I'm working on my 46 Chevy pickup truck and I am going to replace the spark plugs in the 1953 235 6 cylinder that's in it. I would like some input on what heat range of spark plug is recommended for this motor and this 6 volt system. This was my late father's project and I haven't really done much to it. There are two different types of spark plugs in the head right now. Is there any specific make and number a spark plug that you guys would use?
1946 1/2 ton Chevy Pickup 1954 235 cu in 3 speed on the floor
Save a life, adopt a senior shelter pet. The three main causes of blindness: Cataracts, Politics, Religion. Name your dog Naked so you can walk Naked in the park.
Thanks, I appreciate the info. I haven't looked around yet but from what I have read oh, these spark plugs are hard to find. Any advice on a replacement?
1946 1/2 ton Chevy Pickup 1954 235 cu in 3 speed on the floor
Buy an owner's manual copy and write in it important info like engine year and size. Keep it in your glovebox. I have problems remembering so this is what I do.
Last edited by buoymaker; 04/23/20222:04 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Save a life, adopt a senior shelter pet. The three main causes of blindness: Cataracts, Politics, Religion. Name your dog Naked so you can walk Naked in the park.
Many people are obsessed with spark plugs. The choice of which plug to run is not nearly as complicated as the purists claim, unless you're trying to build a 100 point concours correct show vehicle. AC 43, 44, or 45 plugs were used as original equipment, with the "heat range" going up with the number of the plug. 43- - - -a "cold" plug mostly used for long haul highway driving which could dissipate heat quickly to the cylinder head and coolant to prevent the tip of the plug and the ground electrode from overheating and burning away. 44- - - -a "midrange" plug suitable for both short trip and highway driving, that has a somewhat longer path for the heat to travel from the plug tip to the shell that threads into the head. 45- - - -a "hot" plug suitable for short trips and/or engines that start and stop frequently without the engine getting up to normal operating temp every time the engine is started- - - -delivery trucks and cars driven mostly within city limits for short hauls. The 45 has a long heat travel path from the tip to the shell, resulting in the tip running hot enough to burn away deposits that could foul the plug and short out the spark path. "It ain't rocket surgery!"
Run an AC 44, or the equivalent heat range and thread length of any other brand of plug- - - -Champion, Autolite, Bosch, NGK, etc. The only plug brand I've had consistently bad luck with over 50+ years was "Prestolite"- - - -they don't last very long, particularly in a high performance engine. If you really like throwing money away for no good reason, buy some sort of "high output" plug like Accell. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thanks to everyone for the information. Hotrod Lincoln, you have helped me in the past and always have good advice. My truck is not going to any Concours shows and I really only take this old truck to local car shows. I'm going to shop around for plugs today and I appreciate everybody's input.
1946 1/2 ton Chevy Pickup 1954 235 cu in 3 speed on the floor
I'm presently running NGK B6S plugs in my 235 powered 3800. My 1-ton is usually run on the highway fully loaded (9,000 gross w/camper). I just pulled the plugs to check it out after w 4,000 mi. trip and they are a nice light tan color.
Besides NGK, over the years I've run AC C42-1, AC C43, and AC 44S. The AC C- whatever, were a commercial plug with much larger electrodes. I have one remaining new one. The last time I bought C-43 it had the same electrode as any other plug so I never bothered to find the C version after that. I have one remaining of that too.
The B6S NGK are the heat range (6) everything seems to use since emission controls came into being in the 70s, Volvos, Saabs, Toyotas, Chevrolet, whatever; BP6ES being the most common. I suppose emission-controlled engines have the same combustion chamber temperatures regardless of combustion chamber design or load? That seems unlikely but they all use the same plug.
Last week I went my to my local NAPA store looking for a hotter plug for my '60 Matchless motorcycle (it has a B8E). I also needed 2 replacement BP7ES plugs for my R-100 BMW motorcycle. I came up empty handed. My NAPA store sells NGK. B8E or B7E didn't cross to anything in their system. BP7ES crosses to a BPR7ES, which is a resistor plug and was unavailable in the regional warehouse. I didn't even ask about BP6ES as I have a bucket full of them. The counterman did mention that when available NGK plugs come in boxes of 8. For something they don't stock I'd have to buy a box.
Is it just MY NAPA store or are non-resistor plugs for older vehicles now hard to get?
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
The only thing a non-resistor plug accomplishes is that it erodes the contacts of the distributor cap and rotor a lot more quickly. I've cut viewing slots into distributor caps for use on a Sun distributor tester for classroom instruction purposes, and non resistor plugs make the arc that fires between the rotor and the cap terminals look like a stick welder is running inside there. That "bright blue spark" that was popular for ignition systems 50 years ago was actually very destructive. It sold a lot of distributor caps and rotors, and created plenty of AM radio and TV interference, though! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
HRL: Here are some questions that in an oblique way will concern old truck enthusiasts despite the motorcycle flavor of my questions.
So, do resistor plugs create a higher voltage at the plug gap with an auto-transformer type ignition coil? Or are they just current limiting? Would resistor plugs produce more voltage in the secondary winding of an auto-transformer and reflect a higher voltage into the primary winding? If so, would resistor plugs cause a higher voltage within a primary winding and consequently across the capacitor?
I know it's been many, many years since automobiles had magnetos but my '60 Matchless single and '65 Norton twin both have magnetos. One has to kick start them so it's important that they start on the first or second kick. I've seen schematics of Lucas motorcycle magnetos and they appear to be wired as an auto-transformer. The books for both say plug gap 0.020" for the magneto models and 0.035 for the Kettering (battery and coil) models. I have assumed that magnetos at kick-start RPM don't put out much voltage, hence the narrow gap. That may not be true and I've never experimented with a wider gap.
My inquiring mind would like to know because I just replaced the capacitor in one Lucas magneto, which involves dismantling the armature and pressing it back together with no more than 0.002-5" run-out. It's tedious, time consuming and i don't want to do it again soon because of using a resistor plug.
The original condenser (ca. 1960) I believe died from old age, being an electrolytic capacitor. In the 90s I worked in a motorcycle shop specializing in vintage bikes and dealt with the magneto issue many times. I tested many NOS magneto condensers still in Lucas boxes and discarded them as failed. These are of an electrolytic design and are believed to fail from disuse. Are automotive condensers (capacitors) electrolytic? Are NOS ones suspect? I have encountered many more failed new condensers fresh from the FLAPS than failed in-service condensers.
1951 3800 1-ton "Earning its keep from the get-go" In the DITY Gallery 1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.
