Put a motor together and took it to the dyno. Checked and set the timing with the engine shop's timing light. Digital readout on the back, not sure what brand. MSD 7al-2 to power the dyno cell. Set it at 30 degrees and did our testing.

Took the motor home and put it in the dragster. Fired it up and checked timing with my light (old craftsman, no dials or nothing fancy). 28 degrees timing in the car. Msd grid setup. Verified that the grid doesn't have any timing retards active when checking. No one moved the crank trigger wheel or pickup.

Called a buddy and he brought his light down. We checked it at 28 degrees just like my light.

Has anyone seen this before? Is this the difference between the 7al-2 and the grid? What does a guy do? Do I go by my light as gospel? Does the motor have 28 or 30 degrees timing in it?

Two completely different ignition boxes can definitely have different timing between dyno and in the car. Seen it PLENTY of times. So yes, you can reset it with your light and believe it is true.

I would also say do timing runs at the track. A lot of times the timing that produces the highest HP numbers on a dyno, do not provide the best ET at the track.

I always use my timing light on the dyno as some lights read different than others. Also it is good to use your own ignition box for same reason.

Always recheck the timing in the car after setting it on the dyno as noted above.

The correct polarity is the one that has the most timing advance on a Digital Ignition.

Opposite for analog.

Switch the purple and green wire to test.

So if you have 28, then switch wires and you have more timing, switch wires back and you know polarity is correct for analog.

If you switch wires and it's less than 28 leave it, polarity is correct for analog..

Sounds to me like it's correct now, less timing analog ignition.

Set it as you always have, the plugs will tell you what the correct timing is, then your setting is just a reference.

Thanks for the feedback guys. I will set it in the car at 30 degrees with my light and give it a shot. May even try + or - 2 degrees if time allows.

With limited time runs at bracket races nowdays. I think you can set timming were youthink it should be. Run it few weekends then pull or add 2* for the next weekend you are at same track and how it responds. I personally don't like to say ok tried it once and did not work.I would rather make at least 2 runs.If runs the same on those runs then I know worked or stupid to tried it and should have known better. Now if you arte fortunate enough to have a track that is in good condition for test n tune then thats a option,around here that is not happening,plus at most you get is 3 to 4 runs.Might as well go to bracket take TT,1st and if need buy back 2nd or 3rd and get more runs on good track.

quote:

I will set it in the car at 30 degrees with my light and give it a shot. May even try + or - 2 degrees if time allows.

If you are using a 7730 Grid and want to experiment with timing, here’s an easy way to change timing with your laptop vs moving the crank trigger. This is very accurate and works well. Have used this method on a dyno and at the track.

In Grid Setting / General tabs, program the Maximum Timing Reference to a value higher than what you are using now. Example program 33*. In Ignition Timing / Engine RPM tabs, program Engine RPM to 0, and Ignition Timing to 33*. Then with your timing light move the pickup to show that 33* value at idle.

(Note: For the ignition timing to be set properly Both the Maximum Timing Reference and Engine RPM / Ignition Timing should be set to the same value)

After the timing has been set and checked, In Ignition Timing / Engine RPM tabs, program Ignition Timing to 30*. Checking the timing at idle you’ll have 30*. When you change this Ignition Timing value lower or higher (up to Max Timing Reference) the timing can easily be altered.

Thanks for the tips guys. Here's how it played out. Engine guy brought his light to the track. It checked 26 with his. We went ahead and ran it. It was within a hundo of where it used to be. We then checked and set the timing by moving the crank trigger to 32 degrees. I pulled it back 2 to 30 degrees with the Grid box. Ran the car and it picked up .030 in the 1/8. It was a test and tune, and that was the last pass of the night.

As mark mentioned, I can go up to 32 if I want to try it now that I moved the crank trigger.

Was a good night and glad to get some runs in.

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Originally posted by TOP38:
Always recheck the timing in the car after setting it on the dyno as noted above.

x2

Learned this after having my motor dyno'd at engine builder. then installed engine to car without moving crank trigger and different by 5 degrees with car ignition from dyno.

Spark plugs also can tell you if you are close or if you should add or take timing away after a pass or two.

All i can do is tell you how i test engines on my dyno. 1st I WANT the customer to bring their ignition box(es). Each box works just slightly different(same model). If you have a "back up box" that gets tested also. Every back up box (except one) has left with a sticker on that says "Plus 2" "Minus 1" "Plus 4" ect.
The difference between an "AL" box and a "digital" can easily be 4 or 5 degrees @ 7000 RPM. (what, you never stood next to an engine, with a timing light, under full load @ 7000 rpm?)

Things that should be yours when you dyno an engine. Your carb, your Ignition box(es), your coil, your headers, your fuel and your timing light. (had a guy bring 3 timing lights, they all read different)

Joe

This is why timing needs to be checked after it is dyno`d and installed into the car. Where i dyno my engines, they use a digital ignition system and when you check the timing using a MSD 7AL box, sometimes its 10 degrees off. Nothing unusual.

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Originally posted by CHampshire:
Does the motor have 28 or 30 degrees timing in it?

Depends on which ignition box is plugged into the the engine's crank trigger, Grid or 7al 2.

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Originally posted by sr4440: (had a guy bring 3 timing lights, they all read different)

That’s interesting Joe. In this case which timing light did he decide to use that you would consider correct?? They all can’t be correct.

I have limited experience in types of ignition boxes, and have personally used 7al2/3, 6al, Digital 7, 7730 / 7720 Grid and Holley Dominator/ HP. I use a 40+ yr old Craftsman non-adjusting timing light.

When using a MSD 8276 crank trigger set to the mean gap distance, I find now that it is set approximately 1* prior to the desired timing value when complete with Grid 7730/7720 and 6al back-up.

With Holley ECU, you only need to get it close and fine tune in the software. The same can be done with Grid 7730 if desired.

Holley ECU also allows for timing adjustments (Inductive Delay) when the engine is accelerating to higher rpms.

I was thinking the same as Mark Explained. I always set the crank trigger at 40 because that’s max with Grid then use the laptop to set timing where I want it

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Originally posted by markemark:

quote:

Originally posted by sr4440: (had a guy bring 3 timing lights, they all read different)

That’s interesting Joe. In this case which timing light did he decide to use that you would consider correct?? They all can’t be correct.
.

Does not matter which one just use same one every time. You are using the Dyno or track ET to get you best performance. The timing light, EGT's, O2 or anything else is just to help you keep that tune up. It gives you a reference of where it is.

Tire gauge is another tool you want to use same one every time. I have seen significant variation between different ones.

Last year I had a 7al-2 go bad on me and replaced it with a 7al-2 Plus. Timing retarded 4° when the new box was installed. Same light used to check both times.

quote:

Originally posted by markemark:

quote:

Originally posted by sr4440: (had a guy bring 3 timing lights, they all read different)

That’s interesting Joe. In this case which timing light did he decide to use that you would consider correct?? They all can’t be correct.

I don't know which one he used, he had a favorite. I do know he marked the other 2 with info how far off they were from the primary light. It's just like ANY backup equipment, IE air pressure gage, you need to validate it against your primary device. Doing it after the primary breaks, is setting yourself up for failure.

Joe
PS forgot to mention, they were all "dial back" lights.