Tach action - Is it smooth??

[SRTRICK]

I finally got enough miles to really run up the revs, and it seems that the tach is kind of jerky when it gets above 4500 revs or so, not the smooth swing I would normally expect. Is this normal or do i have some electronics to look into??

Thanks in advance!

 

[GR8_ASP]

Haven't noticed it in mine but I will look closer this weekend. Post valve change - Yee Ha - it moves the tach needle quite a bit faster.

 

[wiseasp]

You know at Englishtown last week was the first time I really watched the tach and I noticed the same dam thing. It kind of "jerks" up the rpm's. I said something to some other guys, but no one noticed it on theirs. I am glad I am not the only one .

ROB

 

[Viperzilla]

If you look at the dyno graphs, what it shows what may be a supporting witness. Very rough through the ranges of both torque and HP.

 

[SRTRICK]

Rob - of course it doesn't help too much if we are the only two - Anybody else who has watched their tach carefully while accelerating, particularly in first gear??

Viperzilla - it's not an acceleration thing, only a tach thing. There is no change in the smooth acceleration that would match the tach's uneasiness.

 

[GR8_ASP]

I watched the tach quite closely when driving yesterday. I did not notice erratic tach operation but did experience the "lag" condition. As I was being watchful of the tach I noticed the tach reading was 2400 to 2500 rpm each time it occured. Just after a 1 - 2 shift, with the resulting engine speed when the engine bogged around 2500 rpm. Interesting. I tried to recreate the bog on command and was not able to, even when knowing the engine/vehicle speed that precipitated it.

 

[SRTRICK]

Ron - you are shifting too low & accellerating too slowly to experience what I have been asking about. The erratic tach action is only noticable when accellerating fully, far above 2000 rpm. I have not experienced any bog, although I can't say for sure I have duplicated the conditions you are describing.

 

[GR8_ASP]

I may be shifting too low, but that is about the speed that I shift when driving normally. Usually between 3500 and 4000 rpm before shifting. Under aggressive driving I take it quite a bit higher (of course). I will try to pay more attention to the tach smoothness during aggressive periods. Generally I am watching the tach at those times, but concentrating on when to shift and not the relative smoothness. Have you noticed it (notchy tach) in all gears or more when in the lower gears (faster rate of change)?

 

[SRTRICK]

Only time I have been to redline while watching is in first gear, but it acts a lot like an old Corvette with a worn distributor drive bushing. Like it loads up with tension and then jumps higher then loads up and jumps again. Of course this is not what is happening as I believe it's an electronic tach, but that's what it is like.