Re: Driving comparisons between the Packard Six and 120.

Posted by Peter Packard On 2012/7/16 18:27:20

Hi all, I would urge everyone to consider the use of some form of anti-valve recession agent ( upper cylinder lube) in the unleaded fuel. I believe this is particularly important when numerically low rear axle ratios and overdrives are used, as the duty cycle ( loading up) of the engine is increased. To me this means higher exhaust valve temps and greater risk of exhaust valve seat recession without the previous protection of lead. This is not so much of a problem if the engine uses a bit of oil, but watch out if it is a "brand new" engine. I also run 7 thou inlet and 10 thou Exhaust tappet clearances instead of the normal 4 and 7 thou, to keep the valve on the seat a few micro-seconds more, to help cool the valves. In the past, I have burnt out a few exhaust valves running lean mixtures and high compression in Packards so I write from experience. Best regards Peter Toet