Hello,

I was wondering if the timing belt needed higher tension than average if the head has upgraded parts such as dual titaniam valve springs and after market cams.

I ask is because I have tensioned the timing belt regularly (as I have done many times) after installing the newly built head and cams. Then as I had the engine on and just above 3000 rpm the belt skips.....

Although I have done many timing belt swaps, this is the first time I have dealt with a head with after market springs and it is much harder to turn over than stock, which makes me think the timing belt needed to be tighter than stock. This is a B18b head and block.

Any help is appreciated.

 

there should be no reason running your timing belt any different than factory specs

 

did u have the head milled at all?

 

OEM timing belts are tensioned just as the manual tells you.more valve spring pressure exerts more stress on the OEM belts are designed to run.I would suggest using an aftermarket timing belt still tensioned as the manual says.its not on the belt tension but the quality and make of the belt you're using that matters when an upgraded valvetrain is used.

 

tension to OEM. Do not tighten it extra. If the long run slop worries you there are adapter idler pulleys. Endyn's come to mind.

 

yes the head is milled, and i was using an oem timing belt.

So maybe with the head being milled the belt had a little more slack than normal. That coupled with the oem belt stretching (caused by the extra tension from the new valve springs) could of caused this?

So OEM belts wont work with aftermarket valves and cams?

I'll look into those idler pulleys.

 

OEM belts will work on aftermarket parts but it will shorten its life when used with higher than stock valvespring pressures.I would recommend TODA,HKS,etc timing belts when using higher than stock valve spring pressures.millied heads won't affect tension.idler pulleys like Endyn are used mainly on long blocks(with long belts) due to the increased distance from the crank pulley and camgears.

 

what do you mean, the belt skips?

I have full crower valvetrain w/Ti retainers 62403 cams, on a OEM belt. Works to this day. I never had an issue about it being too tight. seems like something else is wrong....Is your tensioner hooked up properly?

 

Just when I was above 3000rpm (in neutral) I heard some clanking noises and the engine died. then when I when I popped the hood took the valve cover off, the belt was loose and had obviously skipped some teeth, as the belt was sitting on the intake cam teeth rather than in the cam like it's suppose to.

Maybe because the timing belt got stretched a bit, the valvetrain was causing extra strain, and because the head was milled? I dont know.

my tensioner is on correctly but maybe it just doesnt work as well anymore.

So thats why I was asking if there needs to me greater timing belt tension than stock with an aftermarket valve springs and cams.


I appreciate everyones input.

 

Try a new tensioner!

 

if that belts jumps at all you are asking for a very bad day.
and I hope you are not relying on just the spring to tension the belt. dual cams can be a pain in the ***. You have to set the belt, put a small screw driver under the tension and pry it just a bit to get the play on the long side, *then* you will very likely have to stick a wrench on the intake cam and spin it just a touch to take the slack out from between the cams. Of course while keeping tension with the screwdriver so it doesn't pop back.
Then you can tighten down the tensioner. You should also spin the motor around a few times by hand and recheck the slop on that long side.

 

tighten it to stock. you have to make sure after you get the belt on you turn the engine over by hand a few times. if it's not tight enough you'll see the belt slapping between the cam gears. same thing happened with my ls with bc valvetrain/cams.

 

Thanks for all the input everyone.

I did a compression check and it didn't seem too bad everything was actually still decent. So I essentially did what Night talked about a pried the tensioner with a pry bar to make it as tight as possible. So I started it up for a few minutes and the engine can rev up without skipage. But now I'm afraid I made the tension too tight; all sides are tight with little-to-no slack at all. So maybe it did need to be tighter than stock, OR the tensioner is old and can't even get it to stock tension.

I'm taking everything apart anyhow to see what real damage was done. I'm thinking a new tensioner might be in order since the original one had a lot of use over the years. And maybe I was careless and messed up the timing belt install, but I have done it quite a few times before without issue.

I'll give updates as I progress with this.

 

not as tight as possible, there should be a little bit of play on that long side, but it is really hard to tell someone right. I do tons of belts so just feeling it good for me.
I'd say a 1/4" of play fwd/back on that side is what to aim for. and that means a 1/4 total.

 

hehe not the 1 inch play some articles have written?