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m440x timing

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old hatt

Contributing Member
After seeing all the posts regarding the importance of total advance timing I thought I should check mine. Unfortunately my service manual does not tell me what it should be. Does anyone know what is recommended for a m440x engine. Thanks
 
I just did a quick search, and came up empty handed.
Which manual are you using.... OEM or other?
I think that you're going to want the OEM service manual for your engine.
It may not show this in graph form, but will hopefully give you the full-in degrees and RPM.
If you do find a curve graph, be sure that you understand that BASE advance is typically not included in the vertical degree scale.
So you'll want to include BASE when doing the math.

When you strobe this, BASE will automatically be included.

.
 
Thanks Rick, I too came up empty handed when I did a search. I am using an oem manual and can't believe its not mentioned. Still looking for answers everyone. Thanks
 
old hatt,
just curious, what are the advance degrees you show .........
@ idle rpm?
total @ 2000 rpm?
total @ 2500 rpm?

are you reading off the balancer or flywheel?
 
Yeah, it seems to be hard to find this.
The TA (whatever the TA is) @ 2,500 rpm seems to be too early to me..... and TA @ 2,000 rpm seems way too early.
 
fastjeff said:
About 25 degrees total advance at 2,500 to 3,000 rpms.
Jeff
Click to expand...
Jeff, I'm not into the Chrysler engines as you are, so I'm at a disadvantage here.
The only part of that your info that I have an issue with, is the "about" and the 500 RPM spread between 2.5K and 3k rpm!

OK...... the 440 uses a wedge head, correct?
This appears to be the Marine version piston.... or it's at least what I find when doing a search.
This is my source.
ad21a4568b59455c29bdd8f4886ffc15.jpg



If this piston creates the Quench or Squish area underneath the wedge....., then I suppose that Detonation potential is reduced, much like what a Q/E piston does in the Marine version SBC (of which also has a wedge area).
All of this plays a role in ignition timing re; just how much advance we can throw at it, and when (RPM)!

Now.... the 440 configuration may allow for an earlier Ignition TA..... but again, I'm not into the Chryslers like you are, so I don't really know the answer to that..
Basically, I'm asking rather than suggesting!
If this was a SBC, I could give a more accurate answer.

What I do know, is the importance of correct ignition lead (aka advance), and the importance of the RPM where this occurs..... be it GM, Ford or Chrysler.
While many may not consider this, Marine load "detonation" is of great concern.... or it should be!
We've all seen pictures of piston damage due to detonation.

Dog gone it... why is this Marine 440 OEM ignition curve so difficult to find???? :mad: :mad:


old hatt said:
Thanks Jeff. You, Rick and all the other regular contributors make this a great forum!
Click to expand...
Well, thanks for that, and I can probably speak for Jeff as well........., but hold on here.... we haven't quite solved your problem yet! :cool: :eek:
 
"The TA (whatever the TA is) @ 2,500 rpm seems to be too early to me..... and TA @ 2,000 rpm seems way too early."
"Dog gone it... why is this Marine 440 OEM ignition curve so difficult to find???? :mad: :mad:"

When all else fails, reverse engineer!
So lets plot one thats running and see where it goes.
Add more tic marks to the question I asked, say 3000, 3500, 4000, 4500, 5000, 5500.


Is that an outboard or snowmobile piston?
 
You guys are starting to get over my head but don't stop now!! I am just looking for the right answers so I can avoid the detonation issues. Thanks one and all.
 
daves69 said:
When all else fails, reverse engineer!
So lets plot one thats running and see where it goes.
Add more tic marks to the question I asked, say 3000, 3500, 4000, 4500, 5000, 5500.
Click to expand...
I'd agree that if we found a perfectly running 440 Marine Engine, we could check and plot this out on paper.
However, we're going to be looking for TA numbers in/around the 3k to 3.2K rpm range, not 4.5k and above.
At 4.5k rpm and above, we could use quite a bit more advance, but we don't operate our cruiser engines at these rpm.

