1984 Trans AM 305, 150hp 700-4r - Timing
08-13-2023, 09:24 PM
#1
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1984 Trans AM 305, 150hp 700-4r - Timing
My car is a car built for the Canadian Market. Thus, it has a QJ.
I have removed all the TVS & associated vacuum lines & heat riser butterfly & egr..
I then set the idle timing as listed at 4* btc. Car ran like crap at that idle.
I set idle (initial) timing to 10* (vacuum advance port capped on QJ to do this) . Runs great.
I believe that 10-13* & total timing of 30-35* is what the old hotrodders recommend.
What are u guys running initial timing & what then is total timing?
Comments?
I have removed all the TVS & associated vacuum lines & heat riser butterfly & egr..
I then set the idle timing as listed at 4* btc. Car ran like crap at that idle.
I set idle (initial) timing to 10* (vacuum advance port capped on QJ to do this) . Runs great.
I believe that 10-13* & total timing of 30-35* is what the old hotrodders recommend.
What are u guys running initial timing & what then is total timing?
Comments?
08-13-2023, 10:22 PM
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Re: 1984 Trans AM 305, 150hp 700-4r - Timing
How accurate are your "mark" and "tab"? Have you verified them down to the last °?
I thought not.
Put down "light". Close "book". Forget "spec". Ignore "mark" and "tab".
Advance it. Enough to be REALLY significant. (seems like, ALMOST ALWAYS, wherever somebody's "timing" is, it's "not enough")
Does it run better? (you get to decide ON YOUR OWN what "better" consists of... more HP, crisper throttle response, lower fuel consumption, cooler running on the freeway, ... use your imagination to imagine "better") Yes / No
Yes: advance it some more.
No: set it back to where it was, then a bit more.
Better? Yes / No
Yes: Whatever you just did, do it some more.
No: Go back a little bit.
Better? Yes / No
...
Are we getting the hint yet?
EFFFF abuncha "mark", "tab", "light", "book", "spec", ... EFFFFFF EVERY BIT OF THAT. Instead, give the engine WHAT IT WANTS. Keeping in mind at all times, THE ENGINE knows FAR BETTER than you EVER will, what will make it run better. And the coolest eeeeeezyest thing of all is, if you GIVE THE ENGINE WHAT IT WANTS, it RUNS BETTER. Give it something else, ... YOU do the math.
Allow me to paraphrase one of the GOATs in a completely unrelated field, who, had he been working on a car instead of what he was doing (among the best there ever was) for a living, would have answered:
If it RUNS good, it IS good.
Keep adjusting as described above until ANY adjustment you make, in EITHER direction, makes YOUR engine run NOT better, according to YOUR preferences, with the fuel YOU have available, in the place YOU drive it, with the conditions (temp, humidity, altitude, etc.) that YOU are in, on the roads YOU drive on, the way YOU drive the car, and what's important to YOU. YOU get to be the ultimate arbiter of all this, not "book", not "us", not "consensus", not "the Internet". YOU. Once you get to that point, then THIS particular adjustment is as "good" as it can get.
You may well find that OTHER adjustments such as mixture or idle speed or whatever, need to be reset. Do the same with each of those. "If it RUNS good, it IS good". Every one.
THEN AND ONLY THEN, pick back up "light" and look at "mark" and "tab"; and make a note of where it is. Then, if Skillet comes along later and decides THEY "know" better somehow where your engine wants the "timing" to be, better than THE ENGINE knows, you can un-screw-up whatever they did, and put it back to optimum. Assuming of course that your crank damper's inertia ring (blob of SPOOGE) hasn't wandered some more some way somehow, as they all inevitably and inexorably do. Notoriously inaccurate, inconsistent, and unreliable.
Any number we can give you is only as "accurate" as your "mark" and "tab". None of which is in any manner way shape form or fashion, "reliable".
