CIH Head Oil Oil Drain Dam Tube for Improved Cam Life

[jeff denton]

Thank you, Bob. I like your trans pan. Wonder if some fins on the bottom might help cooling, or better yet, some tubes through it like the B&M auto trans pan?
I'm not sure what you mean about the head oil drain. Why do you want to slow the flow? I would think you want to get that oil out of the head, away from the valve seals, as quick as possible and put it back in the pan, not dumped on the rear of the crank.
Any thought about this?
I sure enjoy seeing all your advice on gt.com.

[jeff denton]

Me again. I re-read your note about draining the oil. I guess I haven't quite mapped out the oil circuit in the head. Is the cam not fed oil pressure? Is it just splash lubed from the oil to the rockers? Should or could this be done differently?

[RallyBob]

The cam is pressure-fed from the front of the head. This means that after the oil has traveled to all the cam bearings, and down the lifter passage, around all the lifter bodies, through the rocker studs, etc......there's not much pressure and volume at the rear of the head. So as a result most Opel cams/lifters wear out at the rearmost lobes.

Now, add 2000+ rpms to the factory redline, a more aggressive lobe profile, and substantially higher spring rates, and the cams do NOT last very long under racing conditions.

Adding the oil 'dam' to the rear of the head does not slow the oil return, it just gives a constant 'puddle' for the rearmost lobes to dip into. Ironically this works out very well, as the engine is tilted rearward, so the oil puddle in the rear of the head tapers off towards the front of the head, where it is not needed as much.

HTH.

[IT Manta]

I am looking for information pertaining to adding an oil riser to the drainback hole in a 1.9L head. My search did not turn up the threads I had read in the past. Instructions and materials would be good, and pictures would be great.

[BQS4]

Are we talking about a short piece of brass or stainless steel tube for the drain back hole in the back of the head?

[hrcollinsjr]

Wasn't it a std. copper plumbing fitting? Something like a 1/2" to 3/4" adapter with a slot cut to allow all of the oil to eventually drain.

Harold

[IT Manta]

We are getting somewhere. What size was the fitting and how tall should it sit? Rally Bob?

[nobody]

search is a nice function,

http://www.opelgt.com/forums/showthr...ght=cam+oiling

[soybean]

I hunted like crazy this Am too Ron, so don't feel bad. Thanks "Nobody". I wish I had known this this past summer when I took the engine out of the current car, I would have added "the dam". I'll have it this summer for the next engine. 70 High Comp, solid lifters, saving up for the goodies. Cam & hopefully, Roller rockers. Jarrell

[IT Manta]

I actually remember another post that said what to use for the tube "dam" does anyone remember that one? I will call OGTS if I have to, but I am sure the plumbing store would be cheaper. Bob Legere was going to provide me with one, but he is obviously busy elsewhere.

[RallyBob]

Bob Legere was going to provide me with one, but he is obviously busy elsewhere.

Ya, been very busy tidying up loose ends. Finally going to start a job soon, once these little projects are completed.

I would offer you one of the oil dams I have, but to be honest they cost me about $7 too much to make, especially considering you can get a 69 cent plumbing fixture to do the same job. I figure your money is better spent on things like tires! Make it about 1/2" tall, that works fine.

Bob

[IT Manta]

Sorry Rally Bob, I actually meant Bob Denard was going to supply one but I was thinking that you most likely had the answer and I typed your last name. What plumbing fixture will I want to use by the way.

[Gary]

Originally Posted by IT Manta What plumbing fixture will I want to use by the way.

I do believe it was a 3/4 x 1/2 copper reducer fitting.

[jeff denton]

What you're looking for is in a thread about "crank scraper" and there's more about it in a thread in Forum 6A Engine Mechanical, the thread is called "CIH head oil drain dam tube for improved cam life."

http://www.opelgt.com/forums/showthread.php?t=3214

[kwilford]

I just got around to actually doing this on my first rebuilt head. I used a common plumbing fitting: 3/8" by 1/2" copper reducer. I cut mine down a bit (took about 1/4 inch off the big end) so that it would protrude about 1/2" above the normal drain level. Then I slightly ground the smaller end so that it had a taper and fit in the oil drain hole in the head. Finally, I placed a film of gasket sealer on the small end, and tapped it into place.

I would be interested in opinions of the height; I left mine about 1/2" above the original hole. I read that some folks only raised it 3/8", but at that height the oil level would only catch the cam lobe as it rotated down and not the base circle. Also, is it a good idea to a drill small hole or slot in the dam to allow oil to drain down after the engine is shut down, or is it better to leave the oil level high so that the cam is lubricated at start up?

