Spark Plug Question

[Squirrely Brother]

I wanted to see if anyone could help me out here. When changing my cracked flex plate I realized the guy I purchased my 1981 Silverado from was a storyteller. The engine is a 1991 350 with HEI that had ACDelco 10 spark plugs gapped to .035. I went with what O’Reilly’s showed for the engine, which was ACDelco CR43TS gapped to .042. The engine runs quieter, but is running a little hotter. Just curious what plug number is recommended, because I saw a really old thread recommending the CR45TS on a 1981 350. Any help or suggestions would be appreciated. Thank you.

 

[1987 GMC Jimmy]

In the cuprous plug family, I use the CR43TS. I don’t see more than a negligible difference using the 45 version. I’ve always used copper in my various SBCs and 454s, but I did step up to platinum in a 3.1 that I daily. I’ve read of people objecting to use anything but copper in old style engines, but other than the copper being a physically stouter plug, I don’t see the problem. The platinum is nice in a transversally mounted engine because changing the plugs is a little more of a process, and I can let those go for like 40K miles. Furthermore, I don’t consider the 60* V6 to be an old engine design either.

Spark plug gap is almost as loaded of a topic as, “how much is this truck worth?” I think .035 to .045 is an acceptable range with HEI, you just don’t want too much, which’ll overload your wires, coil, cap/rotor over time. I tend to stick to that .035 number just because I don’t want to be replacing things all the time on a daily driver. The only points vehicle I own has an International Harvester C60 engine, and the point gap is .023 so in my mind, the .035 is plenty, and I wouldn’t go over .045. You might need a little more with a high output coil, but I can’t speak to that from experience.

 

[AuroraGirl]

i use AC delco R45ts because i had NOS ones from the 90s on a shelf for like 3 SBC worth. its the OE called for plug.

my gpa was running r46ts, but the timing on truck was heavily retarded, it ran richer than a politician, and the gap was .35 or .3.

It fouled them plugs BAD and it burned Oil BAD and it barely showed signs of life.

I put a new carburetor on, and instantly burning oil and rich situation improved 100%.

Fixed timing to be much closer and put 45 in, it runs wayyyyy smoother. fixed grounds on truck and new battery, starts so easy, new oil is staying fresher longer, and its noticeably leaking way less and burns very little if any.

I believe my gpa tried fixing his weak ignition and undiagnosed rich problem by hotter plugs, retarded timing, and a small gap

 

[Squirrely Brother]

Thank you, for your responses. I take it the plugs are good to go. I was thrown off by the ACDelco 10’s that were in there prior. The engine used to have more of a growl, but in hindsight it was probably some predetonation mixed in there. It’s just had an issue a couple of times with not wanting to start right away after being warm. Almost acts like the bowls are flooded. After you mentioned timing, I’m going to put a light to it to see where it sits and make any adjustments. Again, I appreciate your feedback. Take care.

 

[Bextreme04]

It's kind of like the age old question... "Is that a miss or a cam?"

I would highly recommend making sure the timing is right, then make sure you have the carburetor set up properly. Properly setting the mixture and idle makes a huge difference in drive-ability.

 

[80BrownK10]

In the cuprous plug family, I use the CR43TS. I don’t see more than a negligible difference using the 45 version. I’ve always used copper in my various SBCs and 454s, but I did step up to platinum in a 3.1 that I daily. I’ve read of people objecting to use anything but copper in old style engines, but other than the copper being a physically stouter plug, I don’t see the problem. The platinum is nice in a transversally mounted engine because changing the plugs is a little more of a process, and I can let those go for like 40K miles. Furthermore, I don’t consider the 60* V6 to be an old engine design either.

Spark plug gap is almost as loaded of a topic as, “how much is this truck worth?” I think .035 to .045 is an acceptable range with HEI, you just don’t want too much, which’ll overload your wires, coil, cap/rotor over time. I tend to stick to that .035 number just because I don’t want to be replacing things all the time on a daily driver. The only points vehicle I own has an International Harvester C60 engine, and the point gap is .023 so in my mind, the .035 is plenty, and I wouldn’t go over .045. You might need a little more with a high output coil, but I can’t speak to that from experience.

I know this is a few months old but I was looking at what plugs others were running and came across this thread.

You must have a Cub.

 

[1987 GMC Jimmy]

I know this is a few months old but I was looking at what plugs others were running and came across this thread.

You must have a Cub.

Sure do!

 

[80BrownK10]

Sure do!

Another squarebody and Cub owner here!

 

[AuroraGirl]

I know this is a few months old but I was looking at what plugs others were running and came across this thread.

You must have a Cub.

whats a cub? cub cadet?
@

I know this is a few months old but I was looking at what plugs others were running and came across this thread.

You must have a Cub.

what plug you run?

 

[Bextreme04]

Just to put some useless info out there.... If anyone goes to a CNP setup(yes you can even on the Gen I SBC's) you would switch to an Acdelco 14 plug with a .060" gap. The CNP setup allows for a much more powerful spark, so you can go to the bigger gap and get a better combustion event

 

[AuroraGirl]

Just to put some useless info out there.... If anyone goes to a CNP setup(yes you can even on the Gen I SBC's) you would switch to an Acdelco 14 plug with a .060" gap. The CNP setup allows for a much more powerful spark, so you can go to the bigger gap and get a better combustion event

whats Cnp

 

[Bextreme04]

whats Cnp

Coil Near Plug... its individual coil packs for each cylinder like you see on LS engines. I'll be running it on my Gen VI 454.

 

[1987 GMC Jimmy]

Another squarebody and Cub owner here!

Oh, cool. Mine’s a 1949 just outfitted with the regular Woods belly mower. It’s been upgraded to a Delco-Remy 10si alternator, points, and 12V. There’s a 1959 with it that my dad bought that was once a nice tractor, but it was mutiliated by him and my brother. Just another clear cut case of some people need to leave **** they don’t understand alone.

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whats a cub? cub cadet?
@

what plug you run?

A Farmall Cub, but the Farmall Cub/International Cub Loboy was the much beefier precursor to the Cub Cadet series of lawn tractors.

 

[80BrownK10]

whats a cub? cub cadet?
@

what plug you run?

Yep, they originally were McCormick Farmall Cubs or simply Farmall Cub as most people called them originally made in 1948, it was the smallest tractor in the Farmall line. About 9hp at the engine. Then Farmall and international merged in the 60s I believe and they became international cubs in the 60s at some point. The motor was upgraded to produce 14hp. The last year they were made was 1979. Basically the same in the whole production run. They also made a Cub low boy which was mostly made for running a mower in the industrial series when they painted them yellow as Internationals. But you could get red low boy cubs as well. The finals were just turned 90 degrees to lower the tractor. The original ones sat up so high cause they were for cultivating. There what is called a one row tractor, as they plant or cultivate one row at the time. The operator seat is offset to the right and engine is offset to the left so that the operator can look down between his legs while cultivating so that he won't his his crop or doesn't have to either lean over to look or stand up and look over the hood. This was called cultivision.

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Cub cadet was a garden tractor made toward the end of the line. Those were real garden tractors and the predessor of the modern riding lawnmower tractor style with the steering wheel.

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I have a 1952. It was my grandfather's only tractor. It replaced the mules that he and the previous generations used all the years before. My grand dad was a gentleman farmer, some truck farming but mostly cows. He worked in the mill for 40 years and the farm. They got it in about the 60s sometime. I own the same property that has been in the family 200 years or so.

As for spark plugs I am running 45ts right now. I have a stock 350 running a quadrajet.