440 Timing

[BSB67]

O.K. guys thanks for all the advise, it has been an overload of information but helpful.

I have my timing set as of this past Saturday at 12 degrees initial, at 2500-2800 rpm I am at 33 with no vacuum hooked up and idel at between 90-1000 rpm. I reconnected the vacuum and I ran the car and got good take off with no bog at WOT and very little ping at all on pump gas. 104 booster took care of that. Ran great but did seem a little slower. Reset the the timing to 14 base (i had marked the disributor because it was set like this initially), did not read the upper this time, pinging at the slightest acceleration under load did just like before. disconnected advance and it was fine with more power. Tried moving timing to 18 but the car hates to idle there very rough weather vacuum is connected or not.

I am sure there is a way to get this motor to perform better but for now I can drive it and if I set the timing to 14 base without vacuum I can play a little harder. Here in Atlanta the heat will determine what happens next but i will have to wait till its spring.

I used to have a very heavy WOT bog, and it made pulling in traffic a nightmare but now it seems to be acting like a normal car. then the timing was at 10 initial, so I am slowly creeping up on the correct set point. I still would like to try the firecore distributor for adjustability. but are there any other tweaks to get a little more out of it without the ping? or would that take a new dizzy or timing curve adjustment to my present set up.

thanks again everyone, you had me in the garage playing, and learning new things and staying away from the honey do lists. Best Weekend in years.

If you are at slight ping under part throttle load, or WOT, try a cooler spark plug, cooler thermostat, and blocking the intake heat cross over. AF ratio adjustment can help too if you are on the lean side.

 

[Bicylindrico]

No, someone that tells you to dial in 50 degrees of total timing does not need to be your friend.. The guy that sits and helps you dial in your car so you can enjoy it, is the guy you wanna call friend..

Everything Bill Monk said is correct. Maybe he doesn't need to be your friend but he understands ignition timing.

 

[Derwud]

Everything Bill Monk said is correct. Maybe he doesn't need to be your friend but he understands ignition timing.

Sorry, being sarcastic... Total needs to be set using whatever methods you plan on setting them too, re

Everything Bill Monk said is correct. Maybe he doesn't need to be your friend but he understands ignition timing.

I was being sarcastic..

 

[///Matt]

So confirm or correct me here fellas...

Been noticing poor (to me) performance and some noise under hard acceleration. My timing was set too far advanced. It was something like 22* @ 750rpm, vacuum disconnected and capped.

I have adjusted it to about 14* @750, and get an all-in mechanical of about 35* @2600-ish. My vac gauge oscillates rapidly between 8-12” at idle.

With vacuum connected, either to ported OR manifold, I get 50* or so all in, and I thought “damn that’s too much” and just went ahead and disable vac advance. I haven’t yet driven again, so I have no opinion about how it feels/sounds yet.

So... is about 50* all-in GOOD with vacuum connected? I have no opinion to provide about how quickly the vac advance kicks, because I have little experience adjusting vac advance.

 

[oldbee]

Matt, sounds like timing coming too quick for your engine. There is ‘race’ & street to think about in the overall picture.

 

[///Matt]

Matt, sounds like timing coming too quick for your engine. There is ‘race’ & street to think about in the overall picture.

The PO (or one of them at any rate) threw a lot of parts/ideas at it that didn’t fit the car... like an 850 double pumper, on a low-stall heavy automatic car.... that couldn’t even get to WOT because the throttle linkage was junk.

I’d love to take this motor apart and find out exactly what’s going on inside beyond the sellers description of “hot 440 with a street hemi cam!”

 

[ykf7b0]

I too am running a 284/484 Purpleshaft with 10.6 to 1 compression. I also have a Firecore distributor and I will tell you this cam likes a lot of initial advance. Mine is performing best at 23 initial and 35 total using a Rev-n-ator ICU.

 

[///Matt]

I too am running a 284/484 Purpleshaft with 10.6 to 1 compression. I also have a Firecore distributor and I will tell you this cam likes a lot of initial advance. Mine is performing best at 23 initial and 35 total using a Rev-n-ator ICU.

So, with the rev-n-ator, can you program initial vs. all-in, or are you still manually recurving the diz?

And what was it doing to you with lower initial timing?

I haven’t driven with my adjustment yet, but how it was set, it lacked bawlz on the low end and definitely was fighting for it on the top end.

 

[beanhead]

Yeah it bears repeating, give the engine all the idle advance it wants until the vacuum peaks and rpm stops increasing...then rev that boy and see what the curve looks like. More than likely needs the total reduced while keeping the high initial. At 14/35 the total will be too much if you advance it so the distributor needs to be adjusted.(I use a firecore unit with the built in limiter plate and mine runs best at about 21° initial and 37° total, with a [email protected] cam and aluminum heads).

 

[///Matt]

It seemed to like some idle advance reduction. Hm. I’ll give it a roll and see how she goes.

 

[Dragon Slayer]

If your all in means 35 total with no vacuum, which is how I read your post. That means you have 14 initial and get about 21 mechanical. That is all fine. Your 50 with vacuum all in doesn't make sense though. WOT means low to no vacuum so where is the other 15 degree coming from at all in?

