AMX 401 Take 5

348AMX wrote: Rebel Machine wrote: Road tested the car this eve.... no improvement. Well, highway oil pressure did go from 35 to 40 lbs. I put my foot to the floor and took it up to about 6,000 RPM. Pressure dropped a bit then kinda fluttered back up to 52 lbs. Guess it'll be okay at full throttle. It's clear I don't have the skill set to figure this out. I'll drive it until the rods start to knock. Maybe I'll sell this pile of misery and wash my hands of it. -Steve- Looks like you did fix part of the problem which was most likely an out of spec pick up clearance on the old pan. But that probably wasnt the only issue with your oiling system...your pressure shouldnt drop at all on the highway when you floor it...this particular problem sounds like an oil pump issue. After putting that nice pan on there I wouldnt give up...pump gears arent that expensive and that is what I would try next....this is assuming of course that your lifters and lifter bores are in spec...there's not much else it could be. Put the oiling system back to stock first.

I may install a Bulltear midplate but that's it, I'm not signing up for any more grief from this thing.

-Steve-

Edited by SKeown - Jul/08/2014 at 9:33pm

I think his theory is the rotating crank is dipping into the oil slightly and causing it to foam, which would definitely cause issues with oil pressure. 

So you've gained about 15% pressure at 40psi cruise vs. old 35psi, pressure isn't dropping to zero with acceleration and getting to 52psi at high rpm? Seems like positive improvements?

How much oil are you running? Remember someone posted they had issues running the Canton pan with 9qt advertised system capacity?

For momentary pressure drop with acceleration, posted in other thread about possible issue with relief and what I did to change it. An adjustable relief also worked better for me.

http://theamcforum.com/forum/amx-401-take-4_topic55796_page48.html

Since cruise pressure and high rpm pressure seems ok, maybe just run it and enjoy?

SKeown wrote: Rebel Machine wrote: SKeown wrote:  Now try it with a quart less oil, that's what I had to do. I've often wondered if H-beam rods don't increase windage? 7 psi per 1000 RPM is plenty. BTW, I run 20w50 Valvoline racing with AC filters. My digital gauge reads 40-45 psi driving at 3000 rpm, but a mechanical reads about 5 or so more. I'm sure an oil cooler would enhance it considerably.    SKeown What's the theory of running a quart less? -Steve- I think adding additional oil to a stock pan is a bad idea. I've tried it and on two different pans the additional oil being hit by the crank caused the spot welds holding the baffle to be beat loose. One time it allowed the baffle to come in contact with the crank.

I have no doubt that has been your experience but in dozens of engine I've ran with a stock pan I've never had that problem...you've had this with stock stroke cranks? I think you have bad luck..
I have a homemade pan with 10-11 qts flying around with a homemade windage tray right up to the rods and have yet to have a problem with it or oil pressure...My scrambler when stock would go from 60psi down to 40 at 65mph....I added a quart and it never happened again and the windage tray was never an issue...
 [/QUOTE]A dry sump is the ultimate system that corrects everything we struggle with. Just experiment with the oil level, find the sweet spot, run a bit heavier oil and you should be okay. 
[/QUOTE]
I can show you a pile of blowed up 401 stuff I bought from Circle track racer Tom Reffner that was all dry sump...dry sump doesn't change the way a 401 crank is drilled...his dry sump 390 crank engines all survived bearing issues...