[Skip Fix]

My new 455 project has a few things different in the oiling system than my previous motors and I think thise are contibuting to a lower than I'm used to oil pressure.

Ususally have used a Mellings and tighter "street" clearances0.002 max and no oil hole on distibutor gear. All previouis motors have had minimum 30 psi at idle hot and usually at least 60 just revving a little.

New 455 has Sealed Power's new high volume pump. Looks like a Mellings. In comparing a Mellings 54D and another Sealed Power RA replacment the Sealed power spring looks a little shorter like less tension than the Mellings. So probably a little less bypass tension. Motor has aluminum rods so running 0.0026 on mains and rods. Did use a oil bleed hole on the distributor gear. Soild Comp roller lifters no oil restrictors. Oil filter housing bypass plugged (actually the same one of my RAIV motor). Oil holes in crank drilled to 5/16 and main bearing holes opened up in groove to a little bigger than they come.

When first fired motor had 60 psi til warmed up the first time then was 40 at idle.Now when cold maybe 35 but drops to 20-25 and only goes to about 40 when reved to 4000(haven't been able to watch it on the top end).

Normal or too low?? Motor has maybe 10 passes and 10 street miles. Just makes me nervous with that much difference. Bypass stuck since it was high at first? but does go up with increase in rpm. No knocks and oil and filter look clean.

[Skip Fix]

My new 455 project has a few things different in the oiling system than my previous motors and I think thise are contibuting to a lower than I'm used to oil pressure.

Ususally have used a Mellings and tighter "street" clearances0.002 max and no oil hole on distibutor gear. All previouis motors have had minimum 30 psi at idle hot and usually at least 60 just revving a little.

New 455 has Sealed Power's new high volume pump. Looks like a Mellings. In comparing a Mellings 54D and another Sealed Power RA replacment the Sealed power spring looks a little shorter like less tension than the Mellings. So probably a little less bypass tension. Motor has aluminum rods so running 0.0026 on mains and rods. Did use a oil bleed hole on the distributor gear. Soild Comp roller lifters no oil restrictors. Oil filter housing bypass plugged (actually the same one of my RAIV motor). Oil holes in crank drilled to 5/16 and main bearing holes opened up in groove to a little bigger than they come.

When first fired motor had 60 psi til warmed up the first time then was 40 at idle.Now when cold maybe 35 but drops to 20-25 and only goes to about 40 when reved to 4000(haven't been able to watch it on the top end).

Normal or too low?? Motor has maybe 10 passes and 10 street miles. Just makes me nervous with that much difference. Bypass stuck since it was high at first? but does go up with increase in rpm. No knocks and oil and filter look clean.

[Bracket Racer]

I ran a Sealed Power pump once but didn't like it and took it out. Seems like the oil pressure was less consistent than with my Melling pumps I have run in the past. I run similar clearances. Don't think that the SP pump is inherently bad or anything just liked going back to old reliable Melling. When looking at the SP pump it seems to have higher quality machining all around and I really liked that thick bottom plate. 40psi at rpm seems low although 15-20 at idle doesn't bother me at all. If you think the bypass may be the culprit try screwing on the long housing and spring from an old Melling onto your SP pump. It should fit just fine. The castings look to be identical.

[Rob]

I used the Sealed-Power one on my 400, the shafts in the gears are supposed to be better steel and the bottom plate is thicker, I don't know of any other difference with a reg melling pump, I have Eagle Rods, my pressure at Idle is 45 and rises to 65 at 6200rpm. Maybe you should look into the 80lb pump.

[77TA]

You might have already checked this but are you sure of your gauge and sending unit? I am using the SP on my 455 with about .003 clearance and my cold idle pressure is indicating 40 and hot about 20 and is at about 50 at 4000. I put a gauge on the thing while it was on the engine stand though and with a drill motor it hit 65 psi although it was cold. I put the engine in the car and used the drill motor to prelube and the gauge in the car read 50 like it does now with the car running. I need to screw the gauge back in a varify with it it running I guess myself. theres just not a lot of room with the distribitor in place !

[Tim Corcoran]

The rule of thumb is 10 psi for each 1,000 RPM. Of course this is only an estimate as clearances, oil type, viscosity, and other factors all play a role. Oil pressure alone doesn't tell the whole story. Besides lubrication one of the primary reasons for the oil circulatory system is to cool the bearings, rods, pistons etc. If your bearing clearance is too close or if you use oil with a viscosity rating higher than needed, you could have great pressure, but still have bearing failure due to an overheated bearing caused by insufficient oil flow. In my LeMans I use Quaker State 50/50 blend synthetic/petroleum 5w/30w. When the engine is warm at an 800 RPM idle my oil pressure is about 12-15 psi and only 50 psi at 6,000 RPM, going thru the traps at about 120 MPH. This pressure may appear inadequate, but I have refreshed this engine twice, both times the bearings looked great with no signs of excessive wear or heat. I use lifer restrictors and no oil hole drilled for the distributor gear. I use the Melling M54D pump with an .100 shim under the spring. My bearing clearances are, rods/mains .0025/.0025. Based on my clearances I believe I should have higher pressure. I think I may be loosing some pressure past the cam bearings due to an improper alignment and/or hone etc., of course this is just a theory. My pressure appears to be low and I would feel better with a tad more pressure. On the other hand based on how the bearings look after tear downs it seems the pressure is adequate for my application and performance level. I tap my pressure gage line from the plug behind the distributor. Some use the outlet at the oil filter housing. Some claim there is a difference in pressures between the two locations. Does anyone have any information about if there is a difference?

Tim Corcoran

[This message has been edited by Tim Corcoran (edited 06-08-2000).]

[Skip Fix]

The sender was working fine when the 400 came out and on the initial start up did show the "normal" higher pressure on the gauge at first. Then it came down and hasn't been up since. Could be a sender I guess, but the pressure went down while it was running that first time. Running plain 30 wt Castrol right now til more broken in.

No knocking so I guess I'll just run this weekend at the PSN and plan on pulling it and adding either another spring in this pump or a new pump. When the pan is off for that I'll probably check a couple of the bearings too.

[Skip Fix]

Got to make some bye runs Monday and at 6000 it does have 65 psi. Just doesn't get there as quick as the Mellings.

11.92@113.3 in the heat

[Floyd Hand]

I watched Skip's car run Monday. It leaves the line very hard. Yes, the weather was far from perfect. We had high humidity,92%% early, and 60%% later in the day with the temperature at 90 degrees and above. The barometer was around 30.00. Floyd Hand