oil pressure cold vs hot & cam stuff

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Ironmike

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Pretty much ready to button this thing up, so I primed the oil pump today and got 78psi. I'm using my drill which supposedly runs at 2000 RPM. Room temp motor and oil(heated shop).

I already have the high pressure spring in the pump, so I should be ok.....I think. Hot oil temp will make a difference, not too much I hope.

Also was surprised I had to turn the motor a bit to get oil to the rockers. Running a Lunati solid roller. I was pretty sure LAST year I got oil up there all the time, no matter where the cam was positioned.

Went out and grabbed last year's Comp roller and sure enough, they machined a groove around the journals that feed the rockers. Kinda surprising. Wonder why they did that and why Lunati doesn't.

Wonder who had the better design?

Check out the pic!
 

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unless Ma Mopar had a good reason to limit the oil flow to the rockers, it looks like the comp cam has the better design

makes me wonder how my comp cam looks...but I'm not pulling it just to find out
 
Well, full time oiling is not the factory way of doing things. For a reason. I think that would be part of "The oiling system being a controlled oil leak." And a high RPM engine could use more oil at the rockers than the factory amount designed into the engine. I'm not saying it is needed or a must to do or have. Though I can see a plus to it at sustained high RPM. Then again, it could be to much.

All things build dependent.
 
rumblefish360 said:
Well, full time oiling is not the factory way of doing things. For a reason. I think that would be part of "The oiling system being a controlled oil leak." And a high RPM engine could use more oil at the rockers than the factory amount designed into the engine. I'm not saying it is needed or a must to do or have. Though I can see a plus to it at sustained high RPM. Then again, it could be to much.

All things build dependent.
Click to expand...

Well one thing we know for sure is that those cam bearing don't have the support surface the others do.
 
Ran a Comp flat tapped solid a few years ago. It does NOT have the grooved journals. I think it's something they're doing on rollers.

Last year while running the Comp, I did restrict flow to the rockers with drilled, homemade setscrews under the rocker shafts. Wasn't my idea but oil pressure seemed to be fine.

Sorry bout the lousy pic. Friggin tablet..
 

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Crap. Forgot to ask what kind of cold pressure you guys are seeing while priming?
 
Just for reference when I start my 360 at room temp in my garage it's at about 72 psi at 1000 rpm. Then when it warms up it goes down to about 35-40. I have a Lunati solid roller and it doesn't have the grooves either.
 
BTW what rocker system are you using Mike? Dang, that is plenty of lift... just looking at the rockers!

Here: Low 70's psi priming with:
- A new Melling HV pump, the heavier relief spring, and oiling mods to the crankpins
- 55* F and 10W30 Brad Penn oil
- Drill RPM at 600 RPM
- Medium sized oil filter
- Stock type rockers and standard oil interruption to the rockers. (The cam being positioned for oil flow to the rockers or not did not effect the priming oil pressure. That oil flow is pretty low anyway with restrictions.)

Pressure drops to 60 psi hot, running, 10W30 with late fall temps in the Appalachains. Will expect a bit lower in summer.

As far as the original design.... limiting oil flow to heads is important for sustained high RPM's and pressure; there were a few engine out there that WOULD overpump oil to the heads and drop the pan level too low and the pump wold suck air: Vega engines were known for this problem when raced and absolutely needed head flow restrictors. Mike was wise IMO put restrictors in with his journal grooved Comp Cam... maybe not so much for preventing too much oil into the heads, but for keeping the pressure up in the #2 and #4 main bearings and in the rod bearings that they feed.
 
rockers are Hughes 1.6. 640/640 lift this cam. 681/688 last year with the Comp. Same everything. Might leave the restrictors in there. When in the correct cam position it's still getting plenty of oil to the rockers.
 
priming pressure cold is all about relief spring and how good of a drill you have.
 
Ironmike said:
rockers are Hughes 1.6. 640/640 lift this cam. 681/688 last year with the Comp. Same everything. Might leave the restrictors in there. When in the correct cam position it's still getting plenty of oil to the rockers.
Click to expand...
Well, you may be leaving a restrictor on top of a restrictor. Kinda depends on what Hughes has in their system for oil restriction. The hole in the bottom of the shaft where it bolts to the pedestal with the oil supply is normally a restriction on purpose. I would measure that hole size; are you using the stock sized 5/16" bolt?

The oil holes in the cam are lined up for <10% of the time, and effectively for real flow maybe only 5% of the time, so the flow when actually operating will be significantly less than you see when priming with the cam holes aligned.

(Looks like you are using the ARP bolts so the restriction with studs is not there.)
 
so are you saying I should remove my set screw type restrictors? I was kinda thinking about that, but don't want to kill oil pressure. You know, you DO lose some pressure when retro-fitting these old LA blocks with roller lifters.

On the other hand, I want to keep my springs nice and cool.......
 
Removed my restrictors today and primed with cam phased for oil to rockers. Man that's a lot of oil to the rockers! Pressure when phased was 62 psi. When not in phase same as before, 78 psi.

Now I'm completely unsure whether to leave my restrictors in or out. Afraid without them, I'll have low pressure.

I was thinking my pressure will be HIGHER when running as opposed to when cam set in phase to oil rockers 100 percent of the time like when priming.

Someone please chime in here..........I wanna button this thing up!
 
OK, you do know for a fact that the restrictors are working!

1) If you would, measure the diameter of the hole in the bottom of the rocker shaft where it bolts to the oiling pedestal and let us know, as well as the bolt diameter. In that way, the usual restriction at that point can be computed to see how it compares to others.

Also, what size is the hole in the restrictors?

2) Keep in mind that the cam 'interruptor' (as I like to call it) effectively only allows oil flow around 5% of the time. The actual flow will be a lot less. And I suspect that will mean you lose only 1-2 psi in actual operation. You really can't see the actual oiling flow with the cam lined up.

3) Call the rocker manufacturer and ask if a restrictor is a good idea.
 
Ok. As for #1,will do. Rockers and shafts are Hughes, though. Run em before with a solid flat tappet. Good pressure. I drilled a .030 hole in my restrictors last year for the Comp. Pressure last year, with that cam was good.

As for #2, I was sorta thinking and hoping the same thing.

And #3, I'm sure Hughes would say their setup is good as is, factory style.

I think between your thoughts and my own, I'm just going to remove the restrictors and button it all up. If I see bad pressure on the dyno I can take measures to correct it.

I'm a real believer in dyno time before install. My guy here doesn't charge much, and it sure is piece of mind as far as potential leaks and stuff. It's such a bear wrestling these things into an A body just to fire up and find a leak.

Will measure holes and bolt diameter tomorrow.

Appreciate the help, brutha:cheers:
 
Yes, easy enough to put them back in. OK, wow a .030" hole is pretty tiny! That works out to a bit under .001 square inches of area. I've worked out the flow areas for the stock system, and with the 'interrupter', it works out to about .002 square inches of 'effective' flow area (which is the smallest stock restriction in the flow path multiplied times .05, for the 5% flow time).

If you are going to dyno..... one suggestion is to get an old set of stock valve covers and cut a log rectangular hole in the tops over the rocker area and put them on with cheap gaskets at some point and directly observe the oiling in actual operation on the dyno. (We have a pair of stock covers prepared that way and are going to do that in-car when we check our roller rockers for any issues.)
 
Have a pair of those myself, and plan to take them with me.

You would be surprised how well the rockers were oiled with my restrictors in (with the Comp cam). I watched on the dyno last year. PLENTY of oil. That .030 goes a long way when it's flowing 100% of the time.
 
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