Lets talk about oil pump relief valve springs
- Thread starter hunt2elk
- Start date
BSB67
Well-Known Member
Rod bearing clearance is not what determines the oil. Use the oil that makes you happy with your oil pressure.
That said, you have about the worst piston/deck height variation that I’ve seen. Not sure why any decent machine shop wouldn’t make that better. Probably doesn’t matter either.
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lewtot184
Well-Known Member
Sounds like stock rods. Normal. What main journal to you have; B or RB?
lewtot184
Well-Known Member
I looked at your spec sheet again and found the B main journal. .0035" is outrageous! Don't give a damn what anyone says.
Most all of the aftermarket rods today are going to give you more than stock tolerance for side clearance. I don't like it but that's the way it is.
lewtot184
Well-Known Member
Yep. It's a mess.
lewtot184
Well-Known Member
Having gone thru this I did fix mine. I had to go thru all the bottom end and fix the leaks. Took time but I went from 18psi at hot idle to 38psi. And, the engine ran much smoother without the crank and rods flopping around.
All this new info is really starting to perturb me more and more. A guy like me who really knows nothing about engine rebuilding searches out a shop with a great reputation to build a motor. No talk on my end of going cheap anywhere, just do it right. Several thousands of dollars later and stuff like this comes to light. Both my big blocks have now been rebuilt 4 times within the last several years. So you guys can imagine the amount of cash I have tied up into them. I would be willing to bet the vast majority of people in the old car hobby have the exact same issues as me and are not aware of it. I'm about ready to sell all of them and just play around with my old Ford tractors instead. At least with those, costs are way less and I can do 95% of everything myself in my garage. Also no need to worry about dinging up a 15K paint job.
We are all having the same problems as you. It is hard to find good shops today that know your brand. I spend a lot of time studying everything so I can do it myself. Then if I mess it up I can fix it. We feel your pain.
lewtot184
Well-Known Member
I'd say the majority of my problems and expenses have been from "professionals ". Do as much yourself. You'll have enough problems fixing your own messes without paying for somebody elses.
Ordered some Driven 10w-40 to give that a try. Curious to see if I can get 5 more psi at hot idle and hot cruise. If so, I will call it a day for now. If not, I'll put an uncut black spring back in.
lewtot184
Well-Known Member
Try some straight 30wt rotella. Inexpensive, easy to find, heavier base stock and still has zddp in it. Multi weights won't get you where you want to be.
You could ever get the side clearance tight enough to restrict the oil that leaks from the rod journals.
The Great Rod Side Clearance Imbroglio: Clearing Up the Confusion.
Doug
The Great Rod Side Clearance Imbroglio: Clearing Up the Confusion.
Doug
lewtot184
Well-Known Member
I'm a total unrepentant believer that rod side clearance is a factor based on putting engines together with anywhere from .019" to .070+". Believe what you want.
I went from 10w-30 to 10w-40 to raise my hot idle pressure. Didn’t make any difference.
Krooser
Well-Known Member
It's fine...
andyf
Well-Known Member
Thicker oil will generate more oil pressure on the gauge, but that isn't necessarily a good thing. More oil pressure due to thicker oil is not the same as more oil pressure due to more volume. What you want is more volume, not thicker oil. Thicker oil doesn't provide better lubrication, more volume would. They are totally different things but it gets confusing since the oil pressure is higher either way.
When you have a loose engine you need a higher volume pump to maintain the oil pressure. If you already have a HV pump then the next step is a higher HV pump such as the Milodon pump.
Using thick oil rather than a high volume pump is dangerous. You can destroy the engine if you go down that road too far. I once blew up a nice 426 on the dyno by making that mistake. Put some 50 weight in it and we spun some rod bearings at WOT. The oil pressure gauge showed 70 psi when the engine blew. There was 70 psi at the pressure port on the back of the block but the rods were not getting enough oil volume because the oil was too thick to move thru the passages in the block.
lewtot184
Well-Known Member
Whole lot of difference between 30wt and 50wt. I'm not 100% with you on this because I've been thru this. I don't like heavy oils and use straight 30wt as my limit but an hv pump will only make very marginal low rpm differences and I think he already has an hv pump on the engine. There are no band aids for this.
gtxrt
Well-Known Member
if I had to go with a straight weight it would have to be 30wt for the simple fact of cold starts. pour a straight wt out of the bottle and you can see and the colder it is the worse it is.
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Woah now, none of that crazy talk about selling stuff. You've already done the homework with the engine
you've got and it sounds like you know how to get at least acceptable pressures by playing with springs,
so why isn't that good enough?
I don't want to see a good man walk away from this hobby; it needs all the good guys it can get.
Further, some of the best are advising you here. We're all benefitting from the knowledge being shared.
See? You're doing a good thing here.
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