timing and engine/head temps., what's the affect? Options

[toon1]

With the type IV timing set right it's about 7.5 to 8* at idle. Has anyp0ne noticed a difference in temps if the timing is advanced at idle?

Reading the MM on the MS site, it say's, if you retard the timing at idle it will produce lower emissions by creating more heat due to the unburnt fuel left in the system.

If retarding the timing makes things hot,can advancing it make things cooler or more stable, temp wise at idle?

With MS it is possible to advance the timing at idle but still keep a 27* cap at the 3500 mark

Keith

[john rogers]

We never had troubles with valve seats, I guess it was the way Tuttle's puts them in? What the Union 76 guy told us was we were buring the a/f mixture when the exhaust valve was open too much due to the slower burn rate of the 100 octane race gas as opposed to the 92 octane street gas. I also noticed that when I ran 110 leaded that the exhaust temps were even worse due to even slower burn rate. We were concerned about the 450 degrees too but never had an issue with the head overheating or distorting but then again at full throttle we had an A/F mixture of around 12:1 so it was pretty rich. He also said this was probably the highest temp we would see since we were reading the temp at the spark plug with a VDO sensor. We were using carbs, Weber 48s which had been gone over by Pierce Manafolds for me and the readings were done on a chassis dyno.

A little more background on the engine, it had flowed heads with 48 mm intakes and 38 mm exhausts (titanium), dual counter wound springs, the cam was a fairly radical road race design from Crower and had a lot of overlap so we had a huge amount of spitting back through the carbs at idle. The compression was 11:1 so race gas was all that was used in the car. It had a dry sump system with a three stage Autopower pump that drew a substantial vacuum in the case at high RPMs so oil circulation was really good.