Packard Forum Index » V-8 (1955-56)

There is no significant difference in the 352 blocks between 55 and 56. The 56 engine would have the heads with larger valves and higher compression. That makes most of the horsepower difference.

I'm still winding up my engine! Kanter sent me 1 piston +0.06 instead of +0.03...
I was wondering what kind of oil pumpe I have?
And other question regarding lifter: I bought one new set from Kanter because one of the old ones was destroyed! I put the new in oil and I pushed the top to replace the air with oil. I have a huge gap between rocker and valve if i push on the rocker on the lifter side. Is it operational only when there is the right oil pressure?

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On the oil pump it appears to have the modification of removing the vacuum pump which was thought to be allowing air to enter and adding a heavy bottom plate substitution. That mod was developed by the Packards International Club back in the late 60s early 70s. Others have also done basically the same PI developed mod but then went farther with an additional mod to the housing to add a bushing and additional lubrication for the drive shaft. Cannot tell if the pump has that change.

In any case the PI plate mod only did not solve the problem and am not sure the bushing did either since it appears only a few of the bushing mods were done. Currently I believe the only change that has so far proven effective is to do the Olds oil pump conversion. I believe that kit is still available from Jack Vines. Note that there are two versions of the Olds pump -- standard and high volume. Reports have come back by some that the high volume version causes leaking oil seal issues.

Ok, but if the vacuum pump was remove, I don't understant why the vacuum line still exists between the distributor and the block. And I can't find the pipe between the pump and the crankshaft bearing

The vacuum pump was for the wipers which originally had a vacuum motor. If still vacuum, they will work without it but my show down considerably or even stop on acceleration. The distributor's advance still needs vacuum from the intake manifold to work properly.

In a stock car there are two vacuum lines supplying the wiper motor. One from the intake manifold -- or more properly, it is from a fitting on the base plate of the carb exposed to manifold vacuum -- for the main vacuum source. A second line comes from the aux vacuum pump that is in the crankcase. That line lays low on the right side of the block a bit above the oil pan and stops about in the middle with a 90 degree fitting threaded into the block. A small check valve is located a short distance away from the fitting.

Both lines go toward the firewall where a rubber hose connects them into the side of a balance valve screwed on the firewall. From that valve a hose goes to the wiper motor. If the optional windshield washer is installed another hose off the valve supplies vacuum to it.

With the crankcase aux pump removed it is important the second line is completely blocked off. Some who did the mod removed the balance valve and second line and added a plug in the block port. Others wanting to maintain a stock look left that part intact but capped the line that went to the aux pump either by blocking the rubber hose at the balance valve or by plugging the final 90 degree fitting into the block. Still others did neither and relied only on the continued functioning of the check valve in the aux line. With your aux pump gone it is important to make sure what ever was done to block the aux pump line is still intact and there is no possibility of a vacuum leak.

Almost all wiper motor vacuum comes from the intake manifold but when the engine is under load and vacuum drops, the aux pump is stronger and balance valve moves an internal mechanism to fully open that port and close the port to the intake manifold. The wipers do slow down since the aux pump does not have a large volume to run it at fast speed but they do keep going. With only manifold vacuum, there is a good chance wipers will stop if the engine is under a large load or throttle is wide open. Once the load is gone and full manifold vacuum is present the balance valve flips again to fully open the manifold port.

Most who did the PI mod with aux pump removal changed the fuel pump to a dual action type similar to the pumps used in 54 and earlier cars. The vacuum lines were rerouted and replumbed so manifold vacuum goes thru the fuel pump vacuum section just as was done with earler cars. A few just ran a hose from the old aux pump line to the inlet port on the fuel pump vacuum section keeping the balance valve functioning. While that may not be the best approach it is the most stock looking and does work. I believe there are pumps for some Ford Thunderbird engines that bolt right on the V8s. Perhaps someone can post the year pumps that will work.

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Thank you for all those informations.
What is sure is that the engine could not work properly with the ignition connected to nothing. I will check all the vaccum line when the engine will be put back in the car. I fund wat I suppose to be a "vaccum thank" in the left fender. Is it original part?

The vacuum tank is supplemental storage for the power brakes and gives one or two power boosts if the engine dies while driving. It gets its vacuum though a one way valve fitting on the manifold which needs to be checked for proper functionality when reassembling everything.