1954 SD220 Plugs

Will someone tell me the correct spark plugs for the SD 220,
I'd prefer an NGK plug first, then next choice Autolite.

Also need the points and plug gap for the SD 220 .
I keep finding different specs everywhere.
For plugs I've found .028 and .030 (I know, it's in the zone)
Points I've seen .017 and .019

Thanks,
Terry

found this at rockauto.com

AUTOLITE 303 Resistor .030 Gap; OE Style $1.10

ACDELCO R43 Professional; Conventional Gap .030 $1.45

MOTORCRAFT SP476 {#AS4C} Nickel Plug Material: Copper; Gap: .030 $1.47

the point setting I saw in the manual was .022

Hi,

You wrote:
found this at rockauto.com
AUTOLITE 303 Resistor .030 Gap; OE Style $1.10
ACDELCO R43 Professional; Conventional Gap .030 $1.45
MOTORCRAFT SP476 {#AS4C} Nickel Plug Material: Copper; Gap: .030 $1.47
the point setting I saw in the manual was .022

Interesting . . .
Today at the parts store they told me 295 Autolite
and so I ordered 6.

But I could still change that to 303 Resistor.
But resistor is only for radio interference suppression, right?

So would the 303 be hotter than the 295 ? I can't remember how that works.

Thanks,
Terry

Uncle,

What the heck does GRD mean?
Is it GREEN DIAMOND?

In this sites specs it shows this GRD designation for the 220
and shows Champion J-8 which I have always had in the truck's engine
and J-8 crosses over to Autolite 295 (which is what we did today)

But my 220 is a Silver Diamond, an SD-220,
so I'm still wondering.

Avoid resistor plugs and wires if still running a 6 volt system, they weren't designed for it, will be ok if running a 12 volt system.

I'm no spark plug expert. normally I go with what the parts book calls for since it's usually a stock motor I'm working on. yes, the resistor is for radio suppression. if you don't need it, I would not use it. I haven't had a vehicle with 6volt since the 70's so I don't have experience with 6v and resistor plugs. I found this at the autolite page and it would seem to me that the 295 is hotter than the 303

http://www.autolite.com/media/11847/spa ... system.pdf

Hey Uncle,

I sent Jim of this site an email and he found this info that he said he really had to dig for.
<https://oldihc.wordpress.com/category/frequently-asked-questions/engine/>https://oldihc.wordpress.com/category/frequently-asked-questions/engine/

"GRD" is indeed Green Diamond and they were the FLATHEADS of the 30's and 40's.

SD-220 Engine Tune-Up
The gross HP of the SD-220 is 100, and the net HP is 90, both figures measured at 3600 rpm…which is also the maximum recommended rpm.

Original spark plug recommendations were AC 45 Commercial, Champion J-8, or Autolite N-7, gapped at .028″-.032″. Ignition point gap is .018″-.024″, dwell angle 31-37 degrees, with initial timing set at 2 degrees BTDC. recommended valve clearance setting is .018-.020 HOT. These specs are from the CTS-11 factory technical service manual for L-series trucks.

My '54 3-ton is now 12 volt, alt equiped.
Thanks,
Terry

https://oldihc.wordpress.com/category/f ... ns/engine/

Now it'll work.

Dean

great info! thanks!

Does this engine need hotter sparkplugs? Probably, because the engine is low performance and not likely able to heat the plugs enough to resist deposits forming on the plug tips. NGK have an easy to follow tutorial on sparkplug heat.