Any advantage to restricting oil to rockers?

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65Val

65Val

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Hey engine guys...is there any advantage to restricting the oil flow to the rockers in a street engine? My engine guy asked me and really didn't have an answer.
 
thats a chevy and ford thing.you don't want to restrict oil to the top end.it will result in scuffed rockers burned out pushrods and maybe short valvespring life as oil cools the valvesprings.
 
Used to pool oil up there with poor drainback, but I dont think Mopar had that problem with its shaft mounted rockers.
 
Not for a street car that sees low rpms.. There is some HP gains for a race motor that is running WOT all the time.
 
Not unless you redirect it to the lower end with larger passages to the mains. Plus - the Mopar system only oils the top end for a few degrees during each cam rotation. There's not much oil going up there normally and not much needed.
 
OK, guys...I'm convinced not to do it. It didn't really sound like a good idea in the first place.

Thanks all for the replies!!
 
The main reason for restricting oil to the top end is with the use of roller rockers. aftermarket shafts and rollers rockers cause the oil to flow more quickly to the top of the engine, which can starve the bottom end of engine at high RPM. if you're using factory style rockers...then you won't need restrictors. if you are using aftermarket rollers...then yes you should do it.
your machinist is probably used to putting race engines together, and thats why he brought it up. i think it was $20 to tap the holes and insert the plugs when i did mine.
 
johnnymac2k6 said:
The main reason for restricting oil to the top end is with the use of roller rockers. aftermarket shafts and rollers rockers cause the oil to flow more quickly to the top of the engine, which can starve the bottom end of engine at high RPM. if you're using factory style rockers...then you won't need restrictors. if you are using aftermarket rollers...then yes you should do it.
your machinist is probably used to putting race engines together, and thats why he brought it up. i think it was $20 to tap the holes and insert the plugs when i did mine.
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johnnymac, thanks. He is a well respected race engine builder in these parts, and that was probably his reasoning. He said he just inserts 2 different sizes of roll-pins in the supply hole at the top of the cylinder decks to restrict the flow.

Thanks again.
 
65Val said:
johnnymac, thanks. He is a well respected race engine builder in these parts, and that was probably his reasoning. He said he just inserts 2 different sizes of roll-pins in the supply hole at the top of the cylinder decks to restrict the flow.

Thanks again.
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cool, i learned something there... i suppose you could use roll pins to do it! in mine he threaded the passage, inserted a plug, and then drilled a small hole in the plug. anyways glad to help!
 
hi,if you want to know how much oil is in upper end, remove valve cover and start engine up. then you can see how much oil gets to top end. it's usually a lot! just food for thought.
 
We would restrict the oil-flow to the cylinder head valve train by off-setting the
#2 and #4 Cam Bearings slightly, so the oil holes between the bearing and block cam
bearing journal were not completely lined up. This lowered the oil volume to the
upper end.

Oil pressure was still excellent, and more oil stayed in the pan.

We did this with our 69' 440 Cuda' cars and all 440 engines.
 
johnnymac2k6 said:
check out the *SPECIAL NOTES
http://www.harlandsharp.com/sb_mopar.htm
* Oil restrictors may be necessary to maintain oil pressure.
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HS are designed for longer valve heads with high lifts and high rpm expectations.
I'm fairly certain no rocker in and of itself will cause a change up or down in oil pressure unless you switch to oil through pushrod. The restriction is the limited time of alignment of the cam hole and the hole in the bearing. Once oil goes past them there is no restriction so running any rocker should not change oil pressure.
 
Without hijacking this thread, what about the guys (like me) who have a hyd roller cam that oils the shafts throughout it's full rotation, not every 180 degrees, in a truck engine. Should the shafts be oil restricted?
 
Most mech roller cams have the 2 & 4 cam journals grooved to provide full time oiling to the rockers. You need oil up there, it cools the valve springs and keeps it from burning the pushrod cups and such. Restricting the oil was a Chevy thing, not needed on a Mopar. Many of these "ideas" come from people that build Chevys and don't know Mopars. Do not do it. In fact if anything you should have your cam journals grooved to provide full time oiling to the rockers.

The reason the Chevys did it is because oil drain back was poor on those old cast iron heads and the oil couldn't return to the pan fast enough and would fill up the valve covers.
 
bad440 said:
thats a chevy and ford thing.you don't want to restrict oil to the top end.it will result in scuffed rockers burned out pushrods and maybe short valvespring life as oil cools the valvesprings.
Click to expand...

It's not a Ford thing either....
 
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