The Stovebolt Site Forums The Shop Area The Electrical Bay HEI Distributor

Can any one tell me if a Mallory HEI distributor for a 261 (235) can fail? Is there a "chip" in them or can they malfunction? My 37 has one and the truck back fired through he carb and will not start. Thanks!

Probably a mechanical failure in the timing system. Gears, chains, nylon gears, gear pin, broken shaft, slipped a tooth, That's what backfire means to me. Electrical failure will just not start. (no spark, no fire, as in no backfire). Best thing to do first: Carefully check timing.

If it was just installed, maybe it wasn't installed properly? Off a tooth or three or more?

To answer your question...yes, they can and do fail. The control module contains a "Hall effect sensor (transistor)". But when they fail, they fail, so I would take the path 'bartamos' suggest. Good luck.

I probably should have noted that this problem came "out of the blue". Nothing has been adjusted or messed with prior to this incident. Everything has functioned and the truck has run strong without any problems for 22 years since the rebuild of the engine. That's why this is so hard to figure out. Any other suggestions will be appreciated very much. I just need a place to start looking for the problem. Thank you all!!

I just came back to this post to add: I appreciate the suggestions and I haven't overlooked them, it's just that I hate to start somewhere and spend time and money unless I have a strong consensus about what I'm looking for. So your comments are appreiated! I just need a good place to start.
I personally think it's the distributor since NOTHING else has been touched.
Again, Thank You all!

When i had standard HEI module fail it just stopped dead. No pop, vibration or warning. If for some reason the distributor was able to work loose and turn a bit it could cause the backfire. So you might check to see if you can move the whole distributor.

Nothing has been touched. Understood...... But something is broken! Some of us think it is the timing system, not the Dizzy. The place to "start" is to check the timing. In other words, check to see if when number 1 cylinder is a TDC, Top Dead Center on the compression stroke, that the timing mark/ball is in the proper position and the distributor rotor is pointing at No. 1 tower. If all that looks correct, then maybe it is an electrical problem and not a timing (mechanical) problem. It's the "backfire" part of your description that indicates out of time. If you said "no spark, no fire" then it would be the HEI coil or pickup or wiring or..... You don't have to "touch" anything for engines to have problems from wear and tear and age and so on. The sooner you start the diagnosis, the sooner you will fix it or advise your findings here for more suggestions. We can suggest and guess all day long. You have provided a very small amount of info to work with so far. We will be patient and wait. It's not a good idea to keep cranking in case something is bad wrong and damage may occur, but is it coughing still, trying to start? One backfire and that was it? popping thru carb while cranking lately? Be careful of fire also.

bartamos is spot on how you should proceed. Not much time or labor involved in checking static timing (engine not running). If the timing doesn't line up, you than need to determine whether it may be due to either a stripped distributor gear or the timing gears. I feel your pain. Its your baby and it is sick. Put your emotions aside and approach it with pure logic. I am not preaching to you, I am relating to you what I often have to overcome when my 'baby' is sick.

I spent some time today just checking wiring, fuel lines and such under the hood. I did find one thing that may not be the problem, but could be a problem. The flexible gas line from the hard line that comes into the engine bay from the tank was not tight on the fuel pump end. It was on, but not wrenched up tight. I check all the other fuel line fittings up to the carbs. A few more were not wrenched tight. This has to be my fault because I'm the only one who works on my truck, so I may have missed tightening them at a point in the past. Got them all tight and it started. I let it run for awhile to see if I had RPM drops or momentary engine stops. Ran it for about 10 minutes at about 1200 RPM's and there didn't seem to be anything negative. Plan to try to drive it tomorrow or Tuesday. I'm not convinced this is the problem, but it could have been another a problem.

Sounds promising. Thanks for the update Joe.

nice going Joe,,I do know that a mallory can fail..
I had the module to go crazy in mine..

love the little Brown truck