I was looking at an old post about blocking the bypass on a TR4 . When you read the write up by Bob Shaller in his More BS on TR3's he makes an argument for blocking the bypass ,when not using a sleeved thermostat,so more coolant would circulate and he was down in Arizona where the temperatures would be quite high. You mentioned in an old post that you would not recommend this as it may increase the likelihood of a cracked head.(I believe TR4's were being discussed in that post though and not TR3's). I've been running a blocked bypass for years now in my TR3 with no issues but recently talked to someone (who has more of a hot rod background) that said he dosn't recommend blocking the bypass either because it could cause hot spots in the head on a TR3? Now I'm getting a little paranoid about leaving the plug in. So why did it seem to work for Shaller down in Arizona? What's the correct take on bypass blocking for a TR3?