Oil return issue with Dart blocks?

[Coloradoracer]

Ok guys, not trying to start another bash thread or anything like that. Just looking for some input. Over on Bracket talk, we've got a discussion going regarding a Merlin block, a Dart block, and Titan oil pumps. The issue is that the guy built a new motor with a Dart block, and ended up with no oil pressure. He was running a Titan oil pump. His previous combo was the same, only difference is he was running a Merlin block. I myself currently run an older Merlin Pro, a Titan oil pump, and have no issues with oil pressure like decribed, except for under hard braking after the stripe at speed, my pressure will drop, then come right back up. I know it's my flat bottom pan causing it, and I know of a bunch of other racers using similar setups that the same thing happens too. The guy in the thread however, appears to have a much bigger problem. Some of the other racers over there told him it's because of the pump, but I'm calling BS on that because it wasn't an issue with his previous combo, only the new one. Their fix is to replace the oil pump, but I'm saying its something else, and he needs to check his whole package and fix what's wrong, not just bandaid it with a different pump. Again, all I'm looking for is some input on this. Here's the link to the thread:

http://drr.infopop.cc/eve/forums/a/tpc/ ... 1017075416

[540 RAT]

Ok guys, not trying to start another bash thread or anything like that. Just looking for some input. Over on Bracket talk, we've got a discussion going regarding a Merlin block, a Dart block, and Titan oil pumps. The issue is that the guy built a new motor with a Dart block, and ended up with no oil pressure. He was running a Titan oil pump. His previous combo was the same, only difference is he was running a Merlin block. I myself currently run an older Merlin Pro, a Titan oil pump, and have no issues with oil pressure like decribed, except for under hard braking after the stripe at speed, my pressure will drop, then come right back up. I know it's my flat bottom pan causing it, and I know of a bunch of other racers using similar setups that the same thing happens too. The guy in the thread however, appears to have a much bigger problem. Some of the other racers over there told him it's because of the pump, but I'm calling BS on that because it wasn't an issue with his previous combo, only the new one. Their fix is to replace the oil pump, but I'm saying its something else, and he needs to check his whole package and fix what's wrong, not just bandaid it with a different pump. Again, all I'm looking for is some input on this. Here's the link to the thread:

http://drr.infopop.cc/eve/forums/a/tpc/ ... 1017075416

You are 100% correct, he needs to check his whole package and fix what's wrong. I built my 540 BBC with a Dart Big M block and a Titan gerotor oil pump and its been perfect regarding oiling. If he has that issue, he really did something wrong. It is NOT because of the block or the oil pump. And anyone who would say it is, has no clue what they are talking about. Jeez, do those morons actually believe that Titan oil pumps do not pump oil and make oil pressure?

While dyno testing my 540ci BBC with .003” clearance on the rods and mains, using 5W30 synthetic oil, and using a Titan “high volume” gerotor oil pump, it maintained a rock steady 80 psi (the preset relief valve setting) from about 5,000 rpm on up, with no pressure drop AT ALL. So, there was no sign of aerated oil. And it has a hot idle oil pressure of about 30 psi. I have .375" (3/8") clearance between the oil pump pick-up and the bottom of the pan.

The thinner oil will also drain back better/quicker, keeping more oil in the sump. But it will have also passed more oil through the engine, providing better flow/lubrication and cooling. One thing I did do during the build, was I enlarged the drain-back holes in my AFR heads, to double their original area for more than enough drain back capacity.

If he just changes his oil pump, he will be wasting time and money. And still have the same problem, unless his problem is a pick-up to pan clearance issue, and that happens to change with a different pump. And that's how stupid things get started. Let's say he does replace the pump, and the problem is solved "only" because of better/more pick-up to pan clearance. But he and those idiots over on the other Forum will all scream that the Titan oil pump was at fault. Unless you know the whole story about something, you cannot believe what a lot of people say.

[john@bmp]

I think the guy may want to check where his distributor seats. I have seen some cases where a distributor or the block would be a few thousandths off and cause low oil pressure. Dart has a priority main oiling system, like ours, that puts the oil on the mains first. Could be a lot of things. But it's not the pump.

Anyway, I thought every time something blew up it was the manufacturer's fault. This was a brand new block and it blew to pieces, clearly he is owed a new block.

[john@bmp]

But he and those idiots over on the other Forum will all scream that the Titan oil pump was at fault. Unless you know the whole story about something, you cannot believe what a lot of people say.

Well, we know that isn't the case, it's going to be Dart's fault. Proven or not. I think Dart should be given the benefit of the doubt and see how the engine was put together before we all start the pile on. Just sayin.

[af2]

If you are talking about a dart block or any other not returning oil to the pan, I don't know what to say! The Dart has enough windows in the valley to sink the Titanic and even with the breathers in a Bowtie without the big a$$ windows have not seen a problem with a good oil pan controlling the point of pick-up. Flat pans In my opinion suck for anything. I would take 2 quarts less oil in a boat just to have the pick-up submerged at all times.

[af2]

1 more thing I need to add. I will take all the junk Titan pumps you guys pull out. I will even pay shipping!

[Racing68]

It's usually a pickup to pan distance problem, or some piss poor scraper that does not allow the oil to drain back to the pan. Example Milodon BB Chrysler scraper with 4.5 inch stroke. It will clear but will pump the pan down in about 8 seconds. Been proven on 3 different builds that had know-it-all customers, they did not.

