What does a bad timing chain sound like?
 

Specifically, a Cloyes Street True Roller in a 390. It's got this obnoxious little tick that it's had for quite a while. I had the fuel pump out when converting it over to EFI (installing block out plate), and I noticed then that the timing chain was somewhat loose. Now, this motor couldn't possibly have 30,000 miles on it yet.

Here's what it does. I can go down the road, at some speed. If I maintain a steady speed, with the engine at about 1500rpm's or above, it'll start to make the noise. It isn't real loud, but my ears are well tuned. It does it the whole time, even when I let off the gas. Actually, especially when I let off the gas. It goes away abruptly when the RPM's get below 1200 or so.

I've already played around with timing, and plus the thing is now running E85 (105 octane). So I'm pretty sure it's not pinging. I just went through the valvetrain and adjusted lifter preload not 100 miles ago, and all the lobes were in good shape. Plus, we already know the timing chain is at least a little loose.

So anyway, back to the question in the title. After that, what is a good brand to get that has given good service for others on here? I thought Cloyes was good, but now I'm not so sure.

does it tick only while driving? how about parked?
i haven had a problem with my Cloyes yet.
but, mine is spankin new.

If the chain is bad it's show under a timing light as a fluctuating mark. Hook the light up, watch it at adle the slowly revi it up... no flucuation.. dont think it's the chain. My truck had an original plastic tooth setup with who knows how many miles on it, chain must have had better than 3/4 slack and it didnt have a wavy marker....

I'm thinking dizzy gear/shaft maybe ?

I'll check tomorrow.

make sure if you check with the timing light that you dont have really good spark plug wires(use old junk). if you use the ones that come with a DUI the light will jump because they are such good insulators.

What ? Just HTF are better wires going to cause a irratic timing sequence? If you installed a DUI in a older motor you timing chain or some other ^*&*(was the reason for the flux not the wires) Dont think so leaver the freeking wires in place and put the old dizzy back and tell me the results. :eek:

LOL, I haven't checked yet, but here's my ignition system:

Duraspark distributor
Crane HI-6 ignition
Crane LX-91 coil
Napa 8mm plug wires.

I have to make sure to disable multiple spark on the ignition before I check it. I have set timing on this motor a couple times before, and the timing light never had a problem.

Our Live Wires should NOT cause the timing mark to jump.

Are you quite sure because this one guys says it's so, and I'm really starting to think he might right and like wow that would be really freeky and uhmmmm yeah!!

Yes, our Live Wires have been on the market since the early '90's with no problems.

http://www.performancedistributors.com/livewire.htm

we needed to pull back some of the outer insulation on the wires or put a older wire on it to correctly time the engine.

That's pretty wild JBrad! Did you try a few different timing lights to see what might happen?

Different equipment, but my state-of-the-art digital test equipment can get locked in a loop, my cheaper rebuilt replacement parts have quality issues...some days I don't know which customer service rep to cuss out! It's up to me to sort things out, no relying on anything but the old noggin.

Nope, nice and stable timing. But I did pull off the block out plate where the fuel pump went, and there's a good 1/2" slack in the timing chain itself.

Or it could just be an exhaust leak. Would I necessarily hear an exhaust leak on deceleration, completely off the throttle?

Hmmm, that's when things quiet down...you are likely to hear a lot of things. Have you tried taking a spin with the belts removed? Tried reproducing the sound in the driveway? I wouldn't rule out a discharge from the secondary wiring just because the engine runs well.

Someone posted a procedure for checking timing chain slack: Pop the cap off the dizzy, turn the crank back and forth, see how much the crank turns before the rotor turns. I don't remember what the acceptable limits are, all my junk is worn out. My chain sounded like a bicycle chain, my dizzy made several different and interesting sounds. This was while playing with a stethoscope in the driveway.

we didnt try a different timing light.....its probably a good chance if you use an older style light you wont have problems, but the digital snap-on used gave us this problem.