56J Speedometer Accuracy

[JoeHall]

Here are some pix from yesterday, on the road in the 56J. Long ago, I removed the face plate and adjusted the hair spring (similar to a pocket watch) for accuracy. Still, after around 30 years and 160,000 miles later, it is pretty close.

[StudeRich]

Out of the box or the factory, those SW Hawk Speedometers were always very Fast like 5 to 10 at least, you are very lucky to get the Tire Size and Speedo adjustment that close, especially at 80 MPH!

[JoeHall]

The secret to adjusting the speed is in the hair spring. It does require dis-assembly of the speedo, but then it is easy to dial in. I suspended the speedo off the lower dash where I could see it, then went for a drive. Back then, stop watch and mile markers were about the only way to dial it in. Once satisfied, I re-assembled it and put it back in the dash. The odometer has always been around 11 percent off, due to the 3.31 rear end I installed. At 89 miles indicated, it has traveled about 100 actual. I have learned to do the math, when calculating things like MPG. Otherwise, I just live with it.

[swvalcon]

Joe where is 80 legal?

[JoeHall]

Joe where is 80 legal?

Uuh, the car was up on jack stands. I swear

[SN-60]

I believe Joe means 89 miles traveled....I'm sure Joe has never driven his Hawk at the reckless speed of 80 mph!

[JoeHall]

For those familiar with 56J, note the oil pressure is sitting on 60 PSI, which is about 15 higher than the norm. That is due to the modern Oldsmobile oil pump mod. Its pressure relief valve pops at 60, so it stays right there on the road. At idle, it sits on 39-40. With valve covers off, at fast idle, the oil that used to drip off the rockers now streams off. Jack Vines now has the kit, available to us all !

[SN-60]

For those familiar with 56J, note the oil pressure is sitting on 60 PSI, which is about 15 higher than the norm. That is due to the modern Oldsmobile oil pump mod. Its pressure relief valve pops at 60, so it stays right there on the road. At idle, it sits on 39-40. With valve covers off, at fast idle, the oil that used to drip off the rockers now streams off. Jack Vines now has the kit, available to us all !

Let's face it,...that is a HUGE step forward for owners of Packard V8 powered vehicles!

[JoeHall]

I believe Joe means 89 miles traveled....I'm sure Joe has never driven his Hawk at the reckless speed of 80 mph!

No Ed, I mean 89 indicated is 100 traveled. That is thanks to the 3.31, which is about 16 percent higher than the OEM 3.92. The smallest pinion I could only gets is to 89/100. But I can live with that, since it keeps the mileage down. But please don't tell anyone.

But you are right about the speed. I doubt that old car would even go 80 MPH.

[SN-60]

We're on the same page here Joe...I meant in my post #6 that you were speaking of miles traveled....not 80 MPH (as mentioned in post #4)

[JoeHall]

Let's face it,...that is a HUGE step forward for owners of Packard V8 powered vehicles!

True Ed. However, with all that oil now going to the top end, either the valve spring baffles must be installed and positioned exactly right, or Jack's positive seal guide seals MUST be used. I always use the baffles with umbrella seals, but got a few of them out of whack in the last rebuild. It did not take long to figure that out, after fouled/oil soaked plugs. Easily fixed, with needle nose pliers.

[SN-60]

Still, it sure is hard to believe a Packard V8 could have TOO MUCH oil pressure!!

[JoeHall]

Still, it sure is hard to believe a Packard V8 could have TOO MUCH oil pressure!!

I believe the standard Olds pump pressure is perfect for the 352. But the 352 needs a few tweaks in order to run it. I first tried a HO Olds pump, and it was indeed too much. It pumps more volume, and the relief valve pops at 65 PSI.

I installed a HO 10 years ago, in conjunction with a modern (GM) neoprene rear main seal, to replace the rope seal. I'd ran that seal in another 56J for 10,000 miles, so knew it would work. But when installed with the HO pump, it leak within 15 minutes. The 3rd time I dropped the oil pan, I replaced the HO with a standard Olds pump. I also enlarged the drain slot in the rear main cap, to accommodate the extra flow and relieve some pressure off the rear main seal. It worked great, and continues today. I've heard of others' using the HO pump, but it was a no-go for me, probably due to the modern rear main seal.

[JoeHall]

Joe where is 80 legal?

On that car, 2500 RPM is 81 MPH. I used to drive off the tack, and when I lived in the California desert, that car traveled many thousands of miles with the tac sitting on 2500
Nowadays, older and wiser, I run around 70 MPH at 2200-2300. But the car never had any problems running at 2500; got 20-21 MPG, and close to 5000 miles per quart of oil.

[E. Davis]

Joe where is 80 legal?

In Montana the new speed limit on interstate highways is 80 mph. Not the smartest idea in my mind but overwhelmingly passed by the legislature last session.