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Discussion Starter #1
Hey HemiKiller, what were you seeing and what did you do to the Melling pumps ? Does that apply to all of the georotor Ford pumps, or is this problem unique to M68 & M68HV ? I am wondering now about a Ford 557 (was 460 ) that we finally solved with a large diameter pickup tube. What'd you see, what do you think, and what did you do ? And did Melling simply copy your fix ? LSG
 

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I'm curious, too.... As a side note, the Melling 10687 is a standard-volume pump for the SBF but differs from the M-68 in that the shaft doesn't stop at the gerotor but continues onward to stub out in the cover, thus having a 2nd support to prevent deflection. The gears also receive additional hardening. While many folks just unbox an oil pump and bolt it on up, there is something to be said for "blueprinting" the pump, just like you would for the rest of the block or cylinder heads. This includes radiusing the ports to prevent unnecessary turbulence in the flow and verifying proper clearances. I ALWAYS recommend using a COPPER gasket between the pump and pickup tube and, preferably, between the pump and block. The copper gasket between pump and pickup tube eliminates the possibility of a paper gasket failing and the pump sucking air.
 

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Hey HemiKiller, what were you seeing and what did you do to the Melling pumps ? Does that apply to all of the georotor Ford pumps, or is this problem unique to M68 & M68HV ? I am wondering now about a Ford 557 (was 460 ) that we finally solved with a large diameter pickup tube. What'd you see, what do you think, and what did you do ? And did Melling simply copy your fix ? LSG
The 302 & 351W pumps have the regulator bypass ported back into the inlet of the pump. If you look inside the inlet, you'll see where its drilled through. The fix I came up with was to drill and tap that port and plug it off with a set screw. Our blueprinting process was pretty basic with hand selecting the pump components for optimum clearance. Outlet of the pump was drilled and honed for improved flow. Basic deburring of the cast pump body after machining and a little blending at the outlet. Regulator valve and spring were reinstalled with a cup plug that had a hole punched in it to allow oil to return to the pan. We never had an issue with the Cleveland or Lima series engines, so that was never explored. Also, at the time huge cubic inch stroker engines were just not a thing yet.

Keep in mind this was the late 90's, so the the Fox body was king and that dictated a rear sump. Stroker kits were still fairly new and the cash rich guys were running 347s with supercharger setups. Problem we were seeing was the engine would hit X rpm and the oil pressure would drop like a stone. IIRC, the Vortech guys had it even worse as their chargers were pressure fed from the engine's oil system. A 7/8" diameter pickup helped a little, but then we had clearance issues when you try to pack a tray, main girdle and stroker bits all into a rear sump pan with a stock K-member. The modified pump solved the problem completely at a good price point and kept guys from having to move into an external wet sump configuration.

As far as Melling copying the design, let's say they "incorporated" it into their performance pumps. At the time they already had the BBC 10 series pump out, but no offerings for Fords. IIRC, it was about 18 months after we introduced the modified pump that they released theirs. What they offer now is far superior to what we did at the time, but again, it was over 20 years ago, done in the little machine shop of a tiny performance parts company. And to be 100% honest, Melling does a great job of supporting the performance aftermarket. They supply a lot of the materials that performance parts are built off of.
 

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Discussion Starter #4
HK, interesting. We have done more early 289s & 302s than the later 5.0 fox body stuff. When we did the later model stuff, the guys frequently had the pan and pickup they wanted, and the 10688 pump that Canton had told them to use. . We also used the larger pickup tubes, even in the early builds. On the Lima that had the issue, the guy was using a narrow pickup tube he had gotten somewhere that fit the very large rear sump pan in his pulling truck. We had to wait for a new larger P/U from the pan manufacturer and then get the height right in the sump and the problem went away. I'm betting the pumps all have the same issue, but that the rear pickup and longer tubes is what makes it show up. This will give me a nice tech topic to talk to the guys about the next time I stop in at the shop. Thanks. LSG
 

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Never have liked the long pickup tube on the rear sumps for high stress applications. As for pumps, I use Precision Oil Pumps They are expensive when compared to a standard off the shelf pump, but well worth it.
 
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