Timing is everything it's said...

[coz 108]

Well it means that to me or at least the Mach. I was noticing the engine was loading up and dumping gas on acceleration. Checked my timing and it was 16 degrees vacuum and -2 w/o vacuum (mech. only). Slipped 4 degrees in - more than I planned - was looking to add 2. Anyway, the loading up is gone as is any little hitching I was getting when on the pedal. Did notice it to be much more responsive now but might have lost a bit at the top.

 

Will try it for the weekend and drop it back 2 degrees to 18 degrees initial to see if I can find a happy medium. It's at 32 degrees total timing and feels "right" or very close.

 

Dumped it on a 2 lane last night and did a 360+. Was a little too much pedal but felt nasty - love posi-traction.:punk:

[gsxrken 21]

I'm not sure I follow your post. You ought to have around 12-14 BTDC intial degrees, with the vacuum disconnected. When you rev it to around 3000 RPM, you should get another 16-24 degrees of mechanical advance.

 

Reinstalling your vacuum advance line to ported vacuum on the carb should give you another 10-12 degrees under certain conditions.

[coz 108]

I'm not sure I follow your post. You ought to have around 12-14 BTDC intial degrees, with the vacuum disconnected. When you rev it to around 3000 RPM, you should get another 16-24 degrees of mechanical advance.

 

Reinstalling your vacuum advance line to ported vacuum on the carb should give you another 10-12 degrees under certain conditions.

 

Naw - no vacuum attached at idle I have 2 degrees, with vacuum I have 20 at idle. This is a 408C stroker with an aggressive cam and crank.

 

When revv'd into 5rpm I have 32~36 degrees with vacuum.

 

Running like a champ for the most part. Again, will probably pull out 2 degrees to have it around 18 degrees at idle with vacuum.

[gsxrken 21]

Well I don't like arguing with a guy with 587HP :)

But I'd be afraid that when you romp on those throttle plates and your vacuum almost goes to zero for a while, you are seriously under-timed.

Different strokes/folks. Nice car.

[coz 108]

Well I don't like arguing with a guy with 587HP :)

But I'd be afraid that when you romp on those throttle plates and your vacuum almost goes to zero for a while, you are seriously under-timed.

Different strokes/folks. Nice car.

 

No not disagreeing with you - I do have 0 vac. on hard throttle. It's just I can't believe I can add in that much more timing... What would you consider good timing w/ vacuum at idle??? The 587hp was on a dyno with no vacuum - instead we did 32 degrees mech. It was suggested by the engine builder to do away with dizzy vacuum and run 32 degrees w/o vacuum. I kinda want to keep the vacuum if possible.

 

Definity adding 4 degrees helped - maybe I advance a degree or two several times to see where it rides best.

[bnickel 10,004]

if it helps my 351w with mild speed pro cam (218/224 @.050, 473/796 lift) with headers, performer intake, 625 raod demon and stock dizzy with mallory unilite conversion the timing is set to 14 initial and 36 total by 2800 rpm. the vac advance is connected but only really does anything just off idle to about 2500 after that it's all mech advance. at idle it has about 16 in. vacuuum. and idle speed as right at 750 in neutral, about 550-575 at idle in gear.

 

i would highly suggest setting the dizzy up so you have about 14-16 degrees initial and 34-36 total.

[coz 108]

if it helps my 351w with mild speed pro cam (218/224 @.050, 473/796 lift) with headers, performer intake, 625 raod demon and stock dizzy with mallory unilite conversion the timing is set to 14 initial and 36 total by 2800 rpm. the vac advance is connected but only really does anything just off idle to about 2500 after that it's all mech advance. at idle it has about 16 in. vacuuum. and idle speed as right at 750 in neutral, about 550-575 at idle in gear.

 

i would highly suggest setting the dizzy up so you have about 14-16 degrees initial and 34-36 total.

 

Actually mine is 20 degrees initial and 34-36 total. But w/o vacuum it's 2 degrees initial at idle. Maybe I knock it down 2 degrees with vacuum to be at 18 initial.

[buening 63]

Sorry but that doesn't make much sense. When setting timing with a dizzy w/vac advance, you unplug the vacuum line and set your initial. SBF's like to run at 36 total timing w/o vac advance, so depending on your mechanical weights you could be around 10-16° initial without the vac advance. My distributor has 10L weights, so i get 20° mechanical timing hence my initial timing of 16°. The 10L weights are the smallest that i have seen, but you can see what size weights you have by looking through the small holes in the dizzy plate.

