First time build questions

[69'Net]

I'm a newb and building my 1969 coronet and have some questions. The engine is currently at the machine shop but will have the following: 74 smogger 440, cast crank, speed pro pistons at 9.4:1 cr, xe274 comp cam, stealth heads, performer rpm intake, msd, 1 3/4" headers, 6qt pan. 727 with 2400 stall and 275/60 rear tires. Questions: I have a 770 street avenger vs, is that too small or would I be better off with an 850dp? I need to pick a rear gear size, would a 3:91 be too much? Maybe 3:55? Car will be mostly street driven, I want it to have good low end power but still be highway drivable

 

[barbee6043]

3:55 willl give good torque multiplication, and decent on the road, 750 cfm is probably nough. try the carb you have first.

 

[aldal]

https://www.summitracing.com/expertadviceandnews/calcsandtools/cfm-calculator

I'm with barbee6043 try the 770, should be okay.

 

[69'Net]

Ok thanks, I appreciate the responses!

 

[lewtot184]

you'd be surprised at how well a 3.23 will perform.

 

[69'Net]

What do u think the difference in rpm at highway speed will be between the 3:55 vs 3:23? Thats with a 275/60 tire. Or even a 3:91?

 

[Bigal75]

Depends on your type of driving. I find 323s are too high. OK for the highway but that's it. If you like to burn tires and light to light fun then 391s. I run 355s and like them but my engine is much larger and can pull the gears. Carb is good too.

 

[forphorty]

http://vexer.com/automotive-tools/speed-rpm-calculator

 

[747mopar]

The carb will be fine (I like the double pumpers better though), 3:55s are a real good all around gear but you'll be up around 3,000+ on the freeway.