I have my 494 going again and am now checking oil pressure at the back of the block. The block is a half-fill just over the top of the soft-plugs. It idles cold at about 50 PSI; hot(250*) at about 18PSI; oil pressure at 4000RPM(250*) is about 65 PSI with 5-30 Mobil 1 oil. Pressure limited to 70 PSI. It is set up tight, hence the thin oil. Is that enough oil pressure for a 494 that revs to maybe 6500? Coated bearings looked perfect at last teardown. (except cam bearings, which were probably dead from 20-50 oil I tried using to help with oil temp issues. The dist gear was a giveaway). This is even after pre-heating the oil with the pan heater I have on it. Can anybody substantiate or dispell the "don't use an oil cooler on a Buick" story? My last idea is to run water tubes that circulate coolant through the pan . My oil-pan capacity is now 12 QT's. (it only delays the inevitable oil-temp rise)
Adam, Why do you think your oil temps are running hot? Do you have an oil temp guage in the pan? When you mentioned what your oil pressures were there was (250*) next to the oil pressure. Are those numbers water temps or oil temps? Answer these questions and then I will be able to give more info. Thanks John
John, thanks for the reply. Yes, I have a temp gauge in my oil pan at the bottom of the sump. I have a water temp gauge too. Water temp runs up to 200* on a 100* day when the oil temp gets around 250*. The oil temp wants to keep going up but I've never let it go above 260*. Oil temp increases faster under load or at WOT as would be expected.
Adam I would be a little concerned. I run an oil temp gauge in my car and i have a filled block. after a pass down the track my oil might get to 190. I do not run an oil cooler etheir the last time I saw oil temps that high I had cooked the engine.
temp Adam - could also be that your engine is still breaking in? You mentioned the tolerences were tight, you will get alot of friction and heat until everything is seated at about 500 miles. Just a thought. - Bill
Adam, I am curious about your statement - "the dist. gear was a give away". What did you mean by that?
As usual, I didn't offer enough information. The engine is supposed to be a streetcar engine, and I was told before doing it that a half-fill would be OK on the street--not so far! The oil temp only gets that hot after street-driving for a while. I could make several 1/4 mile passes before it would get close to 190. I'm running Mobil 1, and it is supposedly OK at that temp, though I sure don't want to test the limits, or keep running it that high. I recently read that ~200* is the ideal. There might be a little engine break-in heat, but I think it's probably already worn-in. I probably have about 100-150 stop-and-go miles on it. I ran 20-50 oil at one point on advice that it might help lower the oil temp; It didn't. However, the distribitor gear began wearing from the extra torque required to pump the thicker 20-50 oil I assume. Bobb, how much oil pressure at the back of the block is enough?
Adam I think the old standard is 11 LBS per thousand rpm I think that is a save number to work with. If you were to run a vacuum pump the oil pressure will drop. Based on the numbers you gave you should be alright. I can tell you that with my vacuum pump on my car I do not get eleven per thousand and I just check the filter and all is well so far.
Adam, Lets start with where you are checking your oil pressure. I monitor my oil pressure from the front and back of the engine. If something is going wrong with your oil pump you want to know right away. Therefore, if I were you I would monitor it from the front also. I have about a 30% drop from the front of the engine to the back but I also have the driver side lifter galley restricted in an attempt to keep as much oil down in the bearings as possible. Now for the oil temp..... 250* seems a bit high to me. But then again I dont do any street driving. This may be a situation where a synthetic oil will serve you better than a standard oil. If you choose to go in that direction make sure the engine has had the proper break-in. In my opinion.... there should be NO reason to run an oil cooler if the engine is properly assembled. If its running hot then I would try to find a way to reduce the water temp. For instance an aluminum radiator. Or atleast run some of the Redline water wetter. It sounds like you have a very nice engine. I HIGHLY recommend the SYSTEM 1 oil filter. It can be disassembled to see if anything good or bad is going on inside your engine. I am thinking you have a great deal of $$$$ into this engine so $100 for the filter is great insurance. Hope this helps!!! Take Care
Thank you everyone for the advice. John, I've been seriously considering the System 1 filter; is there a pressure-drop advantage with it as well? You have a good point about the oil pressure being checked at the front too. Cylinder leakage on the last check was ~2%; I have total seal rings, but that is a separate can of worms for discussion. At the time I figured with the small fortune I have in the engine what's another $100? The bugger of the deal is that the water temp does pretty good, but the hard block seems to hold the heat down low in the crankcase/oil. I've got water wetter and it helps maintain the temp in the water. I think the primary lesson here is don't use hard-block in a street engine. I think Dennis Halliday ran into the same problem with his hard-blocked engine too. :ball:
Yep, The water in the bottom of the water jacket does more to cool the oil than anything else. Not at all uncommon to have to let a filled motor sit on the dyno for 15-20 minutes, between pulls, with a fan on the oil pan. The more the block is filled, the worst this is. This will be a big problem with a half filled motor, in street use, especially something like yours Adam, that's making a lot of HP. I will only fill a block about an inch, for street use. Just a little to help stablize the bottom end.. I would prefer to not fill it at all, and use a girdle instead. In your case Adam, if your 250* oil problem persists, I would put an oil cooler on it. JW
Girdled and filled both. I didn't want the block moving around much. It may not move at all if I can't get it cooled down some. I have some good ideas to try from all the help I got from the board members. I'm going to try an oil cooler and will post when I get something together that works. Thanks for the thoughts Jim....
Geez you guys are scaring me..... I filled mine to the bottom of the water pump ports and drive it 30 min to the local track with the water temp 170-190 in 90 deg heat. I do have a big Stefs (run 7 qts) pan so maybe I'm not driving it long enough to cook the oil (Castrol 10w-40) but I changed the oil right after returning from the track and the oil wasn't super hot (didn't burn my fingers). Bruce BQUICK 10.35/129 Stage 2
Adam Great idea!.....I got a deal on a temp gun but found out it wouldn't go high enough to read my headers so I was bummed. But.....it will be great to read my pan temp. I'll hop at at a light and shoot it!:Brow: I already get some odd stares drving my car so who cares. :moonu: Bruce
Adam, It makes sense that a block filled with hard block would inhibet the ability of the water to help cool the oil as Jim and Dennis have told you. I have been lucky enough to go round robin while bracket racing our car and never saw the oil go over 220*. But I will be honest and say that since we havn't had any problems I rarely monitor the oil temp anymore. From what I have heard COLD oil will hurt an engine more than HOT oil. Now.... I dont know what the definition of HOT oil would be. It seems you have two options.... the oil cooler or synthetic!! Good Luck and Keep us posted!
Correct me if I'm wrong, but isn't it commonly advisable to use an oil cooler for street use if the block has been filled?? If so, and you put an oil cooler in, I would defenitely use a thermostat to allow temps to warm up QUICKLY, and then stabilize. Smokey Yunick once said (I believe) that optimal ring seal and reduced friction happens around 205-215* OIL TEMP.o No: Also boils off any impurities (GASOLINE and CONDENSATION). I would FREAK out if oil temp went over 230*. Time for a cooler!:jd:
