Firing On 3

[steve_wilson]

hi all

after a run out yesterday about 2 miles from home it dropped onto 3 cylinders. thought i'd limp home and check it out tonight.

checked for spark and all is well, took the rocker cover off and it's not pretty.

 

the centre cam tower has smashed off and one of the rockers has snapped

 

 

 

 

 

i didnt build the engine so it was always of unknown quantities but this has really annoyed me!

the valve still seems to move freely so i'm not sure whats caused this!

 

Steve

[steve_wilson]

should probably mention it has had a full rebuild (previous owner) and was set up last week at a very reputable tuner

[steve_wilson]

just a thought but can these cam bearing towers unbolt or are the cast with the head?

 

Thanks, steve

[Snapperpaul]

The head is dead, the cam towers are cast and the process of cutting off the old one and finding a replacement will cost more than a Very good Vulcan Maxiflow.

 

Seeing that makes me consider taking my head off and having steel straps bronze welded on.

Apparently you can't weld to cast metal without cooking the head to 400 degs then after welding wrapping it in insulating materia and letting it cool for days

Edited July 30, 2010 by Snapperpaul

[steve_wilson]

well i've whipped the head off tonight and checked for any other damage. can't see any damage to the pistons or valves so just need a new head which is gutting as it was a high spec head.

 

any ideas what might have caused this to happen?

 

Thanks, Steve

[Guest Christine]

possibly the tower was cracked during the rebuild by the previous owner. another possiblity is the cam is not running true and theres a tight spot at the tower.

[steve_wilson]

thanks chaps, looks like i've got another head so should sort it

 

my current head has a piper 285 cam. i'm planning on swopping this over, does it use the standard cam followers? i've looked on the piper website and not too sure.

 

Thanks

[megadodo]

Get the cam checked for alignment, maybe its slightly out of true and that's what snapped the support tower?

[Guest shaggy]

 

 

any ideas what might have caused this to happen?

 

 

Steve,

 

As you have said the head was rebuilt. Perhaps they weren't too carefull taking the old cam bushes out, or perhaps tapped the casing when putting the new ones in fracturing the casting.

 

Si

[johnlrichardson]

Try the cam shaft in without the followers make sure there's no lift on the bearings and the cam shaft is not tight

(free to turn) for the tower to snap I think its had a knock

 

HTH jon

[steve_wilson]

well chaps ive managed to get another head. got it fitted yesterday and was out in it last night.

 

not 100% still on what caused it, just glad its sorted!

 

Thanks to everyone for their help!