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How much pressure is too much??????

 
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clay
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1972 Chevrolet Nova

PostPosted: Tue Dec 03, 2013 2:33 am    Post subject: How much pressure is too much?????? Reply with quote

Finally got my 383 back together and ready to sell and I've run into something that concerns me. Oil pressure seems to be too high. After cam break in it it just under 60 at a 1200 rpm idle hot and almost touches 100 around 4000 - 4500. I don't really know why it's this high. Bearing clearances are 0.002" on the rods and just under 0.003" on the mains. New crankshaft, standard volume oil pump. I took it apart and lapped the end plate flat and set end clearance at 0.002". I removed the relief valve to clean everything and it moved very freely. Spring was purple and from what I can tell it's Mellings spring for 55 - 60 p.s.i. so what gives? Oil for break in was Delo 15-40 with a zdpp additive since this is a mechanical flat tappet. Should I open up bearing clearance some by splitting a bearing set to gain another 0.0005"? I've got to pull the pan because evidently the rear main is leaking somewhere - thought it was the pan but not that lucky. I could run a thinner oil but I just don't have a warm fuzzy about thin oils on flat tappet stuff with decent spring pressure. What do you guys think?? Clay
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Tue Dec 03, 2013 11:30 am    Post subject: Reply with quote

im a big fan of thinner oils. i saw a 20 degree increase in oil temp going from a 10-30 to a 15-40. i would put 5-30 or 10-30 in it in a heartbeat.
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Big Dave
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PostPosted: Tue Dec 03, 2013 11:46 am    Post subject: Reply with quote

I'm with Keith thinner is better.

The oil isn't going to get any more squished with a thin oil than a thicker one. The only difference is in the viscosity which is now controlled with additives. So all of the clearances remain the same with a thin oil, as do the load carrying capabilities.

Just be sure to tell your buyer to keep adding oil supplement or buy Joe Gibbs or Brad Penn motor oil which still retains all of the ZDDP that was available back in the sixties that allow a flat tappet to live. Otherwise you can believe he will be back at your doorstep with a broken motor and complaining about your motor building skills (which are excellent, better than many pros I know).

Big Dave
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Paul P
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PostPosted: Tue Dec 03, 2013 2:32 pm    Post subject: Reply with quote

I heard the pink spring was the one to use. Sounds like the purple is on target at 60psi at an idle. It has to be the pressure relief setting. It does have a bit too much pressure and is wasting power. Oil can be thinner but I am still paranoid about going to a x-w30 oil. Just can't go there.
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Big Dave
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PostPosted: Tue Dec 03, 2013 6:13 pm    Post subject: Reply with quote

Paul you where probably raised with STP and listening to Andy Granatelli's advertising campaign.

I can remember leaving customer's STP can on the exhaust manifold while I checked out the car after an oil change; only because I didn't want to spend ten minutes trying to get it into the car and was determined not to use one of my funnels to put it in.

This a prime example of a thickening agent being added to oil to increase it's viscosity. The oil refiners add a similar additive to change 5W20 to 20W50. This is because even regular dyno oil isn't virgin oil tapped off the distillation tower.

Today oil refiners take oil and further refine it breaking the huge hydrocarbon chains down into smaller ones. Synthetic oil breaks the raw distillate all the way down to Naphthalene which is the simplest building block for oil. Synthetic oil is then assembled from these Naphthalene building blocks to recreate motor oil that has all of the molecules the same size. To this they add other chemicals that differentiate synthetic oil from dyno oil.

I recommend you try some thinner oil at least once on your wife's car if nothing else just to prove that it won't harm anything. I have to run 20W50 in my wife's 2.7L V-6 Chrysler because the oil pressure sensor is defective (I checked oil pressure with a known good gauge and it is fine never getting below 25 psi and runs up to 55 psi which keeps the bearings alive; but I don't know if it needs more to activate the cam phasing slave cylinders, and I really hate new cars with EFI).

By the way I agree the spring is the problem. I am not familiar with how Melling's rates their springs the way I am with Holley vacuum secondary springs. I will have to research that and see if I can find a chart to share.

Big Dave
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Paul P
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PostPosted: Tue Dec 03, 2013 11:51 pm    Post subject: Reply with quote

Big Dave wrote:
Paul you where probably raised with STP and listening to Andy Granatelli's advertising campaign.

I can remember leaving customer's STP can on the exhaust manifold while I checked out the car after an oil change; only because I didn't want to spend ten minutes trying to get it into the car and was determined not to use one of my funnels to put it in.


