I picked up a Mustangs and Fords magazine yesterday and noticed a building tip... The article was about the top 20 reasons for engine failure. It was a list of all the common mistakes folks make building an engine. One on the list was called "the 2-60 rule". Basically it said that all bearing surfaces should be .002" clearance, and all moving parts should be .060" clearance (valves, rod to block, etc...) Sounds like an easy rule to remember. Dave
Sorry, I meant that "Not properly checking clearances" was a mistake. This 2-60 tip was a guideline offered when checking clearances. Apologies for the confusion. Dave
My Chilton's says .0005-.0024. That's quite a range. Mine should be right in there at .0015. .0005 sounds crazy tight. Apparently, it was good enough for the factory...
Tight clearances to make it last longer under minimal driving conditions and the loose clearances for racing. Higher rpm's mean more heat. More heat neads more clearance. Get the Ford specs or the manufacture's specs if they are different and use them. I know you don't want .060" end play on your crank 1/4 of that would be ok. Use some common sense and the manufacturer's specs whenever you have them.
i was running a high volume melling pump but when i put the engine back together this time i decided to go with a standard volume pump from melling. i figure once everything breaks in i should see the pressure drop about 5psi or so. and for some reason, i believe the high volume pump might have contributed to my spun bearing
Use a high-volume pump only with a larger-than-stock pan. Also; oil pressure that is too high will destroy bearings. Volume and pressure are two different things...
Ive Heard The Same Thing, And Judging From My Rod Bearings That Looks Like What Happened Along With The Mains As Well But Just Not As Bad
The difference between the high volume and standard pumps is that the high volume pumps will push about 50% more oil to the passages than the stock pump. Since the engine passages can only hold just so much oil the rest of the oil goes back into the pan. The high volume pump will be operating at relief pressure more of the time than the stock unit and the relief valve is in the pump - the by-pass oil goes right back into the pan. The old wives tale that it will suck the pan dry is just that, an old wives tale. It is physically impossible for the pump to suck any more oil out of the pan than the engine will hold in its passages. I have also heard that a high pressure pump will make your main seals leak too. Well, considering that those seals never are under pressure how can that happen? The crankcase is under a partial vacuum from the PCV valve the only part of an engine that gets oil pressure is the gallies that are drilled through the block. They aren't connected to any of the seals. Don't listen to me or anyone else - research it from reliable sources. High volume pumps are used to make up for loose bearing clearances used in racing engine and to assure that the pressure remains at the relief pressure in street engines. The two engines that I have built for myself both had high volume pumps on them and the only difference is that my engines idled at the same pressure that they had at 6000 RPM. Neither of my engines were for racing and they both had stock sized pans. I put baffles in them and used a windage tray on one but they only held five quarts of oil when I changed the oil and filter.
Like TL said, we're talking two things here, volume and pressure. If the stock pumps push the maximum volume through the oil passages as possible (as allowed by the passages), then a HV-HP pump doesn't do much good in a tight motor. Otherwise, if a stock pump doesn't pump the max possible, then a HV-HP pump could be to an advantage. Just an idea...
