Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Timing chain, Valve springs and ballance shaft Q

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,988
Reaction score
445
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
you are probably getting some funny harmonic in the springs at that rpm and they are just letting go fit some behive springs for a start and maybe see about letting it rev higher or lower with prop selection if its found to need it
 

Immortality

Can't live without smoky bacon!
Staff member
Joined
Apr 15, 2006
Messages
22,480
Reaction score
19,935
Points
113
Location
Sth Auck, NZ
Members Ride
HSV VS Senator, VX Calais II L67
4200rpm should be right about peak torque on a standard cammed ecotec

just read the entire build/project thread. looks like a lot of though has gone into this. well done :thumbsup: should be great once these last little niggles are sorted out.
 

jetboy

You learn til u die
Joined
Feb 26, 2010
Messages
243
Reaction score
2
Points
0
Location
Gold Coast QLD
Members Ride
VT exec
Hey Andy followed ur boat mod with interest , sad to see this little setback , the advise thrown in the ring from these blokes is all good , one thing id like to add is playin round with the cam to give it a bit more grunt down low , so's you can run a better pitched prop an bring ur top end revs down a bit , whilst keeping ur launch , 4200 rpm isa bit high id be lookin at dropping that to at least 3600 rpm
 

MACE

Well-Known Member
Joined
Mar 30, 2008
Messages
3,185
Reaction score
93
Points
48
I just read your build Andy and it looks like you've got a bit of a machine shop, so I dare say machining up a bush to plug in the oil gallery after removing the balance shaft will be a walk in the park :)

With your new engine build what are you planning for it?
 

bpefi

Tech
Joined
Nov 5, 2009
Messages
260
Reaction score
3
Points
0
Location
Bundaberg
Members Ride
Hilux Ute - Vs Ecotech Engine
I would be going with double valve springs if only to stop the valve from dropping in like that again - double row timing chain is the go - cheap insurance & more power from having the cam aligned properly..
 

chargedvx6

Active Member
Joined
Dec 9, 2006
Messages
1,866
Reaction score
15
Points
38
Members Ride
VY SII HBD Calais L67
Double valve springs add more weight to the valvetrain IMO. A good single will keep up. Just need to rate the valve spring to final lift and desired rpm.

To the O.P., have you thought about going for a low lift cam with good duration and using a higher lift rocker to achieve your final lift at the valve. This way the lifter/ cam followers don't have to travel as far to do their job and it may free up some inefficiencies allowing you to rev cleaner
 

bpefi

Tech
Joined
Nov 5, 2009
Messages
260
Reaction score
3
Points
0
Location
Bundaberg
Members Ride
Hilux Ute - Vs Ecotech Engine
Double valve springs add more weight to the valvetrain IMO. A good single will keep up. Just need to rate the valve spring to final lift and desired rpm.

To the O.P., have you thought about going for a low lift cam with good duration and using a higher lift rocker to achieve your final lift at the valve. This way the lifter/ cam followers don't have to travel as far to do their job and it may free up some inefficiencies allowing you to rev cleaner

I was only recommending the dual valve springs because it might stop what has happened - but after reading your post you might have hit it on the head - if hes running a high lift cam it could be getting spring bind ??? or something like that ....never had a problem with valves springs on these before.
 

4bait

Member
Joined
Sep 24, 2005
Messages
48
Reaction score
0
Points
6
Age
59
Location
Cheltenham Vic
Members Ride
VR
Thanks guys for you thoughts

I have just purchased a double rollermaster timing chain and trying to decide what springs I should put with it
105# or 130# ?? also I thought the old OEM springs were already beehive so will I need new retainers to go with them?

The cam in this is standard and it seems to be well suited to the boat already. I think all that is needed is the manifold insulators and plenum spacer to give it some quicker response from idle.

I wanted to run the standard engine first up as I had no idea how it was going to behave in a boat so the standard engine has given me a base starting point.

I can drop the revs with a higher pitch prop but then the idle speed is too fast for putting down the creek and into the boat ramp and ramming the jetty is probable LOL

The old OEM 4 cylinder engine was designed to rev slightly higher at 4800- 5200rpm WOT (wide open throttle) so the current revs at 4200 seems to be a good medium, the engine sounded good and didn't appear to be getting valve bounce or anything, the springs just let go without warning.

What is max rpm for the ecotech I thought it was around 6500rpm???
Cheers Andy
 

4bait

Member
Joined
Sep 24, 2005
Messages
48
Reaction score
0
Points
6
Age
59
Location
Cheltenham Vic
Members Ride
VR
I just read your build Andy and it looks like you've got a bit of a machine shop, so I dare say machining up a bush to plug in the oil gallery after removing the balance shaft will be a walk in the park :)

With your new engine build what are you planning for it?

Hi Mace at this stage I still want to keep this engine fairly standard as it behaved well for a boat I just need to stop itself being torn apart and keep it reliable for going offshore. The top end seems to be the first week spot needing attention.

However I do have a couple spare engines here which I will build up as spares down the track and a blower is on the cards but this will be a little way off.


cheers Andy
Cheers Andy
 

MACE

Well-Known Member
Joined
Mar 30, 2008
Messages
3,185
Reaction score
93
Points
48
4bait,

If you're running a double row timing chain then I would go the 130 springs. As for running a standard ecotec reliably to 6500RPM, I wouldn't do it. In saying this though I suppose it depends on how many hours you run the boat for and how long it would be acceptable to last for. In you case max I would leave it at the factory rev limit.

Cheers,
Steve
 
Top