I've been reading alot of the posts about a gear swap in a car with a 305, and how 1/4 mile times actually can be worse with lower gear ratios. However, they say you need to match the rear with your cam.
I have a TBI L03 305 with a mild crane cam, headers, hooker catback, and a hypertech chip. I'm looking into doing a gear swap, and would like 3.73's. Would this be too much for my 305? Also, I plan on swapping in a build 350 within the next two years, and don't want to do another gear swap. Should I go for the 3.42's insead?
Thanks!

 

You really need to post the specs on the cam for an accurate answer. I am one of the morons that didn't research it, switched from 2:73 to 3:73 and didn't gain anything. And actually, there's a post on here I believe where a guy to his car to the track after switching gears and he lost time in the 1/4.

3:42s would probably be the safest bet, but like said post the specs of your cam to get a fair judgement.

 

Thanks for the reply Mark.

Here are my cam specs

194-204 @ .05"
.407" intake lift
.429" exhaust lift
crane compucam

 

I can't find the specific cam in Jegs that lists it's power band, but a similar one with .401/.423 say low end TQ and HP, so I would say 3:42s will be your limit. Unless I reading it wrong.

But I do see one for a V6 with the same duration 407/429 and it says power best above 2500rpms, so that would be good with 3:73s.

 

How 'bout for a stock LO3 cam.....would 3.23s be ok?

and for the future LT1 cam....3.23s still cool?

 

Depends what are you interested in 0-60mph, 1/4, 1/8 . You can run lower gears than your powerband permits if you're only interested in 0-60 or 1/8, but the 1/4 is when matching them is most important. I hear some people want the lowest gear that is streetable because they mainly do stop light racing which isn't that long.

 

Well Mark, you made up my mind. Right now 0-60 is more important cause I don't go to the track. . . . yet . . however, once I build my new engine those 3.73's ought to work perfect on the track . I'm thinking SLP's with the take-out posi.

 

Another thing to consider is the fact whether the car is auto or manual, it wasnt mentioned.

Manual cars like higher gears it seems and autos like lower ones.

 

How is that, higher lift cams are more of a factor correct???? the tranny doesn't really have anything to do with it does it, of course I guess the internal gears could play a role.

 

well it really depends on what you doing.. i have a 2400 rpm stall biult trans and almost done with heads and cam and i just recently upgraded my rear end to posi 323..

 

I dont think I would match the same set of gears to a 3 speed TH350 and my 5 speed T5. Yes you have to match the cam for the rear, but you have to match the tranny too. If you have more gears to work with in the tranny, there's no point in having steep rear gears.