Oil restrictors for Dart block

Can someone help hold my hand in the installation of oil restrictors in the back oil gallery of Ford Dart block? I'm getting way too much oil to top end with external oil pump at sustained rpms. Like flowing oil out the top of vc's at 7000 rpm straights. Two circuits to fill catch can.

External pump, 351W Dart block, TFS high ports (small oil returns in my opinion) and wet sump pan. Seeing if I can hold off on going dry sump on this build. I will be doing that on a future build.

Pictures are appreciated. Thanks in advance as I can only find a few vague threads in my internet searches.
Your Dart Block, Iron or Alloy? If same as alloy there are two positions for lifter gallery restriction, front & rear, accessed from valley under small 3/8"? allen screw. Are you supplying oil to front or rear of main gallery, or both. Are you using a stroker crank or std 3.5". Windage tray? From your description I suspect you have a windage problem, does the pan have a side pouch with scraper, front or rear pickup. Went thru this when we tried to run wet sump on TVR ( failed!!). We ran pressure to both ends of block from external oil filter with two outlets, fitted 0.125" restrictors to both positions. breather hoses from upper/inner wall of valve covers between pushrods for #3&7 cylinders. PM me your email & I will send drawing of how to deal with the overflowing catch can issue.

Check out Dart Block prep info sheets, they include pics of galleries & restrictors.
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Assuming your breather is via rocker cover oil filler, is there a restrictor plate welded over the interior which prevents oil splash thrown off the rockers disappearing up the breather pipe? I didn't necessarily want to restrict oil to the top end especially on a high revving motor, but I spent a bit of time smoothing the passages to aid a faster return to the sump.

In reality this meant polishing the entire lifter valley and radiusing the oil return holes..

That might be a little old school today, but it worked well, never had a top end failure and only a dribble in the catch tanks after 25 hard laps.
Thanks for additional thoughts, but its not a valve cover issue as I've gone through three types before recognizing the flow issue. Ive ran baffled and even add SS mesh into three inch circle track tubes. The issue is of complete and entire valve covers filling with oil.

You know how when you are adjusting valves it gets a little messy if doing it old school running? Well if this engine is fired, with NO exagerration, the entire shaft rocker assembly is showered in a sheet of oil preventing it from even being seen. I've never seen oil flow like this. Otherwise the oil pressure and engine seemingly are in top shape with no "oil mist" out breathers at idle or blip'd and no perceivable smoke out exhaust.

So short of converting to a full dry sump system to add active scavenging from covers, I think a flow restriction to top end is best route to attempt.


Yes, it certainly appears that your top end is being over lubed.

Restrictors would seem the way forward...

Perhaps the pump is running backwards!
I think this might be engine in Question. If so from pics it looks like your front oiling, but not using the 'factory' oil filter pad, just using the 'Dart' size gallery where the oil light switch would be in a std 351. nothing wrong with that. I don't think your using the additional rear feed from pic. If that's the case you can simply use a blanking plug in the front restrictor gallery and a restrictor in the rear one . Size is tricky to guess at for your application with limited info and depends on cam choice and other mods you might have done at assy- eg lifter bore grooves, choice of lifters etc. I would start with 0.150" which might be on the large side, but play it safe. As mentioned we feed from both front & rear and used restrictors at both ends but around 0.090" each.

I have put a couple of arrows on your rocker covers where I think the breather tubes should attach, your system with the two going into one hose is not suitable.

BTW, give up that old school valve lash deal:)


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Is your motor -solid lifters or hydraulic? If solid .060 restriction front and back is fine. On our race motors we also add 2 #6 oil return lines from the bottom edge of the heads down to the pan.
I can explain more if you call.
I think the info here gives me more security in moving forward. Yes jac mac that routing was the first crappy arrangement and has been redone several times since.

No, LOL I don't set valve lash with engine running anymore. But do remember the mess it made the first time I ever did it with my dad's advice and oiling down the headers and smoking out his garage some 25 years ago. Didn't know any better, but was trying to give you a visual of what was going on.

THANK YOU all for the sound advise. I'll try to get her apart soon and evaluated what the current setup in the oil gallery is and from there where to go. I certainly plan to start safe and conservative and sure a .120-.150 is big, but if its a full 1/8npt hole right now, it has to make a world of difference. Yes mechanical roller so might just block off front gallery and restrict as advised in rear. And if you looked at my list of projects, rofl you'll understand if I can't remember the lifter choice so I'll double check while in there.

I do plan to on my next build to take advantage of Dart's rear oil port to make it more efficient. Live and learn :)
The reason we restrict both front and rear is for safety-if one gets pluged .
How is your gt-r coming-I got some pics from Fran -they look great.
Yes Luke, I had a quick look around the 'Reservation'. If you need a help cleaning out some of the distractions I reckon I could round up a few Kiwis to remove some of that stuff, generous to a fault they would probably do it for free!:)

A .150 restrictor would be approx 1/8th of area of the two open galleries without restrictors.