Big Twin Flathead Puking Oil

[JBinNC]

Looks like it is puking about as much as it's returning. That just ain't right. Scavenge pump is definitely not keeping up with the feed pump.

Jim

[CDeeZ]

Yep, I think you're right Jim. Aside from the obvious problem still present here, does the return flow look about right to you? It was hard to capture the returning oil on that video, I did the best I could. The only thing I have to compare the return flow I see in the tank is my '61 pan. The return flow I can observe on the panhead appears similar to the return flow observed in the tank of this flathead. I have a stock feed pump ready to go on as you and others have suggested. I'm going to do a little more digging before that, read on below:

My last email to Carl that made the pumps:

"I have checked the breather timing multiple times. I have attached pictures showing how I am doing the breather timing. Please look at them. I think the breather timing can be ruled out at this point. I set dial calipers at the specified distance in the service manual, and push the straight cut gear down to the specified distance from the gear case joint face: 7/16" (.437"). You can see in my picture that the breather gear hole is perfectly indexed in the breather tower notch. I stuck a screwdriver in there for visual reference in the picture. Flywheel timing mark is centered in the timing hole.

I lapped the checkball mating surfaces in the oil pump last night. Cleaned it thoroughly, reassembled and still having the same problem. Picture attached.

I have made a youtube video of the oil return flow. Please let me know what you think about that. It isn't a continuous stream of oil, but the motor is just idling. Is this enough return oil flow? You can also see the oil puking from the cam cover."

Carl's response:

"Wow I've never seen something like that except many years ago on a stock UL motor that was wrong breather gear timed.
I see that you did everything right timing it. Now it slips my mind if the breather gear is wrong marked it could do the same thing.
Please pull the scavenger and compare the breather gear with your stock breather gear concerning the small hole for timing it.
If not, there must be some other issue. The scavenge flow looks pretty normal. Do you use the oilslinger generator gear ?
The flutter valve also is important , but none of that would make it puke like that
I really feel bad for all the hassle you have there."



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The pictures detailing how I have been timing the breather:

The procedure from the manual 1/2:


The procedure from the manual 2/2:


First put the timing mark in the hole:


Straight gear held 7/16" (.437") from cam cover face should put breather gear hole in the notch in the breather tower:


Same as above, different view:


I stuck a screwdriver through that hole for visual aid. This shows that the breather is timed per the service manual:


On a whim, last night I busted out the trusty EVO pushrod and lapped the checkball seats in the feed pump. Of course, this changed nothing:






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So the plan at this point is to pull the scavenger pump and compare it to the stock one in terms of the little hole that is used to time it. If that checks out I will put it all back together (again) and use both the CHP pumps. I expect it to still puke oil like it has been doing. At that point the next step will be to remove the CHP feed pump, install the stock feed pump and see what results that gives.

[CDeeZ]

Well, I modified the right hand side case where the scavenger bolts on. In the stock configuration, oil leaving the engine to be pumped by the scavenger back to the tank had to:

1. Drop down a small hole in bottom of the right hand case

2. Make a sharp 90* turn and begin to fill that cavity with oil

3. Make ANOTHER sharp 90* turn and finally enter the scavenger pump gears.

This mod lets the oil flow directly into the scavenger pump without having to squeeze down and make a bunch of sharp turns.


After doing this, the oil return in the tank was noticeably stronger. It was like a constant stream. So that mod definitely wasn't a bad thing to do.

The CHP feed pump still floods the engine with oil and forces oil to puke from the breather, even after doing this mod (no surprise).

So, I bolted on my replacement stock 2 vane feed pump, fired it up and it definitely wasn't puking oil. It also wasn't making any oil pressure and the return flow in the tank was tiny......

Still experimenting, I swapped the CHP feed pump back on and it is also not making pressure now. It was making 30-40 PSI before I took it off to try the stock pump, and now, both the stock pump and the CHP pump don't make any pressure???

Is there some air lock or cavitation thing going on here? I took the oil feed line off and let it drain into a empty quart bottle until about 1/2 quart had flowed through the feed line.

I've had this problem before where I wasn't able to get whatever pump I was using to build pressure. After trying various things to bleed lines, prime pumps, let it sit overnight etc. it still wouldn't build pressure. Then all of a sudden, randomly, it was making pressure again. No idea what I did or didn't do to help it.


Stock scavenge pump body on case before modifying the case:


Case before modifying:


CHP scavenge pump body on case before modifying the case:


Case after modifying:


Case after modifying:


CHP scavenge pump body on case after modifying case:

[CDeeZ]

Are you guys still here? Cuz I am.

