Indynut

OK, here's more info on my car. Since I posted I've been under the car and changed the rear diff fluid and check out the numbers. I've spun the tires and counted the revs of the driveshaft and also decoded the rear end. My car has 3:55's in it. It is a 1979, L-48 with an automatic. I have added headers, and an Edelbrock Performer Cam and Intake. I've recurved the distributor. Timing is set at 36 degrees total, like Lars advised with the recurve. Is the stock convertor the problem or is my tach not accurate. A review of the details goes like this.
60 mph's is 3100 rpm
60 foot times 2.13 is the best
almost 5500 rpm at the end of the 1/4, @ 98 mph
car weighs 3640 with me in it
rear end is 3:55

trans is a TH350 and is my next thing to tweak. I'm planning on a total rebuild and also a shift kit and was planning on a new convertor (B&M or TCI with about 2400 stall) to help my 60 foots and also my ETs.

Could my tach be messin me up a bit here or what?

With those gears (3:55's) should I have a better mph than I have?

Thanks as always



[Modified by Indynut, 10:09 PM 9/1/2003]

LAvetteman

Beings you have an HEI ignition, install a new aftermarket tach. You don't have to mount it permanently, just to verify your RPM's. But you may want to if you find your tach is way off, not to mention the factory tach cna be troublesome at times.

Jvette73

That rpm is about right for the 3.55's and a th350. A 2500 stall could easily take a 1/2 second off yur et. Thats about the gain I got with similar stall when my motor was still all stock and I was runnin th400. With stock L48 motor I gained 4 tenths in ET by the convertor change alone. Since then, lots of other things have been changed.

Jvette73

on second thought I think im wrong about the rpm reading. I just looked at some charts that said for you to be reving 3100 at 60 you would have a 23" diameter tire. im sure yur tires are taller than that.

Heres the chart I refered to http://corvetteactioncenter.com/tech...gearcombo.html

Indynut

Guess I've gotta take a run with another tach onboard to see if I'm getting bad information from my current tach. Heck if I'm shifting too early, maybe I can find a lower et. Does the 1979 Vette have any bad tach history or am I clutching at straws here?

Thanks as always! :seeya