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restricting / reducing oil to rocker arms
https://www.slantsix.org/forum/viewtopic.php?t=65262		 Page 1 of 1
Author:  DadTruck [ Tue Aug 25, 2020 6:53 pm ]
Post subject:  restricting / reducing oil to rocker arms
The new motor in the 68 Barracuda is an '87 block / head and I had the original OE hydraulic cam shaft re ground to a mechanical lobe profile. So the camshaft has the full time oiling groove in the rear. I am using the oil pump from the hydraulic motor.
The rocker shaft and rockers are NOS mechanical lifter parts. The rear rocker shaft hold down bolt is one for a hydraulic valve train.

I expected to get a lot of oil to the top end, and there is,, a video is below

https://www.youtube.com/watch?v=fb0YKbkFezQ

(I put a black stripe on each of the push rods, the video shows them spinning nicely, this is at about 1100 RPM)

All of the oil up top is probably good for the initial cam break in and I do not plan to be hard on the motor for the first 500 miles or so,, but after that I do intend to push the rpms up to the 5500 / 6000 range and I would like more oil going to the mains and rods and less oil just circulating down back into the pan.

any ideas on an easy way to restrict the oil going up top?

Thanks
Author:  slantzilla [ Tue Aug 25, 2020 7:43 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
I think Charlie does a restrictor in the passage to the top. Maybe he'll see this and chime in.
Author:  Charrlie_S [ Wed Aug 26, 2020 12:03 am ]
Post subject:  Re: restricting / reducing oil to rocker arms
Yep. I tap the oil passage in the rear rocker stand, and make a restrictor out of a set screw/pipe plug/whatever is handy.
Author:  Will [ Wed Aug 26, 2020 4:06 am ]
Post subject:  Re: restricting / reducing oil to rocker arms
I put it in the block ,but same thing
Will
Author:  Charrlie_S [ Wed Aug 26, 2020 10:24 am ]
Post subject:  Re: restricting / reducing oil to rocker arms
Reason I opted for the rocker stand is, it can be changed just by removing the rocker assy. Don't have to remove the head. But any place will accomplish the same thing.
Author:  DadTruck [ Thu Aug 27, 2020 6:26 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
Charlie, Will
I get the part about cutting in threads, running in a pipe plug,,,
assuming that you then go back and drill a hole through the pipe plug.
What kind of a diameter reduction do you target?
I have not measured it, but for example, if the oil line is 1/8 inch or .125, do you put a .060 hole through the plug?
Author:  Doctor Dodge [ Thu Aug 27, 2020 7:33 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
The hole coming up from the rear cam bearing is 1/4 inch. (.250)
.030 to .060 restriction hole in the plug is the range. (start small and work-up)
DD
Author:  ProCycle [ Thu Aug 27, 2020 8:10 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
Is there room to drill and tap it for a carb jet?
Would make it easy to dial in the desired amount of oil flow.
Author:  Rick Covalt [ Fri Aug 28, 2020 4:55 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
Where exactly are we drilling the rocker stand? Any pictures??
Author:  Charrlie_S [ Fri Aug 28, 2020 6:07 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
With he rocker shaft removed, look down in the rear rocker stand. There is the hole for the shaft mount bolt, and also another hole at an angle, which is the oil passage, from the cam. That is the hole that gets tapped, for the restrictor.
Author:  DadTruck [ Fri Aug 28, 2020 6:40 pm ]
Post subject:  Re: restricting / reducing oil to rocker arms
Tapping and inserting a plug then drilling a passage to size would do the job, but I am working with a fully assembled engine, so I am not likely to run a tap into an oil line on an engine already in the car.
So I came up with a different solution. I made a bushing to fit over the necked down shank of the hydraulic head rear mounting bolt.

To know where I was starting from and to find the differences in what appears to be the oil to the rocker arm choke point I measured a hydraulic head and a mechanical head rear rocker shaft hold down bolt shank and clearance bore.
The measurements are on the photos below.

To have a place to start I made the bushing diameter to set the choke point to .040
The clearance was .112 on the hydraulic head. The mechanical head was set at about .100
I will fix the bushing to the bolt with a removable pin, so the bushing is removed with the bolt. If the oil flow is not right, I can remove the rear rocker bolt, remove the retaining pin and push on a larger diameter bushing to further reduce oil flow or a smaller diameter bushing to increase oil flow.

The bushing will go on the shelf for now as I like the increase oil to the lifters - camshaft during the break in, for the first 500 miles or so. after that I will start pushing the rpm's and be more concerned over getting more oil flow to the rod and main bearings and I will install the bushing.

Attachments:
File comment: bolt shank diameters
rocker bolt shank.jpg
rocker bolt shank.jpg [ 91.68 KiB | Viewed 3288 times ]
File comment: bolt hole diameters
rocker bolt hole.jpg
rocker bolt hole.jpg [ 83.4 KiB | Viewed 3288 times ]
File comment: bushing on the bolt
rocker bushing.jpg
rocker bushing.jpg [ 109.34 KiB | Viewed 3288 times ]
rocker bushing in.jpg
rocker bushing in.jpg [ 78 KiB | Viewed 3288 times ]
Author:  Badvert65 [ Sat Aug 29, 2020 6:29 am ]
Post subject:  Re: restricting / reducing oil to rocker arms
That is a neat idea. Let us know how well it works.
Author:  Rick Covalt [ Sat Aug 29, 2020 9:27 am ]
Post subject:  Re: restricting / reducing oil to rocker arms
Quote:
That is the hole that gets tapped, for the restrictor.
I would have thought it would be hard to drill and tap down inside there? I guess I better go look at one in the garage! :D :D
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