Major blow-by on fresh engine

I just purchased a 76 Duster with a 360 that was rebuilt less than 400 miles ago by a professional race shop with all the top parts. Niether the block or the heads were milled but they were surfaced and magnafluxed. It was punched .030, KB pistons, chrome molly rings, bronze guides, stainless valves, roller rockers, heavy duty springs etc. It's a 69 block and heads. I have major blow-by on the left bank.

Here's the kicker. A young kid and his dad bought the car from the builder and had it less than 50 miles. They have no idea what a screwdriver is much less any other mechanical know-how, they addmitted this. Regardless of all the receipts and the knowledge of the original builder they took it to a small 2 stall shop that soaked them hard for new parts and work that didn't need done. Before there was a blow-by issue they took it to this shop who told them the engine needed a ton of work, despite $7,600.00 in receipts from the machine shop that speciallizes in race engines did the build. They convinced them it needed a new intake gasket, new oil pan, new starter,(the receipt for the brand new high torque mini starter was under the seat), new master cylinder(the builder backed off the brakes to load it on the transporter after installing new everything from MC to wheel cylinders, disc brakes up front the whole 9 yards for which all of the receipts were in the folder) and did an oil change. After leaving the shop the engine immediately started having the blow-by issue so they took it back to this same shop and they told them it needed new rings and called every 2 days hounding them that they had the time and could get it right in if they brought it back to them.

I seriously question the integrity of this shop after talking to others and talking to the original builder. No expence was spared on this car and everything was tight and right when it was loaded on the transporter. The kid didn't even know what the recall selector or erase function on the tach were for and I checked it and it had never been over 3200 rpm nor has it ever been above 192 degrees. They put less than 50 miles on the car before putting it back up for sale because the kid was scarred of it.

I've only put about 130-150 miles on the car and have been easy on it. I have no oil in radiator, no water in the oil nor do either get bubbles or foam when the car is running. The left bank has a breather cap but the right bank only has two regular caps on it. When I pull one of the right bank caps it smokes as much as the left. All the plugs are excellent and there is no tell-tale pfssst noise from a head gasket. I do have some moisture out the back but I suspect it may just be condensation because our humidity is way up and the temps are way down. Everything feels equal at the exhuast. I checked the torque on all of the head bolts and they're right at 95 lbs. The shop insured me that the windage tray was put back in when they changed the pan. The PCV valve may be bad as there is no RPM change at all when I hold my thumb over it.

Here's my question. Could that shop have put a light grade oil in the engine that would magnify the blow-by issue from regular break in? I suspect that the rings aren't even seated yet and the original owner feels the same way. Could this be something as simple as the shop putting a light oil in it knowing that they had completely gullable customers with a big checkbook on the hook? I haven't had a chance to check compression accross all of the cylinders yet nor have I done a leak down test on it. My new shop just got finished Wed. and I don't have power yet so I'm trying to do simple things while I wait for it to be ready to move into. How long does it take for chrome molly rings to seat? I haven't been able to wrench on anything for over 20 years so I'm really rusty at diagnosing. I'd like to try as many simple things as I can while waiting for my shop. I plan to change oil and put in a 20-50 synthetic oil.

Any input or guidance on which way to head on this would be greatly appreciated.

Thanks
MOPARDUDE6876

I wouldn't consider synthetic oil at this point. I don't recall the 360 being made in 1969. If there is even a possible problem I'd think maybe gas in the oil causing a problem. I'd change the oil if it has any indication of fuel in it. How does it run? How do the plugs look?

Need something cleared up. You say major blow-by on left bank, then you say the breathers on either bank smoke the same. Do you get smoke out the tailpipes? If so, what color? How does the car run? Do you have vacuum to the PCV?.
I hate to say it, but it sounds like you have been ripped off.
Definitely do NOT go synthetic at this point.You need a good break in oil like Joe Gibbs BR, if this is so fresh.If they did a poor job on the intake, you could be pulling oil and misfiring. It could be that simple. Keep us updated and good luck.

You might do a leakdown test and read this. "break in secrets" at www.mototuneusa.com

A compression test is about as simple as it gets. Do that first IMO

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I just purchased a 76 Duster with a 360 that was rebuilt less than 400 miles ago by a professional race shop with all the top parts.

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I would contact the shop that built the engine, true pro shops will stand behind their product, even after a change of owners.