normal idle RPM

[97SilveradoHD]

i have a 97 with the 7.4 and was wondering what the normal idle speed for this motor is. right now when the truck is at normal operating temp, in gear idle is around 700-750. also everytime i start the truck (hot or cold) the thing revs up to 1600-1700 rpm and then slowly settles back down. i expect this when the truck's cold, but i don't understand why it would do it when hot...? btw, i've already replaced: TPS, coolant temp sensor, IAC, cleaned MAF & TB

 

[Aloicious]

that all is normal. the 5.7's stock idle is ~600-650 IIRC, 700-750 would be about right on the big block (and within the realm of gauge error). the idle flare on start up is completely normal too. the engine has different runing parameters for cranking/starting than it does while it's going, so the engine has a little recovery time between running the cranking/starting tables, and the normal tables....the idle speed will recover slowly when its cold, it should recover fairly quick when its warm.

 

[97SilveradoHD]

ok sweet, glad everything is functiong normal. just wanted to double check since this truck idles higher than the 600-650rpm that i'm used to with my old 350 and even my dad's 6.0 that barely seems to idle at all (~500rpm)

 

[grampadirt]

My '95 7.4l does the same thing,not to worry.