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- - RPM Change (https://67-72chevytrucks.com/vboard/showthread.php?t=445613)

Howdy,

My 86 Chevy has made a change...by itself. Why would the RPM's change?

I have tachometer that shows the RPM's. Previously on start up the RPM's were about 500 and full speed(65mph) about 2200 RPM's. Recently, I've noticed them being about 350 at start up and about 2100 at full speed.

It does not stall initially but requires more gas pumping than it used to. It used to not need any revving but now does after a cold start.

Why would it change by itself? And should I fix it...and how?

Otherwise Grandpa's truck it doing OK. However, I did read the "Death Wobble" :ack: thread and have become paranoid enough to take it in for some tire rotation and alignment.

Weather and carb conditions affect RPMs. Clean up the carb really good. Lube the linkages with WD-40. Check the tach connection. Tach ground may be a problem.

Quote:

Originally Posted by gchemist (Post 4473127)

Weather and carb conditions affect RPMs. Clean up the carb really good. Lube the linkages with WD-40. Check the tach connection. Tach ground may be a problem.

^^^ this... If the tach connection is fine, and cleaning the carb doesn't work, it likely needs a rebuild, It's also posible the truck needs a tune up, plugs wires and such