Timing question

[dipso]

I have an internally stock 2.7. On top I have 40mm PMOs, MSD6AL ignition and a JB Racing 6 plug distributor.
Im trying to tune this thing to perfection and I have a question.

Yesterday I used my LM2 and adjusted the AFR to about 12.9. Now I am trying to find the perfect timing spot.
The distributor was purchased and set up by Steve at Rennsport. I am not sure what the advance is but it comes on fully by 3500 rpms.

When I set the timing at 3500 or above and shoot for 32 it settles back down to 13 BTDC. Doesn't that seem high for an idle timing mark?
If I do what PMO says and set the timing between 6 and 8. It only gets up to about 25BTDC.

What is better? A closer to TDC idle timing or closer to 32 at 3500 RPMs.
All in all in runs pretty good, just trying to find the elusive 'sweet' spot.

[James Brown]

Looks like a good set-up. I run around 7˚ at idle and what ever you get is what you get at 3500. If at idle it can tolerate a little more advance than that's ok, just watch (or hear) for preignition. I'm sure you are happy with the engine.

[dipso]

Yeah, but PMO says that I should be between 6 and 8 at idle and 32 35 at 3500.
I can't reach both. It's either one or the other.
Should I have a wider curve in my distributor?

[James Brown]

Yes but that is a pull and ship thing back to Steve. Maybe you can adjust the dissy at home, not familiar with the JB racing unit.
just read the instructions and it is adjustible 0-28˚ + 7˚ should be 35˚ total

[dipso]

It's fully adjustable and comes with all the little tools to adjust it. I should probably talk to Steve before I do anything stupid.

I am sure it is adjusted properly. I don't think he would of made of mistake. He knew my set up.
I just think it is strange where my idle ends up.

On a stock 2.7 there are 2 lines on the pulley. The line on the right is Z1 and the line on the left is 5 ATDC. When I plugged my retard on the old distributor I retimed to 5 BTDC.
Now I set the advance to 13 on my timing light and use the Z1 mark.
It just seems high.

[dipso]

James, I just looked in the garage for the kit and the 22 is the one it was set at. That explains it.
My distributor is set at 22 not 28.
13 and 22 is 35.

Is 7 and 35 the idle setting? It seems I would have better low end timing if it was set with the 28.
I don't know enough about these things to make the call.

[dipso]

Hey James. On a side note, you really ought to get one of those LM2 AFR meters. They are pretty cool.
I just plugged that thing into my cigarette lighter and stuck the sniffer in the tailpipe.
It showed I was back at 10.? again. I am always running to rich.

Anyways, you can turn the screws on the carbs and see the AFR change right before your eyes.
1/2 turn was about 1 movement on the AFR if i remember correctly.
It sure makes finding the correct mixture a snap.

[James Brown]

Wow, I was just looking at them yesterday! I just might do that.
Go for a ride and compare the two settings. I bet you will like the 28˚ better!

[dipso]

Yeah, maybe I'll get out there and adjust it one day. Looks pretty simple.

On the LM2. Do you have a Mac or a PC?
I have a Mac and the LM2 is not Mac compatible. I can use it as an AFR reader and that is about all.
All the fancy gizmo stuff that it is supposed to do I can't do with my Mac.

I guess if you have a PC it is really cool. You can download graphs and get running conditions while driving and all kinds of things.
Oh well, it is worth just the AFR function alone.
You'll like it.

[James Brown]

Mac here also.

[dipso]

I just checked the measurements on the advance adjustment kit. I've got 14-28 in increments of 2.
I think I'll try setting the advance with the 28.
Then I should be able to set the idle timing at 7 and have 35 at 4000. Or even 5 at idle with 33 at 4000.
Sounds like a plan. What do you think?

I have a 26 too. Then I would be 7 and 33.
Do you think there would be much of a difference.?

[dipso]

Well, I just did it. Set it with the 26 and stripped a torx head screw! I'm committed now.
I ended up with 8 at idle and about 32-33 at 4000.
Had to force a bunch of **** to get it to adjust.
Since I stripped that screw I'll never be able to adjust it again without pulling the distributor and getting a new screw.
Funny how the numbers don't add up.

I took it for a drive and like it.

[James Brown]

Nice, i don't think you will ever change that setting so it's a wash. Time to enjoy all your hard work and drive it!

[dicklague]

Don't get the LM2. Get the Daytona Sensors instrument that our host sells. 2 hours of data logging and lots of other great features for about $400.00