Oil passage restrictors

[Bird 426]

I bought a Hemi clone Road Runner last year and I have the engine apart. Have just changed the rods, rebalance and had the block hot tanked. I noticed that the oil passages to the cylinder head have been tapped and have restrictors in. This engine has stock valve train, should I remove the restrictors or leave them alone? I am of the opinion that restrictors were used for needle bearing roller rockers?

 

[pnora]

For the most part they were used to keep the excess oil out of the heads and to supply more to the lower end bearings. One of the many engine secret books may explain the pros and cons.

 

[radical rob]

Mine are blocked because my heads use external oil lines. ( Indy)

 

[6PKRTSE]

For stock valve train I would leave them out. For a more race build with aftermarket roller cam, lifters, rockers, etc . I would thread them back in. I have them in mine with .050" holes.

 

[Bird 426]

The engine does have a billet solid roller. I have a set of Edelbrock JR aluminum heads for it, but stock rocker valve train at this time . May do the the rockers and stands next year. It's sort of a pro street car, 4-speed. I just checked the orfice size, .063 drill bit just fits.

 

[vance.dykes]

the way i was told by old timers when i was young in 77 you restrict the oil to the heads with stock valve train but on a race with roller rockers was not to restrict as the aluminum need a lot of oil to keep cool.

 

[lewtot184]

If you study the oiling to the rockers as designed you'll notice that oiling was already restricted by design. The upper end only gets oiled every other crankshaft rotation due to the location of the oil feed holes in the #4 camshaft journal. Also the original camshaft bearing rocker feed holes were designed in an offset that further restricted flow. I do believe this restricting oil to the the upper end is taken out of context. I believe the only time to restrict flow is when there is full time oiling such as a grooved #4 cam journal or full time external oiling.

 

[icetech]

No matter what pull them to clean behind them.. if the block was tanked with those in it's a perfect spot for crap to get stuck

 

[Master Gunner]

Per the Mopar Performance Engines book,
pg 368, 426 Hemi (cylinder heads), Basic Cylinder Head Preparation

"Check the cylinder head oiling hole. Be sure that it is open and that the drill didn't break off and remain in the hole. Check the block for a similar hole, both sides. The camshaft bearing holes should line up with the cylinder head oiling holes and not restrict them. It is NOT recommended that oil to cylinder heads and valve gear be restricted."

Also pg 370, Cylinder Head Tips #3

" We DO NOT recommend restricting oil to the cylinder heads. Leave all the passes stock size and be sure that they are unobstructed"

I seem to remember that restricting oil to the heads was a Chevy thing, but Mopar never recommended it. Your motor, your car, do what you think is best.

Mark

 

[BSB67]

1) the details of your situation matter.
2) opinions vary

There is no reason to restrict oil to the rocker gear on a stock like rebuild.

the questions for non stock like rebuilds are: 1) how are the push rod cup/balls oiled, 2) what kind of bearing is used on the rocker/shaft, 3) is #4 journal grooved for full time oiling.

I full time oil, with no restriction, with bushed rocker arms, and upper PR ball oiling from the rocker/shaft.

 

[lewtot184]

Per the Mopar Performance Engines book,
pg 368, 426 Hemi (cylinder heads), Basic Cylinder Head Preparation

"Check the cylinder head oiling hole. Be sure that it is open and that the drill didn't break off and remain in the hole. Check the block for a similar hole, both sides. The camshaft bearing holes should line up with the cylinder head oiling holes and not restrict them. It is NOT recommended that oil to cylinder heads and valve gear be restricted."

Also pg 370, Cylinder Head Tips #3

" We DO NOT recommend restricting oil to the cylinder heads. Leave all the passes stock size and be sure that they are unobstructed"

I seem to remember that restricting oil to the heads was a Chevy thing, but Mopar never recommended it. Your motor, your car, do what you think is best.

Mark

chevy's use push rod oiling so they don't have the pressurized oiling the mopars and ford fe's have. what the chevy big blocks do have is priority main oiling and the ford side oilers are the same but ford maintained pressurized oiling to the rockers.

 

[lewtot184]

from my point of view restricting oil to the top by internal means just doesn't make sense. i've always thought it was silly to put restrictors in the heads and then add spray bars. the valve springs, especially performance springs with big cams, have to have oil. oil is the only coolant the springs get and they do get pretty hot from racing. years back i was working with bracket racing engine stuff and when i seen restrictors i took them out. the only exception i can see to that is indy head external oiling. external oiling MIGHT need some control. glad i'm out of all that crap.

 

[Bird 426]

Okay, I am going to remove the restrictors. They were in when the block was tanked, I somehow missed that they were in there. I will remove them and check for probable gunk, clean passages, fit piston rings, cam bearings, degree the cam , break cyl glaze and reclean the block. Well, lotta little things to check and do. Will try and keep my eyes open!
Thank all of you for your help! I may have other questions down the road.

 

[vance.dykes]

i was under the idea and told that a big block with a high volume oil pump at 5500 to 6000 rpm's can leave little oil in the pan so it was a racing trick but i drove the car every where i could as my summer daily driver and raced once a month in the early days.

 

[PRHeads]

No mention of which block is being used.
The World/Mopar blocks, as well as the BME blocks don’t oil the top end thru the camshaft.
Those blocks have full time top end oiling.
I believe the Indy Hemi block is the same.

If using one of those blocks, restrictors are highly recommended.

 

[vance.dykes]

No mention of which block is being used.
The World/Mopar blocks, as well as the BME blocks don’t oil the top end thru the camshaft.
Those blocks have full time top end oiling.
I believe the Indy Hemi block is the same.

If using one of those blocks, restrictors are highly recommended.

thank you i could afford stock blocks at 19

 

[Bird 426]

No, it is a stock '68 Hemi block.