[Kevin Johnson]

My guess: He already said the volume was low from what he normally ran (filter volume) -- that little difference may have allowed a vortex to form and reach the pump pickup; the Dart block may allow slightly more oil to be held in the windage cloud simply because of internal contour differences with the Merlin block and/or placement/number of drains. The Dart may actually drain more quickly but in areas where the oil would be caught up in the cloud. You would really need to have the two blocks side by side for a detailed comparison.

[hondo383]

It's usually a pickup to pan distance problem, or some piss poor scraper that does not allow the oil to drain back to the pan. Example Milodon BB Chrysler scraper with 4.5 inch stroke. It will clear but will pump the pan down in about 8 seconds. Been proven on 3 different builds that had know-it-all customers, they did not.

Can you elaborate on this at all? I was about to use one of these in a stock pan stroker application..not enough drainage in the tray? pm me if you want

[Racing68]

Yes not enough drainage for the Chrysler scraper. My opinion is that when the louvers are faced down they act more like a drain than a scraper and hold oil back. Every one of these we have used in 4.25-4.5 stroke applications have lost oil pressure after 8-12 seconds of use above 3500 rpm. Longer the stroke the quicker it lost oil pressure. Shut engine off for 20-30 seconds and then everything is fine, idle time does not seem to affect it. The first time we saw this was at the end of a dyno pull on a 572 wedge motor. We added a quart same result. Thought about cavitation so loaded engine at 4000 rpm and held it, after approximately same amount of time oil pressure dropped again. We called a Chrysler expert and after telling them about the oil pressure drop first thing he said was remove the Milodon scraper, funny thing was we never even mentioned it. Removed scraper and pressure problem disappeared.

[Kevin Johnson]

Yes not enough drainage for the Chrysler scraper. My opinion is that when the louvers are faced down they act more like a drain than a scraper and hold oil back. Every one of these we have used in 4.25-4.5 stroke applications have lost oil pressure after 8-12 seconds of use above 3500 rpm. Longer the stroke the quicker it lost oil pressure. Shut engine off for 20-30 seconds and then everything is fine, idle time does not seem to affect it. The first time we saw this was at the end of a dyno pull on a 572 wedge motor. We added a quart same result. Thought about cavitation so loaded engine at 4000 rpm and held it, after approximately same amount of time oil pressure dropped again. We called a Chrysler expert and after telling them about the oil pressure drop first thing he said was remove the Milodon scraper, funny thing was we never even mentioned it. Removed scraper and pressure problem disappeared.

I do modify Milodon trays based on this but the linked thread stated that the same Milodon pan with integrated tray and Titan pump was used successfully with the Merlin block. What was changed was the block and an alteration in the oil fill. What is unknown is the change in installation height (if any) between the Merlin and Dart block of the pump (already brought up) and characteristics of the oil movement and retention in the Dart block.

It is also possible that the drag run was different from previous runs with the Merlin (the attitude of the car (lift?)) and this changed how much air was whipped into the oil, which could cause a large pressure drop.

Broke my merling block last year so went back with a Dart. This is a 565 with Big Chiefs. Got it running and took it out last night. Drove around the pits quite a bit getting the tranny fluid right.
I have Andy's favorite oil pump, a Titan and it always worked fine on the Merlin. Now it was holding 40 at idle and 60 with a little rpm, no restrictors.
First pass, I intended to leave then ease out and check things but it left good so I stayed in it, tires setting all winter and Friday night so was having to drive it some and did not notice the oil light was on until well pass the finish line and guage was showing zero and just before shutting it off I thought I heard the squeaking sound.
Today put the oil primer on it and it took a bit but then the oil pressure came up, dropped the pan and pulled number one rod cap and it looks like new money but looking at the oil in the sunlight I see a lot of silver film in it.
Here is my theory, tell me what you think. Maybe the Dart does not drain back as fast as the Merlin and the Titan pumped the pan dry and the pump lost prime. I had changed the filter and did not replace the oil lost in the filter before I ran it so was down what oil was in the filter. This is a Milidon oil pan 31187 and I run a 3 quart acumalator which actually holds a little over 2 so usually run 9 quarts which would leave me 7 in the pan. I have the old pump a Melling M77HV which I am thinking about putting back on it. Just not sure if I should take the motor out and strip it down and check everything again.
Also not sure what the vacuum might play into this, I have a small guage and also meant to look at it but did not do that either. Always stick to your game plan...
I had lowered the shift to 7000 and it still ran a 4.65 so think it is going to run if I can sort this out.

http://drr.infopop.cc/eve/forums/a/tpc/ ... 1017075416

[john@bmp]

Well, the end of the thread, page 3, says the guy simply didn't put enough oil in. Another example of in more cases than not, it's user error.

From the thread:

I think the main problem was not enough oil although I had gotten by with this little oil with the Merlin.
The Milidon pan calls for 8 quarts plus filter and I have the 3 quart accumalator. I started out with 9 quarts total and then lost almost a quart when I changed the filter.
Will definitely have more oil when I go back.

[383hoopty]

I think I would check if all galley plugs were installed. Not sure what plugs those blocks have above the filter , but I would have a look.