Improve top end oil pressure

[OldSkoolGP]

If you've got a motor far enough apart where you can get to it, this is an easy upgrade that will improve your oil pressure to your cams and lifters. The oil distribution cover has an anti-drainback valve in it on the bottom side where it mates with the block:



It has two problems. 1) It's incredibly restrictive, and 2) most modern oil fileters have anti-drainback rings in them, so the valve isn't necesary. To remove it, just get a flat blade screwdriver inside it and pry it out. Once it's removed you can see the restriction and how much more room your oil has got to get to the top of the engine:



I recommend doing this if you're going to run oil heavier than 5W-30, or for anyone who's goin to run their motor a lot at high revs.

[SappySE107]

Are you sure you need more oil up top? You might screw your bottom end oiling if you pump too much to the top.

[OldSkoolGP]

Going off the service manual flow diagrams, I don't see how. The bottom end get it's oil before the top end ever does. Besides, there are other restrictions to the top end in the block before you ever get to the distribution cover. The drainback valve is only there to keep oil in the top of the engine for startup.

[Dave96z34]

next time I have the lower out all pull it I def need it im always at high revs.

[z34phoenix]

i dont know sappy might be on to something too.., if you pump too much oil up top and it doesnt have time to drain back down you could run out of enough oil at the pick up.

[Mr.H.O]

I personally dont thing that removing the anti drain back valve is a good idea. Removing it would mean that at every cold start you'll have a substantially dry top end which will probably eventually wipe out a lifter or cam lobe or even a cam housing bearing surface. Not recommeneded in my opinion, your engines oil pump increases pressure with RPM therefore there shouldnt be any reason for this modification.

If getting more volume is what you're after than getting a higher volume oil pump or modifying that stock one if possible would seem like more of a reliable decision. All in all engineers dont design OHC engines that would lack top end lubrication seeing as how one of the specific benefits of an OHC engine is higher engine rpm's.

[dohcfiend]

i think it is a bad idea as well as the lq1 is already know to suck the bottom end dry under certain conditions and this may make it worse.

[SappySE107]

Im not sure on our design, but I was thinking of the olds motors. They have to run restrictors to the top end or the bottom end doesn't get enough oil past 5500-6000 RPM (maybe, I just read on it for a bit when we got the 59 olds). I think josh is taking his problem for top end oil, caused by multiple things and going a bit overboard now. I have given thought to running the high output pushrod oil pump to see what happens. The DOHC pump is massive in comparison, so it would pump less oil and hopefully lower pressure a little. 10psi per 1000 rpm is all you need. I know it is near 80 at WOT, which is wasting hp. If we need all the oil, then sure, we gotta run it but has anyone run the medium sized pump on an NA 7000RPM max 3.4 DOHC?

[dohcfiend]

i would suggest either changing the spring or shimming the spring in the lq1 oil pump for more pressure.

but words are one thing, the only way to truly know is to find out through experimentation.

[OldSkoolGP]

I wouldn't be awfully concerned about no oil in the top end at startup. If the drainback ring in the oil filter does its job you shouldn't have an issue. Although, you bring up an interesting point about too much oil. This was an idea that was presented to me by a buddy of mine, and on the surface it seemed pretty reasonable. But the last thing I'd want to do is empty the pan. Maybe just making the hole in the drainback valve bigger would be sufficient. I see enough expressed concern that I need to rethink this.

[OldSkoolGP]

I've done some more research. What it comes down to is the drainback valve is just that. It's nothing more. It doesn't balance oil pressure load from the top of the engine to the bottom. It doesn't offer any kind of resistance that makes more pressure in the rest of the engine. I'm gonna try running my motor without it. If it doesn't work or I have dry top end issues on cold start, I can always put it back in.

[HayesPerformance]

Let us know what you find out