leeroy

I've got a 83' Z-28, with a 400 sb, bore .30 over , Edelbrock Performer RPM intake and cam kit, MSD 6AL ignition, 650 Double pumper Holley carb, 700R4 tranny 1500 rpm stall and a set of stock 3.23's in the rear.
I don't know how much power it's putting out but it's enough to catch a nasty little 3rd.
I was thinking of putting some 3.73's in just to bring out some more bottom end. Would that be too much for freeway driving?

Drkhrse89

What kind of tranny are you running. If you have an overdrive gear you should be ok running on the highway. But if you are not then I would say go with a set of 3.42's

TheGreatJ

With the .68:1 overdrive of the 700-R4 you can get away with running 3.73's, but be warned it's gonna mean real high rpm's at freeway speeds, and your gas mileage is gonna drop like hell because of it. IMHO 3.42's would be more streetable in a daily driver.

leeroy

thanks for the reply. but ive got just one more question. about how high do you think the rpm's would run with the 3.73's?
and if i put the 3.42's in , would i feel the change?

DarthIROC

Ive got a limited slip 3.73 right now behind my 700-R4 becasue I havent had time to go to the 3.55 posi that i have yet.

But the 3.73s really arent all that unberable as long as you stay in OD. I was looking the other day and I run about 2500 to 2900 rpms at 55 to 60 mph

TheGreatJ

35-3800 at 70 is what I hear from a lot of guys with 3.73's behind a 700-R4 or 4L60.

If you go to 3.42's you'll notice more pickup, but obviously it won't be as much a difference as 3.73's would be. However 3.73's will cost you acceleration on the top end, because you won't be able to carry 3rd gear out as far. So what it comes down to basically is how much freeway use the car gets, and whether or not you're willing to sacrifice that passing power for the off-the-line gain.

IgorT.455/406

With a lockup converter, 70 mph in OD with a 700 should be 2400 RPM with 25.5" tall tires. 3800, WTF, that is in drive with no OD. My th350 with a 10" converter and 3.27s spins less then 3500 RPM at 70 mph with slippage. With 3.73s it would spin about 3800 and would not slip anymore. Anything less then 70 mph, and I would probably pick up some highway milage with 3.73s over 3.27 'cause the converter is slipping under 3k.

AutoRoc

Igor is the man.

I have 3.73 gears. 25.7" tall Nitto Drag radials, and in 4th gear with my 700-R4 at 70 MPH, I see NO MORE than 2700 rpm..NON LOCKUP...Lockup would drop it maybe 200-300 rpm.It's very liveable, even on a 700 mile trip with an OPEN SLP Y pipe..No muffler I did that last weekend. I do miss my 3.08 gears that turned a measely 2000 RPM at 70 MPH but not when I step on it at the track With the new carb intake and big slp headers, the ar scoots right into the powerband right away and it's happy so far Wish I had "budget" money to do a nice 3000stall converter.