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Old 12-26-2010, 09:58 AM
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1970 Olds 350 - Inspection Advice

I just purchased a 1970 Oldsmobile 350 long block with #6 heads. The seller advised it was a fresh rebuild but could not provide me with any details as he did not do the work. I heard it run before he pulled the intake and carb (the valve train sounded a little noisy), saw golden oil, a clean rocker assembly (no sludge) and almost no carbon in the exhaust ports.

Now that I have it home, I think I should tear it down and put it back together. Does the forum agree? Anything I should look for?

Couple thoughts I have going into this...

1. Hoping when I pull the cam it has some numbers on it that will help me identify it.
2. Noisy valves... Maybe the valve seats were ground but the valve length was not adjusted? It still has stock style rockers. Maybe I should go to a aftermarket setup with studs so that the valve train can be adjusted.

Thanks in advance for any suggestions

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Old 12-26-2010, 10:14 AM
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Absolutely disassemble and inspect

Check bearing, piston and rod side clearences. Crank and rod bearing clearences should be on the large side.
Make sure crank is ground properly
Check for type of pistons used, cheap cast Olds pistons are short on compression height, which along with replacement head gaskets, will lower compression considerabley
Correct thinking on valvetrain errors. Most rebuilders dont equalize valve stem height. Also make sure that cam break-in was followed correctly with proper ZDDP levels, or you may have a wiped out cam lobe.
Cheap timing sets are notorious for not having the dowel holes in the right location, so degree the cam. A well built Olds 350 should have plenty of low end torque if the right cam is installed correctly.
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Old 12-26-2010, 11:35 AM
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Quote:
Originally Posted by FmrStrtracer
Correct thinking on valvetrain errors. Most rebuilders dont equalize valve stem height.
X2. In our Chevy-centric world, most shops do not realize that the non-adjustable valvetrain in an Olds requires not only equalized valve height but each stem set at a specific correct height.
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Old 12-26-2010, 07:56 PM
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Quote:
Originally Posted by FmrStrtracer
Check bearing, piston and rod side clearences. Crank and rod bearing clearences should be on the large side.
Make sure crank is ground properly
Thanks for the advice. What should the clearances be? Also what would tell me that the crank was not properly ground?

Thanks, Dan
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Old 12-27-2010, 10:33 AM
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Quote:
Originally Posted by dsolomon
What should the clearances be?
Rods:.0028-.0035 seems to be the modern thinking for a performance engine, .0023-.0027 for a stocker.
.0035-.004 for the mains.
.008-.012 on rod side clearence for steel rods.
Melling Oil pump, no oil restrictors

Quote:
Also what would tell me that the crank was not properly ground?
Measure the journals at several different points to make sure its not tapered
Check thrust clearence at several points to make sure the surface is perpindicular to the block surface.

All things a good grinder/builder would do, but you dont know who touched it, so ya gotta check.
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Old 12-27-2010, 10:37 AM
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If the only issue was valve train noise, why would you tear apart a freshly built engine. It makes no sense to me. I would fix the valve train noise and run it. If it gives you issues then dig into it.
Why was the intake and carb removed?
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Old 12-27-2010, 06:22 PM
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If you wait until you have issues to check something out, the motor will be scrap. Its not installed, checking bearing clearences is a simple procedure, and could save a lot of grief in the long run.
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Old 12-28-2010, 06:11 AM
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The intake and carb were pulled as part of the price negotiation. They both looked rough and I already had a new Edlebrock 7111 intake and Holley carb that I was going to use on my old 350. Letting the seller keep these two items got the price where I needed it to be.

I was going back and forth on the bearing clearances myself. It is part of the reason I started this thread. I knew I wanted to check the valve train and I wanted to ID the cam.
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Old 12-28-2010, 07:25 AM
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Quote:
Originally Posted by FmrStrtracer
If you wait until you have issues to check something out, the motor will be scrap. Its not installed, checking bearing clearences is a simple procedure, and could save a lot of grief in the long run.
And if you don't have a good clean place to do it and the proper tools, you could ruin what was a good engine. I believe he said he hear it run and it had some valve train ticking was the only issue.
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Old 12-28-2010, 08:18 AM
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engine..

for me, if your gonna pull it apart, i pay the little extra money for a two pc timing cover. if u ever want to replace the cam it makes it easier for u don't need to drop the pan anymore.. best money i ever spent..
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Old 12-28-2010, 10:23 AM
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Obviously the last thing I want to do is ruin the motor but my garage and tools should get me through. Maybe I will pull the heads and the pan and then make my decicison. Might be able to tell the quality of the work by markings and components used.

One more question... How do I determine if the valves have been correctly comp'd?

Thanks for all the advice guys. I will let you knw how it goes.

Dan
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Old 12-28-2010, 12:44 PM
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This isn't an answer to your question but why not call the seller and ask for the contact info of whoever built the engine, and talk to them?
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Old 12-28-2010, 07:44 PM
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Wish I could. The motor changed hands twice in a car that was too much work to restore. The seller bought it as a parts car and could not give me any details.
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Old 02-05-2011, 03:14 PM
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Just getting into the engine. Amazing how long the holidays can affect your schedule...

I went to check lifter pre-load and I have none. Its my understanding that you put the lobes down with the lifter on the base of the cam load, loosen the rocker bolts then tighten finger tight until the push rod has resistance. When the lifter is down the pushrod is loose. I measured them with my calipers and get a overall length of 8.233"

What is the stock length of a pushrod? How do I determine the correct length when they wont tighten up for me to measure at the base of the rocker?

The up side is that it all looks good. Rockers, trunnions, valves and pushrods are new. Hopefully just a bad part selection on the part of the builder.
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Old 02-05-2011, 03:28 PM
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Did you prime the engine to fill the lifters with oil before you did your check?

Stock pushrods are 8.400".

The stock trunion and rocker setup has no adjustment ability. You torque the bolts to 25lb/ft when the lifter is on the backside(or base) of the cam, and thats it.

You can get bolt on roller rockers(shaft mount) that are adjustable, or Comp Cams sells a basic conversion kit that includes studs, guide plates, push rods, and rockers(roller tipped, not roller pivot)
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