Opinions on gearing please

[Stretch]

Thanks for the link Firefighter3931. Thats super cool. That one is getting saved to favorites!

[firefighter3931]

You know I thought that too. I checked my speed with my hand held GPS and at 65mph on the speedo the gps says 63.5. The Tach may be suspect. It is the factory rallye cluster tach. I've been meaning to hook up my digatal timing light and see what it says the Rev's are at 65 mph. (my timing light is a snap-on digatal advance light. It has a tach feature).

Stretch,

The GPS and factory speedo seem close enough so you have the correct speedo pinion installed in the trans. 

Based on that info i'd say you're on the right track in verifying the stock tachometer reading. You may not be turning as many rpm's as you think 

Thanks for the link Firefighter3931. Thats super cool. That one is getting saved to favorites!

Ya, that's in my favorites as well. One of the members @ DC.com made that handy tool. 

I like the 1/4 mile calculator as well as the speed calculator. Good troubleshooting resource 



Ron

[Stretch]

You know I thought that too. I checked my speed with my hand held GPS and at 65mph on the speedo the gps says 63.5. The Tach may be suspect. It is the factory rallye cluster tach. I've been meaning to hook up my digatal timing light and see what it says the Rev's are at 65 mph. (my timing light is a snap-on digatal advance light. It has a tach feature).

Stretch,

The GPS and factory speedo seem close enough so you have the correct speedo pinion installed in the trans. 

Based on that info i'd say you're on the right track in verifying the stock tachometer reading. You may not be turning as many rpm's as you think 

Thanks for the link Firefighter3931. Thats super cool. That one is getting saved to favorites!

Ya, that's in my favorites as well. One of the members @ DC.com made that handy tool. 

I like the 1/4 mile calculator as well as the speed calculator. Good troubleshooting resource 


Ron

I have been thinking it may be the tach. That would be nice. The more I think about this the more I think its the revs with 39 year old valve springs that worrys me most. The gas milelage really isn't that bad. If the tach is that far off it explanes alot. If the tach turns out to be accurate it pretty much leves the torque converter.

Thanks again Ron. I'm thinking you nailed it. I'll find out when I get off these crutches and get my car out for the year.

[firefighter3931]

You're welcome bud....allways glad to help 

Let us know what you find out. 


Ron

[Argos_Chargers]

There is a huge difference between the 3.23 and the 2.76 as far as funa nd driveability of the 340.  I discovered that with that much wight, the 2.76 gears mde my extremely fun 340 feel much more like a 318.  If you can find2.96 or 3.03 gears out of something older, you might try them.  I do know that the 340 seemed to work fairly wellwith the 3.23's.  It still won't give you the blastyou get from the 3.55's, but it should be all right.  Avoid the 2.76's unless you are dropping the weight to something more along the lines of an A-body, and even then use tires with a fairly low profile.

[Stretch]

Ok I took my car out today for the first time of the year. Don't these revs seem high for having a stock 340/727/3.55 with 295/50/15's?

[Stretch]

When I get my digital timing/ advance light back from my buddy I'll take the car for a ride with the light hooked up and set on tach read. I should also mention my spedo is within 2 mph @ 60 according to my hand held gps.

[Musicman]

Looks perfectly normal to me if you're running an 727 Automatic. My car runs "slightly" less, but I have a 3.23 rear end rolling my 295/50/15's. It all comes down to torque converter efficiency at speed, usually in the neighborhood of 80% & 90% on a typical stock converter... and it's usually closer to 80% than 90% in most cases. Now if you had a Lock-Up converter that would be a different story.

[Stretch]

Does anyone know what the stall speed of the factory converter should be? I haven't "loaded" the converter in yeras. If I remember correctly it's up around 2400 RPM. Next time I take it out I'll see where it stalls.