angelfj Posted November 11, 2012 Report Share Posted November 11, 2012 I have a few questions: 1. Does anyone know of documentation for converting a stock TR250 engine to a TR5 PI? 2. I understand that some conversions have involved replacing the six individual throttle butterflies with a single one. Can someone explain this procedure or provide documentation? The candidate TR250 engine is in excellent condition. I believe a different cam would be required for PI, but could a conversion be done without adding camshaft bearings, thus avoiding taking the engine out of the car? Thanks, Frank Quote Link to post Share on other sites
dingle Posted November 12, 2012 Report Share Posted November 12, 2012 Frank-Goggle "TR6 PI+Tony Gordon" for a well documented venture of converting a TR6 carb to PI. Berry Quote Link to post Share on other sites
Red 6 Posted November 12, 2012 Report Share Posted November 12, 2012 (edited) If you want to convert, it really is simple. 1. change the head to a tr6 one, early or late is not important 2. Fit a new cam to suit your power delivery requirement (285 deg is ideal) 3. Remove the suck blow mechanism from the distributor and adjust the advance curve or better still buy a new adjustable distributor. 4. finally buy the complete pi set up from a tr6 including the distributor pedestal casting and fit. Thats it. And it can all be done in situ. However the plumbing is the hardest part oh and there is no need to fit cam bearings unless the block is well worn. There is one other thing that springs to mind and that is the fuel tank, which will need a return feed. Having said all this, do you want a tr5 spec look alike or do you just want to fit a PI system to this engine? If the latter then my response would be different. Edited November 12, 2012 by Red 6 Quote Link to post Share on other sites
Mk1PI Posted November 12, 2012 Report Share Posted November 12, 2012 If you want to convert, it really is simple. 1. change the head to a tr6 one, early or late is not important It matters in the US - you need a later TR6 head - one that would have had the longer inlet manifold and wider spaced inlet ports. Preferably skimmed to give more than 9:1 CR so about 3.400" thickness which gives 9.5:1 is a good starting point. Quote Link to post Share on other sites
Red 6 Posted November 12, 2012 Report Share Posted November 12, 2012 Good point, I was not aware the early 6's used the same port spacing as the tr250. As far as the head skimming goes you are on the right track again but the impression i got was just a simple conversion rather than a performance hike. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted November 12, 2012 Report Share Posted November 12, 2012 The 'anti-surge' pot inside the fuel tank around the outlet union is a sensible requirement unless you never intend cornering fast with less that 1/4 tank full of fuel. The resultant outcome is the engine cutting out due to no fuel. As you will invariably have the throttle wide open, when the fuel suddenly comes back and the engine restarts at full throttle, it leaps off the engine mounts into the radiator....probably. So a replacement PI type tank is advised. Do not forget an inertia switch to disconnect the fuel pump electrically in the event of an impact. Stops the pump squirting fuel at 100 psi until the tank is empty or the battery electricity supply is killed. Modern cars with fuel injection have these as standard. Your timing chain might be single row only - All TR PI cars used twin row, that just added to your cost. The duplex timing gear set from a TR6 is a direct fitment. In truth, if it were me, I would stick with the carbs. I used to look after a maroon/dark red '69 NAS 'CC' LHD TR6. It was a delight to drive, not as quick as CP PI but easier on fuel and just as capable. It lives somewhere in France now I think. Cheers Peter W Quote Link to post Share on other sites
Peter Cobbold Posted November 12, 2012 Report Share Posted November 12, 2012 For about the same expenditure, a whole lot less hassle, and smoother engine with more torque I'd go for this: http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=14864 Quote Link to post Share on other sites
Don Elliott Posted November 12, 2012 Report Share Posted November 12, 2012 Frank - Ask on the 6-pack TR site. There is a lot of info there and in their archives. At Valley Forge in 2007, I saw all sorts of TR6s with mods such as you describe. Quote Link to post Share on other sites
Red 6 Posted November 13, 2012 Report Share Posted November 13, 2012 The 'anti-surge' pot inside the fuel tank around the outlet union is a sensible requirement unless you never intend cornering fast with less that 1/4 tank full of fuel. The resultant outcome is the engine cutting out due to no fuel. As you will invariably have the throttle wide open, when the fuel suddenly comes back and the engine restarts at full throttle, it leaps off the engine mounts into the radiator....probably. Ah yes the authentic TR5 experience....................................... Quote Link to post Share on other sites
Guest ntc Posted November 13, 2012 Report Share Posted November 13, 2012 (edited) I have a few questions: 1. Does anyone know of documentation for converting a stock TR250 engine to a TR5 PI? 2. I understand that some conversions have involved replacing the six individual throttle butterflies with a single one. Can someone explain this procedure or provide documentation? The candidate TR250 engine is in excellent condition. I believe a different cam would be required for PI, but could a conversion be done without adding camshaft bearings, thus avoiding taking the engine out of the car? Thanks, Frank Frank Yes, as it is the 250 engine if it has been maintained correctly will not have any twist in it and the cam swap is easy Edited November 13, 2012 by ntc Quote Link to post Share on other sites
angelfj Posted November 13, 2012 Author Report Share Posted November 13, 2012 I certainly appreciate all of the comments I have received. However, can anyone comment regarding the use of a single butterfly in the collector box vs the stock set up. I have been told this is being done in the UK and on the continent and that the single butterfly is much easier to set up. Any comments? Thanks Quote Link to post Share on other sites
Peter Cobbold Posted November 13, 2012 Report Share Posted November 13, 2012 I certainly appreciate all of the comments I have received. However, can anyone comment regarding the use of a single butterfly in the collector box vs the stock set up. I have been told this is being done in the UK and on the continent and that the single butterfly is much easier to set up. Any comments? Thanks I think the single butterfly is used in efi setups. I dont see why it would not work with the Lucas PI. BUT if the plenum box came off the manifold - and it does happen, it is only held on with jubilee clips - the uncontrollable wide open throttle experience might be rather too exciting. And especially so if the only way of killing the engine is the ignition switch on the steering lock. Quote Link to post Share on other sites
Alec Pringle Posted November 13, 2012 Report Share Posted November 13, 2012 A TR250 is unlikely to have a column steering lock combined with the ignition switch. Frank, I think you're getting confused here between mechanical PI and electronic EFI systems - the two are quite different animals. If you want TR5PI then you go the whole hog or not at all, there are no short cuts or easy routes or halfway stages. Cheers Alec Quote Link to post Share on other sites
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