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
Ecotec Motor going into a boat

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

[delcowizzid]

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]

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 should be great once these last little niggles are sorted out.

[jetboy]

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]

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]

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]

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]

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]

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]

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]

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

[4bait]

it runs at 4200rpm max it only did 6000 when the boat got air born some time ago and the prop left the water lol
it would clock up about 120 hrs per year and the average life of the chevy boat motors is around 1000 hours so I would expect about the same with this.

it handled 4200rpm nicely untill the springs broke and the piston decided to find a new home in the sump lol
If I could make it reliable with a revs around 4200rpm constantly then that would be nice.

Cheers Andy

[MACE]

I noticed you've come up with a much larger sump, good thing for engine longevity. Another thing which you could consider doing is to polish up the internal oil pump housing, to improve oil flow.

[4bait]

Hi Guys

Another Quick couple of Q's

Q1
I got a new unused double row timing chain of good old ebay, it was sold as, and came in, a roller master red label box but the cam gear is marked "JP 5620 Vr-VS" so it is obviously a JP set.
Is this normal in a roller master box or has the set been switched?

Q 2
the chain is not as tight as I expected it to be and will need a tensionor fitted but in other posts people have said dispose of the tensionor as it is not needed with the double row chain, so I am guessing maybe I should resell this set and purchase another on lol
The JP website only lists 5620 model for the engine so according to them it is correct.

I haven't got everything else here to do the build yet so have only sat it on the engine for a trail fit.
We are heading to Tassie for a couple of weeks R&R so will be placing a mace order when I get back for the valve springs etc

Cheers Andy

[acarmody]

JP and Rollmaster are the same company I believe.

[4bait]

JP and Rollmaster are the same company I believe.

Yeh reading through some other threads I am led to believe there are two types one uses a tensioner and one doesn't.
However some surfing on the net the JP site only lists one type so does Mace and the romac site is not very informative.

I have just placed an order with Mace for 130# Valve springs and retainers etc to take advantage of the Xmas coupon special deal so when they start back after the holidays will ask them.

Cheers Andy