 

[///Matt]

Yup. 21 mechanical, and if I hook up the vacuum can, either to ported or manifold, at 2500+ rpm I’m pushing 50* total advance. not WOT though. Just hand-opening the throttle at the carb, watching timing and RPM on the gun.

 

[Dragon Slayer]

Ok, That is more like cruise condition with about 15 degree vacuum advance. 15 degree vacuum not too aggressive, but I guess it depends on what your vacuum is at that 2500 RPM.

 

[///Matt]

In the garage, I don’t think the vacuum beat 15-18” while revving. When closing the throttle it spikes of course, but while climbing/holding definitely never hit 20”.

I re-hooked up the vac can. At worst, right now I’ve pulled 6-7* out of it, and see what happens tomorrow ha

 

[miller]

My vac gauge oscillates rapidly between 8-12” at idle.

Get a copy of one of those vacuum gauge charts, and see what it tells ya.

 

[Bill Monk]

So confirm or correct me here fellas...

Been noticing poor (to me) performance and some noise under hard acceleration. My timing was set too far advanced. It was something like 22* @ 750rpm, vacuum disconnected and capped.

I have adjusted it to about 14* @750, and get an all-in mechanical of about 35* @2600-ish. My vac gauge oscillates rapidly between 8-12” at idle.

With vacuum connected, either to ported OR manifold, I get 50* or so all in, and I thought “damn that’s too much” and just went ahead and disable vac advance. I haven’t yet driven again, so I have no opinion about how it feels/sounds yet.

So... is about 50* all-in GOOD with vacuum connected? I have no opinion to provide about how quickly the vac advance kicks, because I have little experience adjusting vac advance.

Man, this is odd. At idle, you should have 0 mechanical advance and if your initial is at 14 and you get 50 with the vac can connected to manifold vacuum, then it is providing 36 degrees of advance. Clearly too much! I wouldn't think that much advance would even be possible from the vacuum can alone. Got me stumped on this one

 

[ykf7b0]

So, with the rev-n-ator, can you program initial vs. all-in, or are you still manually recurving the diz?

The Firecore is totally adjustable and allows me to close the gap (or widen) between initial and total advance. I posted I was using the rev n ator because using it requires about 2-4 degrees less total advance.

 

[///Matt]

Man, this is odd. At idle, you should have 0 mechanical advance and if your initial is at 14 and you get 50 with the vac can connected to manifold vacuum, then it is providing 36 degrees of advance. Clearly too much! I wouldn't think that much advance would even be possible from the vacuum can alone. Got me stumped on this one

Bill I don’t mean hooking up the can gets 50* at idle, I mean 14* at idle, 36* at full mechanical, and 50* at combined full mechanical and full vacuum advances.

 

[Dragon Slayer]

Road test can help resolve how it performs where your at now. Based on what you say, you have 14 initial, 21 mechanical, and about 15 max vacuum. That is not far off a stock 440 without CAS emissions. The only difference is your letting full mechanical come in earlier at 2500 rpm for performance purposes, versus 4400 rpm for a stock 440.

So if you put vacuum on ported like a stock mopar, as you open throttle from idle and rev up to a 2500 rpm in neutral which will look like a cruise condition to the motor. You have Vacuum available. But since you are on ported it starts at 0 advance. As the motor revs up your mechanical is adding and vacuum starts to add too. This is not instantaneous. But your going to get that full mechanical, and also full vacuum advance which will push the 50 degree. But you start at 14 and build both advances.

Now if you put vacuum on manifold at idle. You start at 29 degree advance. 14 initial and max vacuum adds another 15. Now as you rev it up, mechanical starts adding too. Vacuum might come down some, but if not you just start with too much vacuum advance too soon. If you nailed it WOT on the road and vacuum drops off your now at about your 35 initial plus 15 vacuum which is retarding timing now as vacuum drops with WOT under load. So you might have too much timing until vacuum advance comes all the way down to zero with zero vacuum. That is the difference on how ported versus manifold vacuum work. How your car is tuned and what advance curves you select will determine how you want to use vacuum advance. Just remember manifold starts with full vacuum advance on and retards vacuum advance at WOT on the road. And Ported starts at zero vacuum advance at idle and advances under partial throttle and mild load (partial throttle blade). If you immediately punched if from a roll you would never see vacuum advance come in at all if on ported. Because as it would start to see vacuum as throttle blades open and tries to advance your would be at WOT and vacuum fall fast to near zero and no vacuum advance at all. Just your total mechanical and initial like most race car set ups.

For MOPAR vacuum advance adjust vacuum based on load and in some cases it adds advance and in others it retards advance. It really helps for cruise fuel economy.

 

[Bill Monk]

Bill I don’t mean hooking up the can gets 50* at idle, I mean 14* at idle, 36* at full mechanical, and 50* at combined full mechanical and full vacuum advances.

OK, my bad, but I still don't know how you are getting 50 (all in) if you are connected to manifold vacuum. Manifold vacuum should decrease by the time you are hitting 3000 rpm