Oil restrictors in a 455
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Joined: Jan 2010
Posts: 2,564
I've yet to have anyone convince me as to how these tap-in restrictors benefit an Olds engine. The pro-restrictor folks say it limits oil to the top end of the engine. Ok. But from where I sit, I still can't see the benefit. It only limits the oil to the cam bearings, which appears to me doesn't have the same issue, or even flowpath, of getting oil back to the pan pronto. Plus, I don't consider cam bearings in the upper end of the engine. I've read about the restricted pushrods, and if anything, that's what I'd use if I was wanting to restrict upper end oil flow in the head area. Keeping hydraulic lifters pumped up and the cam bearings well-lubed seems like it would be more of a priority.
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Joined: Mar 2010
Posts: 1,076
From: Wakeman, OH
I've yet to have anyone convince me as to how these tap-in restrictors benefit an Olds engine. The pro-restrictor folks say it limits oil to the top end of the engine. Ok. But from where I sit, I still can't see the benefit. It only limits the oil to the cam bearings, which appears to me doesn't have the same issue, or even flowpath, of getting oil back to the pan pronto. Plus, I don't consider cam bearings in the upper end of the engine. I've read about the restricted pushrods, and if anything, that's what I'd use if I was wanting to restrict upper end oil flow in the head area. Keeping hydraulic lifters pumped up and the cam bearings well-lubed seems like it would be more of a priority.
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Joined: Jan 2010
Posts: 6,120
From: central Indiana
The oil restrictors make perfect sense, until you study the oiling system road map. Then you understand that they are nothing more than a gimmick.
I hate to admit it, I bought and installed them on the first couple of engines I built. Hey, that’s what everyone said to do, who am I to argue?? It wasn’t until years later I found an oiling system hydraulic chart in a service manual that I began to question it. When I started to actually look at it I realized there is no way restrictors will limit oil to anything other than the cam bearings.
I hate to admit it, I bought and installed them on the first couple of engines I built. Hey, that’s what everyone said to do, who am I to argue?? It wasn’t until years later I found an oiling system hydraulic chart in a service manual that I began to question it. When I started to actually look at it I realized there is no way restrictors will limit oil to anything other than the cam bearings.
Registered User
Joined: Mar 2010
Posts: 3,888
From: Mt.Ary, MD
The oil restrictors make perfect sense, until you study the oiling system road map. Then you understand that they are nothing more than a gimmick.
I hate to admit it, I bought and installed them on the first couple of engines I built. Hey, that’s what everyone said to do, who am I to argue?? It wasn’t until years later I found an oiling system hydraulic chart in a service manual that I began to question it. When I started to actually look at it I realized there is no way restrictors will limit oil to anything other than the cam bearings.
I hate to admit it, I bought and installed them on the first couple of engines I built. Hey, that’s what everyone said to do, who am I to argue?? It wasn’t until years later I found an oiling system hydraulic chart in a service manual that I began to question it. When I started to actually look at it I realized there is no way restrictors will limit oil to anything other than the cam bearings.
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Joined: Aug 2012
Posts: 215
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Joined: Oct 2005
Posts: 7,324
From: NJ
Me too, talking mid 1970's Mondello was the only Olds guru to go to. His oiling system was proven so he advertised so whats not to believe? He had been there and done that and it worked?
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Joined: Nov 2008
Posts: 8,505
From: Central Fl
Restricted pushrods actually help keep oil in the lifter as much as they restrict oil to the top. Their effect is minimal but it works for me.
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Joined: Aug 2012
Posts: 215
[QUOTE=cutlassefi;1559783]He also did other things that later proved to be worthless.
Restricted pushrods actually help keep oil in the lifter as much as they restrict oil to the top. Their effect is minimal but it works for me. [but hopefully not at the expense of the rockers... are they getting enough oil with restricted pushrods.
Restricted pushrods actually help keep oil in the lifter as much as they restrict oil to the top. Their effect is minimal but it works for me. [but hopefully not at the expense of the rockers... are they getting enough oil with restricted pushrods.
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Joined: May 2018
Posts: 782
Looking under the valvecovers after multiple Dyno runs still showed a good amount of oil coming through the restricted Smith Brothers pushrods on our engine with Harland Sharp Roller rockers. I don’t think I would recommend restricted pushrods on a stock rocker system or a ball stud version.
Running .0026 Rod, .003 1-4 mains, and .0035 #5 main clearances.
Speed Pro 1/2 groove main bearings
Dura-bond rear-grooved cam bearings, installed at 3’o clock hole position
10-40 Maxima oil
Melling blueprinted HV oil pump, purple spring
60psi at 6,000rpm hot oil pressure
I included the above info as it all matters on what will affect your oil flow and pressures within the block and on bearing surfaces.
Running .0026 Rod, .003 1-4 mains, and .0035 #5 main clearances.
Speed Pro 1/2 groove main bearings
Dura-bond rear-grooved cam bearings, installed at 3’o clock hole position
10-40 Maxima oil
Melling blueprinted HV oil pump, purple spring
60psi at 6,000rpm hot oil pressure
I included the above info as it all matters on what will affect your oil flow and pressures within the block and on bearing surfaces.
Last edited by Battenrunner; Mar 21, 2024 at 01:57 PM.
Registered User
Joined: Nov 2008
Posts: 8,505
From: Central Fl
[QUOTE=drjr56;1559789]
They’re fine.
He also did other things that later proved to be worthless.
Restricted pushrods actually help keep oil in the lifter as much as they restrict oil to the top. Their effect is minimal but it works for me. [but hopefully not at the expense of the rockers... are they getting enough oil with restricted pushrods.
Restricted pushrods actually help keep oil in the lifter as much as they restrict oil to the top. Their effect is minimal but it works for me. [but hopefully not at the expense of the rockers... are they getting enough oil with restricted pushrods.
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Joined: Aug 2012
Posts: 215
Battenrunner....good to know pertaining to what you noticed after dyno. I have tall valve covers,they come off if I have to jack the motor.What I did notice,when using Castrol GTX 20/50 and lucas oil stabilizer, with an 8qt pan rockers were noisy.I started using Valvoline 20/50 racing oil non synthetic.big difference.Full roller valve train,restricted pushrods. Mark.....Rockers and springs all looked good last summer,but hard to tell just how much oil's getting there,but yes they did look good. TY
Last edited by drjr56; Mar 21, 2024 at 04:11 PM.
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