Intake Cam destruction!

spuddy

spuddy

Ulster Area Rep.
ECC found this little surprise in the head today, the intake cam has lost its head. Quite surprised cause it she could fairly go for a car only getting the correct intake on 3 cylinders, so will be good to see how she goes when its fixed.

I've been very lucky, the lump made its way to the sump where its been kicked about a bit damaged a rod and a piston.

Cam1.jpg


Cam2.jpg
 
spuddy

spuddy

Ulster Area Rep.
They're the original Speedvision cams, not the newer ones, they've had a hard life, revs have been as high as 8500rpm on occasion.
 
350ep70gr

350ep70gr

Member +
Check valve stem to guide clearence or if the valve stem is bent or oherheated. 8500 isnt a really trouble for the cams. They stressed more at idle than 8000 rpm.
If the above checks turn up ok then it is a fault of the metal itshelf.It is a huge piece missing there and very difficult to be destroyed without an opposite pressure somewhere.
I had a similar prob in an EVO 6 head wich had destroyed two cams in the row (specific lobe,specific position) but never got around to check why..second time i replace all the head.

Chris
 
spuddy

spuddy

Ulster Area Rep.
After a little more investigation the guys have told me one of the buckets has 3 peices broken off down near the skirt of it. Not sure if its the same valve, I never thought to ask but I would assume so.

If it is then it would seem the valve spring could be the cause. Speedvision springs in the head.
 
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danturbo4311

danturbo4311

Member +
Sounds like a similar problem a few other guys have had, when using the speedvision springs & cams together, the spring base pressure sounds like its to high which can cause the spring to coil bind. Im using the same springs & cams together but with some custom valve retainers which seat the spring higher in the valve to reduce the base pressue, how many miles you done on them spuddy. Hopefully its not damaged your head & valves.
 
spuddy

spuddy

Ulster Area Rep.
I bought the head with them already in there but from I got it and fitted the cams theres about 1000-1500 miles at most, but alot of them have been drag strip and mapping related.
 
Shorty

Shorty

Member +
bad times :( iv got the speedvision batch ones in mine but with the cruise springs seems the best combo to use tbh, heard nothing but bad things about the speedvision springs :( hope you get it sorted bud.
 
danturbo4311

danturbo4311

Member +
Thats about the same amount of miles the others had aswell you need to measure the springs & check at what height they coil binding & then check them agaisnt the cam lobes.
 
spuddy

spuddy

Ulster Area Rep.
Rory said:
Nicely done Spud :cool:

Well, now you will have to go bigger :haha:
Click to expand...

Lol, aye its not a big problem, was replaceing most of the parts in question anyway, just would have been nice to be able to sell them on lol.

Should have her rebuilt in a couple of weeks. The one part I thought woulda had damage was the bearings cause I had an oil mishap but they're 100% perfect lol!
 
350ep70gr

350ep70gr

Member +
Coil binding can occure at the very high end of lift distance and would have eaten the very edge of the lobe i would say.Like round it.
This is something else..i think. Looks like something was really stuck and the cam faced something solid (not moving bucket) from the very first few mm of lift.Thats why it is a huge piece missing.Also since you have oem valves all the base pressure given by those springs should be at about the same (small variation) meaning if you really have coil binding prob should be obvious to the other cam lobes when examing the edge of them.

Anyway... the guy who has the head on hand can advise better when physicaly inspect and mesure all the moving parts.
P.s. Bucket that is damaged at the very bottom and opposite top means that bucket to head clearence is to big so bucket is pressed by an angle and not vertical by the cam. But again clearence issue of the bucket produce a rattly/noisy head at least when at idle. Similar sound with the sound of the ticking valves.

Chris
 
spuddy

spuddy

Ulster Area Rep.
350ep70gr said:
Coil binding can occure at the very high end of lift distance and would have eaten the very edge of the lobe i would say.Like round it.
This is something else..i think. Looks like something was really stuck and the cam faced something solid (not moving bucket) from the very first few mm of lift.Thats why it is a huge piece missing.Also since you have oem valves all the base pressure given by those springs should be at about the same (small variation) meaning if you really have coil binding prob should be obvious to the other cam lobes when examing the edge of them.

Anyway... the guy who has the head on hand can advise better when physicaly inspect and mesure all the moving parts.
P.s. Bucket that is damaged at the very bottom and opposite top means that bucket to head clearence is to big so bucket is pressed by an angle and not vertical by the cam. But again clearence issue of the bucket produce a rattly/noisy head at least when at idle. Similar sound with the sound of the ticking valves.

Chris
Click to expand...

She did sound like one of the valves was noisey a fairly audiable click sound. Could too much clearance between the cam and the shim do damage? None of the other lobes looks to be damaged.

Or could a bit of the bucket have made its way inbetween the lobe and shim and caused the break.

Hard to know whats going on in there!
 
350ep70gr

350ep70gr

Member +
spuddy said:
She did sound like one of the valves was noisey a fairly audiable click sound. Could too much clearance between the cam and the shim do damage? None of the other lobes looks to be damaged.

Or could a bit of the bucket have made its way inbetween the lobe and shim and caused the break.

Hard to know whats going on in there!
Click to expand...

Clicky sound when turn the cam by hand could be a coil binding. Usually this sound goes faster with higher revs but not louder. Too much clearence between shim and cam will not do any harm apart from the sound and the reduction of the duration and max lift.(Higher the chance to drop a shim tho and maybe wider valve stem head after 100000 miles) For example if a cam has a lift of 9.1mm when mesuring the lobe and you add a clearence between the shim and the lobe of 0.30mm then the actual lift of the valve will be 9.1mm - 0.30mm =8.8mm max valve lift wich will for sure hert the flow and the overall performance. Thats why most performance heads are built to tightest safe valve clearence even tighter to oem specifications. It has a lot to do with the materials involved (mainly valve stem expand figure) and should be kept in mind the driving you do most of the times. For example track cars will need to add to the clearence and drag car to substract from the clearence. Car for overall driving should kept oem specifications if no other mods.

I dont really know if a small piece blocked the bucket movment and cause this but if you exam the head around the bucket should have a deep scratch down the small bore of the bucket place if this is the case.

Chris
 
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