Location for external oil lines

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HMBAtrail
Posts: 19
Joined: Wed Aug 16, 2017 4:07 am

Location for external oil lines

Postby HMBAtrail » Fri Nov 09, 2018 12:10 am

I know there were some discussions on this several years back but I never saw anything definitive on location of the external oil lines. I'm building up a 350 for race season and I've heard this is a modification worth making. So, where do the fore and aft drain lines on the head go? Looking at photos online I've seen them tapped into the oil/timing cover. I've also seen them tapped into the case but draining into the chamber behind the oil/timing cover. I've seen them drain into the case just behind the bevel tower. Then there is the question of the location for the line that taps into the cam bearing cap on the left side of the motor. I've also seen that line tapped into the head just above the cam bearing cover. Regardless of where that end of the line goes, where is the other end of that line routed?

Pics and accurate descriptions would be SUPER helpful right now.

double diamond
Posts: 410
Joined: Thu Apr 28, 2011 1:20 am

Re: Location for external oil lines

Postby double diamond » Sat Nov 10, 2018 12:51 am

Since I made this modification to my own 350 Corsa this year, I’ll share what I did and results.

I didn’t install the drains since I didn’t want to drill holes in the cases. The cases I’m currently using will eventually be used for a different purpose that won’t employ the drains. I have a couple other cases that have the drain modification that I will eventually use. These have the two drains tapped into the front of the timing chamber with 90 degree pipe thread/barb fittings. Had I done the installation, I would not have located the drains in a location where a 90 degree fitting is necessary. I’ve seen all sorts of routing for the drain lines. Some attempt to direct the drain stream at the timing gears, other approaches seem to direct the drain stream away from gears. I think the best method is to keep the drains simple and direct. Tap into the timing case in front of and behind the bevel tower and use a direct path from the head to the crankcase. You don’t need stainless braided lines with high pressure fittings. These are drain lines with no pressure whatsoever (other than crankcase pressure). Pipe thread fittings into the case with a barb to accept the line and banjos with barb that are correct size for the existing 12mm head outlets are fine. I would recommend Stat-O-seals to seal the banjos. My head drains leaked with the stock aluminum washer. Replaced with Stat-O-seals and no leaks. Use drain hose that is rated for oil and appropriate temperature. US Plastics is one of several sources. XRP has the push on hose fittings (pipe thread/barb). Several other sources for this hardware. I use Deering Industries for my hardware since they’re close by and know their products. Deering also has Stat-O-Seals but only in inch sizes. 7/16” was a little tight on the 12mm banjo bolt, 12” was a little loose. Stat-O-Seals are available in metric sizes but hard to come by from most racecar plumbing sources. I think I ended up using 7/16 size, .You can use hose clamps, spring clamps, safety wire, etc, to retain the drain hose on the barbs. Put some thread sealer on the pipe fittings.

I did install the external pressure line from the timing cover to the cam cap. The installations you've seen of the line routed to the top of the head are probably an SC or SCD head. You could route the line that way but it's a lot easier to tap into the cam cap. BTW, it would be a shame to ruin a nice 350 cam cap by drilling a hole through it. Use a beat up cam cap if your 350 cap is in good condition. The hose ends and adapters I used are XRP AN fittings. I was impressed how much I could tighten the 90 degree adapter installed in the cam cap without cracking the fitting. Good stuff. It was pretty simple to cut the hose to the correct length and fit the hose ends but "measure twice, cut once". The cam cap is tapped in the center of the bearing bore and employs a 90 degree adapter. The line is routed over the intake valve cover. You have a few options to tap into the pressure galley from the oil pump: the side of the timing cover, the notch at the upper rear of the timing cover or tap into the galley in the center cases. The side of the timing cover is a pretty vulnerable location for the oil line in the event of a crash. I’ve seen the line tapped into the center cases but that means you have another gasket joint that the oil passes through. I put my outlet into the notch in the upper rear of the timing cover. This is a tricky operation. If you use a large diameter adapter, there isn’t a lot of material in that location so you have to be careful where you locate the hole. Some cases have an obvious plug where the oil line is drilled. If you drill the plug out, your hole will be centered on the oil galley with a direct path to the adapter. But the outside profile of the case is rounded in this location so you don’t get many threads when you tap the hole. If you angle the hole out to make the hole more square with the case, your line ends up pointing away from your intended routing direction. You can also tap the hole further in toward the gasket surface and tap into the horizontal galley after it makes a 90 degree turn. I have another case that was tapped this way; the oil path is a little more convoluted but the adapter has better thread than locating it further out. Once I drilled/tapped the adapter hole, I got in there with a die grinder and opened up the oil galley to get a good path to the adapter. Be very careful with this operation. Put some thread sealer on the adapters in the case and the cam cap. Then you tap the timing cover oil galley at the gasket surface for a set screw to block the oil path into the center cases. Also tap the cam cap oil galley and install a set screw to block the oil galley into the head. Now that both ends of the oil galley are blocked, you don’t have to install the o-ring on the cylinder dowel. When you tighten the oil line on the adapters, it wants to twist the line which unscrews it from the other end of the line. You have to hold the nut on the hose fitting when you tighten the adapter nut so the line doesn’t twist. If you twist the line a little in the opposite direction as you tighten the adapter, the line will self-tighten during operation so it won’t leak. One nice feature of this modification (besides the original purpose of keeping the oil to the cam cooler) is that you can spin the line off the cam cap adapter and prime the oil pump and cam before you start the engine. Also simple to detach when you need to remove the cylinder head. This has been a pretty trouble free modification. Once, the adapter in the timing case unscrewed a little when I didn’t introduce a little reverse twist when I tightened the line. When I noticed oil seeping from the adapter, I re-fitted the line and no more leaks. Your racing organization will want to see some sort of positive retention of the line where it screws onto the adapter. This hardware isn’t suitable for safety wire so I gooped it with weatherstrip adhesive. Passed tech inspection no problem. If I get a chance this weekend I’ll get some pics.

