Timing question

March 21, 2019, 08:01 AM

00 DEAD ON

Timing question

Has anyone had this happen to them
Dragster runs mid 4.40’s with a MSD distributor NO crank trigger with 34* of timing. Now I install a crank trigger, set timing at 34* then phase it
Go to the track and it only runs back to back 4.58’s. Baffled so I disconnect the crank trigger and plugged the MSD distributor back in and set timing to 34* and it runs 4.46. What in the world would cause this. IDK guess I have a killer MSD distributor worth .012 lol.
Thanks in advance

Brian Mollison
2009 RaceTech Dragster
2020 Sumerduck Dragway VA Top ET Champion
2017 Sumerduck Top ET & SSS Track Champion
2017 MAC Top ET Track Champion
2009 Sumerduck Dragway Va Top ET & IHRA SSS Track Champion
2008 IHRA Division 1 Top ET Bracket Final Runner-up
2007 Colonial Beach Dragway Top ET Track Champion

March 21, 2019, 08:40 AM

TOP38

quote:
Originally posted by 00 DEAD ON:
Has anyone had this happen to them
Dragster runs mid 4.40’s with a MSD distributor NO crank trigger with 34* of timing. Now I install a crank trigger, set timing at 34* then phase it
Go to the track and it only runs back to back 4.58’s. Baffled so I disconnect the crank trigger and plugged the MSD distributor back in and set timing to 34* and it runs 4.46. What in the world would cause this. IDK guess I have a killer MSD distributor worth .012 lol.
Thanks in advance

As with any newly installed crank trigger, check the two wire going to it, green and purple, make sure they are reversed.

Next would be to get the crank trigger wires as far away from the coil wires.

Does the motor run clean??? Simple test, try a new crank trigger pick up.

March 21, 2019, 09:02 AM

markemark

The phasing of the crank trigger will depend on the type of ignition you have analog or digital.

With analog ignition you want the trigger to produce the least amount of timing when phased.

With digital, you want the trigger to produce the maximum amount of timing.

By phasing is meant , when the wires from the crank trigger are inter-changed going to the ignition box.

March 21, 2019, 09:43 AM

TOP38

quote:
Originally posted by markemark:
The phasing of the crank trigger will depend on the type of ignition you have analog or digital.

With analog ignition you want the trigger to produce the least amount of timing when phased.

With digital, you want the trigger to produce the maximum amount of timing.

By phasing is meant , when the wires from the crank trigger are inter-changed going to the ignition box.

That should be taken care of at the ignition box by the +/- labels on it. Purple/Violet (+) and Green (-).

If he has an MSD crank trigger sensor it has the same color layout, other may or may not but it should have a plus minus label shown in the paper work.

When all else fails switch the wires

March 21, 2019, 02:18 PM

00 DEAD ON

The ignition box is a 7al3 box. The wires from the MSD and the distributor are the same color and the crank trigger wires are also the same color and the connector can only be hooked up one way. IDK

March 21, 2019, 03:14 PM

SP 124X

The easiest way to check the crank trigger polarity is with a timing light. When it's correct the magnet is directly under the pickup. When they are reversed they won't be lined up.

March 21, 2019, 03:53 PM

markemark

You have analog ignition so you would want the most retarded timing when switching polarity.

To switch polarity of the trigger just reverse the M+ and M- wires on the 7al3 terminal strip. When switched if the timing is now more retarded then this way is correct. If the timing becomes more advanced then this way is incorrect.

What Action said about shinning the timing light at the pick up also works as he said. The magnet should be almost directly over the pickup.

March 22, 2019, 08:52 AM

Curly1

But if both the timing was 34* with distributor and 34* with crank trigger why performance difference? The net timing was still 34*?

That is a pretty significant difference in performance from 4.40's to 4.58.

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March 22, 2019, 11:14 AM

PASS'N THRU

The 7AL-3 will retard your actual timing setting by 4 degrees in operation. If you phased in your timing at 34 your actual timing will be 30 when checked with a light on a crank trigger ignition. So you need to phase in your initial timing at 38 to get 34 in actual operation used with a crank trigger. I use my MSD billet distributor totally locked out. I lost over .06 in et eighth mile when using the distributor only and bringing in full timing well under low side launch rpm.

March 22, 2019, 02:47 PM

Mopar Traitor

Just went thru this with a 7AL-3.. Changed motors and put crank trigger back on, set timing to 34 degrees, went to track and car sounded terrible and would hardly run under power.
Brought it home, checked everything, timing was still on 34, but it was at idle, I just happened to reach up and give it a little gas and timing took off to 40 something degrees. Switched wires and timing rock solid.

March 22, 2019, 03:49 PM

markemark

Here’s a patch cable that I made that will quickly reverse the wire polarity of the pickup when installed between the pickup and cable. The pin extractor in the pic is a Blue Point GA 500A. Use this if needed to permanently change the polarity of the pickup plug in.

March 22, 2019, 07:06 PM

sr4440

if the wires are reversed then your going to lose a he11 of lot more then .12.LOL
I willing to bet you run a timing chain combined with the twisting of the camshaft @RPM. your timing is retarded a little at race RPM.
Easy way to tell, set crank trigger @32 and see if it picks up,if it does take a little more until you get back your ET.

Joe

March 24, 2019, 07:38 AM

00 DEAD ON

It has a belt drive not a chain. I will do some checking

March 24, 2019, 07:40 AM

00 DEAD ON

quote:
Originally posted by Curly1:
But if both the timing was 34* with distributor and 34* with crank trigger why performance difference? The net timing was still 34*?

That is a pretty significant difference in performance from 4.40's to 4.58.

Oh I agree 100%. Didn’t make since at the track. Have to find time and check it out again.
Thx everyone’s suggestions

March 27, 2019, 10:23 AM

MasRacing

My first thought would be is the distributor you are using with the crank trigger a mechanical advance and is it completely locked out. Just wondering whether the distributor could be advancing and going out of phase with the crank trigger.

March 27, 2019, 07:26 PM

fordracer9326

be sure the wheel is on correctly. It is directional and can be put on backwards...

March 31, 2019, 11:06 AM

Strange Magic

Your transducer is junk, most likely.

It's why you will never see an msd wheel or transducer on any of my engines.

March 31, 2019, 11:27 AM

Mike Rietow

quote:
Originally posted by markemark:
You have analog ignition so you would want the most retarded timing when switching polarity.

To switch polarity of the trigger just reverse the M+ and M- wires on the 7al3 terminal strip. When switched if the timing is now more retarded then this way is correct. If the timing becomes more advanced then this way is incorrect.

What Action said about shinning the timing light at the pick up also works as he said. The magnet should be almost directly over the pickup.

Good call.

OP check the polarity on the crank trigger wheel, too.

March 31, 2019, 01:37 PM

markemark

quote:
Originally posted by Strange Magic:
Your transducer is junk, most likely.

It's why you will never see an msd wheel or transducer on any of my engines.

What brand is better iyo? Or do you just use a distributor trigger?

March 31, 2019, 03:33 PM

Strange Magic

I use Moroso. Never had a failure yet. I've experienced over 20 bad msds, most of the time it's the transducer. 2 of the times it was the wheel.