blue thunder

On the wishful thinking side, maybe when the engine was built the assembler did not install the front galley plugs with the .060" holes. These holes are there to provide a source of lube to the rear of the cam spocket so it will not gall up on the block and seize. If this were the problem and if you have enough piston to valve clearance you may be in luck. Lot of "ifs" there, but at least a small ray of hope. Look closely at the backside of the cam spocket for signs of heat and galling.

BT

Pat McPherson

OK Guys, I tore into it a bit farther.
Dropped the pan down and got the timing cover off.
Looks to be a failure of the gear on the crank and the bolts and pin holding the cam gear to the cam. The chain is still in one piece surprisingly...
I pulled the cam and lifters out and they look like new, other than the bolts snapped off in the cam. The oil pump also spins freely.
The piston did hit a couple of the intake valves though. I can see that they are still open when I look down the intake ports.
Next, I guess I'll pull the heads to see what the pistons look like. With my luck there will be holes in them...
If I have any luck, the bottom will be OK. I have the stock cam and heads that I could bolt back on.
Any thoughts?
Thanks again for the advise,
Patrick

kennyo

What type heads are you running? My t/c broke on my engine after upgrading to merlin heads. They neglected to machine the top of the valve guides and it was bottoming the retainer. About 4 hrs later I was running @4000rpm and it broke. Of course they denied it but my very sharp machinest showed me the cause.To this day I am still warning people off of them. I told them I was going to get my money or cost them money. Sorry your missing out on the rest of the season. I know I should have checked them before installing but if you pay $1400 you don't expect to have to do that.

Pat McPherson

Tempest,
I am crossing my fingers the piston are not too beat up... Would be great if I can get through the rest of the year with the stock stuff.

kennyo,
I was running a set of modified l-29 Vortec heads. The engine has about 60hours on it since I changed the heads and cam. I still have the stock heads and cam that came off.

Thanks for the replies,

z.zuperboat

Piston Are Stronger Than You Think.make Shure They Move From Side To Side And The Rings Are Not Frozen.slap It Back Together With The Old Parts For The Rest Of The Year.why Did It Break?did You Locktite The Cam Bolts?cambutton Thrust Bearing What?

Pat McPherson

No, ZZ I did not use locktite, but I will next time. Inch-pound torque wrench is not enough. They must have loosened up causing the failure.
The engine is a Gen 6, so the cam is held in place by a trust plate. The cam slid right out and the bearings look fine.
Ordered up a new timing set, and gaskets; let's hope for the best!

blue thunder

I wacked all my valves in one engine last year. Your pistons will be fine. Your cam will be fine too. No need to change unless it is improper for the stock heads. Just check the pushrods. When I did mine it was all the intake valves bent and only a couple exhaust.

BT

Pat McPherson

I hope your right BT. The cam is too big for the stock heads so I'll use the stock ones. Thanks for the advise; I will check the push rods. Maybe I'll just change them, I have another set. Should I change the lifters too? What do you think?

blue thunder

You cannot use the current lifters with the old stock cam. Lifters and lobes get wore in to each other and cannot be moved to different lobes or used on different cams after breakin. Do you have the original cam and original lifters which are marked for which lobe they belong? If not, I would either continue using the current cam/lifters or buy a new cam/lifter set and breakin accordingly.

BT

Pat McPherson

Original GM roller lifters with about 180hours...
They had about 120 hours when I changed to the 454HO cam.

Guys, I'm only looking to get through the rest of the season (20-25hours).
I'll do a complete rebuild this off season or buy a new base engine.

Thanks for the help,