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TR4/4A 67 TR4A, any tuning mods with Redline/MMO in gas?


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What tuning changes are recommended, if any, when using Redline lead substitute and MMO in 10% ethanol gas? Is 87 octane regular OK with these additives?

Moe Morin


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Unless it changes octane rating, and thus potential to advance timing, I'd not expect much if any change is necessary.

I think most only use 91 given the relatively low miles.

Geo Hahn

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The octane that works for you is going to depend on the condition of your engine, changes that have been made to the engine, where your timing is set, altitude where you drive, where you buy your gas and probably several other factors that I haven't mentioned.

Because of all the variables about all you can do is adjust (timing), experiment (with different grades & brands), listen (for pinging) and read (the plugs after a fast run) to determine what you need.

I use brand name regular (Shell) in the TR4 and it is fine. The TR3A doesn't seem to care what I put in it (somewhat tired engine though it doesn't feel like it).


Great Pumpkin - R.I.P
I saw absolutely no change in optimum tuning when I started adding Redline lead substitute. Only change was that the valves stopped getting tight all the time.

I also didn't notice any immediate difference when I started adding 4 oz of 2-cycle oil to each tank, but later on I had to turn the idle rpm down and I have since made some tiny adjustments to mixture. I still need to tweak the fast idle linkage a bit.

87 should be OK, if you don't get any knock or ping and your engine hasn't had the compression ratio raised (for example, by using larger liners). Mine seems happier on 91, though, so that's what I run (from Costco, which with the 3% rebate works out to be the cheapest gas in town).
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