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11 replies

Dart 427 oiling system advice

edgeedgeMember
I’m after some advice in regards to the oiling system on a Dart Windsor based block.

The block I have is Dart part DRT-31345295
Dart Aluminum, Cleveland/SVO Main, 9.200 Deck Height, 4.125 Bore

The block is set up for priority oiling to the main bearings before the oil goes to the lifter galleries.
Dart recommend restrictors to be fitted to the lifter oil galleries.
But they don’t state the size of the restrictor required or the reason why restrictors are required.
Now although I understand how this oiling system works I have read lots of conflicting reports as to if you should install these restrictors or not.
CNC motorsports built up the short block with a rotating assembly & when I asked them about restrictors they said, No, don’t fit them.
But I’m struggling to get an explanation from them as to “WHY”.
Dart recommend fitting restrictors, but are very short on information as to for what reason & the size restrictor that should be fitted.

Here is the Dart blurb below:

"LIFTER GALLEY RESTRICTORS
The lifter feed at the front & rear of the lifter valley are threaded for an 1/8” NPT plug. There are two
lifter feed passages under the cross over plug (1/2” NPT). It is the one coming from the main oil galley,
towards the passenger side. The threaded portion is between the main oil galley and the passenger side
lifter oil galley. This restricts both right & left lifter galleys. Because it restricts both sides the orifice size in
the 1/8” NPT plug should be large enough to feed both sides. These restrictors are located at both ends of
the block. To restrict the lifters you need to either install restrictors at both ends or plug one end and
restrict the other. Some engine builders prefer to plug the end they are feeding the main oil galley from
and install restrictors at the opposite end. This gives you priority main oiling before feeding the lifters."

Opinions from knowledgeable builders?
I don't want to screw up one of the most important aspects of a new engine.

Regards,
Tony.
Original Post

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panterachrispanterachrisMember
The question of oil restriction to the upper end of the motor and prioritizing the mains would be affected by the type of cam your plan on using, roller cams do not require the restrictions, as opposed to flat tappet cams that need more cam lubrication..
quote:
Originally posted by Edge:
I’m after some advice in regards to the oiling system on a Dart Windsor based block.

The block I have is Dart part DRT-31345295
Dart Aluminum, Cleveland/SVO Main, 9.200 Deck Height, 4.125 Bore

The block is set up for priority oiling to the main bearings before the oil goes to the lifter galleries.
Dart recommend restrictors to be fitted to the lifter oil galleries.
But they don’t state the size of the restrictor required or the reason why restrictors are required.
Now although I understand how this oiling system works I have read lots of conflicting reports as to if you should install these restrictors or not.
CNC motorsports built up the short block with a rotating assembly & when I asked them about restrictors they said, No, don’t fit them.
But I’m struggling to get an explanation from them as to “WHY”.
Dart recommend fitting restrictors, but are very short on information as to for what reason & the size restrictor that should be fitted.

Here is the Dart blurb below:

"LIFTER GALLEY RESTRICTORS
The lifter feed at the front & rear of the lifter valley are threaded for an 1/8” NPT plug. There are two
lifter feed passages under the cross over plug (1/2” NPT). It is the one coming from the main oil galley,
towards the passenger side. The threaded portion is between the main oil galley and the passenger side
lifter oil galley. This restricts both right & left lifter galleys. Because it restricts both sides the orifice size in
the 1/8” NPT plug should be large enough to feed both sides. These restrictors are located at both ends of
the block. To restrict the lifters you need to either install restrictors at both ends or plug one end and
restrict the other. Some engine builders prefer to plug the end they are feeding the main oil galley from
and install restrictors at the opposite end. This gives you priority main oiling before feeding the lifters."

Opinions from knowledgeable builders?
I don't want to screw up one of the most important aspects of a new engine.

Regards,
Tony.
edgeedgeMember
The more I have read on other Forums I'm starting to get a grip on why the restrictors are installed.

It seems that without restrictors too much oil is delivered to the rocker cover via the pushrods.
This can lead to starving the sump of oil as it does not drain back from the heads fast enough.

regards,
Tony.
ausfordausfordMember
If you want to limit the amount of oil to the valve gear it might be a better option to use pushrods with restrictions in them and to not install any restrictions in the oil galleries.

That would help provide good lubrication for the cam lobes and still reduce flow to the heads.

I must say though i'm not familiar with the oiling system in the block you have.
George PGeorge PAdmin.
Tony I believe the two tappet passage restrictors are available as a kit, pre-drilled. This takes the guess-work out of the ordeal.

The oil metering Boss 351 style solid flat tappets work just fine in the Windsor blocks, and they make a fine way to restrict oil to the valve train when the motor is equipped with that sort of tappet. The "edge orifice" style oil metering solid flat tappets designed for the small block Ford (289/302) also work in the Windsor.

Push rods with 0.040" restrictors in one tip (or 5/16" push rods made from 0.120" wall tubing) are the best way to restrict oil to the valve train with hydraulic tappets, but those methods don't work with solid tappets because oil escapes to waste in the lash clearances between the push rods and the tappets.

I'd also install 0.060" restrictors in the passages supplying oil to all 5 cam bearings; for the exact same reason we do this in the 351C.
edgeedgeMember
Thanks for the reply George.
The Dart block does have priority oiling to the mains, likely the same as the Windsor?
As I’m running the engine as a wet sump & the oil pump feeds the main gallery from the front I have blanked off the front feed to the tappet gallery.
So the oil first runs the length of the engine heading to the rear feeding the mains first along the way.
The restrictor I have installed in the rear where the oil will pass through & up to feed the tappets.
Not sure how you gain access to the cam oil feed, under the main caps/crank bearings perhaps?
All of the oil restrictor kits I have seen available include a bunch of plugs like 5/16” threads that don’t fit the Dart block which is 1/8” NPT.
So I figured they were not suited to this Dart block & designed for something else.
I made a restrictor by drilling an Earls 1/8” NPT plug with a No.3 centre drill which is .130” & the centre drill gives a nice 60 degree chamfer lead into the hole.

I’m running a Comp Cams roller cam & Comp Cams roller tappets.

Regards,
Tony.
V 4vandproudMember
cam oil is restricted in the block main bearing saddles as you suspect, this is where the 4 small Moroso/Roush restictors are fitted in factory blocks. the single large plug goes into the angled galley under the #5 main bearing, that feeds the lifter bank on the side that does not oil the mains. you'll need to determine if the Moroso/Roush kit will work in your Dart block, depending upon the existing size of the drillings from the main saddles to the cam bearings

a neat trick that allows you to forgo the restrictors, you can simply drill your own oil orifice holes 180* from the original holes in the bearings and install them to use your holes instead

or you may subscribe to the concept that cam bearing restrictors are redundant because the cam journal itself is being pressured by the valve springs to seal off the cam bearing oil feed holes?

but Dart blocks are different. all the cam bearing bores in the block are the same size whereas Ford used 5 different size holes. Dart uses SVO style bearings that all have the same OD but change the ID to suit the cam, you can use a stock Ford layout with 5 different journal sizes, or choose from 2 specialized variations using typical journal sizes; 2.081" or 2.051
http://www.dartheads.com/produ...tfile/aitfile_id/39/

have you seen what the Dart cam bearings have going on the backside? they're grooved and have multiple oil orifices rather than a single hole at the bottom

http://www.dartheads.com/products/cam-bearings.html

it's possible that the groove itself is all you need in the way of a restrictor, and the bearings should be installed so that none of the holes aligns with the drilling in the block

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