Trying to adjust timing & no vacuum advance hose

[norcalsvt]

Bear with. First time adjusting timing. The car seems to run rich at idle, but lean at wot(what I have been told). Thought I would check the timing & noticed there is no vacuum advance hose on the distributor. It's a MSD Pro Billet. Is this right do ineed one? Wondering why there is not one. I see a hole on the distributor cap. I assume thats where the hose starts, but where am I supposed to connect it to. I have a Speed Demon 650 carb & see a capped port on the passenger side.
Also, if anyone else has a 347 stroker, what is the recommended timing?

Thanks everyone

 

[67GTA-FB429]

Is it a mechanical advance dist??

 

[norcalsvt]

Is it a mechanical advance dist??

I really am not sure. Actually I don't even know the difference between the distributors. The part number on the distributor says MSD Pro Billet 8579.
I'm basically a 36 year old newbie when it comes to working on cars.

 

[Ozsum2]

At idle, the vac advance cuircut is cut out anyway. It won't kick in untill about 1200 rpms. Richness at idle is easily corrected by adjusting the idle jets on the carb.

 

[6t6stang]

Are you posotive your lean at WOT.

I also have a demon and it seems pig rich at idle and thought was leaning out at WOT until I dynoed it.


First run little rich at idle then perfect 3 runs after that


I don't have the graph but I believe demons are like that

 

[dodgestang]

ummm....is there a big arse vacuum canister sticking on the side of the dizzy? If not, then you don't have a vacuum advance setup.

 

[norcalsvt]

ummm....is there a big arse vacuum canister sticking on the side of the dizzy? If not, then you don't have a vacuum advance setup.

No vacuum canister by the distributor. Since I don't have a vacuum advance setup, do I need to have one? Wondering why it wouldn't be installed.

6t6stang

I'm only going by what my neighbor told me. I wouldn't call him an expert, but he has built many hot rods including the one F100 he has in his garage. He tried to adjust my speed demon & after adjusting the idle mixture & speed screws, he said it's still running rich at idle & when he revs it he can here a fluttering. He is the one that told me to retard the timing a bit, so thats what I'm trying to do. Right now it's at 6 degrees.

 

[Great68]

No vacuum canister by the distributor. Since I don't have a vacuum advance setup, do I need to have one? Wondering why it wouldn't be installed.

You do not need a vacuum advance, it's primary purpose is to provide better fuel economy. I ran my car for a couple of years with the stock distributor and a broken (and disconnected) vacuum advance.

It seems like the person who bought the MSD distributor just didn't purchase one with a vacuum advance. No biggie.

 

[Ozsum2]

If you're at 6 DBTDC, you actually need to advance the timing. I'n at 12 on a bone stock 289.

 

[norcalsvt]

No vacuum canister by the distributor. Since I don't have a vacuum advance setup, do I need to have one? Wondering why it wouldn't be installed.

You do not need a vacuum advance, it's primary purpose is to provide better fuel economy. I ran my car for a couple of years with the stock distributor and a broken (and disconnected) vacuum advance.

It seems like the person who bought the MSD distributor just didn't purchase one with a vacuum advance. No biggie.

No wonder I can't get better than 7 MPG

 

[norcalsvt]

If you're at 6 DBTDC, you actually need to advance the timing. I'n at 12 on a bone stock 289.

I tried to advance the timing & noticed the rpm's increased as well. Right now it's at 1100 idle & 850-900 in gear. If I advance the timing, do I adjust the idle mixture screws to lower the idle back down to the 1100 idle? Also if you have a stock 289 at 12 what should a 347 stroker be around?

 

[302 coupe]

you'll have to adjust the idle speed screw(right next to the throttle linkage, should looks kinda like a set screw), not the idle mixture screws. I'm not sure about demons, but on regular holleys the idle mixture screws are on each side of the metering block. They take a small flat screwdriver to turn. Set your timing at 12, set the idle speed back to 800, then turn the mixture screws until you hear the idle just start to speed up. Then back off a half turn. The increase in idle speed means that its leaning out. Do one side at a time, and yes they will both need to be adjusted. You probably want it to idle at 800 in park, 700 or so in gear.

 

[302 coupe]

almost forgot, your total timing should be about 34 or so, all in by round 2800-3000 rpm. If you have too much it will ping, if you don't have enough you lose power and efficiency. MSD sells springs that control advance and they are cheap and easy to install. Just tell them you need a 22 spring(12 initial +22 advance =34 total).

 

[Ozsum2]

I tried to advance the timing & noticed the rpm's increased as well. Right now it's at 1100 idle & 850-900 in gear. If I advance the timing, do I adjust the idle mixture screws to lower the idle back down to the 1100 idle? Also if you have a stock 289 at 12 what should a 347 stroker be around?

OK, you need to be around 12. Maybe a tad more or less. But 6 is a 30 some year old factory recommendation. As you increase the timing, you will need to back off the curb idle screw to lower the rpm back into the 7-800 realm. The idle mix screws have no play in the rpms, except that you want them adjusted to have as high a rpm as you can. Remember to readjust the idle screw after making all other adjustments.

 

[norcalsvt]

Finally was able to adjust the timing to initial 12, but I still hear & feel a slight pop around 2800 rpms. Do I keep advancing until the pop(backfire?) goes away. Also, the total when I reved up to 3500 only went to 20 degrees.

 

[302 coupe]

initial timing at 12 is good, 20 at 3500 is bad, probably whats causing your problem. Call MSD and see what it takes to get your timing to advance more, should just need a spring swap.

 

[Ozsum2]

Slow timing at WOT won't cause a pop. It will only cause bad economy. You do need to figure out how to speed up the timing as the rpm increases. I ran without my advance hookup up because of weal springs for a month and couldn't really tell the difference. My weal springs were letting it advance too much. I would get a ping and then a noticeable miss. Plugging up the system worked fine while waiting for the dist to come in.