3.73 vs 3.90 gears

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Bluchip

Not-quite-so-new-guy
Jan 16, 2010
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Hey guys need your opinion
I have a 461 BBC in a 86 monte with 700r trans. Looking to up grade gears from 3.42 to either 3.73 or 3.90. The car with be only a street car sometimes hitting the hwy for short trip like 2 hours. Car lags on take off with 3.42. Help me out with some thoughts please. Carb is a holley 750 dp
 
If a 461 lags on take off with a 3.42 you got bigger problems to deal with than finding the optimum quarter mile gear for y our combo. If you are trying to find the optimum gear for your combo it could be worth a tenth or maybe as much as two tenths coming from a 3.42. It won't be dramatically quicker like if you were coming from a low to mid 2 series gear.
 
... I'm thinking the same thing... The 700r4 has a short 1st gear, so there shouldn't be a question of "lag". A big block shouldn't struggle at that, not even with a low highway gear like 3.08s.

by "lag", do you mean there is a bogg coming off the line? It seems like there might be a tuning issue to resolve before playing with gear ratios. Specially if there will be minimal track time envolved.
 
By lag I mean when it comes off the line ok but it really bogg down and then picks up and jets out almost like a turbo would do. Im sure its not tuned correctly all the way but still should not be getting that lag after a decent take off. Im just not sure in what direction to go from this point.
 
are you at idle, then tromping the gas, or holding rpm's and launching?
stall converter?
 
I don't care if you have 2.56 gears, if a 461 ain't lighting the tires like a blow torch there are other issues in play.
 
Snowman51 said:
By lag I mean when it comes off the line ok but it really bogg down and then picks up and jets out almost like a turbo would do. Im sure its not tuned correctly all the way but still should not be getting that lag after a decent take off. Im just not sure in what direction to go from this point.


HI snow you have converter lag or bog off the line. your engine is not running in its rpm range u need a converter with more flash stall. What is your converter now stock?
 
If you got a big cam, low compression, and a stock stall it could be the converter but it sounds more like a carberator issue. It sounds like what Q-jets do when they need a rebuilt or some attention. Other carbs can do it as well. I would look at the carb first.
 
I will start from a dead stop hit the gas and it will smoke the tires but then it drops off for a few seconds and kicks in like a turbo and hauls butt from that point. I had a carb rebuild down about a month ago. I am going to change the carb anyway to a 770 street avenger. Im new at the hotrod stuff some im still learning so please bare with me guys.
 
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