MississippiTR4 Posted May 18, 2009 Report Share Posted May 18, 2009 Is it necessary to change out the valve guides/seats (and any other head components) on my original TR4 head? The engine was rebuilt 10,000 miles (and 35 years) ago so I am not anxious to pull the head again, but since the manifolds are currently off it would not be that much work. It has the 2.2 kit in it with slightly higher than stock compression. Will I need to be adding a lead additive and an octane booster and if so, any recommendations? Thanks for your help. Quote Link to post Share on other sites
4Mal Posted May 19, 2009 Report Share Posted May 19, 2009 I have heard all levels of advice from....run it until it has a problem to make the change now. There are various additives out there, such as Millers, and you could probably Google for some reviews or maybe some forum memebsr are using it and can let you know. My own experience......I was going to let it run a bit longer, but the engine needed some other work anyway, so I went the unleaded ( and then some ) route. If you have the manifolds off, maybe this is the time to do it. Quote Link to post Share on other sites
ianc Posted May 19, 2009 Report Share Posted May 19, 2009 Leaded fuel is still available, but in a limited nomber of places. I am fortunate to have a petrol station not too far away, on the north of Dunstable, where it is still available. Not cheap, but the car loves it! If I make a long trip and need more fuel, I buy unleaded, but get back to leaded as soon as I can. I think the supplier of leaded is Bayford Thrust, which lists outlets - try Google. Ian Cornish Quote Link to post Share on other sites
Badfrog Posted May 27, 2009 Report Share Posted May 27, 2009 Hi, The cheap way: alternate leaded and unleaded fuel. The safe way : unleaded head conversion (valve seats or head swap) The wrong way: any additive (either inefficient or highly pollutant). Alternate safe way: locked garage (not a smart advice) . Badfrog Quote Link to post Share on other sites
tthomson Posted May 27, 2009 Report Share Posted May 27, 2009 Hi there, If the exhaust valves are still the same as before the rebuild, then you can use unleaded quite happily for a considerable time. The lead memory in the deposits on the valves will protect them for thousands of miles, but the performance of low octane fuels is a bigger problem. An octane booster if available is a good idea. TT Is it necessary to change out the valve guides/seats (and any other head components) on my original TR4 head? The engine was rebuilt 10,000 miles (and 35 years) ago so I am not anxious to pull the head again, but since the manifolds are currently off it would not be that much work. It has the 2.2 kit in it with slightly higher than stock compression. Will I need to be adding a lead additive and an octane booster and if so, any recommendations? Thanks for your help. Quote Link to post Share on other sites
RogerH Posted May 27, 2009 Report Share Posted May 27, 2009 But why go for low octane lead free. Shell do a very high octane (compared to the rest) with Texaco & BP running close. 99, 98 etc. They work well Roger Quote Link to post Share on other sites
Badfrog Posted May 27, 2009 Report Share Posted May 27, 2009 The engine was rebuilt 10,000 miles (and 35 years) ... Hi, I missed that point. At this rhythm of use, just forget about everything. The ol' gal won't even notice. Still you might consider shaking her booty a bit more, just for spider webs. Badfrog (not advisable in any gumbo recipe). Quote Link to post Share on other sites
Tom Fremont Posted May 28, 2009 Report Share Posted May 28, 2009 If you want to drive it lots, spring for a gas-flowed unleaded head. Performance will be noticeably improved and it will pave the way for cam, carb ( Weber ) and exhaust mods in the future. You'll be able to keep up with the Miatas then Quote Link to post Share on other sites
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