What is the difference betweent the Melling 10777 oil pump and the 10778? I saw that Jegs has a melling 10778C pump, is it different than the 10778? What pickup should I use if I do use the 10777? My oil pan is 8 1/2" deep from the rail to the bottom.

The 10777 and 10778C pumps fom Melling both are high volume, hex shaft drive new style pumps with the gears on extended shafts which extend into the bottom covers and keep the gears from flexing away from each other and dropping pressure and scoring the cover. The 10778C is the anti-cavatation model which has anti-cavitation grooves to help eliminate pump cavatation that can airiate (foam) the oil and reduce effective oilling at higher rpms. Definitly worth the extra money in a high HP buildup. I believe both use the same pickup tube sizes and mountings. don't forget to tack weld the pickups in place!

Ray @ Raylar

On the 10777 and 10778 pumps there should be no need for tack welding the pickup in place as it is threaded in the side of the pump w/1/2 inch pipe threads,not press fit.The fact that it has a threaded pickup limits your choice in pan pickups(obviously you will need a pickup that threads in). Also,the 10777 pumps have already went thru a redesign,if you get one that has the shafts extending thru the bottom cover it is the old design,AVOID IT,the newest version has a greyish black coating on the cast iron and better cleareances plus the extended shafts go into bottom cover but don't stick thru it.
Also,they say if your running big bearing clearences the 10778 has less hot idle oil volume/pressure (due to the anti-cavitation grooves) so consider that too.These pumps both use a special drive shaft that is included w/pump too,Smitty

So which one to use then, the one with the groves or not if my bearing clearances are in the .027 to .030 range?

Here is everything ya need to know about them

http://www.offshoreonly.com/forums/s...light=oil+pump