454 Spark Plugs

[Desert_Eagle02]

Hey guys, sorry if this has been asked before, but I couldn't really find anything. I'm going to do a basic tune up on my 454 and pulled a plug out. Definitely can use new ones, anyway the plugs in it are NGK V-Power UR4. I've never owned a big block before, but that seems like quite a hot plug. The engine isn't a built hotrod, but it has a high rise intake and an Edelbrock 750 carb. Sounds like there may be a mild cam in it too. Nothing crazy. So should I replace the plugs with the same or go with a slightly colder plug?

[Dead Parrot]

Check the rest of the plugs. If the colors are good, replace with same heat range, otherwise adjust heat range base on colors. If you wind up making significant tuning changes to timing, jets, metering rods, etc, you might wind up buying a 2nd set of plugs. You buy plugs to match the engine's setup, not to change it.

[Desert_Eagle02]

I checked a few plugs. They are pretty old and worn. Also some carbon buildup on them. Truck was running rich, a carb clean seamed to help a bit, but it is still a little rich. It's from the mountains out west so it might be jetted richer. Runs great otherwise. I just bought and I'm going to put in new plugs UR4's and new wires and check them after a bit to see how they look. I'm thinking I need to lean out the carb a bit and put in UR5's.

I haven't dealt with many older carbed vehicles. Well besides motorcycles, I can tune those no problem, 2 or 4 stroke.

I'm not looking to change the engines setup, just dial it in to where it should be. Engine mods, including a ground up rebuild are down the road.

[Dead Parrot]

Assuming your carb is one of the 14xx series, buy a carb rebuild kit for it. While it is open, check the float levels. Often they are set high which leads to a too rich mix. Check your jets and rods. Many of the carbs are set too rich from the factory since several models are marketed as performance race car parts.

One nice thing about the 1400 set of carbs is you can change the metering rods and power piston springs without taking the top off.

[RotaryRocketeer]

Don't discount the advantages of a good fuel pressure regulator either. My '76 w/Edelbrock carb runs pretty rich at idle, and I know it's because it doesn't have one. Aftermarket carbs don't like more than 5-6 psi fuel pressure, from what I understand.

[Desert_Eagle02]

Thanks guys, I'll get a rebuild kit and check the floats and jets while I'm working on it. Also I'll look into a fuel pressure regulator. It has an electric fuel pump so it probably needs one. It might already, I don't know. I'll see if I can borrow a pressure gauge from a neighbor so I'll know where it's at with the current setup.