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low oil pressure in a '55 331

Started by woodillac, March 08, 2018, 03:23:17 PM

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woodillac

I built a '55 331 a while back and after some early issues got it to run well. It produced about 30 lbs oil pressure under normal conditions. This was with a bypass remote oil filter. I was using '52 heads. I developed more issues with the motor and had to disassemble it again (rings installed wrong). The oil pump was removed. I reassembled the engine but this time with '57 365 heads and the redesigned lifters and push rods. After reassembly I noticed the oil pressure was falling off. After initial start, the pressure would climb to just over 20 lbs then after a few moments dropped off to <10 lbs. and would not come up again. I switched the new lifters and push rods back to the "old" style and that had no effect. Then I isolated the remote filter (blocked it). This time after starting the engine the pressure went to about 30 lbs, held for a little longer but then dropped back to <10 lbs. Did I do something wrong installing the oil pump (bought new from Terrell Machine)? Even though the block is a '55, the oil pump does not a have a vacuum pump, it was blocked off early on (and didn't affect oil pressure).

Jeff Rosansky CLC #28373

I absolutely chased my tail on an oil pressure issue for no reason at all.
Are you measuring it from the stock location with a known good gauge? If it is an aftermarket electric/digital gauge please remember when the generator goes off line the voltage will drop and the pressure will read low.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

walt chomosh #23510

doug,
  Here's my 2cents. I rebuilt my 1955 331 and noted that if the oil level got near a quart low the rockers would chatter. Over time I fought OP problems and just couldn't solve it. At one time I did a lot of oil pan work on drag race cars thus am no rookie. However, in the back of my brain I remembered assembling the 1955 oil pump pickup tube and wondering "why isn't there a seal between the pickup tube and block"? Other CLC members tell me that the manual doesn't show such a seal for certain years,1955 included. I had another CLC member (Roger Zimmerman) physically look at more then one pump and confirm this. Well,bottom line, Fel-Pro told me that there is a felt seal (which wasn't in my overhaul kit) that I had left out. When the oil level would drop to a certain point the pump would suck air. (ruined all my rod bearings but no crank damage....simple repair done in the car in no time at all!) Thus, OP problem solved! Thank you Roger and other CLC members for getting me on the right track....by the way, I did install a tee where the OP switch outlet is so I can monitor OP...walt...tulsa,ok

woodillac

You are right. I had to make a "gasket" out of Felpro material, it has two holes for the bolts and a center hole for oil. That's probably not an issue here. We ran a SW mechanical gauge off the tapped hole at the rear where the indicator is located. The oil sump is full. We noticed one thing, when we removed the pass. side valve cover and ran the engine, oil was squirting from the rear of the rocker shaft where the oil enters the shaft. Maybe cracked bracket? Maybe misalignment. The v-marks on the front of each shaft point towards the center as shown in the shop manual. The drivers side rocker shaft ran dry (no oil while running).

walt chomosh #23510

doug,
  If I remember correctly the seal between the oil pickup tube and pump was felt without any holes other then the one down the center. I made mine myself using a hole punch. This allows the pump pickup to swivel so many degrees. I remember turning my pump using a drill motor thru the distributor hole and watching rockers get oil, which takes quite a while for all to receive their dose....let us know what you find out...Fellow CLC member John Washburn could possibly give some insight on the problem. He just overhauled a 365 and the details are in the last couple of "self starters".....walt...tulsa,ok

Jay Friedman

#5
Quote from: woodillac on March 09, 2018, 11:02:29 AM
We noticed one thing, when we removed the pass. side valve cover and ran the engine, oil was squirting from the rear of the rocker shaft where the oil enters the shaft. Maybe cracked bracket? Maybe misalignment. The v-marks on the front of each shaft point towards the center as shown in the shop manual. The drivers side rocker shaft ran dry (no oil while running).

If oil is squirting from a rocker arm shaft, this will cause low oil pressure since, of course, oil inside the shaft is under pressure.  Also, it's possible your driver's side rocker shaft is dry because of the low pressure.  Some years ago I had low oil pressure in my '49's 331 which I eventually figured out was caused by a cracked bracket.  I took apart the rocker arms, brackets and springs, replaced the bad bracket with a good one from a "parts shaft" and the problem was solved. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

woodillac

Problem solved! It turns out that the aftermarket rocker shafts I bought were marked incorrectly. The passenger side was squirting oil because holes in the shaft were misaligned. The end (presumed front) of the shaft that was notched was correct only if the mark was pointing AWAY from the block. The holes were pointing down but the ancillary "offset" holes were in line with the holes with the rocker hole. If I turned it around with the mark at the rear, it faced the engine. AND the ancillary holes were well off the rocker holes, the correct arrangement. Beware of markings on aftermarket shafts. I now have 30-35 lbs at 1500 rpm.

Jeff Rosansky CLC #28373

Good for you. Thanks for the update.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

walt chomosh #23510

doug,
  VERY pleased you solved your problem before doing any damage!....walt...tulsa,ok