I was talking to my boss and he said one of the most notorious failures in the 305 is the timing chain. He told me to get a timing light and watch the engine and if the timing raises and drops and keeps doing that then the chain is failing and needs to be replaced. He said this is a comon problem.

Can someone explain this to me...also what is the cost to fix this. I am making a list of all the stuff I need to get done to the car come spring so far I have the following

• Change spark plugs
• Change Spark Plug Wires
• Clean ground, battery poles, and maybe change all the wires
• Trany fluid flush
• coolant flush
• Replace every filter in the car
• Install the Open Air Element Breather (Mr. Gasket)
• Terra clean on engine
• Fine Tune Timing

I am thinking if this item is a known problem then I might as well remove and replace it as well.

Also if you see anything else in that list that I should add, please let me know

 

The 305's were known for that as well as the cam lobes wearing early, but since GM went with a roller cam set up (which yours has) you shouldn't have a problem.

190K miles on mine and it's fine so far. I guess it still wouldn't hurt to check it though.

 

All of that stuff is cheap. If your car is holding its set timing than don't worry about the timing chain. Your biggest cost will be if you get a set of aftermarket wires. Is your car doing anything right now that would lead you to belive that the timing chain is going?

 

Is the timing chain on our tbi cars roller?

 

Yes. So when you replace it you need to make sure it is for roller applications. They should say 87 on up. If not get a true roller. If it is under 50 bucks than you have the wrong one. Sgoggin dickey sells one for 49.

 

Yes I understand our blocks are roller blocks and the cams are too. What I was asking is if they are true roller? I don't really understand the difference between "roller" and "true roller." Care to explain?

 

Yea I thought you knew that. I thought maybe you got confused or something. As for the difference I am not sure. I think it is along the same lines as roller and hydraulic roller.

 

Thanks for trying to explain it to me shifty. I guess it's something I'll have to learn first hand. I get confused though sometimes when people talk about roller and true roller timing chains. Wish I knew what the difference was. Is it something I can visually see like the obvious difference between roller and non roller rockers or is it internal?

 

I think the true rollers have the adjustment keys for advancing and retarding the cams. The regular rollers do not. There is an obvious difference and I think that may be it.

 

As long as your changing things I'd change the differential fluid as well. Did it in mine, and the fluid wasn't exactly, clear... Also, some dealerships (I used to work at one) will do an engine oil flush on your car. I'm getting mine done as soon as I get the chance.

Bruce (90RS305)

 

A roller chain has little round links on the chain. They're fixed though. They just ride along with the chain.

A "true roller" has a metal sleeve on the links that actually rolls with the teeth on the chain.

The factory chain doesn't have either. The links are wierd looking.