. I believe there were early and late cam specs for the saloons as for the TR6s so different performance as well. You would most certainly need a PI cam to get the PI system to run properly as it relies on a certain ammount of vacuum to be created for the metering unit to meter properly. However, a PI engine (with PI cam) should also run OK on carbs. Link to comment Share on other sites More sharing options...
Glenn Posted September 7, 2006 Share Posted September 7, 2006 Hi Glen,The MM engine would be from a TC or S. They had a much milder cam than the PI and gave about 106bhp. The head was also taller and gave a lower 8.5 compression ratio. The PI head has bigger valves but the MM head flows a bit better.Your early PI engine should have made 132bhp in standard form. If you are converting to carbs, the late SU HS6 carbs and manifold from post '75 saloons are recommended matched with needles to suit (speak to Chris Witor). A friend ran his PI on 1.5" Strombergs like the Vitesse has and it really flew - a good choice if acceleration is more important than outright top speed.One problem with the PI on carbs is running on. I think this is due to the 9.5 compression ratio. With yours being bored out 20 thou this will be higher. Mine's not too bad but I might go for an electric fuel pump to sort it out one day.All the best,(another) Glenn Link to comment Share on other sites More sharing options...
Greeks Posted September 7, 2006 Share Posted September 7, 2006 There's some good 6-pot engine info. on this page, kindly produced by some Triumph-loving Kiwis:http://www.triumphclub.co.nz/technical.html Link to comment Share on other sites More sharing options...
Freebird Posted September 8, 2006 Author Share Posted September 8, 2006 All good news so far, thanks to everyone. My MM engine was already running on twin HS6 SU's, not sure what needles though.How do I contact Chris Witor?I hope my Rotoflex couplings can cope with the torque and power, I had to change one the other week and it's no fun at all!CheersGlen. Link to comment Share on other sites More sharing options...
Tim Bancroft Posted September 8, 2006 Share Posted September 8, 2006 Chris Witor- is possibly the best supplier of Saloon 2000/2500 parts, based in Somerset.Google 'Chris Witor'. Link to comment Share on other sites More sharing options...
Deleted User Posted September 8, 2006 Share Posted September 8, 2006 Who should I go to for my estate parts then? Link to comment Share on other sites More sharing options...
Dave2000 Posted September 8, 2006 Share Posted September 8, 2006 [quote by=canleyclassics link=Blah.pl?b=2000,m=1157631136,s=6 date=1157701647]Who should I go to for my estate parts then?[/quote]There's always one, isn't there???Although, to be fair, it's usually me!!! ;D Link to comment Share on other sites More sharing options...
Richard B Posted September 8, 2006 Share Posted September 8, 2006 :B for big saloons & estates.Well I'd say either; Canleyclassics Chris Witor Earlpart TD Fitchet James Paddock or look in the magazines for other suppliersDave, I suggest you go to whoever fits your budget and specification best. :) Link to comment Share on other sites More sharing options...
Richard B Posted September 8, 2006 Share Posted September 8, 2006 :B for big saloons & estates.Well I'd say either; Canleyclassics Chris Witor Earlpart TD Fitchet James Paddock or look in the magazines for other suppliersDave, I suggest you go to whoever fits your budget and specification best. :) Link to comment Share on other sites More sharing options...
Tim Bancroft Posted September 8, 2006 Share Posted September 8, 2006 Also Rimmers?Bit pricey, but good service. Link to comment Share on other sites More sharing options...
Deleted User Posted September 8, 2006 Share Posted September 8, 2006 Well done Tim as diplomatic as ever. Tim for PM! Link to comment Share on other sites More sharing options...
Deleted User Posted September 8, 2006 Share Posted September 8, 2006 [quote by=Richard_B link=Blah.pl?b=2000,m=1157631136,s=8 date=1157707424] :B for big saloons & estates.Well I'd say either; Canleyclassics Chris Witor Earlpart TD Fitchet James Paddock or look in the magazines for other suppliersDave, I suggest you go to whoever fits your budget and specification best. :)[/quote]Thanks Richard but my lemons are so reliable I don't actually ever need to buy anything for them bar petrol and Feu Oranges! Link to comment Share on other sites More sharing options...
Greeks Posted September 9, 2006 Share Posted September 9, 2006 [quote by=canleyclassics link=Blah.pl?b=2000,m=1157631136,s=11 date=1157717818]Thanks Richard but my lemons are so reliable I don't actually ever need to buy anything for them bar petrol and Feu Oranges![/quote]... and seat mountings :B Or does the Herald not count? Link to comment Share on other sites More sharing options...
