Looking for Spark Plug Help

[Jason Bourne]

My son is looking to replace the spark plugs on his truck. Normally I'm a big believer in replacing with OEM. The problem is the engine in my sons truck isn't OEM. The truck originally had a 350. At some point the engine was replaced with a 283 that possibly was bored out to 305. It has a 4 barrel Edelbrock carburetor, headers, and sounds like it might have a mild cam. The 283 might have come out of a 1964 Chevy II.

It currently has R44T spark plugs installed. Don't know much about distributors but the one installed is labeled Delco Remy. It doesn't have a coil wire leading to a coil like I have seen on other engines. It has a block on top that I assume is some type of electronics maybe? I'm attaching a pic of the distributor.

Can anyone give a recommendation on a good spark plug replacement? Should we just replace them with new R44T's? Is there something better available? What should the spark plug gap be set at? Also looking to see if new plugs can enhance the trucks performance. Currently it sounds like Tarzan but runs like Jane.

Any insight is appreciated.

[truckster]

That's an HEI distributor. The block on top is the coil. It has an electronic module on the base plate (where you would find the points on an older distributor). Make sure it's getting a full 12 volts - the original coil wire had a resistor in it.

The R44T or R44TS is a good choice. I would gap them at .035 - 0.40.

[67C10Step]

^^^^What truckster said. I am still running the stock 283 in my 67 but converted it to HEI. I am guessing the red wire in the photo is power to the coil on yours but do double check it for the full 12V.

[RichardJ]

R44T spark plugs have a tapered seat. If the heads on the 283 are still the original '64 heads, it would probably call for gasketed plugs such as R44.

[Jason Bourne]

Originally Posted by truckster

That's an HEI distributor. The block on top is the coil. It has an electronic module on the base plate (where you would find the points on an older distributor). Make sure it's getting a full 12 volts - the original coil wire had a resistor in it.

The R44T or R44TS is a good choice. I would gap them at .035 - 0.40.

The next time my son and I work on the truck I will try and verify it’s getting a full 12 volts. What are the symptoms if it is not getting a full 12V? Right now the truck seems to be running fine.

I assume the 12V you are talking about is at the connector where the red arrow is pointing in the photo? Do I need to remove the connector to verify the voltage? Or do I need to back probe with it connected? Does the truck need to be running to perform the voltage check?

Does the R44TS provide a advantage over the R44T? From my quick google search I see the TS has a extended tip. Does the extended tip provide better performance? Do I need to be concerned about any interference with the moving parts in the engine if I choose this plug?

Thanks for your help.

[Jason Bourne]

Originally Posted by RichardJ

R44T spark plugs have a tapered seat. If the heads on the 283 are still the original '64 heads, it would probably call for gasketed plugs such as R44.

I don't know anything about the heads. Currently R44T plugs are installed. Is there a easy way for me to determine what type of heads I have?

[RichardJ]

You can tell by looking, but you have to get the holes really clean. Plenty of light, a mirror or a camera are needed with the heads in the vehicle.
Head casting numbers are in the rocker box under the valve covers.

[truckster]

If the truck isn't misfiring, it's probably not a resistor wire. The resistor wire will limit current at higher RPM and can cause misfiring.

The "S", as you discovered, is the extended tip. The tip is about 1/8" longer. It shouldn't interfere with the piston. It gives a slight advantage in putting the spark further into the fuel-air mixture.

[Jason Bourne]

Thanks to everyone for all the good information!

[Steeveedee]

If it were mine, I'd pop the distributor cap off and look at the rotor and inside of the cap. Enough corrosion on the electrodes can give doggy performance. Depending on mileage and plug and wire condition, a common failure is for the rotor to burn through and the spark can go to ground on the shaft. Take the rotor off and see if there is discoloration on the bottom of it. It'll still run, but sub-par performance would be a result. You could clean the corrosion off the weights and springs while you're in there, if any is present.