AMR Wet Sump Conversion

Yorkie

Yorkie

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I installed a AMR checkball conversion onto my ‘72 and the oil simply drains straight into the crankcase over the course of a couple of days. I removed the cover and replaced the seal on the pump but it still drains. The ball bearing and spring are present and I used a length of wire to hold the ball back in the bore as I installed it. Am I doing something wrong?
 
Did you also do the timing cover mod and the crankcase mod or get AMR to do it.

Crankcase, plugging the outlet.

AMR Wet Sump Conversion


Timing cover, new outlet from OPRV area

AMR Wet Sump Conversion
 
And this one to the oil pump, adding seals so the feedside cannot link direct to the sump via the return gears.

AMR Wet Sump Conversion
 
Besides what kommando says, if you really fully wet sump in a couple of days, you have a bigger problem. With no mods, it should no drain anywhere near that quickly so the oil pump probably needs service.

If the ARM mod is letting oil by, you have a problem with the seal most likely. There are some covers that require shims behind the seal. You should talk to AMR about this - I'm no expert on their mod, just read about the issue long ago and had to put two shims behind a seal. One symptom of this is low oil pressure so it's important.
 
marshg246 said:
Besides what kommando says, if you really fully wet sump in a couple of days, you have a bigger problem. With no mods, it should no drain anywhere near that quickly so the oil pump probably needs service.

If the ARM mod is letting oil by, you have a problem with the seal most likely. There are some covers that require shims behind the seal. You should talk to AMR about this - I'm no expert on their mod, just read about the issue long ago and had to put two shims behind a seal. One symptom of this is low oil pressure so it's important.
Click to expand...
Greg - you might be onto something about shimming the seal. I took the cover off today and there see no witness marks on the cone side of the seal. I’ll call AMR on Monday to discuss.
 
Yorkie said:
Greg - you might be onto something about shimming the seal. I took the cover off today and there see no witness marks on the cone side of the seal. I’ll call AMR on Monday to discuss.
Click to expand...
Cone? Are you sure AMR did the work? Typically the cone seal is replaced with an oring
 
AMR definitely did the work and I did see an o-ring in place when I removed the cover. I actually thought that I’d screwed up and fitted a standard o-ring by mistake ( It’s a couple of years since I built the motor) so I fitted a cone seal. I’ll put the o-ring back. Thanks for catching that b
 
One of the pics I posted has the AMR O ring showing, it sits proud of the steel extension.


AMR Wet Sump Conversion


So it will engage the timing cover before the cone seal, if your cover fits without the need to press down the last few 10's of thou then its not going to seal the oilway.
 
Are you using one of the thick aftermarket gaskets? They hold the cover off too far to have a really good seal to the pump. Also, I have found that if you can find a similar sized ball, hold it onto the pump outlet with needle nose pliers and give it a few taps with a hammer. That way the ball will sit tightly on to the pump. The bypass mod helps a lot as well.
 
So I see on Kommando’s post the outlet is blocked off. When I removed my cover I see oil pouring out of the threaded hole. Surely not right? (I took the seal off)
 

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Yorkie said:
When I removed my cover I see oil pouring out of the threaded hole. Surely not right?
Click to expand...

Yes, it is right unless the OPRV vent drilling has been changed.
The hole should be threaded so a cover screw can be used to prevent the oil draining while the timing cover is off.
AMR Wet Sump Conversion
 
Last edited:
An update - I called Mike at AMR and he informed me that I was doing a number of things wrong. First, the ball bearing is supposed to seat onto the oil pump tube and not the o-ring. He actually coins the tube with the ball bearing before sending out the cover. I therefore made sure the tube was slightly proud of the o-ring. Second thing I had done wrong was not blocking off the threaded oil feed adjacent to the pump - the one that the outer cover screw uses. I blocked that off with a 1/4” x 20tpi set screw. I screwed it all together a few days ago and zero wet sumping.
 
I wonder if the AMR solution could be proved upon by fitting a tailored seat in the timing cover with a conical aperture which the ball would seal against. The seat would have a partly conical seat at the outside too which interacted with the rubber seal. This would have to be designed such that the oil pump tube stub would have a little clearance to the ball. With this idea, tolerance issues are limited to the timing cover. Fabrication and gasket tolerances occurring at the crankcase half would be taken up by the rubber seal. What are your thoughts? AMC used this design in their 1964-68 single engines.

- Knut
 
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