old hatt said:
You guys are starting to get over my head but don't stop now!! I am just looking for the right answers so I can avoid the detonation issues. Thanks one and all.
Click to expand...
At first glance it may seem complicated to understand, but its actually quite simple!
I'll take a crude stab at a short explanation:
Just image that the spark for one cylinder must occur before the piston reaches top dead center.
This is called spark lead or spark advance, and is measured in crankshaft degrees, or crankshaft angle... commonly refered to as BTDC.
This spark lead or advance varies for each rpm range.... IOW, it is progressive as rpm increase........ and up to a certain rpm.... then it stops advancing.

The risk is spark advance that occurs at too many crankshaft degrees before TDC and during a certain rpm range where detonation potential is greater.


Typically, we set what's called BASE or Initial advance, and we look no further.
We put our trust in the components in that they are all working and are progressively advancing correctly.
A reall NO NO in my book... and the reason for 0 - 35 degree timing marks and a good strobe light!

It's so easy to do that there is no excuse NOT to! :)

If all is OK.... there are no issues......, but if we were to see too much advance, we can make the correction.

.
 
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fastjeff said:
I hope THAT piston shown is not put in a 440 Chrysler since it belongs in a Merc outboard!

Jeff
Click to expand...
Jeff, sorry about the wrong image....... My bad! :mad:
I guess that it will be my turn in the barrel this week!
Maybe greasemonkey and I can grab a sandwich together! :D I'll even let him slap me around a bit!

As I noted, I'm not into the Chrysler engines.
That piston comes up when you Google it, and is listed under the search title "440 Chrysler Marine pistons".
I think that I got hasty, and grabbed the wrong image.

Here is a search result from just now.
Looks like this one is Automotive..... perhaps it's used in the 440 marine application.

140.jpg

Here is another, but again Automotive..... definitely not for the Marine application.
images



Here's an inverted 440 dome piston.
This similar to what a correctly built SBC Marine engine would use underneath the wedge.
The dish would lower C/R.
This principle works well with the SBC and the smaller 64cc combustion chambers that incorporate the wedge area (as they all do).
I have no idea what the 440 Marine version requires under the wedge area.
jep-232452-8_w_m.jpg





My point was the Quench or NO Quench related to the wedge and Ignition timing.
 
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I have been running my 440s for many years and I think the total timing runs about 30 degrees. I have rebuilt both stock engines and the pistons are stock truck or motor home parts, the only marine specific parts in the engines are the reverse crank, cam and dist drive.

Dan
 
tolly_family said:
I have been running my 440s for many years and I think the total timing runs about 30 degrees.
Click to expand...
Dan, the 30 degrees must have an RPM associated with it.
Do you know this RPM, and can this be found in the OEM service manual?
If so, could you please post this for us? That would much appreciated.

.
 
I don't have my manuals as home but I remember it being in by about 2800 rpm. Most people in the Tollycraft with 440s have figured out in the last 40 years that if you run them between 2700 and 3000 rpm they last for ever. There is one member with 5000 hours and has only done the heads twice.
Dan
 
This is what I got:

Timing: 5 deg BTC

Distributor advance:
0 deg @ 275 - 425 rpm
0 - 7.5 deg @ 425 rpm
12.5 - 14.5 deg @ 700 rpm
19 - 21 deg @ 2200 rpm

Hope that helps
 
WoodieMan said:
This is what I got:

Timing: 5 deg BTC

Distributor advance:
0 deg @ 275 - 425 rpm
0 - 7.5 deg @ 425 rpm
12.5 - 14.5 deg @ 700 rpm
19 - 21 deg @ 2200 rpm
Click to expand...
Woodie, I have a few questions and comments:

I would agree with 0* @ 275 - 425 rpm.
We should see NO distributor advance below approx 900 rpm.
If we add a BASE of 5*, it becomes 5* @ 425 rpm.
That sounds like a good BASE advanace, but that is a relative low idle RPM.... Yes/No?


Your next RPM spec is 0* - 7.5* @ 425 rpm.
My first question is, why would we see any distributor advance at 425 rpm?
If we then add a BASE of 5* ..... that's 5* - 12.5* @ 425 rpm.
Second question is, why are we still at 425 rpm?
This is a problem while in idle rpm range.... Yes/No?


Your next RPM spec is 12.5* - 14.5* @ 700 rpm.
Two questions: why are we stil within idle RPM, and why the advance all of a sudden?
Now if we were to add a BASE of 5* to this........ that's 17.5* - 19.5* @ 700 rpm.
The 700 RPM may be OK for idle RPM.........., but that much advance @ 700 rpm is a problem, given what occurs progressively after this!


Your next RPM spec is 19* - 21* @ 2,200 rpm.
First question: why the jump from 700 rpm to 2,200 rpm?
If we were to add a BASE of 5* to this ..... it becomes 24* - 26* @ 2,200 rpm.
Second question: for the Chrysler Marine 440, isn't 24* - 26* @ 2,200 rpm is a potential for detonation??????

I know that I can't compare the GM numbers (that I'm used to seeing) to the Chrysler Marine 440 advance curve.... so I may not be correct on my thinking here.
However, I would tend to think that Dan's number of 30* @ 2,800 rpm is closer..... but that is simply a guess.

I'd still like to see the OEM specs from a Chrysler 440 service manual.


.
 
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Fastjeff's Immutable Law of Timing: Too little timing burns gas; too much timing burns pistons!

Take your pick.

Jeff
 
quote_icon.png
Originally Posted by WoodieManThis is what I got:

Timing: 5 deg BTC

Distributor advance:
0 deg @ 275 - 425 rpm
0 - 7.5 deg @ 425 rpm
12.5 - 14.5 deg @ 700 rpm
19 - 21 deg @ 2200 rpm

Woodie,
Is that out of a Chrysler manual? If so, for the "distributor advance" check if it says "degrees at distributor".
 
Yes Dave, sorry, I neglected to mention that, and it is taken from the manual:
"Distributor Advance (Centrifugal Automatic) - All Models. Distributor Degrees at Distributor RPM"
Make sense?
 
Woodie, maybe you can help me understand those numbers.... I'm not doing well with them.


While this is not the Chrysler 440 graph (image below)...., it should be very similar in general.

Using the darkest line graph, I roughly come up with these numbers:

Distributor advance only,,, no BASE shown
0* @ 800 rpm
6* @ 1,500 rpm
12* @ 2,000 rpm
16* @ 2,500 rpm
20* @ 3,000 rpm
22.5* @ 3,800 rpm

You can see that when plotted, the curve is rather linear, until she flattens out near the Full-In rpm.

171135.jpg


**********************************************************

Using the higher of the numbers that Woodie found.

Distributor advance only... no BASE shown
0 deg @ 275 - 425 rpm
7.5 deg @ 425 rpm
14.5 deg @ 700 rpm
21 deg @ 2200 rpm
then I factored in Dan's number of 25* (30* minus 5* BASE) @ 2,800 rpm (to get us further from the greater detonation rpm range).

These numbers would look more like this when plotted out in graph from (image below).
This is unusual for me to see in a Marine ignition curve.
 

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  • Chrysler 440 wrong curve.jpg
    Chrysler 440 wrong curve.jpg
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This is one more example of a Marine gasser Ignition curve.
Again, note the ZERO advance at idle rpm, and the rather linear curve up to the Full-In rpm.

Using the more agressive graph, the numbers would look like this:

Distributor advance only......... no BASE shown
0* @ 650 rpm
7* @ 1,500 rpm
12* @ 2,000 rpm
17* @ 2,500 rpm
21* @ 3,000 rpm
24* @ 3,500 rpm
26* @ 3,800 rpm




2009-08-17_155950_7.4firingorder+timingcurve.jpg
 
I'm pretty sure these numers are used to set up the distributor; note that the RPM figures are distributor RPM so I too assume double at crank as Dave mentioned. No engine RPM advance graph is supplied. I'm trying to get a hold of a buddy to confirm the numbers albeit these were out of the manual (printing error?) but he is not easy to get a hold of...usually out of the country. Sorry guys, best I have for now.
 
Woodie, I'd also say that it is likely a printing error.

Two things that I have not seen:
  • A V-8 Marine Engine advance curve that plots out like that.
  • Specs showing distributor RPM........ I have always seen crankshaft RPM refered to.
 
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I began typing this late last night, but figured that my old brain may be making a few mistakes. Thought I'd see if I could be sharper this morning!
Here's what I had typed out regarding the specs that Woodie found.... and then a comment re; the graph and distributor RPM -vs- Engine RPM.

If these curve graphs reflected distributor RPM, then the horizontal scale would read differently.
The 1 would then actually be 2,000 crankshaft RPM.
The 2 would actually be 4,000 crankshaft RPM.
Fast forward, and the 3 and 4 on the horizontal scale would actually be 6,000 and 8,000 crankshaft RPM.

That would be delaying Full Advance until at/near 6k RPM.... (far far too late, IMO).
Besides that....... who operates a Marine Cruiser Engine @ 6k rpm? :rolleyes:

**************************************************
Let's look at this from another angle:

Let's assume that the horizontal scale did represent Distributor RPM (not crankshaft).
Lets say that the OEM Full Advance is 30* (this includes 5* of BASE advance.... so it's actually going to be 25* on vertical the scale).
This Full In Advance would now occur @ 6k crankshaft RPM (not 3k crankshaft RPM).
IOW, 25* of distributor advance @ 6k crankshaft RPM..... offering a TA of 30* @ 6k rpm.

Using a fairly linear curve, let's read the graph and look at the 3k crankshaft RPM on the scale.
At 3k crankshaft RPM, that would be roughly 10-12* of advance.
Add a BASE advance of 5* to that...... and we have approximately 15-17* @ 3k crankshaft RPM.
As I see this, 15-17* @ 3k crankshaft RPM isn't nearly enough advance for a V-8 Marine Engine!
It will not cause any detonation issues, but it certainly will not allow for any performance, and will certainly cause excessive fuel burn.
Unless the 440 is unique in this area, I just don't see this as being accurate. I could be wrong.

Main point being.... I believe that the horizontal scale usually represents crankshaft RPM, not distributor RPM.


Woodie, I hope that you are able to get a hold of your buddy. I'm very curious as to what his specs show.

.
 
The more I read up on this the more it makes sense and believe these figures are right. What I do know is that "Distributor Degrees at Distributor RPM" is old school; best way to check distributor operation on a distributor machine independent of any performance issues that may be present at the engine thus affecting the ability to get accurate advance diagnostics as well as setting up and repairing the distributor of course (wish I had one). With this advance menthodoligy/numbers you are supposed to double RPM AND DEGREES at the crank. The only issue I'm having is with the last set; 19-21* @ 2200 which would translate to 38-42* @ 4400 plus base. Seems high to me however not unusual for higher performance specs as I understand, and given the higher advance I would expect to see the lower base of 5* and in some Chrysler apps 2* as is the case. Of course the app makes a big difference, in general, Chrysler was all over the place on base timing with anything from 0 - 10* which will affect advance curves but this is the only 440 one I have. Rick, I see a different curve than you. Given the above info, it`s pretty much linear to 1400 rpm then off on a different slope to 4400 so not quite a singular linear advance line as customary with your Merc example but I`m ok with that. I need some clarification on where you`re getting 6000 rpm. I`ll pass on anything else I find.

PS; checked a couple of old Chrysler automotive manuals and found the same refference to Distributor degrees and RPM for advance info
 
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