block/deck oil restrictor

[iTurbo]

Just how important is it to have the block/deck oil restrictor in place?

Right now I'm just about to put the head on an '87 Turbo II motor I'm building. It doesn't have a restrictor at all. I ran it this way for a long time in my Shelby Lancer with no issues that I could tell at all. I didn't even know it wasn't there until tear-down; although I will say that many years after installing it, I did toast a rod bearing racing a VW Golf GTI. There was also some 'chipping' of the main bearings. I probably over revved it.

I've since rebuilt it all, but finding one of these restrictors is proving to be very hard, since they are NS1.

I did find a thread about a guy that made one out of a 9mm casing, but when I tried it just didn't quite have enough outside diameter and it would just fall through the hole. Any ideas here?

[going4speed]

Does Martin have any at arizonaparts?
Believe the restriction from that part keeps oil pressure in the bottom end and stops all the oil from pumping out of the pan into the head.

[johnl]

Won't any chunk of rod, of the same length and OD and drilled to the correct ID, work?

[iTurbo]

Won't any chunk of rod, of the same length and OD and drilled to the correct ID, work?

I got lucky on one of the last engines I built (a TI), and found a guy that had the stock part. I'm starting to think maybe just a small pipe plug with the proper size hole drilled and chamfered carefully should do it. Or maybe if the 9mm casing could be resized just slightly.

[iTurbo]

I talked to my Dad tonight for a while about this. He has much experience in reloading ammo. He got his Hornady book out and the 9mm round is .380" diameter. It is just slightly too small to fit. The .380 ACP round I have is even smaller so that is a no-go. He says my best bet is to try a 30-30 next. It necks down from the mouth to head, but at least I can put it in the hole and get an accurate measurement of the oiling hole with it (measuring where brass contacts the hole and measuring the score line with a micrometer). I'm guessing it's right around .400".

Does anybody know the *inside* diameter of the oiling hole? The primer pocket of these rounds is obviously larger (about 1/8"), but the firing hole behind them might be very close. Brass seems like an ideal material here.

[ajakeski]

I have a junk block on the engine stand. I can measure the ID of the bore and the OD of the restrictor.

[iTurbo]

I have a junk block on the engine stand. I can measure the ID of the bore and the OD of the restrictor.

That would be awesome. And if you can get a close approximation of the actual oiling hole diameter with a drill bit or something that would also be great.

[raccoon]

Whats this thing even look like? Im redoing my first engine I built for my acclaim years back and low and behold, no restrictor.
I was nothing but abusive to this poor 2.5 for 150k kilometers, till it started to have bad blow by. didn't even have a lubrication failure.

maybe just maybe its redundant.

Still, knowing what I know now, I wont be able to reassemble this thing without it.

[ajakeski]

The oil gallery bore ID in the block measured .400 inch. (13/32 inch)

The restrictor is tapered with the widest point of its OD being .460 inch. (3/64 inch)

The ID of the bore of the oil restriction is about .142 inch. (9/64 inch)

The restrictor is an interferance fit and compresses slightly when pressed in the oil gallery.

The fractional equivalents posted above are approximates taken from an engineering chart.

[4 l-bodies]

Jeremy,
.125 to .150 hole is about what you are looking for 8v applications. The factory varied the size throughout the years. 16V applications were smaller yet. If you find some used ones you can braze the hole shut and re-drill, as sometimes removing them makes hole a bit bigger. I use to to buy them at Mopar all the time. Not available anymore through Vintage Parts?
Todd

[ajakeski]

I would think you could tap the oil gallery and thread a set screw in there. Drill what ever size hole you like in the set screw.

The 0.40 bore is just under 10mm.

[iTurbo]

Thanks for the help and information Andy and all. Very much appreciated and I'll let you know what I end up doing for a solution.

Hopefully I can make my own, since they aren't available at the dealership and I can see this happening again on future builds. I haven't tried Marty or looked into Vintage parts yet though.

[Vigo]

Last one i did i just tapped it for 1/8npt (which is 0.407) and then drilled the npt plug with the biggest drill bit i had that would fit through the restrictor hole in another block that still had the restrictor. I didn't want to mess with trying to remove and reinstall it when the real problem was needing more of them than i had, so i just made one.

[83scamp]

Last one i did i just tapped it for 1/8npt (which is 0.407) and then drilled the npt plug with the biggest drill bit i had that would fit through the restrictor hole in another block that still had the restrictor. I didn't want to mess with trying to remove and reinstall it when the real problem was needing more of them than i had, so i just made one.

+1.


That's what they did in the old days. Especially when they were running the IMSA motors. The pressed in plugs would work loose in the high rpm environment. Plus they wanted less oil to the head anyways because of the mechanical cams, so they made their own thread in plugs with smaller restrictors...

[iTurbo]

+1.


That's what they did in the old days. Especially when they were running the IMSA motors. The pressed in plugs would work loose in the high rpm environment. Plus they wanted less oil to the head anyways because of the mechanical cams, so they made their own thread in plugs with smaller restrictors...

I have thought about this, and also trying to get a ~.400 brass plug to press in and drilling it to match. I'm not wanting to stick a tap in there at this point because the short block is already built. I'm sure I would do everything in my power to get the iron shavings out, but I'd rather avoid it. With a good press-fit, I doubt the restrictor would move, and with the cylinder head on, it seems like it would just stop at the HG anyway...

I plan to put this motor in with a FWDP S2 roller cam. Seems like that would need even less oiling than an old slider considering there won't be cam oil squirters in the caps.

....this would so be a non-issue if I could only buy like 4 of them at the dealer. If I'm not mistaken, even the later 2.0/2.4 used these, so I'm surprised they are no longer available. I'm not sure how you'd go about removing one after the fact, unless you had some sort of super special slide hammer.

[Vigo]

like it would just stop at the HG anyway...

The headgasket doesnt stop it and the head has a pretty large recess above it so if it WERE to pop up i think it would stop restricting oil at all and then you'd probably run into oil starvation issues at sustained high rpm.

The NPT plug i used actually had a tall square 'head' for tightening that stuck well up above the block. I actually drilled the orifice in it sideways so that if it backed out enough to hit the head it wouldnt block the oil hole.

[iTurbo]

I worry a bit about the length of the oil passage. It seems to me a .125-.150 oil passage (like Todd mentioned) would be more restrictive through a longer passage such as that drilled through a 1/8" NPT pipe plug (~1/2" thick) versus the stock part or a shell casing or a press in plug (thin).

As long as a decent press-fit is attained (like with the stock part), I can't see it getting dislodged or even moving at all by oil pressure alone. Seems to me this restrictor was incorporated by the factory after about '86 or so to better balance the oil pressure/volume to the block and top end to prevent the kind of failure I've already had.

[going4speed]

the pressure drop over such a short distance is negligible. However if this is the concern enlarge the drill hole slightly to over come the pressure drop. The factory used all manor of sizes for that hole size anyway.

[supercrackerbox]

I've got a few handfuls of spent .40 cal brass if that helps . . .

[going4speed]

40 cal ftw