Big Dave


Not a big fan of STP oil treatment (motor honey) except for the last trip back from Hershey, PA in the summer. The 5w-30 oil in the our wagon was getting a bit hot and the oil light was flickering when I came to a stop after blasting down the highway for several hours. A bit of STP was all it needed.

Seriously most of what I heard back in the late 80s as a mechanic was all the stories about 10w40 oil flattening cams on many of the GM v-8s. I always remember that and know that when the oil gets hot viscosity can save the engine. There is a good article on the Joe Gibbs oils site about this. http://www.drivenracingoil.com/news/dro/training-center/guides/viscosity/ Nascar uses 10w30 oil!

It does say on the link to Hot Rod use that likely 15W50 hot rod oil will work for my application. Service intervals being key with this oil. The race oils are designed for more frequent changes. I haven't finished the break-in oil yet! http://www.drivenracingoil.com/dro/hr3-synthetic-15w-50html/

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2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
15.63@87 MPH 1/4mi

1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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af2
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1933 Willys Coupe

PostPosted: Wed Dec 04, 2013 8:12 pm    Post subject: Re: How much pressure is too much?????? Reply with quote

clay wrote:
Finally got my 383 back together and ready to sell and I've run into something that concerns me. Oil pressure seems to be too high. After cam break in it it just under 60 at a 1200 rpm idle hot and almost touches 100 around 4000 - 4500. I don't really know why it's this high. Bearing clearances are 0.002" on the rods and just under 0.003" on the mains. New crankshaft, standard volume oil pump. I took it apart and lapped the end plate flat and set end clearance at 0.002". I removed the relief valve to clean everything and it moved very freely. Spring was purple and from what I can tell it's Mellings spring for 55 - 60 p.s.i. so what gives? Oil for break in was Delo 15-40 with a zdpp additive since this is a mechanical flat tappet. Should I open up bearing clearance some by splitting a bearing set to gain another 0.0005"? I've got to pull the pan because evidently the rear main is leaking somewhere - thought it was the pan but not that lucky. I could run a thinner oil but I just don't have a warm fuzzy about thin oils on flat tappet stuff with decent spring pressure. What do you guys think?? Clay



Pull the pump and install the factory spring. Everything else is good and is within the norm.
Did I say screw the thinner oil?
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clay
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1972 Chevrolet Nova

PostPosted: Thu Dec 05, 2013 2:54 am    Post subject: Reply with quote

I'm going to get the pan off this Saturday hopefully and see what's up. I'm going to pull the pump apart and verify the relief valve is still free and look at the passage it feeds. I ran into this problem on my sister in laws engine but that had a high volume pump. I ended up putting a stock spring in it which helped but it was still higher than I thought it should have been. This is the same pump setup that's currently in the Nova and it might have had the same problem but it's feeding oil to two turbo's and they flow a good bit of oil through them. It runs around 20 or so hot idle and gets up to around 60 at rpm. I'm going to shoot the pan with a temp gun when I get it back together an now I'm thinking oil temp probably wasn't as hot as I thought it was and that could be a contributing factor. I'll have some more information and hopefully the solution on Saturday. Thanks guys, Clay.
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af2
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1933 Willys Coupe

PostPosted: Thu Dec 05, 2013 6:39 pm    Post subject: Reply with quote

Paul P wrote:
Big Dave wrote:

Big Dave


Seriously most of what I heard back in the late 80s as a mechanic was all the stories about 10w40 oil flattening cams on many of the GM v-8s. I always remember that and know that when the oil gets hot viscosity can save the engine.]



I worked at a local Chevrolet dealer in 1982/83 and the cam changes were coming in weekly.
GM changed to a different cam mfg and that alone was the reason.
I left/ got fired/ laid off in 1983 because the service manager told another mechanic to put a new timing chain and gears on a cam change so the dealer could get some money out of the customer being it was NOT covered under warranty.

I told the customer in front of my manager that he ( manager) was full of shit!


That didn't go well....

Back to 10/40..It was still good until 2000.

The oil today is a joke.
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Knarley Darley
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PostPosted: Sun Dec 08, 2013 3:50 pm    Post subject: Reply with quote

I also like the thinner oil. Going from 10-40 to 20-50 raised the oil temp 40 degrees. The delo is pretty thick stuff. I run 5-30 in newer engines winter time, and 10-30 for summer. In my V-8 classic cars I run either 10-30, or 10-40 depending on the oil pressure. For some reason my 76 Chevy 454 truck has too much oil pressure also, and I have 5-20 in it, and it still idles at 45-50 hot, but at least it isn't pegged all the time anymore at cruising speed. This was a GM crate engine, and it seems like they used a high volume pump, but I never took it apart so I have no idea what they used.
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