After letting the bike sit overnight, and then coming back to it, I was getting pressure again from the stock style 2 vane pump. No idea what causes this the 2 or 3 times it's happened, must be slight air lock or cavitation that just burps its way out overnight?

Anyways, when I came back to fuck with it again, I fired it up, with the stock 2 vane pump. Made pressure, but not much. But, no puking oil from the breather!!!

I was using an old pressure gauge that goes up to 50 psi, so it was basically barely registering anything. I bought a fuel pressure gauge for a carb setup from the parts store today and bolted that on, 0-15 psi is the sweep. I have about 3 psi of pressure at cold/warmish idle, and basically 0-1 psi at hot idle. I can see the needle moving around at hot idle, even though it's basically 0 psi or close to it.

Matt, what kind of pressure do you see with your big twin flatty? I know you have the 4 vane pump, but still wanted to ask..


What was the stock pressure for a flathead, does anyone know??? I don't know what to compare to, but my '61 Pan makes 40 psi cold idle, and basically 0-1 psi hot idle on a warm day. I never worry about it, because I know that HD's in general need flow, and do not need a lot of pressure. But I would like to know what a flathead should be just for reference.

Also, I cranked the pressure regulating valve in the stock 2 vane feed pump ALL THE WAY down, which should max out the pressure it makes. That didn't really change the pressure noticeably at all. Service manual states average maximum oil pressure should be about 30 psi when the pressure regulator screw is 3/8 from the top of pump body. Yeah right....... That seems unrealistically optimistic to me based upon what I have seen.




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Carl, the guy at Cala's High Performance who made the aftermarket pumps has stop responding to my emails, again. I asked him if he would take his feed pump back and refund my money since it has 0 miles of actual use on it. I don't expect him to respond. At least his scavenger pump seems to work good.

I have been in touch with another fellow who has been having the EXACT same problem as me, same pumps on his UL HD. Found him on instagram and have been corresponding via DMs and emails with him. Carl has told both of us, individually in separate emails that we have now shared with one another, that he (Carl) is not aware of anyone having the issue of oil puking from the breather. So he's basically lying IT SEEMS. Makes me wonder of all the high volume gerotor style feed pumps he has sold, how many people are experiencing this issue? Surely more than just me and my new friend

Carl recently told my new friend who is having this same issue that by cutting down or changing the pressure regulation spring in his CHP feed pump, that it will reduce the pressure and solve his issue of oil puking from the breather. Well, I don't see how that will work. Yes, it will reduce the pressure, but that oil just gets bypassed into the cam chest anyways, so I would think it would still just end up puking from the breather. Vane style stock feed pump, or gerotor style like the CHP feed pump, the pressure regulation is still bypassed into the cam chest.

See diagram below:

[JBinNC]

In an earlier post, it was pointed out that the correct gaskets were necessary for good performance from the vane type feed pump. I know that is the case for the gear type big twin pumps. Too much side clearance and the pump will flow some oil but won't make much pressure. I think the stock original gaskets were thin paper, maybe only six or seven thou? That side clearance to the vanes needs to be tight, just a thou or two for free running (that is my limited understanding of that type pump).

Jim

[CDeeZ]

Just checked the gasket that was on there. It was .013 " thick. Swapped to a .005" thick gasket. Makes no difference on the tiny 0-15 psi pressure gauge.

[flatman]

Cant really add much just an observation. The stock feed pump you have is the skinny early model not the thicker later one, but you probably already know this. Also if using the stock return pump, the victory guy, recomends a z modification to the breather tube (with the gear) window. This is similar to the mod dragstews did to a OHV breather in one of his threads. Supposed to help with the breathing. The flatty gets one on top (like dragstews) and also the bottom thus the z configuration. Just throwing this out. Interesting thread, am hoping you find out the fix. Keep us posted.

[CDeeZ]

**For clarity for anyone who is reading or later searches up this thread, since there is a growing amount information gathering here, this entire time I have been using the CHP scavenger pump with it's larger gears. Only the feed pumps are being changed and experimented with here**

Flatman,

Unless I'm totally ass backwards, the stock feed pump I have here is the later style centrifugal bypass feed pump:



The only reason I posted the diagram for the earlier flatside pump was to illustrate how despite what Carl has said about cutting or modifying the spring in his CHP feed pump to reduce pressure, that seems like it wouldn't help anything. Because, his gerotor pump, like either of the stock vane feed pumps, bypass extra oil through the pressure regulation circuit into the cam chest. The cam chest which is obviously overfilled with oil as it is with the CHP gerotor style feed pump. So I can't see why he thinks that would help anything. Maybe I'll try it, but I don't think that would help keep the CHP feed pump from flooding the cam chest with oil.

