Timing chain, Valve springs and ballance shaft Q

[4bait]

I Have an Ecotec in a boat with several broken valve springs due to the engine revs fairly hard for long periods etc, it's not the first time the standard springs have broken, this time the broken valve dropped in and it has destroyed the engine at only 10 hours old, so lesson learnt and I will be upgrading the springs etc with a new engine build.

The Mace site says that with upgraded springs I also need a double row roller timing chain and in order to fit this the ballance shaft needs to be removed and oil hole plugged.
Is this correct? and will any adverse vibrations etc be noticed or other problems with the ballance shaft removed or will the engine need to be internally ballanced to suit?

Also it says that no tensioner is used on this timing chain so also wondering about chain back lash.

The rest of the engine and cam etc are fairly standard at the moment

Cheers Andy

 

[D3V14NT]

Balance shaft does not need to be removed, can be disabled and left in place. Saves having to plug the oil hole.

Some people have mentioned that they have slight vibrations in different parts of the rev range, others have reported back with totally smooth engines. I imagine it mostly depends on the quality of that particular engine. A lot of people here that have fitted double row chains have also fitted aftermarket cams so any vibrations introduced by the lack of balance shaft are hard to notice against the lumpiness from the new cam.

Double row chains are a much tighter fit than the single row. They are much more durable without the tensioner than the single rows with a tensioner. Double row chains usually allow for adjustment too which can be handy.

 

[acarmody]

Steve is the expert here, but I believe you don't NEED the double row for just 105lb springs, but definitely for the 130lb springs. Since your engine will have constant high revs, I would probably go for the double row. If you run the double row you have to remove the balance shaft drive gear. You can just remove the drive gear and leave the actual shaft in there, this saves you having to plug the rear oil feed hole, or you can take it out but than you MUST plug the hole. And you can run the tensioner with the double row, not really much point but it won't hurt. I've still got the tensioner in with mine and it is fine.

There aren't any real adverse effects with not running the balance shaft, so people notice a slight vibration at about 1700rpm, but nothing big.

EDIT: Dammit D3V14NT beat me too it, LOL.

 

[D3V14NT]

Haha ninja'd You added a bit more details than me anyway.

 

[chargedvx6]

If you are building the engine again anyway it would make sense to remove the balance shaft altogether and tap and screw the rear oil feed to where the balance shaft was. IMO a double chain is good regardless of what spring rate you are running. Holden V6s are known for destroying timing chain tensioners which is fine.................until the tensioner material gets caught in the oil pick up and starves the oil feed= bye bye bottom end.

Mace will be able to match a spring rate to your cam specs I guess but my tip would be to run a double row rollmaster timing chain regardless of which way you go with the rest. Obviously you will be getting the engine balanced due to it living in a consistant high rev situation so this will best help smoothness and longevity. A balance shaft doesn't actually aid in balance of the reciprocating mass IMO (helps smooth out 3rd and 5th order harmonics is all which are only momentary through the rev range) so I wouldn't stress about giving it the heave ho

 

[Immortality]

Go with the double row timing chain and remove the balance shaft and plug the oil feed hole, more oil for where it is needed.

the single row tensioner is one of the weak links of the V6 engines and it's worth every penny to eliminate it if possible.

maybe consider a new sump to ensure a good oil supply at high revs

 

[chargedvx6]

4bait, can you post a few pics of you set up along with some info on cam choice, fuel, transmission (if at all). Also, what oil are you running?

 

[MACE]

If you're going to the trouble of a new build definitely run a double row chain set with the chain tensioned disabled, for the reasons mentioned. By doing this you'll either have to leave the disabled balance shaft in place or plug up the oil gallery. The later is a much better option, considering the motor is apart, option if you can do it.

Cheers,
Steve

 

[4bait]

Thanks guys for the replys

Here is the recently destroyed engine due to a broken valve spring. There were 3 more busted springs on this engine, however only one valve dropped into the cylinder whilst at 4200rpm.

The sump is already modified with a 9 litre capacity and the sump well is at the rear of the engine so it doesn't starve when the nose of the boat is in the air

here is a post of the engine going into the boat
http://forums.justcommodores.com.au/general/125013-ecotec-motor-going-into-boat.html

Cheers Andy

 

[acarmody]

The sump is already modified with a 9 litre capacity and the sump well is at the rear of the engine so it doesn't starve when the nose of the boat is in the air

The words of a guy crazy enough to have a 150kw boat motor! LOL