Little top end oil pressure on a fresh 502 cid

[Joey Baggs]

We bought a freshly rebuilt 502, which we didn't build. The guy who owned it needed a few dollars. Naturally we can't get in contact with the builder. This engine has 60 lbs of oil pressure, but the lifters aren't pumping up. We tried priming the pump with a drill attached to a tool my buddy borrowed. still hardly any oil flow up top. Before I tear it down, is it possible for this to happen if oil galley plugs under timing cover were left out. Any suggestions on what to try before we tear it apart? I really would like to find something stupid I didn't check. Thanks in advance.

 

[bigblock72]

Does the tool look like a distributor? if it is just a straight shaft/screwdriver looking thing then you'll never get oil to the top of the motor since the distributor plugs the galley to the lifters.

Since you have 60 psi of oil pressure you likely do have the right tool and there probably aren't any plugs missing. Big blocks Chevys are terrible for oiling the top end especially after a rebuild. I just built one 2 weeks ago and it took 25 minutes of priming before I had oil to one rocker arm !!! and that required spinning the motor over every minute or so, then another 20 minutes before I had oil to all the rockers.

Use the right tool and be patient and you'll get it.

 

[Joey Baggs]

First, Thank you for the response. I got the dyno results from the builder, at 4500 rpm it's showing about 575 hp. I would imagine it was primed. My question is can they loose the prime? The oil seems to just trickle through the rockers, and the rockers clatter.

 

[Bent77]

Does this motor have solid lifters?

 

[Joey Baggs]

no, it has hyd lifters

 

[Greg72]

Does the tool look like a distributor? if it is just a straight shaft/screwdriver looking thing then you'll never get oil to the top of the motor since the distributor plugs the galley to the lifters.

Since you have 60 psi of oil pressure you likely do have the right tool and there probably aren't any plugs missing. Big blocks Chevys are terrible for oiling the top end especially after a rebuild. I just built one 2 weeks ago and it took 25 minutes of priming before I had oil to one rocker arm !!! and that required spinning the motor over every minute or so, then another 20 minutes before I had oil to all the rockers.

Use the right tool and be patient and you'll get it.

Didn't the later model BBCs have a revised "priority oiling" system to increase oil flow up top... Or am I confused? (Also quite possible!).

-G

 

[sweetk30]

ask scott 4x4high he is our motor man here.

 

[bigblock72]

Do you have any cam specs? What rockers are on the motor? Have you checked the valve adjustment? What oil is in the motor?

The later Gen 5 and 6 do have a better oiling system but they still can be difficult to get to prime. I don't think this is the case here, sounds like it has primed ok but may have some noisy lifters or an agressive cam that makes the lifters noisy.

 

[1-ton]

you might have those high performance lifters that bleed off oil pressure at idle