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Finally got my car running with my 427 and had a few fun test drives. The car drives fine, no shortage of power and torque!
I have noticed however that the car runs hotter than before - the dash shows 190 - 230 despite having a huge Becool rad in it. Oil temp is about 180 and there is plenty of new synthetic oil in it.
The bug worry is the oil pressure. When the car is cold it hovers around the 50psi mark. As the car gets warned up tick over drops to about 34 but under load it drops, sometimes enough for the warning light to come on.
However, I am a bit worried about the accuracy of the digital cluster. The FAST system shows the Temperature to be much lower (160 to 180). The battery volts are always about 2 -3 volts off what I read at the battery.
Anything recommended or what could cause the oil pressure to be low?
Cheers
Last edited by Gareth; 10-06-2015 at 10:16 AM.
Reason: append signature + Update
If your gauge is accurate those reading are fine, the rule of thumb for most pushrod v8s is 10psi of hot oil pressure per 1,000 rpms. You might want to put a mechanical oil pressure test gauge on it.
I am worried because the oil pressure degreases with demand, so at 4000 I am dropping to 10psi not increasing.
Originally Posted by ex-x-fire
If your gauge is accurate those reading are fine, the rule of thumb for most pushrod v8s is 10psi of hot oil pressure per 1,000 rpms. You might want to put a mechanical oil pressure test gauge on it.
Did you say new engine? Has it done this since the install? 427 huh.....that sounds like a boatload of fun. Oh, back to your question.......did you check the oil pump pickup to the oil pan clearance when you built the engine. If the pickup is too close to the bottom of the pan the pump/oil will cavitate and do exactly what I believe you're describing. You'll want at least 3/8" and if a high volume pump maybe up to 1/2". I don't know that to be correct but it always works for me.Just a thought. And......quit going to 4000 and 10 PSI until you check with another gauge and sending unit. If it is a cavitation problem you'll be killing your engine.
Did you say new engine? Has it done this since the install? 427 huh.....that sounds like a boatload of fun. Oh, back to your question.......did you check the oil pump pickup to the oil pan clearance when you built the engine. If the pickup is too close to the bottom of the pan the pump/oil will cavitate and do exactly what I believe you're describing. You'll want at least 3/8" and if a high volume pump maybe up to 1/2". I don't know that to be correct but it always works for me.Just a thought. And......quit going to 4000 and 10 PSI until you check with another gauge and sending unit. If it is a cavitation problem you'll be killing your engine.
Yes, it is a lot of fun for the 50miles I have done in it - sounds awesome. I didn't build the engine but It was built by a very respected builder
Last one I took.
An older pic.
Originally Posted by 1963SS
Did you say new engine? Has it done this since the install? 427 huh.....that sounds like a boatload of fun. Oh, back to your question.......did you check the oil pump pickup to the oil pan clearance when you built the engine. If the pickup is too close to the bottom of the pan the pump/oil will cavitate and do exactly what I believe you're describing. You'll want at least 3/8" and if a high volume pump maybe up to 1/2". I don't know that to be correct but it always works for me.Just a thought. And......quit going to 4000 and 10 PSI until you check with another gauge and sending unit. If it is a cavitation problem you'll be killing your engine.
I'm not a big block expert, but I have run big block oil pumps in small blocks successfully, so I have some familiarity with them
make sure the oil pump pickup hasn't fallen out or shifted around; I've never seen one that actually fell out, but I did see one about ready to fall out.
make sure that the screw in plug that secures the oil pump relief spring (it's not pinned in like a small block) hasn't backed out or unscrewed itself;
replace the oil pump relief spring with the high pressure (white ?) spring;
make sure no piece of grit or trash has become lodged between the relief valve plunger and seat;
also make sure you have adequate engagement between the oil pump, the oil pump drive shaft and the distributor gear that drives the whole durn thing; there should be only a minimum of vertical play, and not say, a 1/4 inch.
and please no debate about running big block pumps in small blocks
also make sure you have adequate engagement between the oil pump, the oil pump drive shaft and the distributor gear that drives the whole durn thing; there should be only a minimum of vertical play, and not say, a 1/4 inch.
and please no debate about running big block pumps in small blocks
Actually that's really interesting. I have had some problems with the dizzy engaging and the height is different because of my hack up mk1 miniram - but then I would expect the issue to manifest itself all the time. Could this be both poorly engaged or over engaged and restricting the movement of the pump?
I think my next course of action is to get a manual gauge and do some idle / low rpm tests to see how the oil pressure changes without load or G force.
This will take the digital gauge out of the equation anyway.
An engine guy at work suggested that under very heavy load the oil could all get pumped to the heads and take too long to drain down. Anyone experienced this?
Actually that's really interesting. I have had some problems with the dizzy engaging and the height is different because of my hack up mk1 miniram - but then I would expect the issue to manifest itself all the time. Could this be both poorly engaged or over engaged and restricting the movement of the pump?
I think my next course of action is to get a manual gauge and do some idle / low rpm tests to see how the oil pressure changes without load or G force.
This will take the digital gauge out of the equation anyway.
An engine guy at work suggested that under very heavy load the oil could all get pumped to the heads and take too long to drain down. Anyone experienced this?
Suggest adding an extra quart of oil to test.
Might rethink the stock 4 qt pan or add an accusump system.
09-27-2015, 01:25 PM
Oil pressure reducing as engine gets hotter
