So actual clearance will be an individual choice.Here's the list of Central Ohio events for the last weekend in June.
The higher the rpm you are turning the more flow you need, but you have to decide whether less flow is better when 99% of the driving is crusing. The question you asked about which flow rate was best. I would comb the manufacturers website and see what they recommend before listening to anyone else. Maybe it will help, and maybe it won't but I definitely cleared out any cast in obstructions and made the passages capable of flowing even if the bearings will be the ultimate decider of actual flow.ĭifferent people will recommend different bearings and different clearances. Also, on my block I started at the oil pump mount and radiused the steps in the machined passages and bought a gun drill that I could run thru the oil passages and open them slightly. This is why I suggested looking to see what things may be available for your Chevy Big Block that may be better than the original stuff. Builders are learning to use some aftermarket cam bearings that have a groove on the outside and a second hole that is clocked to a position where it provides the best "wedge" to the camshaft journal. On the 500 Cadillac engine I'm building, its known that the last two cylinders in the block are usually problematic at higher (above 5,000 ) rpms because they are the last to receive oil. If your engine has sufficient oil pressure at all rpms, then a higher pressure pump will use additional HP and basically accomplish nothing. If the engine cannot flow more oil, then adding a high volume pump will only allow the bypass in the pump to open farther and you use HP to pump the oil in a useless circle. Lets face it, with millions of Chevy engines out there, sometimes changing the pump has helped someones problem. As I mentioned earlier, people believe that a high volume or high pressure oil pump will cure their problems. Most factory engines aren't priority main systems. That means the main bearings receive oil first. Most people consider a "priority main" as the best set up. By that I mean whether the crank receives oil first or the cam receives oil first and then the other components feed off of them. Sometimes its the way the system is designed.ergo the order in which the components receive oil. Now it is possible that in some engines there are other restrictions in the oil passages due to their size or shape. The oil can only flow when there is an avenue for it to flow and bearing clearance USUALLY is the determining factor.hence the video. Usually the amount of bearing clearance is the limiting factor. An engine can only flow a certain amount of oil.
Many people like to put high volume or high pressure oil pumps on their engines. Also too much flow can create windage around the crank as the oil flows back. Too much flow can pump all the oil out of the pan and if a particular engine doesn't have good return flow, the valve covers fill up and the pan is empty. You could actually have pressure, but no flow, so your guage would show good pressure but you have no flow or reduced flow.which is bad.
You need an additional 10 psi to overcome those centrifugal forces. The reason for the 10psi per 1,000 rpm is that as rpms increase, so does centrifugal force. With most engines you are going to exceed that when idling, which is good. The general rule of thumb is that you need 10 psi of oil pressure for each 1,000 rpms. Generally engines which are expected to see higher rpms are generally set up with a little more clearance than grocery getters or cruisers. Pressure is not as important as flow.basically. but it brings up the second question how does that affect the clearances, or is that not enough to make a difference? (Im hoping that it just needs polishing). So my question is this true with the 396?Īlso the crank has been turned, rods 30 and mains 20. " I said what?" Would a manufacturer make a crankshaft with 3 journal sizes.? And Im thinking the 69 396 would have the same crank of course. There was a footnote for the main journal size and when I read the foot note it said there was 3 different sizes to the main bearing journals.
#HOT ROD FORD BY THE GO GETTERS MANUAL#
So I found an old Glenns repair manual today that went from 58-1967 and it did not have the clearances but it had the rod journal size. But I would like to see the actual specs in a printed manual. I know a lot of the guys say generally rods and mains clearances go by the journal size. Now Im trying to find a book that has the crankshaft clearances.
I just dropped the crank, block and heads off in a machine shop last week. So i have the motor out of my 69 Chevelle that Ive had for 2 months and decided to go through it and frashen up this 50 year old motor.
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