Short or long reach spark plug in a 315 poly engine??

[Rjpond]

Currently I have short reach spark plugs in my dodge truck. They seem to foul too early. The engine is old, but she starts so well and runs and idles so smooth, that I want to procrastinate a bit before looking at the rings and cylinder walls. I’ve researched   what spark plugs are recommend but a clear consensus amongst part suppliers is elusive. The early poly engines and the hemis seem to get combined by the part suppliers.

thanks

Scott

[Plymouthy Adams]

Per motors manual, 1956 Dodge  315 V8 were factory serviced with the Autolite AR52 spark plug....these are long reach.  If you have been running short plugs...you may now have carbon fouled threads and require chasing prior to installing the correct reach plug....

Edited March 18, 2021 by Plymouthy Adams

[Rjpond]

Thank you for clarifying what the manual said. My truck is a late series1955 which I have the manual for. The donor engine, however, i need to find a manual for.

 

I still need to familiarize myself with this truck. I almost wonder if my battery is not fully charging even though I drive it 20-30miles on the weekends. When it didn’t start the other day, getting fuel wasn’t an issue. So I replaced the spark plugs and charged up the battery from wearing it down trying to start it. When I barely touch the key, she started instantly even as a six volt system. I will take a reading with the engine running to see how many volts that I’m getting across the battery terminals

 

Thanks again for your help

Scott

[Rjpond]

I checked the battery and the reading was  6.4 volts. Then with  the engine running the reading was 6.7 so I don’t think the battery is an issue. I’m wondering if a cold running engine is giving me problems. The temperature gauge never comes much off cold. Maybe the thermostat is stuck open and that may cause early spark plug fouling??

[JBNeal]

If ya want to heat up that engine, block the radiator airflow with cardboard or a big plastic bag...the flathead engine block has a lot of mass so it takes awhile to heat it up enough that the thermostat stays open