For all the half-century or so that I've been in this hobby, THAT'S how we got a car to run right. Measured interval on the Earth whether pavement or not (this culvert to that, this stoplight to the next, lap times on the track, how hard it comes up off the corners on a tacky/sticky/loose/dry oval, ET and MPH, etc.), and a stopwatch. Modern conveniences like WB O2 sen-sores and cell phones and GPS and things like that, are a MAJOR help, but by no means indispensable. We have always called this process "TUNING". Learn it, live it, practice it, LOVE it, it works EVERY TIME. If the car goes faster, your change was good; if the car slows down, not so much. Tweeeek whatever handles your setup has (static timing, dist curve, carb parameters, etc.) until it's as good as it can be. Once you get to that point, it's ... as good as it can be.
Questions?
I thought not.
Put down "light". Close "book". Forget "spec". Ignore "mark" and "tab".
Advance it. Enough to be REALLY significant. (seems like, ALMOST ALWAYS, wherever somebody's "timing" is, it's "not enough")
Does it run better? (you get to decide ON YOUR OWN what "better" consists of... more HP, crisper throttle response, lower fuel consumption, cooler running on the freeway, ... use your imagination to imagine "better") Yes / No
Yes: advance it some more.
No: set it back to where it was, then a bit more.
Better? Yes / No
Yes: Whatever you just did, do it some more.
No: Go back a little bit.
Better? Yes / No
...
Are we getting the hint yet?
EFFFF abuncha "mark", "tab", "light", "book", "spec", ... EFFFFFF EVERY BIT OF THAT. Instead, give the engine WHAT IT WANTS. Keeping in mind at all times, THE ENGINE knows FAR BETTER than you EVER will, what will make it run better. And the coolest eeeeeezyest thing of all is, if you GIVE THE ENGINE WHAT IT WANTS, it RUNS BETTER. Give it something else, ... YOU do the math.
Allow me to paraphrase one of the GOATs in a completely unrelated field, who, had he been working on a car instead of what he was doing (among the best there ever was) for a living, would have answered:
If it RUNS good, it IS good.
Keep adjusting as described above until ANY adjustment you make, in EITHER direction, makes YOUR engine run NOT better, according to YOUR preferences, with the fuel YOU have available, in the place YOU drive it, with the conditions (temp, humidity, altitude, etc.) that YOU are in, on the roads YOU drive on, the way YOU drive the car, and what's important to YOU. YOU get to be the ultimate arbiter of all this, not "book", not "us", not "consensus", not "the Internet". YOU. Once you get to that point, then THIS particular adjustment is as "good" as it can get.
You may well find that OTHER adjustments such as mixture or idle speed or whatever, need to be reset. Do the same with each of those. "If it RUNS good, it IS good". Every one.
THEN AND ONLY THEN, pick back up "light" and look at "mark" and "tab"; and make a note of where it is. Then, if Skillet comes along later and decides THEY "know" better somehow where your engine wants the "timing" to be, better than THE ENGINE knows, you can un-screw-up whatever they did, and put it back to optimum. Assuming of course that your crank damper's inertia ring (blob of SPOOGE) hasn't wandered some more some way somehow, as they all inevitably and inexorably do. Notoriously inaccurate, inconsistent, and unreliable.
Any number we can give you is only as "accurate" as your "mark" and "tab". None of which is in any manner way shape form or fashion, "reliable".
For all the half-century or so that I've been in this hobby, THAT'S how we got a car to run right. Measured interval on the Earth whether pavement or not (this culvert to that, this stoplight to the next, lap times on the track, how hard it comes up off the corners on a tacky/sticky/loose/dry oval, ET and MPH, etc.), and a stopwatch. Modern conveniences like WB O2 sen-sores and cell phones and GPS and things like that, are a MAJOR help, but by no means indispensable. We have always called this process "TUNING". Learn it, live it, practice it, LOVE it, it works EVERY TIME. If the car goes faster, your change was good; if the car slows down, not so much. Tweeeek whatever handles your setup has (static timing, dist curve, carb parameters, etc.) until it's as good as it can be. Once you get to that point, it's ... as good as it can be.
Questions?
Last edited by sofakingdom; 08-13-2023 at 10:37 PM.
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