cutting out

[smokediver]

I went out for a little run today as it was 78 , seas 1-2 feet :D anyway, i noticed that when I got in my upper rpm range , the tach was bumping back around 500 rpm when i went above 4700 rpm . i don't think it was my rev limiter but who knows ... maybe my tach is off ? it is a gaffrig 2 which i have been reading on here isn't one of the better gauges ... thanks for any advise...

[smokediver]

was it the sunny and 78 statement or does anyone have a clue .... sorry i live in paradise ..... if it helps i did live in detroit .... in the winter ..... i moved .....

[Mr X]

John,
yes the Gaffrig II ,IMO, are very low quality.
Check all the connection on the back of the tach.
Was your engine doing what the tach was indicating?
Cutting out, etc?

[smokediver]

The engine itself was acting as though it was hitting the limiter . the rpms were at 4700 on the gauge then the engine would knock and the rpms of the engine would drop . then go back up etc .... under 4500 all was fine but from the engine sound I wasn't near the upper end ... thanks ...

[MOP]

Just maybe! If both the tach and the engine are responding the same it may not have any thing to do with the tach. I would hook up a service tach, un hook the dash tach and see what it does. When it comes to fuel or ignition it can go a few ways! It would also pay to pull a couple of plugs to see what color they are.

Phil

[Fish boy]

Just curious, but what size prop are you turning? Is this a new prop, and if not, what rpms have you reached before with this prop? What motor do you have?

Fish

[smokediver]

the plug color is a light tan ... good ... fish , the prop is a laser2 , same one i have had .... i am wondering if the cooler air is giving a little more power and it is the rev limiter ... the tach just may be off ... oh, carbed 4.3 vortec .. switched to a 4bbl last year .. good move ..