["Whitey Ford"]

So a few months back I was riding and heard this tinging sound in the top end, almost like the gas tank is loose, well i got on a long stretch and then it got pretty bad but before i could do anything, BAm, i was dead. So I took the heads and rockers off and notcied that I broke a valve right at the retainer clip. The top of the piston had some marks in it but nothing that went all the way through and if i wanted to I could have knocked the marks down and reused them. Anyway so I went ahead and did a complete top end rebuild and took it out for the first time Sunday...sure as shit i can notice that noise again. Not as bad but its that same "gas tank loose" noise.

There is no noise at idle, even reving up. There isnt any noise when im shifting through the gears but as soon as hit 4th gear and riding the noise omes back. Its liek only under load and at a higher mph. I had the tope end done but an old school guy who only works on older bikes.

Any ideas???

 

[FeHd]

Maybe you have an intake leak now on the front cylinder only, and your hearing slight detonation.

 

["Whitey Ford"]

hmmmm....thats a good assumption. Why would you think it breaks the rear exhaust valve? Maybe the force acting against the spring?

 

[kickstarts]

What lift cams are you running? What kind of springs are you using? Did you have the heads set up to allow for spring bind or the top spring retainer from hitting the guide? Lots of clearance questions to answer.

Remove the head and take it to a shop to have it set up and to measure all the travel accurately and you'll probably find the culprit right away.

 

[Dr. Benway]

I think your choice of sig line jinxed you.

 

["Whitey Ford"]

I think your choice of sig line jinxed you.

hahahha....yeah things like this is exactly why i chose that. Always seems as if Im saying that whether its the bike or my old ford...

 

["Whitey Ford"]

What lift cams are you running? What kind of springs are you using? Did you have the heads set up to allow for spring bind or the top spring retainer from hitting the guide? Lots of clearance questions to answer.

Remove the head and take it to a shop to have it set up and to measure all the travel accurately and you'll probably find the culprit right away.

pretty sure stock cams and ill check the box for the springs but i do know that there was more room for a bigger cam if i wanted so its not an aggresive set up.

 

[Guest]

I think your choice of sig line jinxed you.

Doc...Your a funny guy....

On your problem with the noise at load ...
Sounds to me like pre-ignition...???
Too much spark (ignition timing), Too High of compression, Too Low of octane...???

http://en.wikipedia.org/wiki/Engine_knocking

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["Whitey Ford"]

Do you think this would cause a valve to snap? Also, the noise is only in the rear jug. Only reason i ask is because its more of a tapping rather than pinging. It doest lug or anything it just makes a noise as if the gas tank is loose. More metallic sound than a pinging. Man I just had this whole thing redone and its acting just like it did before the valve broke. Im wondering if its a clearance issue on the rocker to the top of stem...but its all new and was machined.

 

[Guest]

Could be something playing tag...If the valve seats has been sunk from many valve jobs over the years would throw off the rocker arms....

If this is the case, you would have a hard time installing the pushrods...
Also should be able to see what has been hitting when it was apart...

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[shovithead]

I would pull the head, and see if the piston has any new marks installed by the valve. If it does, you have a clearance problem. Even the old greybeards miss something every now and then. Go ask the guy who did the rebuild. Most decent mechanics would be happy to find your problem.

 

[gasketscraper]

Breaking at the valve retainer groove can be caused by the retainer bottoming on a guide. But chances are the "New" valve job would have fixed that. Let us know what you find.

 

[Rob Axel]

you may have a loose guide.... had this problem in a v8... thought it was a collapsed lifter, poss pressed in stud coming loose. it was neve at the same rpm or temp.... it ended up being a semi loose valve guide

 

["Whitey Ford"]

well the heads were all done at a machine shop and had the valve seats grinded and lapped. I think im going to have to bring it back and have it taken apart again. When this first happened the valve started smakcing the top of the piston which cause this so if its still happening even after all this work then something is obviously off. You cant hear it at idle or even revving the engine up oits mostly at 60 mph and above. And if I let the throttle off it goes away. Mostly under load. But then sorta goes to an issue of a different kind I would think. If the valve is going up or down whether under load or not woulnt it still hit the piston and make that sound?