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gtx8



Joined: 20 Feb 2007
Posts: 1




PostPosted: Wed Feb 21, 2007 9:34 am    Post subject: 400 motor Reply with quote

rebuilot 4oo primed oil pump started engine 60 psi oil psi ran for about 10 min went to 40 psi then to 20psi no oil up to rockers #8 hole lifter is still not pumped up bought a comp cams kit how can i get more oil psi and get oil up to rockers hasnew oil pump melling unit have chevy lifters in engine? all cleareances seemed to right any help
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Larry
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Joined: 01 Jun 2006
Posts: 4768




PostPosted: Fri Mar 02, 2007 12:37 pm    Post subject: Oil Pressure Reply with quote

You don't mention if the oil pressure was OK before rebuilding. That would probably eliminate questions of plugged passages, etc.
The 60 psi was probably just because the oil was cold, unless you have a high pressure pump now. Normal pressure at 2600 rpm is 38-42 psi (at least shown in a 1977 manual).
A drop to 20 psi? What engine rpm?
#8 lifter not pumped up? Is it hammering? Was it dry when you installed it? Is there no oil whatsoever at the rockers? Any of them?
I'm leaning toward an oil pump spring problem if pressure was high and then suddenly dropped in an engine that before did have good pressure.
I don't understand the reference to Chevy lifters..?
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rexs73gto



Joined: 17 Sep 2015
Posts: 94
Location: Niles MI

1973 GTO

PostPosted: Thu Sep 17, 2015 3:33 am    Post subject: Reply with quote

You say you have chevy lifters in your Pontiac block. Thats the 1st problem right there. A chevy lifter has the oil hole in the lifter in the wrong place for them to pump up correctly. Your lifters won't pump up if they can't get oil into them. You need to take the chevy lifters out before you do any damage , which you may have done already. But you need to put a set of PONTIAC lifters in it & then go back & PRIME that engine until all the lifter & rockers have oil coming out of them. Now I do have a question ,, WHY & WHO told you to put chevy lifters in your Pontiac engine.??,, & why did you listen to them.????Before you do any more damage to your engine get them out of that engine NOW. Also drain the old oil out & put new fresh oil in it. Next your Melling oil pump is made with& as a 60lbs pump & they no longer make the cheap 40 lbs pump any more. The pump you have should be an M54D if you were to get the only other pump that Melling makes right now if the M54F which is the 80 lbs pump which I use on all of my builds. You have a good pump , also make sure your using an oil filter that has the bypass in the filter in it so you always get full pressure through your filter no matter what. Do NOT use FRAM filters ever on any Pontiac or any engine you want to last.
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I have a 73 GTO that I bought new, well it was a demo because the car I ordered was an SD car which never came in & i had to take what was left because I was in the Navy & had to talk to the dealer when I could.
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