Interesting. Could this not have an impact by overheating by not circulating the coolant as quickly?
I too would be a little concerned not just with coolant flow but with charge rate as well. It could be that at idle the charge warning light comes on. During heavier electrical loads the alternator regulator will attempt to drive the alternator harder leading, maybe ironically, to greater belt loads. This can also lead them to make a noticeable whine until the rotor speed approaches at least 2500 rpm
Finally the smaller pulley will offer less traction to belt due to reduced surface area in contact with same leading to possibility of belt slip and increased wear.
If the new pulley is just a modest reduction you may get away with none of above issues but worth being wise to possible consequences.
Don't worry - lots of research done before purchase!
Remember, this is a 1972 Crossflow - so little electrical drain. I have the addition of electronic ignition, but also have LED lights all round. Fan has been removed and converted to electric but only tends to come on if I'm running for 30+ mins on the drive. I do have a new uprated alternator.
Everything was running fine at 850rpm this afternoon - ammeter showing charge and Voltmeter showing 14+V. Slitght drop when I bunged the heated seats on, but I got this with the old pulley as well, so no great shakes
Charge light stayed off.
Belt it right at its length limit so going to wait till the shorter one arrives before I test on the road.
