Talk with me about L76 springs please :-)

[Schwuppes]

hey people,

Can I get away with a single row timing chain and tensioner when running L76 springs?

Over here in Australia almost every performance shop recommends running Double row chain with anything higher than stock springs.

The reason given is that when running stiffer springs there is the risk of the tensioner breaking/disintegrating and ending up blocking the oil pickup... which, needless to say, will have devastating results lol

What you guys think?

Cheers

 

[coolone]

I don't believe the 76 springs increase pressure much at all... If I recall correctly.

 

[FoSHO99]

We usually go with a new stock timing chain and dampener on the L76's. There's quite a few running 130#'s on stock timing chains. Raising the idle a bit helps.

We had an issue in the U.S. that had partly to deal with the chamfer on the crank sprocket on the double rollers/JP/rollmaster. I believe the design was based off of the Australian crankshafts and there is a difference there vs. the U.S. Some sprockets would split, some chains would rub on the timing cover and eventually break. Some have been running fine, others machine the timing cover or run double gaskets and a few have machined the sprocket itself to match the stock. So after all of that, you are going to see more people here running stock chains. I don't think i have seen someone come forward with a failure of a stock timing chain. But then again, most do not push it's limits.

 

[darkhorizon]

The crank campher problem is a myth... it has been proven to not cause any issues time and time again. The JP that failed in my last motor was due to the chain digging into the motor... not the front cover... so go figure.

 

[Schwuppes]

cheers guys,

Im guessing the choice of rocker ratio will also influence how quickly the stock chain tensioner wears? 1.95 ratio will put more stress on the tensioner than 1.8s, right?
I was planning on going with YT 1.95 roller rockers....

How often would I have to get the tensioner replaced on such a setup? (L76 springs with YT 1.95 roller rocker)
Is it a big job to take off the timing cover and swap the tensioner?

I'd be willing to take the risk if I replace the tensioner every 10.000 miles or so... or 18 month intervals... which ever comes first.

 

[coolone]

I'm about to install the Yella Terra 1.9 RR's, L76 springs along with new seals and retainers. In my conversations putting it all together and in reading, I don't remember seeing anywhere the need for a new tensioner or increased wear due to the rockers higher ratio. The L76's will afford a higher spring rate (avoiding valve float) while keeping the seat pressure just a little above stock, thereby avoiding the unnecessary increased wear on the valve train that the heavier spring rates create. You could always do the tensioner as preventive maintenance if you like, it just might not be needed.

I don't plan to... If I was going to open all that up then I'd just do a cam. Lol... Just my $.02

Again, anyone correct me if I'm wrong!

 

[Schwuppes]

The L76's will afford a higher spring rate (avoiding valve float) while keeping the seat pressure just a little above stock, thereby avoiding the unnecessary increased wear on the valve train that the heavier spring rates create.

I thought its the other way round... only slightly higher springs rate but increased seat pressure?

anyways...

Im still undecided whether to do rockers or cam... over here complete cam package is $2300,- AUD. Thats a heap of money for me... and there is an increased list of a cam bearing spinning when doing a cam swap on a older motor... so if I spend 2300 bucks only for it to spin a bearing I'm up for another 3 - 4 grand for a rebuild... not sure if thats a risk Im willing to take....

Someone mentioned PBM 110# springs in my other thread... i found a graph that shows them having a even lower spring rate than stock L67 springs but with a seat pressure of 110 lbs! So I might consider those even...