Anyone ever break a camshaft in two ?
 

I have a 38 Cigarette with 94 502's Last week i was driving along at 4000 RPM @50 MPH when one of my motors just shut right down. Myself ad EPEEK tore the front of the motor down last night and found my cam in 2 pieces. WTF ?? What would cause this. The motors were gone thru and redone 47 hour ago and they have a total of 448 hours since new. I have had no problems with them except that both of them love to use oil. Proably a quart every 5 hours or so. I had just checked the oil the day before and add 2 quarts so I dont, and I repeat, dont think the oil was low when this happened

Any input would be great

We prepared the motor to come out of the boat last night, and should get it out this week and tear it all the way down. Hopefully not alot of internal damage ??!!

Bob

I've seen one that broke, probably due to a failed cam bearing. It also destroyed the block when it let go.
Gary

I've seen several break was it a flat tappet hyd. or solid ??? where did it break ?? useing that much oil it changed itself ,wow

you'll need to clean even the wrist pins ect that metal falls everywhere

I am curious what would make a cam bearing fail. Relative to the rod and main bearings cam bearings are lightly loaded. Does excessive oil temps hit cam bearings hard? With a BBC oil starvation will show in mains first. How can one tell if cam bearings are a problem before disaster?

BT :cool:

My wife did when she drove my Bronco in low loc at 75 for 25 minutes! 400 M at 6200 for 30 miles should about do it. Very different situation but a cam will break.

Well that sounds like an oil temp problem Bad dog :eek: I bet you got reamed for leaving it in low loc, if she is like my wife :mad:

BT :cool:

Bobby Daniels, It broke between the first & 2nd lobe. I dont
know the motors,but I think its a hyd flat tappet cam.


Rick

I beilieve the 502 run rollers.

A customers boat threw a rod and broke the cam. Customer said engine just died. Cranked fine but no spark!!

Things to look for with a broken cam:

All cam bearings-may have uneven wear on one.

Cam bore-may cause one brg to wear.

Loss of oil to cam brgs causing friction-look for scoring.

Too much endplay at cam-rocks back and forth and unevenly loads timing chain-force is transferred to cam.

Rick if its the stock cam I've seen 2 others break there and your is the third ,If you need a stock cam I have several take outs I'll give you if needed or you could go custom in both motors I think the cams were bad parts unless you find something please advise ;) ;)

Hey Bobby.... you ARE using the MSD lifters with the MSD camshaft, aren't you, or did you use the brand X cam, and the MSD billet lifters? rotflmao

Bob
Sorry to hear of your troubles.
Please let us know what you find.
Chris

CAMSHAFT BROKE IN TWO
 

yep!!!!!!!! snapped in half.Looked like it was defective:mad: Not sure though,Broke off at the front of the motor flush.:rolleyes: :D /Darin:cool:

Broken Cam??
Yea, when the crank, rod, piston,lifter, cylinder wall all broke on fathers day!
I'm reduced to riding the ferry to Block Island this weekend AHHHHHH!!!!!!,

Im going to be away in Buffalo this week on FD union buisness, so I wont have a chance to tear it down. I will advise all of what we find next weewhen I get the chance to do so

Bob

Yes sir The MSD cams don't break or eat lifters now brand X thats another story but they build one hell of an ignition :D :D :D :D :D

This seems to be a common problem with gen5 hyd roller cams. A buddy of mine pointed this out to me years ago. When I build my roller 496 I'm going solid.
I guess I'm going to have to stay happy with the mag motor until I get around to putting the 496 together. I also wont need to worry about blowing up my Bravo either. It's ok guys if you wanter go faster than me. I will someday have a serious piece of machinery! ;)
All it takes is $ $ $ and More$$$ BBB

Try a billet cam. If there is a buzz in the harmonics, cast cams will snap.

575 SCi 75 hours broke between 4 and 5.
Running below 3000 rpm at the time.

When mine broke it was because a rod cut it in half. Of course, the rod wasnt connected to the piston anymore. Ive seen real high lift solid cams break when something went wrong up above in the valve train and the lobe couldnt push the lifter up, sometimes, pushrods that are too good are bad.

A common cause of cam breakage can be the harmonic balancer (dampner) itself.Either being "bad" or the wrong one for the application".

The 575SCI I mentioned that broke a cam had no broken valvesprings. Had no thrown rods.

Sure, it bent a bunch of valves and bent some pushrods.

But that's all.
This was in November.

odd

I have one in the garage I saved thats in 5 pieces.Started with valve,then piston,then rod,then piston pin sliced block,and upon disassembly a 5 piece camshaft.There was not a piece of piston more than 1" square.What a horrible noise that made.Its kinda cool how the piston gets sucked into the intake and redistributed into th other bores.

Re: Anyone ever break a camshaft in two ?
 

I have Crane solid rollers, cam broke at very rear, just before distributor gear. After talking to a couple builders, this is not new with Crane..Apparently this is the reduced cross sectional area that is where the gear is attached to the cam? Bottom line was that no damage other than cam! Oh baby, was I lucky!

Re: Anyone ever break a camshaft in two ?
 

I know this thread is getting old but if the next cam bearing behind the break was not installed with the oil hole lined up properly I'm thinking that journal might not have got oiled. May have led to it seizing and then causing the break.
Good luck. , Jerry.

Re: Anyone ever break a camshaft in two ?
 

Like Bob,
I broke a cam just in front of the distributor gear. It was a Crane hydraulic roller with the iron distributor gear, cam #168731 running in an HP500 motor. Only 60 hours on the cam and lifters. Everything else looked fine: the distributor gear, the oil pump, the cam bearings, etc... The motor was running at 2500 rpm at the time and simply shut off. Fortunately did no damage to anything else. Crane will warranty the cam since it is within one year of purchase, but what a pain in the rear. Makes me nervous about my other motor that has the same cam. With the cam in two pieces, you can see that the shaft is necked down at the point where the iron distributor gear is pressed on. Is this a bad design or what?

Re: Anyone ever break a camshaft in two ?
 

Yep, Sure Did. Broke a SBC Isky during break-in. no pun intended

Roby

Re: Anyone ever break a camshaft in two ?
 

add another crane cam to the list. 741 hydr. roller, broken at dist. gear after 65hours.......................................suck s, but still hoping for no other damage.....................

Re: Anyone ever break a camshaft in two ?
 

I heard of a 454 breaking a cam last week from my mechanic, secondary to hydrolock.

A quart of oil every 5 hours sounds a little high *to me*.
High oil temps wont kill your motor in the short trerm.
I ran a 377ci race motor for 3 seasons in my vette @7500 rpms, oil temps at 300*+ (water at 220*), but the mains finally let go durring a race at Laguna Seca, (still took 2nd place though).

Sorry to hear about your motor.

Re: Anyone ever break a camshaft in two ?
 

You know, spinning a bearing at Laguna Seca doesn't sound like such a bad thing to me - has anice ring to it -- it would mean I was actually racing at Laguna Seca---:D!!!!!! Someday, I'd like to break something there:D