Very sorry to see / hear of the fires in both cars. Hopefully you'll have it all sorted out soon and be back on the road.
I have a related question for all interested parties. A fire needs a combustible and an ignition source to start. The foam filters are in my experience horrible because they easily absorb fuel vapors and are then highly flammable. BUT, it still takes an ignition source to light it off. On both FI and carbed cars this is commonly a "backfire", the cars ignition fires when the intake valve is partially open and ignites the fuel resulting in a "power stroke" of flame backwards through the intake, often dramatically up through the carb..
Back fires can be the result of improper valve timing or overlap or improper ignition timing or of course some combination of the two, combined with sufficient air fuel mixture in the cylinder at the time. So my question is about the Computronix and carbed cars.
Let me start by saying I think it is a VERY GOOD product and I am not bashing it. I have had a FI car with one and liked it a lot and recently had one for a short time on a carded car but sold it. Here's why: the Computronix is a "dual fire" system. That means simply that in our four cylinder cars it fires on two of the four cylinders every rotation of the crank, both the cylinder that is supposed to be firing and the one that is just beginning its intake stroke. The intake valve opening for cylinder on the intake stroke of course actually happens somewhat before TDC as does the ignition event.
If for any reason there is sufficient unburnt fuel in the cylinder (not enough exhaust scavaging or some new intake charge entering the cylinder before the ignition event) you get a backfire. This is most likely when the car is cold and perhaps being choked creating a very rich mixture. It would also be worse with more radical cams where the intake opening and ignition event are closer together.
This also happens in FI cars if timing is off but is rarer since FI is much more precise and is injecting only to the runner for the cylinder that is on the compression stroke (except of course when the cold start valve is supplying fuel to the general manifold). The result there can be a busted intake hose or damage to the FI air metering unit.
But on a carbed car it usually means fire back out the carb. This is more likely the shorter the intake runner (multiple carb setups) and the more radical the cams. So for me, having run it for a while with dual carbs I decided to sell the Computronix and go with a more traditional setup, albeit a modern version of a distributor, the 123 unit. Since then I have experienced very little in the way of backfires, mostly only when very cold and choked and that was before setting up the air fuel mixture to a "best lean".
I am sure many people have Computrinix running with carbs who are happy. Just looking to see what the community's experience has been?
Mark, as the seller I am interested in your insights but please again note I am not saying it isn't good, just posing questions.
Good luck with a speedy repair.