Oh, and in one of the photos you can see the threaded plug I had the machine shop install in place of the expansion plug in the oil galley.

HTH

[tekenaar]

Originally Posted by kwilford I just got around to actually doing this on my first rebuilt head. I used a common plumbing fitting: 3/8" by 1/2" copper reducer. I cut mine down a bit (took about 1/4 inch off the big end) so that it would protrude about 1/2" above the normal drain level. Then I slightly ground the smaller end so that it had a taper and fit in the oil drain hole in the head. Finally, I placed a film of gasket sealer on the small end, and tapped it into place. I would be interested in opinions of the height; I left mine about 1/2" above the original hole. I read that some folks only raised it 3/8", but at that height the oil level would only catch the cam lobe as it rotated down and not the base circle. Also, is it a good idea to a drill small hole or slot in the dam to allow oil to drain down after the engine is shut down, or is it better to leave the oil level high so that the cam is lubricated at start up? Oh, and in one of the photos you can see the threaded plug I had the machine shop install in place of the expansion plug in the oil galley. HTH

I leave mine full length and drill two 1/8" holes at the bottom of the fat part, 180 degs apart for drainage after engine usage.

[hrcollinsjr]

Originally Posted by RallyBob oil dams I have, but to be honest they cost me about $7 too much to make, Bob

Is this what we are talking about?

Harold

[RallyBob]

Yes Harold, that's one of the steel Irmscher-made oil dams. I used to import those but they kept getting pricier and pricier plus harder to get. So I ended up having them made locally eventually from aluminum. While I was at it I also had them made 1 mm taller (13 vs. 12 mm).

[jeff denton]

You got it, Keith. Nice pictures. I never have quite figured out what all this is about, though. The idea is to puddle up oil so high there to help lube the cam? Good enough to zip around town.
I like my way better, I lube each cam bearing externally, forget the tiny stock "oil feed hole to the head" crap. Then I use the little cover at the rear of the head to externally drain all said oil right back to the pan. The riser you built is in my head, but it only would, could, or might drain any oil that backed up through aforementioned drain...
Didn't mean to "baffle" any one one here, my point is I HATE where some German thinks we should dump head oil back into the pan. At 7000 rpm.
Ya DON'T purposely make more windage, (oil/air spinning around the crank) ya do your damnest to REDUCE it!
Of course, I'm talking about circle tracking, street use is a bit more casual engineering...
I must report that the valve cover mods I made work very well for our use, we have no oil (fluid) mess any more! It was simple! Stock GT valve cover baffle redesigned in complete reverse, and the plate that strips oil off the chain and keeps the oil from the floor of the head from climbing up the right side. The (un)natural slant of the engine, the G-forces of hard left turn, all that oil up there hopefully doing its thing, I want it out of there, right back to the bottom of the pan.

[GTJIM]

Originally Posted by tekenaar I leave mine full length and drill two 1/8" holes at the bottom of the fat part, 180 degs apart for drainage after engine usage.

Would it not be an idea to leave the oil puddle there so the cam lobes are oiled right from start-up? That is the high wear period - before the pressure fed lube gets under way. I note that the Risse MotorSport item listed in the next posting does not have drainback holes drilled in it .....

[opelgtworld]

I got it by http://www.risse-motorsport.de:

Risse Motorsport

[RallyBob]

Originally Posted by jeff denton The idea is to puddle up oil so high there to help lube the cam? Good enough to zip around town. I like my way better, I lube each cam bearing externally, forget the tiny stock "oil feed hole to the head" crap.

Jeff, the cam bearings seem to do just fine, it's the cam lobes which wear badly at the back of the head due to low pressure there. Add an aggressive cam profile and stiffer valve springs plus high rpms and they wear damn quickly! Even the OEM Opel heads started to get the rolled sheet-metal tubes back there to help the cams to last longer in street use. Just high enough to allow the lobes to dip into the oil bath, not much more.

Bob

[jeff denton]

Thanks, Bob. Then my way of oiling the head just evens out the distribution, that has to be an improvement. Maybe it could help to raise my "rear cover drain" up a bit to allow more puddling back there.
I'm gonna dust off the spare head and look at it a little...
What I've noticed about all three of my heads during teardown is that the front lifter faces show little wear, but the rear ones are shot. Progressively worse front to back.
That teeny tiny oil feed to the head just never looked adequate to me!