The pressure regulation circuit between the earlier style flatside vane pump and the later style centrifugal bypass vane pump seem to work the same:




What is this Z modification? Anyone have any pictures?


Thanks for weighing in and I appreciate the fact that you think it is interesting. Makes it a little easier to suffer with company LOL!


As far as fixed? I mean, as far as I can tell it is "fixed" with the stock feed pump and the CHP scavenge pump. It's pumping in oil, but not so much it pukes from the breather. But the tiny amount of pressure and flow from the stock 2 vane feed pump is NOT confidence inspiring.


I should have made a video of the return flow after I modified the case where the scavenger pump bolts on. With the CHP feed pump, the return flow in the tank was a strong, constant and steady stream. Stronger return flow than ANY other HD I've seen, But, it STILL puked oil from the breather.



Again, does anybody know what to expect pressure wise from a stock 2 vane pump? Just hoping to compare what this is doing to what others know/have experienced.


Next step will be to slap in the 4 vane rotor kit and see what kind of oil delivery that gives. Should double it theoretically right??? Maybe that will be enough without being TOO much.

In the interest of still maybe finding a way to make the CHP feed pump work this brings me back around to my initial idea of building a catchcan recycling system that simply pipes the oil lost from the breather back into the oil tank. As long as it's vented, I see no reason why this wouldn't work.

Also, another thought I just had looking at my spare cam cover which may allow the use of the CHP feed pump.... There are two holes in the cam cover responsible for delivering oil into the engine. The hole circled in RED takes oil to the crankpin and then everywhere else. AND, the hole circled in GREEN bypasses oil into the cam chest:



What about tapping both holes and threading in a pipe plug, then experimenting with strategically sized holes which will allow just enough oil into the motor to have some better pressure and flow than the stock pump affords, and not so much to fill the cam chest and cause it to puke on the ground??????????


Or maybe just block the bypass all together like Dick did on his ironhead pump conversion on his big twin flatty "The last modification to the supply pump isn’t actually done to the pump. It’s done to the cam cover. The hole in the cam cover that used to let oil that was released by the bypass pressure ball needs to be blocked. This is done by tapping the hole to ¼” NC and threading in an Allen set screw and sealing it in place. I used silicon sealant. A major difference with using the sporty pump is that there is no pressure regulation; the supply oil is never bypassed into the cam chamber. It wasn’t done on the Sportster, and it isn’t done when used on the flatheads either."

[flatman]

I am bad I thought the pic of the early pump was yours. You got the late pump alright. I will try to get a pic of the z modification, for you tommorrow.

[CDeeZ]

Thanks Flatman.

Just called Wheels Through Time and asked to talk to someone there about my flathead travails. With a place that has as much vintage iron as they do that all runs, someone there must know something that I don't. A lot of their stuff is older than this. We'll see if Matt calls me back.

I've lurked on here for a long time before posting, and still do a fair amount of lurking. There's some real knowledgeable people that have posted in this thread in particular.

However, it seems that these prewar bikes are something that most people don't know much about. My question about what kind of pressure should one expect with the stock 2 vane feed pump, still unanswered.

That's part of what has been really challenging with this bike is, the people who know these prewar BTSVs are few and far between, and probably half of the people that do know, don't use the internet.

[pan620]

I take it that your 2 vane pump is aftermarket, if it is it is a crap shoot as to the quality of it, so trying to compare it to a "stock" pump is not valid.

[flatman]

here are some pics Also good luck with the Wheels thu time inquiry, my experience was less than uuuuum, stellar. Respose to my inuiry was zero, zilch.

[CDeeZ]

I take it that your 2 vane pump is aftermarket, if it is it is a crap shoot as to the quality of it, so trying to compare it to a "stock" pump is not valid.

Correct, the 2 vane pump is aftermarket. From AAOK.com

I'm not infallible by any means. I'm also not a stranger to understanding tolerances, mechanical cause and effect relationships, how to swing and wrench, fabricate etc.

The pump seems decent. It seems at least as good as a true OEM pump. Based upon what I can tell.

