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Changing Oil Pump on a Big Block

 
Old 05-02-2019, 07:28 PM
  #41  
derekderek
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You could put a crank in it. I would also do rings. Now you are at the precipice. Rebore, new pistons, now I should go forged crank and pistons. New rods. Oops. Just spent as much as a 496! Buy a crank. Cores are cheap if you want a 10 cut. Done 10-10 cranks are the price of cutting yours to 20. This is a weekend cruiser. Not trying to get into the low 12's. Ok, heads are off. Leak test. Put either port side up. Fill ports with water. Any coming thru the valves? Flip over do other ports. I am not a fan of 40 year old valve springs anyway. Valve spring compressors are well spent 50 dollar bills.

Last edited by derekderek; 05-02-2019 at 08:25 PM. Reason: Bill's.]0988up0ppp and and 8p
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Old 05-06-2019, 11:13 AM
  #42  
pl2000n
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Ok, I had time this weekend for a tear-down. Here's the damage: main journal (all are the same), cam lobes, and lifters. The cam is a Howards roller. I don't know the brand of the lifters. The cam, lifters, push rods, and valve springs were all provided by a local shop. Heads were rebuilts by the shop. I've never seen anything like this on the cam lobes. All lobes are damaged. On the lifter, you can see a groove on the side of the roller. The other side of the roller is a nice chamfered end. Any ideas? Are the lifters simply incompatible. By the way, I'm grateful to all who steered me away from installing the HV pump. I'm lucky I didn't spin a bearing!



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Old 05-06-2019, 11:46 AM
  #43  
Jebbysan
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Look in the back of the block above the cam tunnel....are there oil restrictors in the two threaded holes?

Jebby

Last edited by Jebbysan; 05-06-2019 at 11:46 AM.
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Old 05-06-2019, 12:18 PM
  #44  
stingr69
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Cam walked forward?
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Old 05-06-2019, 12:31 PM
  #45  
Jebbysan
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Good question....did it have a cam button?

Jebby
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Old 05-06-2019, 01:59 PM
  #46  
jackson
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Originally Posted by Jebbysan View Post
Look in the back of the block above the cam tunnel....are there oil restrictors in the two threaded holes?

Jebby
Originally Posted by stingr69 View Post
Cam walked forward?
Originally Posted by Jebbysan View Post
Good question....did it have a cam button?

Jebby
???? also core shift? lifter bores never aligned with cam centerline?
-edit- Also, ? valves too tight? Springs too weak (lifter launch) ? Coil Bind ? Too little retainer-seal clearance ?

Also, I note the roller cam is the cheaper cast core.

Have an acquaintance who installed cheaper howard's cast roller in a 350 roller block. It quickly failed & looked like PL2000n roller. AND it wrecked valve guides in new brodix heads. I suspect he did not know to achieve correct rocker arm geometry & pushrod length. IIRC, howard did Not warranty cam etc. IIRC he did replace cam with GM steel roller AND achieved correct RA geometry & PR length.

Last edited by jackson; 05-06-2019 at 02:15 PM.
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Old 05-06-2019, 02:32 PM
  #47  
derekderek
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It does look like the cam was not lined up with the rollers. The edge of the roller was in the center of the lobe. Does the engine have the machined surface and 2 threaded holes like the gen 6 bug block for a real cam retainer? Requires a cam with a step nose, but you can be sure cam is staying put. It was the hunks of cam that ate the bearings. Is it possible this is a flat tappet cam that had rollers run on it?
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Old 05-06-2019, 04:37 PM
  #48  
pl2000n
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Well, some lessons are learned hard both in money and time. But at least it's only time and money. derekderek wins the "find the cause" contest. Looking at the photo you can see that the lifters on the left are installed incorrectly while the ones on the right are correct. The slight rotation of the rollers must have caused them to dig into the cam. I can't believe I didn't notice this when they were installed, but there you have it. Six were installed this way.

Other answers: No cam button. I'm using a Gen 6 engine cam retainer, factory GM part. The cam can't walk with the retainer. The cam, lifters, and push rods were all from Howards. Correct new valve springs were installed. Once together with plenty of assembly lube I rotated the assembly and checked for bind. All was good.

The block, main caps, rods and crank are at the shop.

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Old 05-06-2019, 04:51 PM
  #49  
zwede
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Oh, that brings back memories. Did the same thing years ago on my 454. Luckily my cam was steel and damage was minimal. New cam, one new lifter pair and all was well again.
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Old 05-06-2019, 05:39 PM
  #50  
jackson
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Originally Posted by pl2000n View Post
Well, some lessons are learned hard both in money and time. But at least it's only time and money. derekderek wins the "find the cause" contest. Looking at the photo you can see that the lifters on the left are installed incorrectly while the ones on the right are correct. The slight rotation of the rollers must have caused them to dig into the cam. I can't believe I didn't notice this when they were installed, but there you have it. Six were installed this way.

Other answers: No cam button. I'm using a Gen 6 engine cam retainer, factory GM part. The cam can't walk with the retainer. The cam, lifters, and push rods were all from Howards. Correct new valve springs were installed. Once together with plenty of assembly lube I rotated the assembly and checked for bind. All was good.

The block, main caps, rods and crank are at the shop.

awful fugly ... sorry.
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Old 05-06-2019, 10:43 PM
  #51  
TimAT
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Make double sure the shop pulls ALL of the oil galley plugs-- the ones down the left side of the block AND the ones at the cam tunnel..
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Old 06-11-2019, 01:20 PM
  #52  
pl2000n
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Well guys, I can't thank you enough for holding my senses to the fire. Had I installed the HV pump, I would have had good oil pressure but only for awhile! I could have damaged the crank beyond repair, or worse, a spun bearing. So it's take awhile, but the mains and pins are at a happy 20/20 with chamfered oil holes and radiused journal ends. She's back together, fired up second try. Best of all, I have excellent oil pressure! When at full temperature, oil pressure is just below 35 psig shown on the factory gauge. That's an incredible improvement over what was doing. So thanks again! Now, does anyone want a brand-new-in-the-box Melling HV pump?
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