Lost Timing Chain Again!

[coupe72001]

After 2 weeks of trouble free motoring with my rebuilt head and triple dell'ortos I decided to show off to a mate and took my car up to the redline (6250rpm) in first gear. The car immediately threw the timing chain of its sprocket (again), and the valves clattered against the pistons (again), and then the timing chain tensioner popped out and fell into the timing cover jamming up against the crank sprocket stalling the car. I got to go home on the back of an RACV truck (AGAIN!!!).

Regular readers might remember that I made this problem for myself late last year by putting in the clutch with the accelorator jammed on full, but this was only redline for a fraction of a second. This is really irriating, I've spent hours watching videos of Datsuns in Kuwait doing burnouts till the rubber runs out without stuffing their engines - I don't know why mine is so vunerable! For those who haven't been keeping tally this is the 6th time I'll have had the head off my car while still on the first set of brake pads.

Anyway, has anyone got a tip for toughening up the timing on an L28 (chunkier spring in the tensioner etc)? There is some wild Kameari stuff (sprockets/tensioners etc) available out of Japan via the USA, but its really expensive and will take many moons to arrive in Australia.

Also, anyone want to buy half a dozen slightly used L series head gaskets?

[adznight]

Dude, sorry to hear

[Silent Shadow]

my engine has done several red-lines and clutch drops man and it's still perfect. maybe get a new motor and start again? i cant believe this has happened twice.

[coupe72001]

I have called around some and found that Nissco only use Rollmaster Billet chains on their Datto's, and they spoke poorly of some of the cheap and cheerful Chinese/Indian aftermarket timing chain kits around. To be honest I didn't buy the best quality chain on Earth, and recycled some of the existing timing gear (it looked ok though!)

[Silent Shadow]

ok... save and buy some parts that you cant destroy. happy days!

[Ghostrider]

You might find it necessary to replace the chain & tensioner & guides etc as a kit. I saw such a kit on ebay recently for an L28

http://cgi.ebay.com/ebaymotors/NISSAN-280Z...sQ5fAccessories

You might find the top & bottom gears are worn, allowing the soft tensioned chain to jump teeth.

Cheers, D

[-hgc110-]

No way dude. i was looking forward to saturday so i can check ur car out. sorry to hear.

I dont understand why it did that, I havnt got the best of timing chains either and so far iv had no drama (knock on wood) + i rev mine to 7500rpm.

I dont think u need the best of the best bits to build a reliable engine, it must be something little or stupid that uv missed (as is always the case).

if u have any questions let me no, ill help to the best of my ability.

[coupe72001]

Thanks for the ideas and condolences guys.

Ill do a really good inspection of the timing gear over the weekend, but regardless of the culprit it looks like Ill be investing in a decent Japanese kit, and possibly a billet chain to boot. Ah well... if nothing else I'm getting really, really effiecent at head, timing and sump work. Only 2 years back the thought of pulling the head off by myself used to terrify me!

Bobby, you are welcome to check out the car any time you are St Kilda way, running or not, and hopefully I'll catch you at the factory this Saturday anyway (Ill bring some pics if nothing else). Adam, you should think about turning up for a beer and to meet fellow K nut Bobby.

[noddle]

Did you bend any valves ?

Nigel

[coupe72001]

I heard the clatter of valves on pistons, so I'd wager that I have. I'll have the fella's at Motor Improvements inspect for me to confirm/replace any bent valves. They give me a frequent engine mutilator's discount.

[-hgc110-]

ill come past the factory on Sat. im just unsure what time, i should be done at work by 2:30ish, but give me a call when u get there n ill see if i can escape a bit earlier.

I think i have an idea why ur timing chain is playing up. ill speak to u in more detail on Sat.

Edited September 11, 2009 by -hgc110-

[Ghostrider]

On the strength of this, I have just ordered the Kameari Adjustable Chain Tensioner & Reinforced Timing Chain from www.rhdjapan.com for the princely sum of AU$388 delivered by Express Air Mail. I have an Vernier Cam Gear from Stewart Wilkins, will purchase a new bottom/crankshaft gear, but will stick with the Taiwanese guides.

If anyone is interested, I have a new tensioner and chain that will no longer be required, up for grabs.

I also have a Nismo 8 hole cam gear, it's been offered elsewhere, but if it's not taken up, it will be up for grabs too.

As my new motor is being built to rev to 7~7500rpm, I thought this was best for durability.

Cheers, D

[coupe72001]

PM's away!

On the topic of saftey first, I found that some of the bolts that I had torqued to factory settings (cam, crank etc...) were loose when I inspected what's left of my head and timing gear. Plenty of bent valves, more scoring (but not catastrophic - mercifully) on the pistons.

I'm kicking myself for not rechecking EVERYTHING when I retorqued the headbolts before giving the car a bit of a trashing, and will certainly be investing in the Kameari crank bolt from the rhdjapan site. You can imagine the disaster of a crank pulley working loose at high rpms!

[coupe72001]

Also Bobby, you should know that no-one at the factory could stop talking about your car. It's the duck's guts!

[mid life crisis]

PM's away!

On the topic of saftey first, I found that some of the bolts that I had torqued to factory settings (cam, crank etc...) were loose when I inspected what's left of my head and timing gear. Plenty of bent valves, more scoring (but not catastrophic - mercifully) on the pistons.

I'm kicking myself for not rechecking EVERYTHING when I retorqued the headbolts before giving the car a bit of a trashing, and will certainly be investing in the Kameari crank bolt from the rhdjapan site. You can imagine the disaster of a crank pulley working loose at high rpms!

loctite is your friend

[works 510]

I have called around some and found that Nissco only use Rollmaster Billet chains on their Datto's, and they spoke poorly of some of the cheap and cheerful Chinese/Indian aftermarket timing chain kits around. To be honest I didn't buy the best quality chain on Earth, and recycled some of the existing timing gear (it looked ok though!)

Last time i head rollmasters are made in india... Originial chain in my l20b was sourced from SWmotorsport and was advised on this chain which was made in japan.

Chain has seen 7400rev limit, one mis-change which wiould have spun the old l20b to 8500+. Motor only rebuilt due to oil leaks and because it was getting fitted to another car...WITHOUT replacing the chain because it was fine.

[-hgc110-]

Also Bobby, you should know that no-one at the factory could stop talking about your car. It's the duck's guts!

Its good to know that there are people that appreciate all the work thats gone into that car.

Cant wait to see your car in action!

[coupe72001]

Im back up and running. From dropping on the head to turning the key now takes me less than three hours!!!

Will be taking it really easy for the next few weeks as I recheck everything is torqued up correctly, and will be subbing in better quality timing parts in the not too distant future when all the bits and pieces have arrived. Hopefully will also get a carby tune and dyno within the next week.