Piston454

hi i was wondering if i put some 3.73 gears behind my 350, which is pushing 350 hp, will that gearing be too low? i also have my stock 5 speed manual trany in. so will i burn through 1st gear to quickly or will i be okay?

sofakingdom

iTrader: (1)

Well, the L69 cars came with that gear stock; so I'd say, prolly OK, as long as your engine contnues to make meaningful power above 4000 RPM or so (meaning, NO TBI heads).

In mine, I actually thought I could use MORE gear than that sometimes, especially after I put a T-56 in it.

JamesC

iTrader: (5)

Had a friend say that he could hardly cross the street before needing to shift with 3.73's. I like 3.23's with my application.

JamesC

Piston454

really. so what would you recommend? 3.73. or 3.23? because i have an axle sitting in my garage with 3.23.

sofakingdom

iTrader: (1)

Depends on your 350.

Take it to the chassis dyno and find out. I'd say, if it makes peak torque below 2500 RPM, stick with what you've got; 2500-3000, 3.23 would be OK; 3000-3500, 3.42; above 3500, 3.73.

There are few things worse than having gears that force the motor to run in a range of RPM where it doesn't produce power. Either too low of a RPM (what you have now), or too high RPMs (the situation where it has terrific launch but can't pass a semi on the freeway at 55 mph). No fun either way.

rowdy_51

I'm in the same boat in a way. I have 3.23 but am looking for a 4th gen with 3.42. I found one but $550 is a bit high I think. I have some 3.42 for my rearend now but it's a drum brake and single side pull.

midias

I have a 1984 TA with the L69 package and a 355 swap. I dont find it too bad. Yea first and second seem a little short and at 70mph I spin about 2600 RPM. I don't find it undriveable but I do wish I had a 6th gear but I pull like a raped ape in 5th, seriously the highway is amazing and fun I never downshift. I do plan on new heads soon I am gonna go patriot vortecs but this is what I have now.

I have a 355 with
12-246-3 xtreem energy cam
RPM performer manifold
333882 heads rebuild
roller rockers
edelbrock 600cfm 1405 carb
headers
3 inch magnaflow pipe
other various things.

Gumby

Heard sort of similar, but he had a 4000stall TC and had problems taking up boths lanes going sideways through an intersection after stoping at a light.

midias

I should mention I only get about 10-12mpg mostly in town

JamesC

iTrader: (5)

18/19 on the highway. Much lower in town, depending on how quickly I shift into third or better.

JamesC

paul_huryk

You can do it, but the question is what tire diameter you are running and also the rpm where peak power occurs. You don't want to be above your HP peak by much at the end of the quarter mile, or too low for that matter...