4.10 gears on auto?
In an auto, it's brutal on the highway. I am running 3.73 + LT1 combo in a B-body (Buick Roadmaster) and I don't like it very much on the highway, although it really comes alive at speeds around 50mph.
IMO, for the mostly highway, either 3.42 or 3.23 is a much better choice, and maybe 3.73 if you are dedicated. But you need to ask yourself where you drive most of the time and that will decide that. I would go nuts if I had to drive with 4.10 at even 70mph for 10 hours.
Use this RPM gear calculator to get an idea where you would be:
http://www.car-videos.net/tools/spee...B1=Recalculate
Regarding upgrading the rockers, you should definitely do valve springs and 1.6 roller rockers at the same time. I don't know how much extra lift the factory valve springs can take.
In hindsight, I would suggest holding off on the 1.6 Roller Rockers for when you go with a cam as well, and just do the cam/rockers all at once. That way you won't have to tune the car twice, and it will feel much much better.
My 60mile a day commute is mostly rural so I am OK with the 4.10s currently in my car but if I did a lot more highway I would not keep them.
Far as rockers, I would say only do them if you do springs too. I think the LT4 springs can be found for like $40 they are perfect for a stock cam with 1.6s this will let the cam keep making power to a good bit higher rpm.
The car has a 7.5" rear, the series carrier is dependent on the gears it came with, look at the SPID tag and tell us what the codes are that start with "G" for example "G80" is the GM code for posi other "G" codes can tell us what the factory installed gears were.
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Does the 90 have an LT1 in it????
The LT1 likes rpm more than it's predecessors and the computer is MUCH more adaptable.
While I agree 3.73s are a good choice for most, your argument is just not valid due to being a very different engine/computer setup in a 90.
It's fun as ****, but gas mileage sucks, not that it matters cause it's a muscle car.
You can run a higher stall with them and it will still be tight on the street.
Honestly, If it was a track only car that will see alot of high MPH I'd go with 3.73's. 4.10's are perfect for the street though.







