unplug the brown ignition wire behind the relay cover under the hood, start the truck and put a timing gun on it. This will tell you if the timing is off. If you are above 8* you are way too high. Run no more than 2* advance on 87 octane, and no more than 4* on 93 to start off with, if you get absolutely no knock after it starts to run fine and during normal driving, such as pulling hill or part throttle take off, then you can start to add timing 1* at a time until you hear knock, then back off 1*. You will have to have an exhaust system on the truck to hear knock unless you have a scan tool such as the Snap On. If you can not fix the problem with the distributor, pull your timing chain cover to make sure and double check the alignment on the gears. Good luck

 

On a TBI you have to set base timing manually. There is a brown wire going to the distributor that must be disconnected in order to begin the procedure. Using a timing light it's a matter of using the #1 or #6 plug wire with your timing light to get it to TDC. Having never owned or worked on a TBI truck myself that's about all I can tell you.


*EDIT* Kyle beat me to it!

 

180* off would be my guess, too. Been there, done that.

 

With the wire unhooked, will the computer advance the timing at all? Will the base timing be the same at normal idle as it would at higher engine speeds?The throttle is tied back to idle at +- 2000 RPM's for the cam break in.

Has anybody ever used header wrap? I would imagine that if it would work anywhere, it would work on a mild daily driver?

I can remove it if need be though.

Guess I'll pick up a fire extinguisher, turn the distribuitor, and try it again this evening.

Mike

 

P.S. If it were 180 out, would it even run???

 

No it wont

 

I agree with it being retarded. I had a 90' GMC TBI and its idle was set at 8* to get it running the strongest and not ping. It had crazy power after the cam and 454 injectors.

 

I think the problem was simply from running the open headers and running the RPM's needed to break in the cam, on an untuned motor.

I'm sure those trucks have 02's. Do they control fueling like our motors, LS1Tech guys? ... or is the fueling hard-programmed in the computer or TBI system?

The glowing thing is actually quite common. Check out a dyno-pull in a dark room...

My four-stroke dirtbike and streetbike will both glow the stock stainless steel headers quite bright if I idle them for more than 5 minutes at night. That's all it takes. A friend of mine lit a cigarette off my dirtbikes header.

The header wrap thing has me a little confused... was it new, high quality stuff?

How far down the headers was the glowing reaching?

Do you have a timing light handy to see what you're getting at 2,000 rpm?

 

no when you unplug the wire it goes to base timing that is suppose to be zero on the tbi. then you will have to go from there to advance it. but when the computer comes back in play that might mess it up or run right.

 

I did this once on a 16v vw motor and even tho it only ran enough to get the header glowing it warped the head and cooked the jethot coating right off the header....