427 CBB oil pressure
 

Hi

I have a 427 cbb motor, 80s stocker built. L88 with stock L88 camshaft.

The motor have a stock GM modified oil pump (anti-cavitation grooves).

The oil pressure is very stable, about 18-20 psi at idle and then it goes up to about 42 psi when I hit the throttle. but then even If a run the motor in 7000 rpm I never have more then 42 psi oil pressure.

I run quaker state 20w50 mineral oil. Have also tried 15w40 mineral, but with no difference.

The motor ran straight 40 quaker state oil when it was raced in the 80s.

Is it safe to run this motor with the low pressure? with the 20w50 oil.

Thank You

Re: 427 CBB oil pressure
 

I'd want to look at the oil pump and find out about the clearances, as well as the condition of the bearings.

The idle oil pressure is fine, for a hot idle at 750-1000 RPM, but the high RPM oil pressure is a bit low for 20W50.

You may well get by with it, but it is not what I'd call ideal.

Re: 427 CBB oil pressure
 

Is it better to run 15w40 ?

Re: 427 CBB oil pressure
 

I don't know that 15W40 will be any better.

I'd suggest you try 20W50 Racing Valvoline, or Brad Penn, if you want to run mineral base oil.

Re: 427 CBB oil pressure
 

Try it with 10- 30 if it's the same I say your OK---Trevor

Re: 427 CBB oil pressure
 

Bad oil pressure gauge???Been their done that,just a thought

Kevin

Re: 427 CBB oil pressure
 

if the gauge is OK you might want to consider changing the bypass spring in the pump - as Alan said, not ideal pressure at RPM

Re: 427 CBB oil pressure
 

That is why I suggested a look at the pump. In an engine that old, it is possible that the oil pump bypass spring is bad.

Yes, the gauge too is a possibility. I did not mention it and should have. I always check my gauge right after I check my oil and filter if I have an oil pressure problem. I need to remember not everyone does.

Speaking of oil filters, I suggest using either a long Wix racing filter, or a long K&N filter. By long, I mean the 1 quart filter. Oil filters have been known to cause that problem. I've even seen it with what used to be good filters, the AC PF1218 included. The only AC that may still be good is a PF2232 Duramax filter, but I'd check to see before I used it, and it will be the same price as a K&N or Wix Racing, and you'll know what you have then.

Re: 427 CBB oil pressure
 

The motor is modified like this, I know that the oilpump is modified to give this pressure. And they rew this motor 7400 rpm when it was raced in the 80s. But I dont want to risk anything now, ......so there isnt any problem with the pump or oilfilter :) but is it safe to run a cbb with this oil pressure?
But What oil should I run 40 or 50 ?

Thanks

Re: 427 CBB oil pressure
 

If this hasn't seen daylight since the 80's it sure would be a good idea to pull the pan and look it over if you can. Much cheaper to do that than to wait for trouble.

Re: 427 CBB oil pressure
 

Have done that, and it looks great. And it has new head gaskets ect. :) The motor is in perfect condition.

But maybe I need to change the oilpump go get more oil pressure.

Re: 427 CBB oil pressure
 

If you dont know what bearing clearances you have I would check them most likely they are a loose, you can test oil pump by taking old main cap and tap it to accept gauge where oil come from pump,stick in bucket oil spin it w/drill and can see what pressure pump is bypassing at,have someone help hold it or mount to bucket it's hard to hold by yourself.
Mike Taylor 3601

Re: 427 CBB oil pressure
 

If I going buy a new oilpump, what should I buy?

Melling has one Anti-cavatation design pump.
"Approximately 25 percent over stock volume. Anti-cavatation design. Reduces cavitation effects in high RPM applications. Using this oil pump will reduce pressure at idle. Chromoly steel drive shaft included. Standard pressure spring is included."

http://www.summitracing.com/parts/MEL-10778C/

Is this a good choice? Or can you recommend something else?

Or maybe a GM pump?

http://www.summitracing.com/parts/NAL-3969870/

Or a standard Melling?

http://www.summitracing.com/parts/MEL-M77HV/

Going to rew this engine about 7-7200 RPM

Re: 427 CBB oil pressure
 

The Schumann pump is probably the best off the shelf pump for under $200.

Re: 427 CBB oil pressure
 

70SS/RS396
Evidently this is less oil pressure than this engine had when ran before or you probaly would'nt be concerned about it? I ran and seen lots of engines live long lifes with that pressure.
If this is lower than engine had before,does it have main studs or have you changed to a stud set? The reason I'm asking this is because BBC main studs alot of them have a 12 point nut that goes next to oil pump,because the hex nut alot of times won't clear the oil pump and will hold pump off main cap.
If nothing else is wrong and you have HV pump w/hi press.spring that comes in them you probaly have about .004-.0045 bearing clearance
std. vol std.press pump you probaly have about .003-.0035 bearing clearance,that is if you don't have leak somewhere.
I would test pump before I bought another one installed it and had same results,if pump puts out around 60 lbs then you know it's not the problem.
Mike Taylor 3601

Re: 427 CBB oil pressure
 

Hi

No the engine has the same oil pressure as before (in the 80s, when it was raced in stock eliminator).
I know the engine has ALOT of 1/4mile runs with this oil pump and pressure. So it sould be fine. Talked to the builder of the engine and he modified the pump to have this low oil pressure. He drove QS w40 oil, he tried thinner oil, but he had some problem with the puchrods went thrue rockers when he rew 7400+ rpm. But with the w40 oil it was OK.

But when I talk to people now all say, change the pump....you need more pressure....7-10 psi / 1000rpm.

So I dont know what to do :)

Re: 427 CBB oil pressure
 

Unless the rockers are turning blue, the pushrods did not go through the rockers due to oil weight. If they did turn blue, there are probably a pair of oil flow restrictors in the back of the block, take them out and throw them in the garbage, put a pair of pipe plugs in the block in their place. Then put a good oil pump in the engine with a 70 psi relief spring. I'd put a high volume pump in it with anti-cavitation slots, but that's just me. Then you could probably run a decent 10W30 racing oil and be just fine.

Why didn't you say the oil pump was intentionally modified in the first post? It would have saved a ton of time and effort.

Re: 427 CBB oil pressure
 

Please read the first post again ;) Sorry, didnt mention that it was modified to have less oil pressure.

"The motor have a stock GM modified oil pump (anti-cavitation grooves)"

The rockers isnt blue, they looks just great :)

I have looked at this pump, what do you think about this pump?
http://www.summitracing.com/parts/MEL-10778C/

Its a Anti-cavatation design pump, but it says "Using this oil pump will reduce pressure at idle"
Is it any problem to drive this pump on the street with the reduced idle oil pressure?

Re: 427 CBB oil pressure
 

Anti-cavitation grooves did not reduce your idle oil pressure too much in your current pump, did they?

I would not be surprised to find that the relief spring in your current pump has been clipped to reduce the oil pressure.

You could probably just call Melling and ask them to send you the high pressure relief spring for an M-77HV, and just put that in the pump you have now.

The weight of the oil had nothing to do with the pushrods going through the rockers if the rockers did not turn blue.

You can run whatever oil you want, but as a customer once said, "I wouldn't pour Quaker State on a rusty plow".

Re: 427 CBB oil pressure
 

When pushrods went through that was valve float that caused that,if engine has ran this way parts look good I would leave it alone.
Oil has changed since it was last run get something made for racing that has zinc,Brad Penn,Lucas are what I use most of
Mike Taylor 3601