Deleted User Posted September 20, 2006 Share Posted September 20, 2006 [quote by=Rust_Spot link=Blah.pl?b=2000,m=1157631136,s=2 date=1157653636]Hi Glen,The MM engine would be from a TC or S. They had a much milder cam than the PI and gave about 106bhp. The head was also taller and gave a lower 8.5 compression ratio. The PI head has bigger valves but the MM head flows a bit better.Your early PI engine should have made 132bhp in standard form. If you are converting to carbs, the late SU HS6 carbs and manifold from post '75 saloons are recommended matched with needles to suit (speak to Chris Witor). A friend ran his PI on 1.5" Strombergs like the Vitesse has and it really flew - a good choice if acceleration is more important than outright top speed.One problem with the PI on carbs is running on. I think this is due to the 9.5 compression ratio. With yours being bored out 20 thou this will be higher. Mine's not too bad but I might go for an electric fuel pump to sort it out one day.All the best,(another) Glenn[/quote]I am running PI engine on carbs and electric fuel pump and it still runs on like a bugger I have fitted an antii run on valve which some (apparently) american spec TR6s had I havent fitted it close enough to the inlet manifold so it still runs on! ...will let you know how I get on when I install it correctly! my pi lump on carbs was rolling roaded at 130 bhp so performance should be fine in a vit in fact it will be a hoot! Link to comment Share on other sites More sharing options...
Freebird Posted September 21, 2006 Author Share Posted September 21, 2006 Hi ajp and allDo I need and electric fuel pump or has the PI cam got a lobe to drive a mechanical one? I've decided to use the PI head as the MM one needs tons of money to get it up to scatch and also has smaller exhaust valves. I ground quite a bit of metal out of the combustion chambers to smooth out the steps as suggested in Dave Vizzards article. This will lower the CR a bit. Will Tesco 99 octane fuel help running on?Glen. Link to comment Share on other sites More sharing options...
Richard B Posted September 21, 2006 Share Posted September 21, 2006 The cam has the pump lobe; it's the same part number as a GT6 MkII cam. Link to comment Share on other sites More sharing options...
Deleted User Posted September 21, 2006 Share Posted September 21, 2006 mine always goes better on optimax or v power as it is now known,just turn it of in gear and stall it! it becomes and art! Link to comment Share on other sites More sharing options...
Jason Posted September 29, 2006 Share Posted September 29, 2006 Put the PI back on :-) To stop running on, as you turn off the ignition, floor the accelerator, worked for me until I sorted the problem properly. Link to comment Share on other sites More sharing options...
Freebird Posted September 30, 2006 Author Share Posted September 30, 2006 JasonI haven't got the PI stuff, just a bare engine - all ancillaries will be coming off the TC lump.Glen. Link to comment Share on other sites More sharing options...
Freebird Posted September 30, 2006 Author Share Posted September 30, 2006 I stripped the PI block down today and found a huge score in number 5 bore from top to bottom a good 0.5mm (20 thou) deep and 2mm wide. Sod it!It is already 20 thou oversize, so unlikely it will clean up at max oversize.So I've got two engines, a late recessed head TC (eng No MM20405HEA) with standard bore, but needing a rebore and an early PI (eng No MG126HE) at plus 20 with a score in number 5. Oh, and no money left as I had the head converted to unleaded and the gearbox needs a rebuild too.My cunning plan, to save buying a set of pistons, is to re-bore the TC block to plus 20 and fit the pistons, with new rings, rods and camshaft from the PI lump. The PI crank is good, so if the TC proves not to be, I will want to fit the PI crank to the TC block. Can anyone see any problems with this plan?CheersGlen. Link to comment Share on other sites More sharing options...
Jason Posted October 5, 2006 Share Posted October 5, 2006 [quote by=Freebird link=Blah.pl?b=2000,m=1157631136,s=18 date=1159603425]JasonI haven't got the PI stuff, just a bare engine - all ancillaries will be coming off the TC lump.Glen.[/quote]Shame :-( Where in the world are you? I've got some blocks here sat doing nowt Link to comment Share on other sites More sharing options...
Freebird Posted October 6, 2006 Author Share Posted October 6, 2006 Hi JasonI'm in Merstham, near Reigate in Surrey. I took my TC block in for reboring today to plus 20. I will use the PI pistions which are fine.Glen. Link to comment Share on other sites More sharing options...
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