Car gets noisy at exactly 3500 RPM

[90 GSX]

This is my friend's user name, my car is actually a 1990 GSX. Only mods are a timer, filter can removed, a pcv catch can, and a chipped '91 EPROM ECU (no fuel cut, 5500 launch and shift). I ordered a Joe P MBC and Boost and EGT gauges, and will soon order a K&N/DejonTool intake and a big sidemount with hard ICP's.

I'm new to the DSM scene but I have some theories on why my car makes so much noise after 3500 (on the dot, every time). The noise is almost like a loud buzzing/rice rocket type sound. It is coming from the side of the motor with the accessories and belts. I ran the car with the upper timing cover off and right about when the car starts to make noise, the timing belt starts freakin' wobbling up and down and moving around in a weird manner. It doesn't skip any teeth or anything while I was revving and watching the belt (but I wouldn't be surprised if it did while the previous owner drove it). So here are my questions:

1-Is there a special method that you use like on Hondas to put the timing belt on? The guy who I bought it from told me he installed a new timing belt so I don't know if it was installed correctly or not, but the belt does look fairly new.

2-Is it standard procedure to replace the tensioner or any other parts when replacing the timing belt? The tensioner looks older than the belt to my eyes.

3-The car is missing a lower timing cover. I'm sure it's important during the winter, but how important is it considering there is no rain. Could it be contributing in any way to the problem.

4-How do you degree the cams? The V8's I have always delt with are as simple as lining up the dots on the timing chain and using marks on the cam sprocket to advance or retard the cam. But with DOHC, I have never touched it. Is there a guide or torque specs, instructions, anything taht can help me?

And lastly, are there any suggestions on things I could check out? I do have a small exhaust leak where the header meets the turbo but that can be fixed easily (hopefully it will prompt me to get a 16g as well).

Thanks.

 

[phastalon]

same problem i had, it's more than likely the t-belt tensioner. check out www.vfaq.com for detailed instructions and pictures of a timing belt install. just don't be like me and not set the tension before you try to start it or you'll end up with bent valves too.

Regards,

Brad

 

[90 GSX]

Don't worry I won't bend any valves =) I will replace the idlers and tensioners and recheck the balance shaft distance, belt, and tensioner. I think this problem is also contributing to my belt squeaking when I downshift fast with matching revs. Thanks for the info.