brand new 377 broke the timing chain after 16 laps

[roundboy]

Had a all new motor built by a awesome engin builder and it broke the timing chain with only 16 laps on the motor... this is a steel headed, stock block 2-barrel motor and didnt turn it over 6800 rpm's... could it be just a weak chain or could something else have caused it?? Thanks in advance..

[roundboy]

Stock 400 block with splayed caps, has been line bored, flat tappet cam with .550 lift on both sides, dart heads set up with the correct springs for the cam, roller rockers, and if there is anything else you need to know, ill tell ya... im really frustraited on why this happend after buying the best of the best to put in this motor...

[FLYNBRYAN]

2 things
How much crankshaft end play?
Do you have a broken main web?

[roundboy]

I honistly dont know, we are going to tear it down thursday, i was just trying to get some ideas ahead of time... when i got the motor, it was ready to bolt in and fire up so i dont know any of the detailed specs on clearances and everything... the block was a 2 bolt block and he put the splayed caps on it so it could have cracked a web through the machining process... and it could have just been a defective chain or gear, i was more or less fishing for ideas... thanks for the response....

[stock car driver]

There are 16 dollar chains and 100 dollar chains, big difference.

If you havent taken it apart are you sure it didnt break the cam or something else first?

[DaveBauerSS6]

Seen a cracked crank snap a chain..

[roundboy]

When it happend, the motor would crank over really fast, the crank pulley was still turning, but the rotor on the distributor wasent, so my first thought is timing chain.. it could be the cam, but im not 100% sure yet... the builder said its the same chain he uses in all his racing motors, from hyd cams to roller cams... ill let u guys all know forsure what happend thursday... i was just looking for ideas... im just sick that i have put so much money into somethimg for it to last 16 laps and then have to come apart again, but thats racing... thanks for all your responses....

[Hammer]

if the distributors rotor is not turning and your spinning it over 1 you have a hell of alot of piston to valve clearance which IMO is in possible to have that much and spin it over without hiting the valves. i never had that much clearance.. i would think you striped the gear on the distributor or cam JMO

[gun91]

Also when you pull valve covers you can see if all the rocker arms are moving or not. If they are but the dist isn't then I would pull dist and look at it. I have sheared the pin on the dist gear before

[roundboy]

I pulled the distributor when i found the rotor wasnt turning and it was fine, didnt pull a valve cover, i didnt want to get into the motor because the engin builder wants to tear it down...when the motor was spinning over, u could hear the valves slapping the pistons, so thats why i though timing chain to begin with... ill let you all know forsure what happend tomorrow... thanks again for all the responses....

[Crash 4]

Possibly spun cam bearing.

[rubbinsracin]

We broke the snout of a cam one time right at the 2nd or 3rd lobe one time. A couple of valves sorta worked. But the rest slapped the pistons. Broke a couple pistons and destroyed every valve it hit as well as the cylinders that slapped. Probably gonna take alot of parts to get'r going again.

[roundboy]

The builder said he would make good on it because when we started, i told him, build it like you was building it for your self... dont spare no expense... and when i told him i had trouble, he told me, yank it out and ill make it right.... so we'll find out tomorrow what all is good and what all is broke... as soon as i find out, ill post it on here and let you all know what we found out... thanks again for all the responses...

[turner]

Maybe sheared the roll pin in the distributor gear??

[sj valley dave]

He said he pulled the distributor and it was good...look at 4 posts before yours..

[perfconn]

Flat tappet cams are cast iron.They break very easy.I've had them come in from UPS broken.Thats the reason Comp Cam uses FedEx.

[stockcar5]

Flat tappet cams are cast iron.They break very easy.I've had them come in from UPS broken.Thats the reason Comp Cam uses FedEx.

yea cause fed ex NEVER damages anything..lol

http://www.youtube.com/watch?v=PLoIGu3mm5o

[roundboy]

Well, just left the engin builders shop and the cam bolts backed out and let the top gear come off the cam.. i dont know if he didnt tighten them down, lock tight them, or fold the tabs down on the lock deal that locks them in place, but either way, he is going to make good on his word and fix whatever is broke.... didnt mean to jump the gun and blame it on a broken timing chain, but that was my first thought... thanks for everybodys input in this whole subject.....

[stock car driver]

Well, just left the engin builders shop and the cam bolts backed out and let the top gear come off the cam.. i dont know if he didnt tighten them down, lock tight them, or fold the tabs down on the lock deal that locks them in place, but either way, he is going to make good on his word and fix whatever is broke.... didnt mean to jump the gun and blame it on a broken timing chain, but that was my first thought... thanks for everybodys input in this whole subject.....

Sounds like a good guy to make it right. He clearly didnt bend the tabs...

I had a wire lock on a je piston puke out a pin first night on a all new most expensive motor I ever built and my guy to this day wants to argue it wasnt what happened first...

[roundboy]

Parrot, thats exactly what happend... the lock plate was on there, but not bent agenst the head of the bolts... we got lucky cause it only bent 3 valves, 2 ex and 1 in, how we got that lucky, i will never know.. but yeah, as parrot said, people coming in and out and the phone ringing, it just got over looked, but hes already got it done, so im putting it back in today and hoping mother nature gives us a break here tomorrow.... thaks again for everyones input, it was a pretty stressfull time waiting to find out what was wrong with it because i dont have a spare and didnt have the money to start over right now.... but he was good on his word and hopefully the rest of the season goes smooth!!!