Where in the block exactly are these located?

If you happen to have these in should you in all cases remove them if moving from mechanical flat tappet to mechanical roller?

 

Just above the cam on the back of the block there should 3 holes above the cam they would be in the outside galley holes and the center hole is your main feed to your cam, mains and rod bearings.

If your roller lifters don't have the oil feed holes in the oil band of the lifters I would not restrict them.

 

Back of the block at the end of the cam valley.

They come with a small dia hole like .060 Which is way to restrictive. Just drill them out to .100 or .110 So you have some priority oiling to the crank. My solid roller 383 has had them for for many years

 

To access them you need to remove intake manifold and thats it?

I have Merlin X block and they say it has priority main oiling systems. So the passages bring the oil from pan first to crank and then to upper parts like cam, lifters and top end. Does that change your opinion regarding those restrictors?


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Lubrication: Priority main oiling system. We recommend oils designated SM/SL/SJ, 15W-40 or 20W-50.
Oil System Features: As is, block is set up for OE style internal oil pump. Block may be converted to a dry sump oiling system. Oil pressure can be drawn from rear of
block, at the top of the bellhousing.
Oil Restrictors: MERLIN III blocks use oil restrictor part # 832660-2. MERLIN X blocks use restrictor part # 832665-2.
Filtration: Integral mount for spin on filter. The oil filter mounting boss has been relocated to clear kickout style oil pans. If use of a remote oil filter is desired, Use World
Products by-pass plate part # 832535.
Oil Pan Rails: Solid (stock width) can be clearanced for strokers. Oil pan rail is dual drilled for stock oil pans and aftermarket race oil pans
--------------------------

 

Restrictors are to correct stock blocks. My Motown doesn't even have plugs to pull out and replace with restrictors

You have to pull the flywheel

 

I'm with George on this one. Drill them out to at least .080 or more. I used them because my solid roller lifters had no direct oiling and I wanted to keep more oil in an around the middle / bottom of the motor to oil the rollers instead of the top end of the motor.

I put over 20,000 street miles on the Comp Cams 818's with no direct oiling like they have now so my theory worked or I got lucky

 

Hi

Just for thoughts about having enough oil or not.

My friend just got a new cam installed into his 350 CI 78 Vette block.

While doing this, the garage found all 3 plugs missing of the same holes but on the front of the block, so behind the chain.

This obviously dumped lots of oil into the cover area back into the oil pan.

The engine run for 10 years like this. Cold oil pressure 35 PSI, hot about 10-15 PSI. He thought having a indication problem.

What saved the engine was the high volume oil pump.

What I,m trying to say is, regardless of having the restrictors installed or not, there is enough oil .

Rgds. Günther

 

I personally would leave them out. I want all the oil I can going to the top end on a street motor. I don't have them in my Merlin II block and regularly go 7500 RPM with no issues.

If you do use them, make sure you get the ones for the Merlin because they ARE different than regular ones.

JIM

 

Two different opinions and who knows who is right. I do know 20,000 miles on first gen. Comp solid roller lifters with no pressurized oil holes to the rollers or bearings and rely on oil splash for oiling is pretty good. And only one was going bad

I am not telling anyone to use them and I don't have them installed in my new 427ci small block

 

I know lots of folks who use them. I've used them in the past too. ML67 has them in his 548" motor but he has them drilled out to .080-.100" it seems like. Having priority oiling changes things a lot because the mains/rods are going to get a full load of oil anyway. Restricting the lifter galleries to the proper amount has to do with all the lifter bore clearances, type of lifters, cam (how much time the *band* in lifters is receiving full oil flow), pushrods, rockers etc etc. As long as the restrictors don't cut things down too much to flow enough to all of those internal *leaks* there is no issue.

I can see them on a killer race motor as they would help if something broke and a lifter jumped out of a hole. Plus a drag race motor needs very little oil flow up top because it doesn't run that long.

Small blocks are an entirely different animal with respect to roller cam life as compared to BBC's. The lightweight valves, pushrods in line, less spring pressure etc all help things a lot. Plus for a given HP per cube, they usually don't run cams anywhere like what it takes to run a BBC in the same range. All with the same lifter size.

Getting 20K out of solid rollers is great for sure. And that's a pretty stout cam you have there! I know of some folks that have done similar. Even some Pontiac guys are way out there too...but again...valvetrain is very similar to SBC's.

I just believe that if the bottom end is living well...then I will do everything I can to flood the top end with oil to keep things alive. I have 7-8 years on my heads with the same guides in them using a .774 lift cam and the springs are about 6 years old and were only changed because a set were lost at the machine shop! Oil is good stuff!

I agree with you..use what works for you!! There's a heck of a lot of ways to make this stuff work for sure!!

JIM

 

Everything I have ever read they say to drill them out to at least .080". I agree a small block is a different animal but it did have the non oiling type roller lifters and the reason for using the oil restrictors was to allow more oil in and around these lifters rather than sitting on top of the head. Is this the reason they lived to 20,000 miles on the street ? I would like to think so

 

You're restricting the entire lifter gallery..so that means the lifters themselves have less oil going to them right off the bat. And once you do the math of 16 lifters all bleeding off oil, and if it's a big cam that pushes the lifter band above the gallery or a small base circle that lets it drop below the gallery and completely shuts oil off to the entire line of them...you can see the ones at the end of the line don't get much at all.

Many roller lifters are edge/orifice design anyway, so the only oil going to the top end is what gets between the lifter bore and the lifter. If they feed out of the *band* area of the lifter then they supply more up top...but best way is to use pushrods with limited hole size if you want to limit top end oil and let lifters have all they can get, especially if they aren't pressurized. They need to be flooded. In fact many race teams build tunnels to run the cams in where they will constantly be in oil....even some new race designs are completely submerging the cam in oil. Good stuff!

I agree you don't want too much hanging out up top...but that's more of an oil return issue than a supply one. If you don't want it on the rotating assy you can build paths into it at rear of block or let lifter valley flood and return all up by timing chain area.

Restrictors became popular with early race teams, but edge orifice lifters pretty much eliminated the need along with priority oiling.

At least that's my thinking...


JIM

 

Most after market blocks don't even have the holes to install them. I don't know about your Merlin x block. But the Motowns have oil pressure fed to both ends of the cam valley to ensure that you don't have dry lifters at the front of the block.

Ford blocks are worse than chevy. At the shop we drill and thread 4 holes in the upper cam valley. Then install 1/8 inch oil feed lines from the rear pressure area to the front lifter area. (real gt-40's and GT 350R historic race cars)

 

I called World Products and they say they never install oil restrictors when they build Merlin iron or Merlin aluminum engines so I do not have them in.

 

Chevy engines have one of the best oil systems there is in stock form so why mess with it!!! Now if you run solid lifters of any kind and have roller rockers you can safely run restrictors, if you have anything else leave them out, your hydralic lifters and stock type rockers need the oil for sure. But each to thier own ways.