Did it on the big end at bowling green. 6000 rpm still had 65 psi oil pressure, a quick rattle noise & it shut off.
Not good, based on the color of the rods.. that's an oiling issue, based on the fact they are the last two on the crank. Common issue with the 455, with an unmodified oiling system. JW
Jim, Does the added effect of supplying oil to the rear gallery ports via "coronary bypass" provide more benefit than the other oil mods? (especially addressing 7&8) I did all the other mods, except the external feed line, and mostly curious about the extra line to the rear. (percent improvement)
#7 rod bearing completely disintegrated. #8 rod bearing Burt to a crisp. Crank is toast. I have another crank that is 10, 10 under. I did all the oil mods & a balance line from the front oil sender to the passenger side oil galley 6 an hose. Also had a 4 an hose to my oil pressure gauge. Use 20/50 vr1 oil. 6 quart oil pan.
I am glad you were able to shut it down as soon as you realized it was going south, rather than dropping parts and oil under your ride at the big end. Race it. Break it. Fix it. repeat. My little brother lost a rear end at 100MPH @ the 1/8th the other day (9" Ford) and lucky it did not lock. He said he puckered the seat and had to beat it flat with the BFH.
My engine that runs 20/50 has looser clearances than that. Is that the oil your builder suggested for that?
These failures are always challenging. Due to the discolored rods, heat, and bearing failure from lack of oiling is indicated. What do the mains look like? A common failure here is Main housings that are out of round.. If the main housings are not round, you end up with a ton of oil bleed off at the mains. Keep in mind, the standard Clevite P bearing is not round.. it's eliptical, with an extra .0015-.002 at the parting line.. so if your housings are not round, I have seen upwards for .005 clearance at the parting line. This will bleed the oil off, and not pressurize the bearing. The mains will look fine usually. Getting the housings round and to an equal size is the biggest challenge in machining the BBB.. and is the reason why folks have always said "stay away from Chevy machinists". Even if they did not know why.. The large housing size of the BBB requires the correct honing mandrel.. if one tries to use the same mandrel they use on the much more common 2.5 or 2.75 journal engine, you end up with it being wide at the parting line.. and unfortunately, there is no way to really fix this. All you can do is shrink the vertical clearance down to about .002, to attempt to limit the amount of bleed off at the mains. First thing to do in that motor is check the main housings and see if they are round. JW
In a correctly machined block, with round housings, oil pressure drop from front to rear should be around 5-8 psi. You can account for that by bumping the read pressure at the front of the block to around 80 psi at max rpm. The equalization line is just that.. it's function is to equalize the oil pressure in the RH main galley, front to rear. But it will not fix other issues, as was seen with this motor. I consider the line optional, downsides are more external connections and lines to leak.. that needs to be balanced against the benefits.. I usually only put them in full race motors these days. JW
Thanks, Jim. I did all the oil mods from your writeup except the line and was curious if it was worth the effort to go back and add it, so thanks for saving me that trouble. I take the reading of pressure off the right rear gallery plug. My pressures are 80 when cold and any RPM off idle when hot. (TA's cover and set up) Hot (and I mean hour or so of running) are 20PSI with the few pounds needle jiggle at idle @7-800.
I agree with Jim about the mandrel too many shops don’t have the correct equipment been there done that. I’d rather see .003 on the mains and .0027-.003 on the rods.the old saying goes if it’s tight everybody knows, if it’s loose nobody knows!
Yes, I did run the cam in with vr1 10-30. Oil pressure was 85 cold & 45 warm @ 1500 to 2000 rpm. Broke in the cam with the inner valve springs out. Drained the oil & changed the filter, even cut the old oil filter open & it was clean, no metal shavings. Put the vr1 - 20/50 back in it and oil pressure was up a few pounds. Got 11 passes on the motor. The last 2 passes is when the oil pressure dropped to 15 pounds @ 2000 rpm. Almost 0 @ 1500 rpm.
Jim, I bet your spot on right with that assumption. My mains look ok, other than some fine metal flakes that scarred the bearings up.
Sorry to hear Billy. You really need to see 75 minimum at 6000 thru the traps in my experience. I run 80-85 hot at 6400 thru traps with a mix of 10/30 and 20/50 VR1. What pickup is that? Looks somewhat restrictive.......