 

Once the timing is set with the vac advance unplugged, you can unplug the vac advance and go. The vacuum advance will bring the total timing way above 36° when cruising, but this helps with gas mileage. If it were me, i'd set the timing to around 34-36° total w/o vac advance and leave it unplugged unless you are worried about fuel economy. I would think you are way undertimed when your vac advance is not receiving any vacuum. I'm not trying to argue and i'm sure you know what you're doing, but the purpose of the vac advance is to increase the total timing during certain conditions to get better fuel economy and not assist in reaching the total normal timing of 36°. This is why most aftermarket distributors don't have vacuum advance because most are used on drag/race cars that aren't worried about fuel economy. I think you are leaving some horsepower on the table with the way you have it timed. Just my $0.02 though.

[bnickel 10,004]

Actually mine is 20 degrees initial and 34-36 total. But w/o vacuum it's 2 degrees initial at idle. Maybe I knock it down 2 degrees with vacuum to be at 18 initial.

 

if the vacuum advance is working at idle then you have the unit connected to full manifold vacuum. it needs to connected to ported vacuum so it only works when the vacuum goes up enough to pull the advance up slowly.

 

what you need to do is set the timing with the advance unplugged and it should be set to probably 12-16 at idle. total timing should be 36 degreees or so by 2800-3000 with NO vacuum. when you reconnect the vacuum advance make sure it is run to the ported vaccum port. on your car it is most likely plugged, at least it sounds like it probably is. you can tell the which nipple is ported by putting your finger over the nipple at idle, it should not suck on your finger again only at idle, when you rev the engine a bit you will feel it start to try to suck your finger into the engine.

[Pakrat 1,043]

I know I've said this a million times before but I still believe in timing by ear personally, then check where it's at with a light and speedo if you want a record of it for future reference. I have a mechanical dizzy and my 302 with 4V, intake, headers and Cam likes to run at 13* BTDC.

 

Just for shits and giggles, advance it until it starts to ping then back it off a little, that should be your optimal setting. Then check it just to see where you land vs. where you are tring to intentionally set it.

[coz 108]

OK you all have me scratching my head. I guess I have to go back out there again and look it over. I tore up my finger pretty bad last week so engine work really hurts. I'll take a look at this week and report back. Never an argument from me - it's been a while since I had a timing gun in my hand but thought I did it right.:cursing:

 

Here's my finger - OUCH!

 

Last Page...

 

http://www.1969stang.com/gallery/COZ-69Mach1

[Protowrxs 111]

Geesh.. that hurts just looking at it. Man, how did you do that? (So I can make sure to add that to my do not try that at home or work list).

 

-Stephen

[bnickel 10,004]

most of my fingers have looked like that at one time or another. building models as a kid and constantly cutting the tips of your fingers off with an exacto knife is pretty tough at times. seriously most of my fingers have scars on them from doing that all the time. i've literally cut the tips off of 3 fingers, just in front of the fingernail. luckily they all still had some skin holding them on or my fingers would look really f-ed up. also being a guitar and bass player the tips of my fingers got a lot of use so most of them still look pretty damn normal but there are a couple that you can tell had serious cuts on them

[coz 108]

Geesh.. that hurts just looking at it. Man, how did you do that? (So I can make sure to add that to my do not try that at home or work list).

 

-Stephen

 

That my friends is a CAT bite. We rescue strays and I came across a hurt Tom. We were doing good until I tried to move him from the trap cage to a carry cage. He bit all the way through my finger - the top fang hit the nail and then found skin, the bottom fang went into my finger pad and went upwards. The fangs met in the middle - man did it hurt. Felt like a hammer on my finger. Bled for a week.

 

Of course the stray got away so I'm taking rabies shots to add to the enjoyment. I'm a pin cushion between them and the tetnus shots.

 

Jammed the finger into the hood hinge on Friday night making final adjustments to the hood. That really hurt. Even my buddy didn't feel good after seeing that...

[Protowrxs 111]

Wow... I think I better be nice to our cat more often. Damn, and rabies shot to boot? - Definately on my NOT to do list. Hope it heals up ok.

 

Man bnickle.. I remember stabbing myself a few times but never lost a finger tip building models.

 

Guess it's all in the 'timing' and that is what this thread was originally about so we're not too far off topic.. lol

 

-Stephen

[R4K 10]

Well, crud.

 

This thread was finally turning into something I understood with cats. Everything prior to that translated into "blahblahblahblahtimingchainblahblahblah".

 

:taz: