Engine help, 1957 Chris Craft

Hey guys, a buddy and I restored his 1957 Chris Craft last year and it's back for a little maintenance. It has the original B series Hercules 4 cylinder flat head engine that we rebuilt using hard to find NOS parts. It seemed to lose power suddenly on his last outing, so I did a leakdown test because I suspected a blown head gasket. As I suspected, it is leaking badly between cylinders 1 and 2, so we've ordered a new head gasket. I've also requested a new set of head nuts since the acorn nuts supplied were too soft to take the torque and a couple of them stripped.

My question is concerning the rings. Even on the cylinders that weren't leaking at the head gasket, we were getting excessive ring leakage. The engine was bored .020 and new NOS pistons and rings were installed. The cross hatch pattern was still very visible in the bores with the head off. How long should it take for these rings to seat? I'm assuming they are original cast iron rings from the '50s or '60s and I don't have any experience with them. I've never had a ring problem with any modern components, so this was surprising for me. Should I re-ring the engine using a set of total seal rings like I use in the race car, or should I continue to run in the engine to see if the seal improves? Compression on this thing is only about 7:1 (stock rebuild), so I'm not sure what's going on.

Any thoughts or advice are welcomed. Thanks, John

Put a mast and a sail on the boat and problem solved.

Could it be valves seats, rather than rings?

Leakage is into the crankcase, not out the exhaust pipe or the intake manifold, definitely rings.

John
I am all for NOS parts but in the case of engines I think you'd be a lot better off with modern parts especially when it comes to gaskets. You don't say how many hours you have or if the motor was properly broken in. That would imply not over reving until the rings had seated. Given the cross patch is still visable, I'd say they haven't. Were it me, I'd go ahead and re ring and use Hasting or some other better quality. Some prefer Perfect Circle. Just avoid the Deves and off brands IMHO.

I'd re-ring with plain rings too. It could have been ran too hard and "burned" new rings. I did that riding motorcycle with a fresh overhaul too fast for the 1000 miles from here to Norfolk, VA once.

As you know and should tell the owner: Cast iron rings need to be seated fairly gently with long term easy acceleration and deceleration whereas Chrome rings need to be ran hard with long hard accelerations for a relatively short period when the engine is warmed up the second time.

Thanks for the info. I'll talk to the owner about re-ringing using a modern ring pack. The engine only has about 50 hours on it, and only runs 3200 RPM, but he may not have followed proper break-in procedures.

John, who was around when Henry began mass production nailed it....cast rings need low rev break in and Chro-moly need the other he advised. Break in is absolutely critical even with a marine motor.

My hats off to John....a real mud romper who is from the same town as Rush Limbaugh....
:devil:

You better have the head checked. Sounds like it might need to be decked. That is unless you just could not torq it in the first place. Rings should have seated in 50 hrs of run time.

Dave

"I love boats, can't wait to sell mine."

I'll check to make sure it's flat and crack free while I've got it apart. Thanks again!