Having said that, I'm already on the trail of a stock HD feed pump to recondition. **Just to rule that out**
I am currently watching a stock flatside pump body on Fleabay to purchase. I already have several rotors, sets of vanes, checkballs and springs with which to fit into the pump.

I WILL bet you a keg of beer that there is absolutely no difference between what this aftermarket repop feed pump does, and a reconditioned stock version.

I am confident in this. Because, the guy I've been corresponding with (Mark is his name) who also has been experiencing the same trouble with his CHP feed pump, he installed his OEM stock 2 vane pump and got the same pressure as me; "Fuck all" in his own words. (He's British)

Mark is 3rd from the bottom here:

http://www.chopcult.com/news/articles/hotp-greasy-kulture-magazine-issue-85.html

I don't know what you know about prewar bikes, but the source of truly original parts, that are in usable condition is limited at best. Sometimes it seems that all you have to choose from are aftermarket parts.

here are some pics[ATTACH=CONFIG]107923[/ATTACH] Also good luck with the Wheels thu time inquiry, my experience was less than uuuuum, stellar. Respose to my inuiry was zero, zilch.

Thanks for the pic flatman. If I ever have reason to pull the scavenger pump again, I will probably open up the breather window a bit.

Don't know if it would help with the CHP feed pump. The consensus I've arrived at is simply, that the CHP feed pump pumps WAY too much oil into the engine. Even so much as to overwhelm the CHP scavenge pump which has the much larger scavenging gears.

With the stock feed pump, oil is effectively scavenged back to the oil tank, and not puking from the breather, as is.


Matt from Wheels Through Time called me back!!! He was nice enough to return my call, and I do appreciate that. I do understand the frustration you must have experienced in trying to pick the brains of some people that might know about stuff like this though. What was your experience exactly? If you don't mind me asking?

Matt was as helpful as I could expect him to be over the phone to some jackass in Oklahoma like me.

Having said that, he didn't know what kind of pressure to expect from a stock flathead feed pump. He told me he never bothered to measure pressure. He said: "I just stick a finger in the oil tank and if I feel oil returning, it's fine"..

He also cautioned me against overheating it. I asked him what that looked like and he said, burning the paint off the jugs and pipes... I told him I had been measuring temps of the jugs and heads with an IR heat gun and measured heat as high as 300*F or so and he said "Oh that's fine".

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Like I have said:
The MAIN reason I tried fitting the CHP feed pump which pumps more oil was to help this thing stay together. When I built this motor a couple years ago, I fabricated and installed piston squirter jets. They spray a jet of cooling oil on the bottom of the piston crowns to help keep them cool. (Borrowed that idea from Dick Linn's website posted previously in this thread).

However, I haven't been able to use them because:

A.) The CHP feed pump which makes plenty of pressure to power them, just flat out pumps too much oil into the engine

and

B.) The stock feed pump is nowhere near powerful enough to supply oil to them. (As far as I know?)




Also, let's reiterate something here, NO-ONE can tell me what kind of pressure to expect from one of these with a stock pump. Even Matt, from Wheels Through Time............


I have been worried about the dismally low pressure the stock feed pump makes but I have been considering a couple of things:

My 61 pan, which is the closest I have to compare to, (again, no-one can tell me what kind of pressure to expect from a stock feed pump on this old flatty) the pan makes about 40 psi cold idle, and hot idle after riding around for a while is basically 0psi.

And, these HDs are roller bearings on the crank and rods..... Everything else is basically a Oilite bronze bushing, cam cover etc.
The main reason why say, a car or truck motor makes so much positive pressure all the time????? They are using bearing inserts.... Bearing inserts which have a small orifice which allows just enough oil to pass through so that the cam, crank etc. are riding on a microscopic film of oil...... These HD's don't have bearing inserts.... So it is probably unrealistic to expect pressure given that..........

[CDeeZ]

Here's a video I made showing the difference between an aftermarket feed pump with a 4 vane rotor conversion, an OEM genuine Harley-Davidson feed pump, and, the CHP feed pump after I tapped into the pressure regulation circuit.

As expected, the genuine Harley-Davidson feed pump makes basically 0 psi of hot idle oil pressure.

It looks like at this point, I can either run the 4 vane aftermarket pump, or, the CHP pump with the modification I have made to it.

https://youtu.be/JCNS5lb-MzI

[montuckymatt]

Great video and thanks for making that. Answered some questions I've always had on pump pressure. Improving these old machines for modern speeds is essential to keeping them in real use. To many just putt to the local bar and back.....