MJaggard Posted March 24, 2005 Report Share Posted March 24, 2005 Found to my shock the other day that my tr6 had a cheap i.e. additive bag in the tank conversion done. Does anyone have any views on conversions and what is required. Also how much it all costs. Is it worth going to whole way and getting the head done. Cheers Matt Quote Link to post Share on other sites
Richard Crawley Posted March 24, 2005 Report Share Posted March 24, 2005 Being a mechanical engineer, I have absolutely no faith in the ‘bag in the tank’ conversions in spite of all sorts of advertising claims about ‘secret use’ in WW2 Spitfires in places where only **** fuel was available etc. etc; I just don’t see how a ‘bag of marbles’ in the fuel tank can make any difference at all & those that claim it does are probably running on ‘lead memory’ or never rev their units above 2500 rpm. If the unit is running OK & you don’t want to strip it yet, it’s probably worth waiting until valve recession gets to the point where something has to be done. Then get a proper head conversion done but shop around for the best price & the right spec; crack test, hardened valve seat inserts, new valves (stainless steel I believe) & new valve guides. I would not advise phosphor bronze guides on a road engine as the extra clearance necessary on these can lead to excessive oil consumption. I believe you can get away with the standard inlet valves but it’s probably not worth the hassle. The rest of the engine won’t need any additional work although you may have to retard the ignition a few degrees to stop detonation (pinking). I didn’t have any problems in this department & run the standard 11 degrees. I am convinced that this is down to the stage 2 tune I had done at the same time & for that bit extra money involved is well worth doing. Quote Link to post Share on other sites
Richard Crawley Posted March 24, 2005 Report Share Posted March 24, 2005 Matt. Sorry, forgot to add cost; my conversion was £480 incl. VAT but, as I said previously, this included a stage 2 tune. The head work was done as part of a full engine rebuild but I don’t think this affected the price. Quote Link to post Share on other sites
jonlar Posted March 24, 2005 Report Share Posted March 24, 2005 Matt, for the time being at least, I'd suggest going the additive route, and check tappet clearances every 3,000. There's Castrol Valvemaster Plus, which is LR plus octane booster, but Tetra actually produce a true lead replacement additive, handle with gloves! http://www.fbhvc.co.uk/fueladds.htm http://www.defra.gov.uk/environ....307.pdf http://www.tetraboost.com/ Quote Link to post Share on other sites
Rog Posted January 22, 2008 Report Share Posted January 22, 2008 <font color='#000000'>Being a mechanical engineer, I have absolutely no faith in the ‘bag in the tank’ conversions in spite of all sorts of advertising claims about ‘secret use’ in WW2 Spitfires in places where only **** fuel was available etc. etc; I just don’t see how a ‘bag of marbles’ in the fuel tank can make any difference at all & those that claim it does are probably running on ‘lead memory’ or never rev their units above 2500 rpm. If the unit is running OK & you don’t want to strip it yet, it’s probably worth waiting until valve recession gets to the point where something has to be done. Then get a proper head conversion done but shop around for the best price & the right spec; crack test, hardened valve seat inserts, new valves (stainless steel I believe) & new valve guides. I would not advise phosphor bronze guides on a road engine as the extra clearance necessary on these can lead to excessive oil consumption. I believe you can get away with the standard inlet valves but it’s probably not worth the hassle. The rest of the engine won’t need any additional work although you may have to retard the ignition a few degrees to stop detonation (pinking). I didn’t have any problems in this department & run the standard 11 degrees. I am convinced that this is down to the stage 2 tune I had done at the same time & for that bit extra money involved is well worth doing.</font> Hi Richard, I've been reviewing some of your posts (thanks) in the context of assessing the move to unleaded conversion. I currently use Millers and the car runs brilliantly (IMHO) and so theres no rush especially considering contemporary prices. I suspect I know the answer but I assume that along with head conversion a change of M/U and pump are also essential? This being the case I think theres not much change for a grand. I'd appreciate your comments. Rog Quote Link to post Share on other sites
Red 6 Posted January 22, 2008 Report Share Posted January 22, 2008 My TR 250 on carbs has run quite happily for as long as i can remember (16+ years) on unleaded without any problems. I know this is going to sound a bit "flat earth" but other than checking the tappet clearances each year in conjunction with its annual spring tune up i have witnessed no issues at all running unleaded in an unconverted engine, and it will still "wop" and standard TR5 without having to resort to "drugs in the petrol". Quote Link to post Share on other sites
88V8 Posted January 22, 2008 Report Share Posted January 22, 2008 Balls in the tank? Balls is right, I fear. A couple of years ago I foolishly bought one of these for my 205 GTI in the hope of being able to run standard unleaded instead of super. The spark plugs soon told me otherwise. £45 down the drain. I believe that unleaded will eat the seals in the M/U and the pump, as well as making olde rubber fuel pipes porous - got an untraceable smell of petrol? The 6 already has Stellited valve seats, I read somewhere, if so this may be why they seem to handle unleaded relatively well. Ivor Quote Link to post Share on other sites
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