Matt

HMBAtrail
Posts: 19
Joined: Wed Aug 16, 2017 4:07 am

Re: Location for external oil lines

Postby HMBAtrail » Sat Nov 10, 2018 1:50 pm

Matt,
Thanks so much for the in depth description. What size oil lines did you use for the returns into the timing case? And what size AN fittings did you use? Pics would be AMAZING.

Again, thank you for taking the time to write out such a thorough response.

DBDBrian
Posts: 45
Joined: Mon Mar 30, 2015 11:29 pm

Re: Location for external oil lines

Postby DBDBrian » Sat Nov 10, 2018 2:31 pm

That's a very comprehensive reply Matt, I don't want to hi-jack the thread, but I did tag a post on the end of the checking engine oil pressure discussion 09-10-18, with a question re external oil line's, but with no response.
With your new external feed to the camshaft outer bearing housing, did you put any form of restriction in the line, as would be the small bore hole in the head joint dowel, to prevent compromising the oil supply to the crankshaft ?

Brian

blethermaskite
Posts: 22
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: Location for external oil lines

Postby blethermaskite » Sun Nov 11, 2018 2:23 pm

I have experimented with both external cam feed and oil drain pipes over a number of years on quite a few bevel single engines, (as a precursor to my comments below, I need to point out that on all my engines I modify the timing case bronze crankshaft end oil feed bush to take a rubber lip oil seal which improves both the oil feed control and flow to the crankshaft and the valve gear).
1. I am not convinced an external oil feed to the end of the camshaft has any advantages over the standard design other than maybe? a little cooling effect on the oil, I have always restricted an external oil feed to the same bore dimension as the head/barrel dowel. Unless something has broken up inside an engine (at which point it probably doesn't matter) I have never found the standard oil feed to the head failed/blocked with debris.
2. I have plumbed external oil drains to 2 positions one to the timing case to the front of the bevel tower tube more or less directed at the timing gears, and the other drain to above the gearbox, the main advantage I see in these drains is they stop the head from oil flooding when cold ( which I think doesn't really happen once the engine is at normal operating temperature) but in the main, the extra supply to the gearbox can only help under extreme use situations.

However, neither of my two current road going widecase Ducati's (250 desmo disc, and 350 mark3) have external oil piping and I don't think I would bother to modify either of them.
Cheers,
George

DBDBrian
Posts: 45
Joined: Mon Mar 30, 2015 11:29 pm

Re: Location for external oil lines

Postby DBDBrian » Mon Nov 12, 2018 8:26 pm

Thanks for your interesting reply George. When I make the banjo bolt for the cam bearing housing connection, I will incorporate a restriction in the bolt.
Re your crank feed oil seal, do you leave the bush out completley, or bore the flange the depth of the seal, retaining a shorter bush.
I have fitted a new bush in the cover, and line bored it through the main bearings to size.
Thanks for your input.
Brian

double diamond
Posts: 410
Joined: Thu Apr 28, 2011 1:20 am

Re: Location for external oil lines

Postby double diamond » Mon Nov 12, 2018 8:54 pm

The only restrictions in the oil delivery is the roll pin in the end of the cam and the roll pin in the end of the crankshaft. I'm considering plugging the end of the cam as there is no reason to have oil exiting there. Not too worried about oil delivery since the oil pump, timing case bushing and crankshaft end are all in excellent condition and the engine is turning over 5k RPM on the track. As I mentioned in my description, I do not employ return lines, just the stock oil return through the bevel tube. By the time the engine has been started, warmed up and idling on pre-grid, I'm sure the oil is sufficiently warmed to drain via the original design. Winter tear down will reveal if oil circulation has been adequate. I wouldn't install any external oil lines on a street engine. The AN fittings are identified as "#4".

I've come across cylinders with the oil passage blocked but this was due to using sealer on the base gasket. Might have found some other junk plugging the oil passage/dowel but this should always be checked with a cylinder of unknown history.

first pic: this is a timing cover I acquired with the external oil line already tapped. Location is inward from the "notch" at the upper rear of the timing cover.

Matt
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double diamond
Posts: 410
Joined: Thu Apr 28, 2011 1:20 am

Re: Location for external oil lines

Postby double diamond » Mon Nov 12, 2018 8:57 pm

Second pic: This is the timing cover tapped a the notch in the upper rear of the timing cover.
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IMG_0895[1].JPG

blethermaskite
Posts: 22
Joined: Thu Mar 01, 2018 1:06 am
Location: northern ireland

Re: Location for external oil lines

Postby blethermaskite » Mon Nov 12, 2018 9:05 pm

Brian,
Yes, I shorten the bronze bush by about 3.5mm to allow fittment of a 3mm deep steel body single lip oil seal in the bored out boss.
Cheers,
George

double diamond
Posts: 410
Joined: Thu Apr 28, 2011 1:20 am

Re: Location for external oil lines

Postby double diamond » Mon Nov 12, 2018 9:23 pm

third pic: oil line tapped into the notch on upper rear of timing cover.
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