Stock 52 F1

3

30-9

Well-known member
Hi

I have a buddy wanting to take his truck on long highway run. Engine has been well maintained but never rebuilt. Oil pressure 30 or more.

What’s thoughts running 3k RPM for couple hours?
 
If it maintains 30 psi when warmed up then that is fine. Flatheads don't need a lot of oil pressure to function. Most 3/4 and 1-ton trucks are geared pretty low due to the Timken Detroit type rear axle ratio. I'd recommend not getting it wound up too high. They were never designed to go much more than 60 MPH and even that gets the rpm up there. Chuck's Trucks is the only place to finds taller ratio gears for the Timken Detroit rear end.
 
I just returned from a 2300 mile road trip in my stock 52. It has 3.92 gears, and is able to cruise in the 55-62 mph range hour after hour. I've made four extended road trips with my truck in recent years--three to Pennsylvania and one to Kentucky.

Jim
 
Mine is currently out of the truck for rebuild, as it was time. Struggled to maintain 25 when hot. Started to dip below that pressure and I came off the highway one day at about 18 psi on the mechanical gauge and a new knock. Drove an 1/8 mile, went up the driveway and yanked the engine…..
 
I have a '51 Merc with reworked Edmunds heads, a 2GC on a bored Mercury manifold, and a Mallory dual-point. The car runs great and, really, quite strong. However, rpm's over 2700 rpm feel uncomfortable and I don't like maintaining anything over that for any extended period of time. With the tires I have and 3.55 gears, 2700 is about 65 mph, so it's a decent highway car. Running through the gears, it accelerates well until about 4200 rpm; anything more than that is just more noise with little effect.

With 30 psi oil pressure, it would seem that the engine in your friend's truck is not in tip-top shape. If it was mine, I wouldn't try "running 3K RPM for (a) couple (of) hours". But that's just me.
 
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