Normal oil pressure ?

[patrickt]

Fascinating thread on the jiggle pin used in the 427.
http://www.network54.com/Forum/74182...ter+galleries-



EDIT -- From that thread: This valve would have been placed at the front of the top oil passage, behind the timing cover, the purpose apparently to quickly "burp" air out of the gallerys to speed oil flow into the lifters upon cold startups.

[Argess]

According to my 1966 Ford Factory Manual, the "jiggle pin", which is installed in the front of the engine, center gallery, is there to let air out of the system. It goes on to say that oil for the chain and sprockets is suposed to come from the front cam bearing/cam journal.

I never bothered with the jiggle pin. I just tapped and installed a threaded plug.

As I mentioend before, bearing clearances, particularly crank main bearing clearances, is what affects oil pressure at lower rpms (where the pump bypass is not yet activated). My clearances are at 0.0025". I think the book says the normal clearance is from 0.0005 to 0.0015 inches. With these latter tighter clearances one can expect higher oil pressure at hot idle.

A HV pump helps keep oil pressure up at those lower rpms, but once the rpms are high enough to open the pump bypass, the oil flow (into the engine galleries) from a stock or HV pump will be the same. The excess from the HV pump will come out the bypass and return to the pan.

10 psi per 1000 rpm. OK...say in a SBChevy you get 10 psi at the guage, but only 5 at the bearing. In a BBFord, with 10 psi at the guage, you may only get 3 psi at the bearing. Just throwing out numbers.

[Michael C Henry]

Thats's pretty much what I remembered on my two 428 block's . It appeared to be a cotter pin in a plug. Factory used pound in soft plug, but anybody that had to live with it in the event that those plugs might come lose, would have converted to threaded plugs. I figure it was there to, as you and I said, evacuate the trapped air out of the system radidlyat start up and then flow would slow once oil arrived. The pin was supposed to move around a little so it wouldn't plug closed with sludge and or varnish. Resulting in a controled leak that you could live with.
The article was more information than I would have found on my own. Thank you
On the old FE blocks 332,352 390, and so on pre 63 center oiler .there was an oil gallery coming up from the pump across the face of the block and when you converted the cam from the old cam with the spring and button to the newer 63 on up with the thrust plate. The two oil gallery holes had to be threaded for bolts to hold the thrustplate One of the oil gallery holes that had to be threaded for a bolt had to have a groove groun in the side of the threads and the length had to be shortened to not block the oil flow from oil pump to the gallery. Oh by the way that also lubbed the distributor. I had a friend that haistily converted an older 390 and stuffed it in. The distributor froze. He had the most of the car off the ground by the distributor before it let lose. Same guy lost that special cam bolt so he used a shorter bolt in a Ford 324° cam. The bolt was only into the centering snout that centers the escentric for the maechanicle fuel pump on the camshaft andthat snout broke off in Kansas City. He had to be towed back to DesMoines Ruined a perfectly good 324° cam.