Since I had the rear journal on my last cam grooved, it had an over abundance of oil to the rockers. I was thinking of installing a restrictor
in the block at the deck to neck it at an accessible location, and so it is
captured between say the drilled block oil passage and the head (I think Chevy guys have done it that way). Looking at the passage, it looks like a Holley jet could reasonably be installed with little drilling and some figuring, which would allow the restriction to be 'tuned', and provide a good use for those jets that are 'toast'.

Has anyone done this mod, or have a best idea of how much restriction is needed to keep flow to a nominal amount but keep the pressure directed at the bottom end?

TIA

-D.Idiot

Seems to me like Charlie or Seymour may have done it.

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Official Cookie and Mater Tormentor.

I had the same problem, too much oil on top with a grooved cam. I didn't want to remove the head so I cut a shallow groove in the rear rocker stand bolt and slipped an o-ring around it. It still flowed too much oil but I never tried to fine tune it. I finally changed cams and since then I always specify that the cam grinder use a billet with the drilled rear journals if he can find one. Charlie is the one that talks about using a restrictor jet but unless you konw the right size I would think you might have to take the head off to get it right. Maybe there is a way to install the jet in the rocker stand so it would be easier to change. My feeling is that grooved journals are for hydralic cams and you should avoid them with solids.

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If you didn't drive it there, it's not a street car.

Thanks for the input Seymour, much appreciated as always.

I'll see if Charlie weighs in with a comment...

I was thinking since I had a couple of #73's that no longer are able to be installed due to screwdriver damage that might be a good start (I can always drill it out more if needed.) Definate-ly don't want to pull the head more times than I have to.

Insted of putting a restrictor between the block and head what about putting a hole in somewhere in the hollow rocker rocker shaft to let the extra oil drain out. If you did that then you could do something fancy like put a pressure valve on it so it will open only when needed so you wont risk starving it for oil at lower rpms.

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85 d-100 HEI 2BBl
06 Toyota Corrola

There isn't a lack of oil at that point, it already oils enough out of the rockers to innundate the peanut plug drain holes creating a series of pools on top of the head which eventually compromise the valve cover gasket, in turn this lack of restriction may also translate to less pressure at the bottom end bearings (path of least resistance), so the restriction has to occur somewhere before the rear rocker bolt (typically it's moderated by the clocked holes in the mech cam's rear journal and restricted by the rear rocker bolt.

-D.Idiot

Gotcha, I just thought it would be a hassle to change the jet/restrictor if its trapped between the head and block, but I can see if there too much oil going to the top then the bottom could be starved.

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85 d-100 HEI 2BBl
06 Toyota Corrola

I like the 'tunable' jet idea but I'd want it to be external so I wouldn't have to pull the rocker cover, shaft or head for jetting.

Idea - Mod the the external oiling mod.
You know the external line mod, i.e., supplemental oil from main galley via external hardline ported to back of the head?
Well, do that but have your jet inside the fitting that screws into the head so you can swap the jet externally. This of course is after you remove the head and plug (or partially restrict) the oil feed passage just above the deck/gasket surface so little/no oil comes up from block.


1/8" npt male X 3/16" inverted flare female
Could jet go inside (threaded) the male end?
Remove hardline, unscrew fitting and swap jet?

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1966 Coronet Deluxe

When you think about it you must need lots of restriction. Those holes only line up for about 10-15 degrees every other time around. With the groove you have full pressure feed all of the time, potentially 48-72 times as much oil! Slant six mechaniclal valve gear doesn't require much oil to operate properly.

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If you didn't drive it there, it's not a street car.

That was my line of reasoning, the original metering system has the oil at about 40-60 psi, and it gets a 'spurt' out of a 1/4" hole on a regular interval when the holes line up...with a regular constant passage, we now have to provide the same volume of oil as the timed 'spurt', but now it is a constant squirt gun sized stream at 40-60psi... (Probably if i had an ME cert, we could take the flow rate of the oil in the passage and determine the proper orifice for the constant pressure stream vs. the intermittent 'spurt'.)

The deed is done, I drilled and press fit a holley jet into the block yesterday afternoon... given the size of the passage and eyeballing the volume of the stream, I decided to drill the junk jet to about the equivalent of a #90 stock jet.

-D.Idiot

I wanted the extra oil and made sure a small groove was in the cam to provice extra oil up top. I made stand pipes for the lifter gally and grooved the nonthrust side of the lifter bore so the pooled oil would provide extra oil to the cam and lifter faces.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

I would have agreed if a juice cam or a roller cam, but I have had no problems thus far with lifter oiling and camshaft wear on stock style cam blanks (but you are running a different setup where you may need it- ) . I had this one grooved because I had an Erson cam and a comp cam that did not have the oil holes drilled in the correct angle (too tight), and one that the holes were off when the timing chain was installed, so I asked for my last grinds to be grooved to prevent that from being a problem.

We'll see what happens.

-D.Idiot

I can't remember if I ground the peanut head for oil return when I ported it.

I have done 2 drool tube heads for sure!

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick