VP Dynamic Timing Vs. Advancing

GRotman said:
I say you will get a truck that runs like crap and has a check engine light on.
Click to expand...
Mine runs awesome, and I'm running 1 tooth mechanical advance right now. No check engine light, no codes, it requires a little more cranking in the mornings when its down below freezing, but so far, thats the only issue I've encountered.
Sean
 
Have you got a timing light on the truck to see what the timing is say at 35-4000 rpm.
 
sstockton said:
Yeah, different VP's are calibrated with different keys, and they are all marked as such. Since different keys have different offsets, that makes me think that the ECM doesn't compensate for different timing, or else there wouldn't be a need for a different offset, they could all run the same key. Or if you switched keys it wouldn't make a difference.
Sean
Click to expand...

that is my thought exactly. if they list all of the different keys per the same group of cpl's under the same computer calibration then I dont think that the computer sees the difference. it is my thought that the computer bases the timing off of cam timing so if you move the pump for mechanical advance the computer sees the same cam timing ultimately and has no electronic effect. (check engine light etc.)
 
I would think that you would lose alot of bottom end moving the gear more than one tooth.
 
That is strange...seems some may not be as sensitive? I have had trucks come in where someone did not line up the key exactly to the gear and deformed the key as they pressed the gear on. These set codes and ran poorly.
 
kjpcummins said:
Have you got a timing light on the truck to see what the timing is say at 35-4000 rpm.
Click to expand...

Simple timing light wont do it, would need something like stanadyne's time trac to tell injection timing.
 
GRotman said:
That is strange...seems some may not be as sensitive? I have had trucks come in where someone did not line up the key exactly to the gear and deformed the key as they pressed the gear on. These set codes and ran poorly.
Click to expand...

Well, the key is very close to the center, so a very small shift sideways makes a much greater effect than a shift at the edge of the gear, where the radius is much larger.

These are just rough numbers right here, but they should be relatively close, and illustrate the point. If the Diameter of the gear is 8", each tooth represents roughly 5/16 of an inch around the gear and is equal to 5 degrees. I have seen smashed keyways, that are up to 1/8th inch off from what they should be. If the diameter at the keyway is 1", the 1/8th inch shift caused by the keyway would result in a 25deg change in timing. If this timing was retarded, that would drop the injection down to at best -1deg before TDC when the pump was at full advance. If this shift advanced the timing, you'd be running 49deg. at full advance. So thats why a small shift in the keyway would make a big difference.
Sean
 
So you can use that snap on thing in conjunction with a timing light to figure out what your injection timing really is? That would be a really useful tuning tool.
Sean
 
somebody erased a post
oh well
sstockton said:
So you can use that snap on thing in conjunction with a timing light to figure out what your injection timing really is? That would be a really useful tuning tool.
Sean
Click to expand...

yes it would but there are cheaper options than snap on
 
Know of any links to them? I will look into picking one up, as that would do wonders for this experiment, and would off the bat what is really happening too our timing.
Sean
 
24vriviera said:
somebody erased a post
oh well


yes it would but there are cheaper options than snap on
Click to expand...

I edited my post because I knew someone was going to reference spark plugs, and then I would have to explain it anyway.

sstockton said:
Know of any links to them? I will look into picking one up, as that would do wonders for this experiment, and would off the bat what is really happening too our timing.
Sean
Click to expand...

Do a search over in the Dodge Competition forum. They are talked about frequently.
 
Found the Ferret 765, know if that is a decent unit, or a piece of junk?

Awesome, I'll go search over there.
Sean
 
I edited my post because I knew someone was going to reference spark plugs, and then I would have to explain it anyway.
Click to expand...

no problem.. i still found a way to throw you under the bus:poke:!



also found a mac tools adapter
and there better be more than 3 manufacturers out there
 
OTC makes one as well, but its just as expensive as the snap on. I'm sure that there must be more though.
Sean
 
24vriviera said:
no problem.. i still found a way to throw you under the bus:poke:!

also found a mac tools adapter
and there better be more than 3 manufacturers out there
Click to expand...

LOL Better luck next time.

I'm partial to Snap-on tools which is why I posted that one. There are others, but I can't think of any other name brands off the top of my head.
 
kjpcummins said:
That is what i am refering to. Its rather simple before and after to see what happens to the timing at given rpm. You can guess what the timing is goin to be but this is the only way to find out.
Click to expand...

Yep, thats true. I wish I could run all the way up to 4k, but I currently don't have that capability. I don't have a box that will do it, and my valve train wouldn't like it either. I really think that that is where extra timing would shine the most though.
Sean
 
You must log in or register to reply here.
Back
Top