Plug Confusion

[Tail_Gunner]

Engine 2001 4.3 volvo TB injected...vortec heads PEFS

Change plugs the other day went from a short plug to a long plug..(406 to 708)... Lost 4 mph and heat went up 7-8 degrees (168-170)....Ran all day on the river no damage and ran consitent temp and speeds

The old short plugs were showing a very rich run...carmel apperance...Is it possible my timing is messed up or has anyone experinced this before

 

[JustJason]

Re: Plug Confusion

Can you elaborate by what you mean by you went from a short plug to long plug? Were you running MR43s in vortech heads when you should have been running the LTS's?
What plug number were you using, and what plug number (and manufactor) did you go to, and why the change?

Your timing wouldn't/shouldn't have changed unless you touched the distributor.

 

[Tail_Gunner]

Re: Plug Confusion

From AC Delco mr43s to LTS version...Plugs were old...8 yrs...100 hrs on the engine...didnt touch the timing..lost 300 or more rpm...why the jump in temp loss of rpm and speed..(at the top) midrange is dead on that is mph to rpm..3000rpm..32mph...

 

[TiredoleBoy]

Re: Plug Confusion

From AC Delco mr43s to LTS version...Plugs were old...8 yrs...100 hrs on the engine...didnt touch the timing..lost 300 or more rpm...why the jump in temp loss of rpm and speed..(at the top) midrange is dead on that is mph to rpm..3000rpm..32mph...

Plugs will make a large difference in the power of an engine. It will also have it burn a bit hotter. When I built race cars we experimented with plugs to determine max efficiency and power, some made it worse and hotter other made it run like a champ. A cross reference manual of plugs actually can help determine the correct plug for optimum performance.

Or you could just go with what the manufacturer recommends.