mag problems i think??

my motor starts and revs fine until i step on it to do burnout it goes to popping and snapping running a super mag4 27lbs boost. anybody else had this problem??

 

magneto

run 18gap and the wires arent really that old. this problem started all at once the car left good and started busting up b4 2nd gear then basically just quit running. i came in and found the mag was loose the clamp was messed up, so i fixed it all checked the points gap it was a lil tight so i put it at 18 also started motor up it sounded good reved good , as soon as i touched the throttle for burnout it started busting up so im just assuming its a mag problem, the only othe change i made was upping the boost from 22-27lbs and maybe that extra psi causes problems.

 

we gap at 16..have you ohmed your coil/transformer..Dave

 

blower rotors installed wrong way made a friends car act that way years ago.

 

A SM IV is just fine for 27 psi boost

I'd look at the cap real close to see if there are any carbon arc marks or I'd just change it.

 

Been down the same road of problems, filed the point faces in the mag regapped at .016 no more problem.DAVE

 

What kind of Mag kill switch do you have? Had them short under load before and cause an issue like that. Just something else to check.

 

magneto

talked to spud today he said put a new set of points in it and most likely that will cure it so i will do that and see what happens i will post results to maybe help the next guy.
thanks for all the replies

 

Also look for hot wires that are grounding to the chassis.

 

Do you have any type of rev limiter installed?

 

magneto

yes i have a etc rev limiter, im wondering now if if a set of spark plugs might could be fouled out and cause this problem? any thoughts on alky fouled plugs?

 

Unhook that rev limiter and try it again. I have had 5 of those and have tried and tried to make them work. I guess I'm just that damn dumb as I can't make them live. The times they have worked I like the soft touch as its the only "soft" one I know thats available for Mallory. But they cost me too many wasted runs.

PS Qty 4 ETC rev limiters for sale, cheap... (unless someone can show me how to make these live)

 

I had a conversation with Spud (FIE) and he mentioned that if you are running a really hot Mallory mag the "regular" ETC limiters tend to get cooked. I understand that the ones he gets are designed for mags past 8.5 AMPS. You may have gone down this road already but figured I would mention that.

 

We had a coil go bad, it was cracked on the back side and had the same issues. Motor sounded great on jack stands but another story on the track! I've also seen rotors in blower be backwards and do the same thing as well.

 

The reason i asked about a rev limiter is we have tried 2 of the etc rev limiters to no success one was bought through FIE and our mag iv puts out 5.8 amps and we had erratic rev control. It sounded off in the burnout, the 2 step side seemed to be ok (low rpm ) but the high side rev limiter came in about 3000 rpm to soon, and the rpm switch made my shift light act like it was at a disco. removed it and problem solved, apparently just turning the unit off will do the same as taking out so i was told from ETC.

 

Did you find the bad coil by ohming the coil?

 

I appreciate the idea, please keep them coming as I would love to be able to make these rev limiters reliable.

We have 4 mags, they put out between 3.9-4.2 amps depending on which one you are talking about.

 

No actually it was a visible crack on the back side, after the second qualifying shot was lost we removed the entire ignition system. That is when we saw it, replaced it and problem fixed! We were thinking the kill switch was the culprit because we always killed the ignition after the car shut down. We were told that contacts could weld themselves together by doing that and that was where we went first.