what would be a good total timing for a 289 with the stock compression ratio.. i was leaning towards 38-42.. somewhere in that ball park.. im trying to tune the dizzy a lil also, change the advance curve a bit.. any help in this department is welcome.

 

best idea to try on a track, retard and advance so to find the sweet spot. I'd rather lean towards 34-36 though

 

what about advance curve? i was thinking having total timing kick in at 2500-3000 somewhere in that area.. kinda new to this whole tuning the dizzy, im just so used to working on 5.0l efi engines where the dizzy just tunes it self.. haven't been to the track yet but i will go to "test and tune" and play with it a little.

 

I agree with kalli. It sounds like your motor is pretty much stock? I have mine set at about 35 (conservative). You don't want to go to crazy especially with a stock motor. You don't want to stress the motor or make it harder to turn over, etc,etc.

 

Total timing is only a very small part of distributor timing. The curve of timing at which the advance increases with rpm or vacuum is critical. You can't just say "32° is perfect for such and such engine", at what- 1500 rpm? 2100? And if the timing hits the target at 2000 rpm, will 16° be perfect at 1000 rpm? Maybe, maybe not.

You can adjust timing on the car, at least the centrifugal, but without a controlled vacuum source you won't get reliable vacuum advance, which is pretty important, too. For best results, a professional with a distributor machine is the way to go.

Here's the simplest curve I know:



The BOSS 302 was a bit more complex:

 

it is near stock.. i have the stock 289 heads on there but have a weiand stealth intake with a 650 4 barrel.. going to cam it and call it a day.. but i have a msd dizzy without the vacuum advance, so just looking more into the tuning part. wont be that much of a street car.. 91 octane will be put in it all day.

 

With bigger carb and cam, use the BOSS 302 specs to set up your distributor, and if you use a single diaphram advance, ignore the "vacuum retard" part.

 

2+2: is there any way to convert all that in engine rpm and crankshaft degrees?
i don';t have that machine. we had one in germany where i*worked, but i moved.

So what i'm looking to see is a table that gives me engine rpm vs ignition adanvce (degrees at crank)
I was thinking of doubling up everything, since crankshaft 2x camshaft

like this (boss numbers)
engine rpm === "added timing on initial (vacuum plugged at carb)"
700 === 0-1 deg
1000 === 0 - 1 deg
1300 === 0 - 3.5 deg
2000 === 5 - 9.5 deg
3000 === 15.5 - 20 deg
4000 === 17 - 22 deg

max advance 22 at 4000

it sounds reasonable to me which would put me in the ballpark of my 36 total at 4000 (with 14 initial)

Kalli

 

thanks kalli... thats about what i was going for. will post pics of the build later today

 

it's just an assumption. but somethign I'll try as well