Twitchy TAC

[Seabronc]

Has anyone had any experience with TAC problems after installing a MSD system with a 8920 TAC adapter? Mine reads accurately but starts jumping round, sometimes high and sometimes low.

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[steechfinger]

just throwing this out but have you tried checking the connections maby somethings loose or maby theres sone corrosion on a connector

 

[Seabronc]

just throwing this out but have you tried checking the connections maby somethings loose or maby theres sone corrosion on a connector

I think that was it. I was running some wires this afternoon to improve the voltage to my wimpy horns and decided to disconnect the tac adapter while I was under the hood. To my surprise the wire pulled out of the connector, so I replaced the connector. I didn't have time to run it tonight but I will find out when I drive to work tomorrow.

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[Seabronc]

Update, the problem wasn't the loose wire. As it turns out, the twitching was caused be arcing at my #1 plug wire. The spark plug boot was damaged with a hole in it. When the humidity was high enough it was arcing through the hole to the head.

Oh yah, that MSD system really packs a wallop. After changing wires, one was loose at the distributor and I made the mistake of grabbing it to push it on while the engine was running [-X . I pulled about a 10 inch spark from my forearm to the radiator support @-) . Insulation or not, it took the easiest path from the distributor plug post to ground, which was from my finger tip through my forearm to the radiator support frame :-& .

 

[BLADE262US]

Yeah those MSD boxes are BAD . How do you have the tach adapter hooked up ? What box are you running ? I have a 6A wired into mine just hooked the tach to the tach output on the box it works but the tach reads way too high sometimes . I had another truck that the front plug wire had fallen off of sounded just like a header leak from in the cab went home expecting to have to take the headers off and saw that wire hanging there with a 6 inch spark jumping from the plug to the block . Man I dont ever want to get caught by that . /emoticons/[email protected] 2x" width="20" height="20" />

 

[Justbust1n]

yeah i had a rev limiter tester for a msd box ... well for those who have never seen one you hook them up with a spark plug and you turn it up with a dial , to test the rpm rev chip on the box .. well my uncle held the controll and b4 i could put the spark plug down he hit the switch tio test it well it causes a hellchios arch on spark plug and it felt like someone punched me in the chest ... so fair warning if you ever get one, even though common sense tells you not to hold it ,"DONT"... lol.. but those do come in handy if you got a MSD box and would invest in one considering msd boxes can be a pain

 

[Seabronc]

Yeah those MSD boxes are BAD . How do you have the tach adapter hooked up ? What box are you running ? I have a 6A wired into mine just hooked the tach to the tach output on the box it works but the tach reads way too high sometimes . I had another truck that the front plug wire had fallen off of sounded just like a header leak from in the cab went home expecting to have to take the headers off and saw that wire hanging there with a 6 inch spark jumping from the plug to the block . Man I dont ever want to get caught by that . /emoticons/[email protected] 2x" width="20" height="20" />

My box is a 6AL with the TAC connected through an 8920 TAC Adpter. I couldn't get it to work directly off the TAC connection on the 6AL.

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[BLADE262US]

HMMMMMM Ive never used an MSD box with a tach adapter maybe Ill have to get one I have always used the tack output from the box but Ive always had autometer tachs too so thats why Ive never had a problem . This is the first one connected to the factory tach Ill be driving down the road about 3500 RPM and all of a sudden it will jump to around 6000 very strange when you see one of your guages come close to maxing out . Ive got 2 other trucks with the MSD6 offroad box . I wouldnt recomend these to anyone yeah there cool they say offroad on them and there all sealed and the board is epoxied and they have weather pac connectors on all the wires but what they dont tell ya is MSD will norammly fix a bad box for $100 . The offroad box is the exception to that they will not fix them because the board is embedded in epoxy ( personal experience ) So the next best $100 lower cost one is the 6T it has internal bracing and a coated board but one they can repair if need be . Have you ever used the MSD timing computers Seabronc ? Those make it pretty nice to not have to mess with the mechanical advance in the dizzy . Ive got most all of mine set up with those the only vehicle I have that still uses the ford dizzy is my 95 extended cab other than that its all MSD . The magnetic pickup in an MSD distributor is the same one in a ford duraspark distributor thats kind of interesting shows the high quality of an OEM part . My plow truck has an MSD 6T / MSD 8981 timing computer / MSD 8738 soft touch rev control / and an MSD 8207 blaster SS coil / with an MSD 8584 dizzy / MSD heli core wires with bosch platinum plus 4 plugs . Pretty sure if there gas in the hole its going to light LOL and thats my plow truck /emoticons/[email protected] 2x" width="20" height="20" />