Anti Dieseling Aids on Carbureted Vehicles in 70's and 80's

[SimplerTimes]

So back in the 1970s and 1980s when we were starting to see simple vacuum and temperature-controlled logic devices on engine controls we also started seeing little tricks being used such as engaging the AC compressor when the engine was shut off to put the engine under a slight load to help prevent dieseling.

What methods would be used on non AC equipped vehicles? Would they have a fuel control solenoid like some lawnmowers?

Any other tricks that were used to prevent dieseling?

I will admit that I used to find it rather amusing the attention drawn to a vehicle as its dieseling and carrying on in a parking lot, especially when it finally would stumble to a stop in a fit and backfire!

 

[PF52]

Would they have a fuel control solenoid like some lawnmowers?

That is probably a good way to describe the "Idle Stop Solenoid" that was in my 1971 Nova six-cylinder. The solenoid had a little plunger that would withdraw when you shut off the engine and thus it would draw down the idle speed so low it couldn't run. The problem was, the solenoid no longer worked and the engine would run-on forever creating clouds of noxious, evil-smelling smoke. My "fix" was to stall the engine with the clutch when I turned off the key.

 

[KGMtech]

Well tightening the fan belt to the nth degree was one way, not a great way, but it worked.

 

[wings&wheels]

My TR6 has an 'anti run-on device', a solenoid that uses voltage inputs from a three-prong oil pressure switch (with one being a non-switched hot feed) and the ignition feed. It is plumbed to the inlet manifold and carburetor fuel bowls. By combining these feeds and grounds, it activates only after the ignition is switched off but there is still oil pressure above ~7 psi, winding down. When activated for its 1-2 seconds, the solenoid shuts the fuel bowl vents (which are to the carbon cannister) and routs vacuum from the inlet manifold to the two carburetor bowls, pulling off the fuel to the jets. Rather ingenious and durable. Still in place and functioning on ours.

Old Rover w/ a period retrofit Weber has a simple solenoid that stops fuel flow to the jet when ignition is shut off.

 

[Malo83]

Never had that problem on my 74 Grand Prix or 83 Silverado.

 

[nwjones18]

My folks 83 caprice would diesel sometimes and I would always just shut it off in gear (not moving) then shift into park. That always put enough load on the engine to prevent it.

 

[Andrew1972]

My 85 Jeep CJ-7 with AMC 4.2 would do it, solution dump the clutch.

 

[Chris142]

That was definitely a low time in automotive history. Many cars had an idle stop soloniod. When you turned off the key the soloniod retracted which completely closed the throttle blade or blades.

The best cure for this was to put the timing where it should be,not where the sticker said. Retarded timing makes the cylinders hot which contributed to dieseling.

 

[nthach]

Toyota and Honda carbs would have a dashpot close the choke or throttle to make sure the engine shuts off.

 

[vwmaniaman]

A can or 2 Of Berrymans B12.

 

[Motu]

Revisited this last week. I was working on a woodsplitter powered by an old 1200 Nissan engine. The carb was a mess, with many things disabled - secondary choke, accelerator pump...and the idle shutoff solenoid. The govenor is also set for operating speed, no way to lower rpm for shutoff. Some serious run on, and backwards spinning on shutdown. It's coming back after he's finished cleaning up from the cyclone, and I'll fit a handthrottle....but I suspect it's still going to run on.

 

[addyguy]

Dad’s 1978 Chev Malibu 305 would run-on endlessly after shut off late in the vehicles life. Sometimes over 5 minutes worth.

 

[Dinoburner]

Had a s10 Blazer had many problems that were solved by routing the the distributer vacuum hose to manifold bypassing all the poorly designed and manufactured devices.

 

[berniedd]

This reminds me of my old air cooled VW bug (1968) where the original engine was replaced with the bigger 1500 cc version. Naturally the carb was also changed with a bigger 30PICT carb, which had the anti-runoff solenoid.

 

[weasley]

Many an engine was damaged through dieseling - the ignition is uncontrolled so backfiring at best and crank damage at worst. Usually driven by combustion chamber coking, caused by low quality fuel, burning oil and poor combustion control. I only ever experienced the occasional few seconds of dieseling at a time and was schooled to stall the engine as soon as possible if it ever happened.