What is the stock ignition timing on my 1990 RS 305 TBI?

 

dead on zero, be sure to disconnect the est bypass before setting timing.

 

I've heard around here alot that advancing the timing "makes the car faster" how do i do this and how does that work?

 

Disconnect the EST bypass, and with your timing light, set the mark on 8 degrees BTDC. Shut the engine off, connect the EST bypass, then disconnect the battery for a few minutes. Failure to disconnect the battery will throw an inadvertent Code 42....

 

okay now we need an explanation how you came up with the 8°, isn't that an aweful lot of timing for a stock tbi?

 

Why would it be too much? If he's using a timing light, he can gradually work his way from zero to 8°, and if he happens to find a happy medium in between, then so be it. However, why would you imply 8° being too much to start off with? If it pings with a load at 8°, which I highly doubt, then he can simply back off in increments until he's happy....

 

you didn't mention anything about working your way from 0 to 8° in your previous post..
anyways, i was convinced that you'd already have to go one step up to higher grade fuel in order to get away with 2-3° initial timing? also, it'd be better to use some sort of aldl logging to determine how happy the engine is, speaking in terms of spark advance. there are knocks that you can't hear but your ESC (knock sensor) can, which will retard timing and you'll maybe experience even poorer performance then the stock 0° setting.
btw, you did notice we're talking tbi here right? (just saw you have a tpi, yeh these cams would prolly want more timing)

 

Since your deterring from the subject at hand, I'll do my best to entertain. First, anyone employing a "timing light" should be pretty well versed with the fundamentals of both retarding and advancing the distributor. To consider 8° of timing as, a lot, is absolutely ridiculous, and by the way, nobody said that it was written in stone. From my experience, and I've had countless third gen's, 8° is fine. However, since it is not written in stone, nobody is telling him that he can't set it to 6° or 4°, as it is personal preference....

Exactly how much factory compression do you think his TBI is squeezing...?

You are getting way ahead of yourself, and from the sound of it, the original poster is not ready to start burning his or her own prom's. In terms of knock, a noisy valvetrain for that matter can throw the ECM for a loop. There are way too many variables. 8° of timing will not be a problem, nor will it call for a higher octane. But again, there is nobody stopping him from going to 6°, or even 4°. As far as experiencing poorer performance, the track has the final say in that matter, not the seat of your pants....

How ignorant. Yes, I'm aware I'm speaking about TBI, as I have been on this website for six years now, and currently own three 3rd gens, if you must know. One blown TPI, one blow-thru carb, and one blow-thru TBI. Buy yourself a clue the next time you elect to try to argue some ridiculous point masquerading as relevant coherency....

 

Street Lethal I have to respectfully disagree, only on the basis of stock TBI with swirl port heads. The stock 187 heads are fast burn heads and don't necessitate any initial advance. For non 187 headed cars I agree 100% with your assessment on all accounts. I ran between 4 and 6 degrees for years, with poor results and had to do so with 93 octane, yet still had some audible ping. Once I learned a little more about the 187's and datalogged, I went back to zero and had better results (no more audible ping under certain conditions and back to 87 fuel). It has been years since I reviewed that datalog (or since when my car ran, ha) so I cannot produce the exact results I had, but my knock counts went way down and my MPG went way up. I now have 081 heads on the car, and as soon as I get it back together, plan on running somewhere around 8° advance.

 

So shifty are you saying there is no point in advancing it at all because if my swirl port heads?

What exactly is it that i am turning 4,6, or 8 degrees? the distributer?
I don't know much about timing, sorry for the inconvenience guys.

Thanks for your help so for guys.

I also use the highest octane, so detonation/preignition would not be an issue for me, unless i advance the timing too far of course.

 

Yes you are physically turning the base of the distributor (after loosening teh hold down bolt/clamp) while simultaneously looking at your timing light to see where the timing is going (crank groove in relation to timing tab, highlighting timing postion by timing light gun). This must be done with the EST wire unplugged or you will not see the correct value and you will get nowhere.

On a base 305 TBI with SP 187 heads you do not need any advance. A few degrees or two will give you "snappy" throttle response alluding you that the car is quicker. You really do not need any advance with these heads. However, this is not true for 99% of most heads as StreetLethal pointed out, where you do want a base advance.

Check the stickies above. There are more instructions for setting the timing.

 

there is a groove on the balancer that will indicate your current set timing at the flash of the timing light. it's connected to cyl #1 spark wire and will flash on #1 ignition, allowing you to actually see the groove. it's called a stroboscopic effect, or temporal aliasing, you'll see once you are aiming the timing gun down there and push the trigger

here's some pics of the timing tab above the balancer:





hth, ownor

 

Ahhh alright, thanks alot guys, i understand now.