How To Set The Timing On A 1987 350 Tbi

haulincats · February 1, 2011

I have a 1987 350 small block chevy TBI.

It is in my mud truck. It backfires really bad when its

cold. I've done a few things. So I thought I should check

the timing.

1st a little history. It has headers with about 2 ft of exhaust

pipe. No idea what they did with the O2 sensor. If I unhook the

temp sensor it doesn't seem to miss, so I changed it, hooked it

back up and it misses bad.

It has about 90,000 miles on it.

How do I check the timing? I guess there is some brown / tan wire

I need to unhook but can't find it. Any help would be great.

Thanks,

Vance

8.1HD/ALLISON · February 1, 2011

Should be a single wire behind the electrical center cover on pass side of firewall. Don't remember on the color. Disconnect this wire to set base time so the computer can't compensate while you set timing. Other then that wire its same as any other, timing light and timing mark.

scott473 · February 1, 2011

Brown wire with a black stripe. Its right behind the distributor. Its a single wire and can be a pain to get two hands onto it. Unplug that wire bring the motor up to operating temp set your timing at 0* shut the truck off plug your wire back in reset the computer and you should be good to go.

ChevyTech77 · February 1, 2011

That engine is going to run like crap without an O2 sensor, just an fyi. That's why it changes with the cts disconnected.

haulincats · February 1, 2011

That engine is going to run like crap without an O2 sensor, just an fyi. That's why it changes with the cts disconnected.

So what wire or wires is suppose to go to the O2 sensor

It ran ok when I bought it. and it wasn't hooked up.

Is there a way to bypass it. Or can I weld a port in the exhaust?

Thanks,

Vance (ps how do I get rid of the double spacing)

GMstrong · February 1, 2011

Some headers dont have o2 ports thats why they are made for offroad use only

ChevyTech77 · February 1, 2011

Single wire connector on the driver's side rear of the engine compartment as the O2 sensor on that truck, would have went in the driver's side manifold. Weld a bung in the pipe and plug it in. I'd bet that it probably needs spark plugs by now too.