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Kirkham Motorsports

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  #1 (permalink)  
Old 06-24-2009, 10:46 AM
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Lightbulb brain dead@#$%%!@#$$%

priobe Phil The reason you have low idle oil pressure is the crankshaft. If it is the nascar steel shaft, IT"S CROSSED DRILLED. It uses twice the normal oil and cuts the pressure twice as fast. Sorry for being brain dead. The other thing is that you may want to run a HV oil pump and use your spring kit for 80 psi. I found the blueprinting for this motor. .002" on the mains and .0025" on the rods. this is with your rods. This also includes the correct rod bearings that are .080" wider. This is from a 1967 manual on this motor. Caution note was not to let motor idle for any period of time. What ever that means. I would have to look for specs on the GPM for each oil pump but off the top of my head there is a 30% supply differents between the too. Maybe a HV pump is a better deal with more supply to offer. It may also give you another 5-10psi at idle. This may help extend the motor life. Sorry for the brain fart. Rick L.
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Old 06-24-2009, 12:38 PM
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Originally Posted by RICK LAKE View Post
priobe Phil The reason you have low idle oil pressure is the crankshaft. If it is the nascar steel shaft, IT"S CROSSED DRILLED. It uses twice the normal oil and cuts the pressure twice as fast. Rick L.
So Rick, is it your opinion that his idle oil pressure is normal for an engine with a cross-drilled crank?
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Old 06-24-2009, 02:08 PM
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Default C'mon Rick, I've got documents in the manilla envelope...

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Originally Posted by elmariachi View Post
So Rick, is it your opinion that his idle oil pressure is normal for an engine with a cross-drilled crank?
Uhhh, Rick... isn't it true that the oil pressure sending unit for oil pressure lights was pre-set to 7 psi at the factory? And, the owner's manual assuaged the driver by telling them that it was perfectly normal for the light to flicker when coming to a stop? (N.B. -- Unless you admit to both of these, you'll just force me to post the excerpts from the service and owner's manuals.)
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Old 06-24-2009, 03:41 PM
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(N.B. -- Unless you admit to both of these, you'll just force me to post the excerpts from the service and owner's manuals.)
Man, you guys are brutal.

I guess this is the first I have heard of low idle oil pressure being directly related to the cross-drilled cranks. Not disputing, just wanting to learn.
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Old 06-24-2009, 06:01 PM
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Default I am not an engineer or master engine builder

elmariachi Here is what I know from 1 motor that was built about 23 years ago. It was a dirttrack motor, SBC destroked to a 267 from 283. 9,400 rpms it would spin. This motor had a Hank the crank, chrome harded surface crank in it. It was cross drill and ran for a full season without any bottom end failure. The oil pressure was 12 -15 psi at 1,000 rpms and go to 65-70 psi on the track. Left hand turn all the time. The rods where Carillios. Mike said that if the oil pressure dropped to 8-10 psi the motor needed new bearings. Mike ran the NE coast dirt track like flemington, which is long gone. I did see the bearings at the end of the season with about 15 events with 3 rounds at each show. The coating was gone and you could see bronze coloring of the bearing. He said that this was the hardest bearings he could get and this is why the bottom end lasted so long. Every body had tricks back then and still do. As far as Priobe motor, he is not running the extra wide bearings. I have heard that they are not needed on a street motor, Again a GREY AREA. .080" is alot in todays world BUT may be not 40 years ago. The only reason I can fine for wider bearings is Load surface and the nascar rods could weight up to 1000 grams each. Crossdrilling the crank gave two locations to help keep the rod bearing floating on the oil film. They also used straight oil in the 40-60 range wieght. That is thick. Today we run 0 wieght. 1 of the builders on this forum and others said that the Scat kits redid the oiling of the crank shaft. The oil is pushed in the rod bearings about 30-50 degrees after or before TDC. I forgot which it was. This pressure helps keep the bearing off the crankshaft on the compression cycle and even more important the exhaust cycle. Oil act as a cushion. Kieth Craft, Kuntz, and a couple of other pro racers would be the ones to ask about this. IMO and this not being a SBC motor, 10-15 psi would have me nervious. As long as the rocker arms are not maken any noise, I GUESS it's OK. I wouldn't let this motor idle for any length of time.
patrickt Patty my boy, I believe it was from 8-15 psi depending on motor and automobile. If the car was idling at 600 rpm with AC running and trans in gear, the light might flicker on a 100 degree day in traffic. Again in the old days running heavier oil with cligging elements in the oil or a bottle of Richard Petty's little blue bottle. No Pat I am not talking about sex pills in liquid forum.STP. I do know that GM motors that had the lights come on at idle, 90% of the time came with a rod knock on a cold startup. The end was near. Some motor lasted for years even with the knocking. My grandmother had a 57 4 door with a 6 cylinder and iron power glide. In the summer in traffic the oil light would come on and the motor would start clicking. Rockers where not getting any oil. This motor lasted the life of the car. In the old days if was pretty hard to kill a motor unless you never changed the oil.Your turn, POST AWAY!!!!!! Rick L

Last edited by RICK LAKE; 06-24-2009 at 06:03 PM..
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Old 06-24-2009, 06:28 PM
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patrickt Patty my boy,... in the summer in traffic the oil light would come on and the motor would start clicking. Rockers where not getting any oil. This motor lasted the life of the car. In the old days if was pretty hard to kill a motor unless you never changed the oil.Your turn, POST AWAY!!!!!! Rick L
Hmmm, I remember a better one than this.

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Old 06-24-2009, 07:17 PM
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Originally Posted by RICK LAKE View Post
1 of the builders on this forum and others said that the Scat kits redid the oiling of the crank shaft. The oil is pushed in the rod bearings about 30-50 degrees after or before TDC. I forgot which it was. This pressure helps keep the bearing off the crankshaft on the compression cycle and even more important the exhaust cycle.
..................
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