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Author Topic:   HEY HENDREN'S oil pressure
fast19
Dirt Full Roller

Total posts: 26
posted May 01, 2002 04:16 PM
Sorry Steve, Let me try to re-phrase this post.
I have a 430 sbc wet sump SBC engine. High RPM Oil pressure drops to about 45lb (after a few laps) from 60-65LB at 150 degrees. Oil runs HOT-280 deg. The idle pressure drops to about 30lb hot. I use straight 40 wt oil. ALL clearances are excellent and fresh bearings and oil pump only helped slightly. I have the oil in the valley diverted to the front and rear drainback to keep it off the crank. Do I need to worry or is this adequate? I always heard you need 10 pounds pressure for every 1000 RPM. The only reason I worry is this is the worst engine I have ever built as far as oil pressure, although the oil temp is also the worst I have seen. I have tried several pans on the dyno and only helped the oil temp slightly. (Dyno time is getting expensive) Are the 4" strokes tough on oil in a wet sump?
Thanks for all the help, you guys are great!

[This message has been edited by fast19 (edited May 03, 2002).]

sdhnc29
Dirt Freak

Total posts: 467
posted May 01, 2002 09:19 PM
There are a number of different reason's that you oil pressure could be dropping . Your idle oil pressure would be common with 280 degree oil . I would be a little concerned though with your high oil temp . There are too many different variables , and I really don't have enough info on your engine to give you a good educated opinion on your loss of oil pressure . Perhaps you can give me a call at work and I could ask some questions that would shed some light on your problem . I'd be happy to help out , and feel free to call me at any time of the day , 8:30am - 5:30pm Eastern time .

The 10 lbs per 1,000 rpm is an old theory . On most modern race engines , oil pressure is run much lower than 10 lbs per 1,000 rpm . I'd say if you were running a steady 50lbs all the way around the track , then I would not worry . But dropping from 60 to 45 as you accelerate , could be a problem .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

ryan
Dirt Freak

Total posts: 430
posted May 02, 2002 12:40 AM
Just out of curiousity how high of oil pressure is acceptable

birdcage
Dirt Full Roller

Total posts: 57
posted May 02, 2002 05:51 AM
if oil pressure decreases at more rpm the
filter might have collapsed or is plugged.
also if its an after market block sum don't
have enuff drain back holes in lifter galleys
I had this happen on a dart block. instructions said to drill 9/16 hole in back
part of lifter block it wasn't enuff. steve
you ever had that problem. ended up opening
up several holes in galley.

sdhnc29
Dirt Freak

Total posts: 467
posted May 02, 2002 10:26 PM
birdcage ,

No , I've never had any problems with the Dart blocks . I'm assuming your speaking about the Little M block ? I've got a lot of Little M's running as wet sump engines , and have had no problem's with oil returning to the pan .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

sdhnc29
Dirt Freak

Total posts: 467
posted May 02, 2002 10:29 PM
ryan ,

Much above 65-70lbs is excessive .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

birdcage
Dirt Full Roller

Total posts: 57
posted May 03, 2002 04:33 AM
steve no it was a dart alum. block

sdhnc29
Dirt Freak

Total posts: 467
posted May 03, 2002 09:19 AM
I actually only use the Dart aluminum block as a dry sump engine . But yes , you would definitely have to make provisions to get oil back in the pan if you ran it as a wet sump .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

birdcage
Dirt Full Roller

Total posts: 57
posted May 04, 2002 03:04 AM
If you do open up lifter galleys alot more
then dart tells you in their instuctions.
they say a 9/16 hole is enuff but it ain't.
was just curious if you ran into it before.
I didnt know if the iron eagle blocks or
little M's have the same type of sealed off
lifter galley and you had to drill or they
already had drains put in so i thought i'd
ask
thanks

sdhnc29
Dirt Freak

Total posts: 467
posted May 04, 2002 12:26 PM
fast19 ,

It sounds now like you have a oil temp problem more than anything . Your oil pressure when cold , is normal . Your oil pressure with 280 degree oil would also be normal for such hot oil . The 4" stroke crank will not make an oil temp. difference . However , if you are restricting your oil to the top end , and are running a high lift cam , such as a roller or a radical flat tappet , then the temp from the valve train will heat up your oil . Also , depending on the type of head your using , and how much timing your running , you could be heating up your piston's enough to run your oil temp up . I would definitely open up your lifter valley return's also . If your running restrictor's , take them out and get the oil to your valve train . I assume that your running a good oil pan such as a Canton or a Competition Components , that will give you excellent oil control in the pan . If you are using a good pan , and not a Moroso or some other inexpensive Taiwan pan , then you can probably eliminate the pan as a source of your oil temp problem .

Realistically , if your using a high volume big block or small block oil pump , and your oil temp is down around 220 or so , then your high rpm oil pressure should be around 55-60 lbs or so . This would be normal . I think that all of your existing problems are coming from your high oil temp . if you fix the oil temp problem , then I think your oil pressure will be normal .19

------------------
Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

fast19
Dirt Full Roller

Total posts: 26
posted May 07, 2002 03:33 PM
Thanks Steve,
Lets see if I read you right, removing the oil restricters and opening the lifter valley holes would help the oil temp? I do have a roller cam and the engine block is GM and Dart heads are iron. Oil pans have varied from Canton to several others, all good quality US companies-no economy type. The pistons had run a bit hotter than I like to see but showed no damage.

Thanks again,
19

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