Torque convertor and detonation
It's funny, you talk about this motor like it is a dog based on the compression and mild cam, but to me it feels great with tons of power, its all relative I guess. I am satisfied with what I have, just want to tune it properly.
Yes it is relative.
Here's the thing;
At a compression ratio of a true 8/1, and with the 262 cam your cylinder pressure is predicted to be ~130psi. And the V/P index is expected to be ~115; read about V/P here;
V/P Index Calculation
Now; at split overlap, and at sealevel;
1) A stock 9.0Scr 318 is predicted to make a pressure of 161@133V/P
2) A stock 8.0 smoggerteen.................................... 138@114
3), A stock 8.0/360 with 360 stock cam..........................139@130
4) Pumped up to 9.0 with stock 360 cam ....................... 154@138
5) Your 8.0 360 with 262 cam in at 109 .................. 128@111
6)for comparison, my alloy-headed [email protected] .....193@167
So compare your combo, to some of these numbers; Your engine has the least amount of predicted pressure, which leads to the least amount of V/P which is a measure of low-rpm performance and is directly comparable no matter the engine.
>Compare 2 and 3. Notice they both make about the same pressure; one is a 318, the other a 360. Notice the 360 is up 6% in V/P; that's the cid
Compare 1 and 4. The 360 is - 4% in psi but +3.8% in V/P; again the cubes
>Compare your 360, to the smoggerteen.
Now you know the rest of the story.
The V/P difference is most noticeable at low-rpm, and diminishes with rpm, and eventually, beginning at somewhere between 3000 and 3600 is no longer meaningful. But with a 2000 stall and 3.23s, you can see where this information is useful. And you can see that getting the timing right, down in that never-never land, is a pita.
Find your stall rpm. Then determine your maximum stall timing.
Then build your low rpm curve to the stall rpm to be as fast as possible.
Then find your max PowerTiming at say 3800. Then connect the two parts of the curve. This usually requires a two-stage curve because the two lines are rarely climbing at the same rate. And that takes a fat-wire one-long-loop spring, which you adjust to slam the brakes on the high-rate low-rpm spring. Followalong on some of
@Mattax 's diagrams, and you'll get the idea.
After this you can experiment with bringing the PowerTiming in earlier, and or increasing it.
But the Big Deal is to sneak up on the Optimum Timing and not worrying about not being able to get it right on. Without a Dyno, and without a Distributor-machine, or without a dial-back timing module, AND without a knock-sensor; it can take weeks to months to get it dialed in just right.
And the idle-timing always gets the chit end of the stick.
Getting the timing right is easier with a stall that is closer to where the V/P has decreased to being meaningful, cuz like I said, your engine doesn't much care about the low-rpm timing until it hits the stall-rpm, AND you cannot give the engine the Idle-Timing it wants, anyway, in stock configuration; and if you could, you would lose the idle-lope that everyone is so keen to have.
Happy HotRodding