Hot Rod Forum banner

rear gear selection

3K views 20 replies 6 participants last post by  dave350v8 
#1 · (Edited)
Hi Everyone
My car is running a 350 sbc with procomp 210 heads, 480/480 magnum cam,600 holley,rpm intake,and about 9.8 comp ratio.
At the moment it really doesnt pick up very quickly, no big difference over the camel humps I replaced.(intake runner on the large size)
A few on here suggested a rear gear change.

My car weighs 2470lbs
5 speed T5 manual (2.95 1.94 1.34 1.1 0.80 ratios)
23" tyres
3.08 rear gears

Just been offered a 3.73 and a 3.31 set of rear gears.

Mainly want to use it on the strip, standard bottom end so I dont want it reving past 5500

What rear ratio would you choose??
Thanks in advance
 
#9 ·
5500 rpm nets you a top speed of;1st=41 ////// 2nd=63 //// 3rd=91 /// 4th=111 /// 5th= 153
you should be shifting into 3rd after 4 seconds?

what carb are you using? what is the model number?

if you changed to 3.73 gears,then your speeds would be;

1st=34,,2nd=52,,3rd=75,,4th=92,,5th=126? That would be silly.
 
#11 ·
Hi
Thanks for the infomation, Im using a holley 1850 600 vac sec at moment
I just feel it has more to come in the higher gears! 1st gear waste of time!
2nd ok, 3rd feels feel a little slow to pick up,I suppose I need to get down the strip in the spring and get it timed.
 
#14 ·
short tires and drags do not go together usually.Slicks are tall and quite often grow under acceleration. If first gear becomes useless then essentially 3rd gear becomes your second gear,,,,
with out MPH its not possible to determine what to do for your combination.What you feel in the seat of your pants is not usually a very good indicator of what is happening .If it was my car,I know I would have a single plane intake and a 750 or 850 double pumper carb.That hydraulic cam does no justice to the heads you bought.Also,the gear spacing you posted is a big jump from 2-3,the rpm drop is bigger than 1-2.Raise your shift point for 2-3,maybe shift 1-2 about 200 rpm sooner?
 
#15 ·
Thanks for that! People did mention before about going up to a 750 carb.
Because Im changing the plates in the diff I thought I might give the 3.36 a
go.
I think I will look at upgrading the cam as you suggest,I think it was you who
thought I needed more cam before!

Thanks again
 
This post has been deleted
#17 ·
Thanks for that, on the strip last year 1st gear would not grip, so recently
boughts some toyos r888 super softs,took it down the road broke the rear diff
(ford atlas axle out of capri 3.08 gears) just putting a explorer axle under,the axle has:
3.73 gears at moment,but have got a set of 3.31 and 3.08 gears as well.shall
I stick with 3.08 then? More cam and better headers? I have only block huggers at moment?
I thought 5500rpm would be max on standard bottom end?
Thanks for your imput!
 
#18 ·
Have you ever considered an automatic? I would use a minimum of a solid flat tappet cam.If the engine is balanced,then 6500 rpm is usually safe.
I ran my small rod 454 to 7,000 rpm with no problems,what parts are in your bottom end? What parts are in your valve train?
 
#19 ·
Hi
I built motor with standard rods/bolts, 10.5" flywheel.480/480 cam
I used 210 procomp heads,hardened pushrods,stainless valves,and
springs to suit up to 550 lift hyd flat tappet cam.

I never tried it down the strip with the sticky tyres I ruined the diff
when I give it some gas!

Shall I use 3.08 gears in my 8.8?

I was hoping to get into the 11 secs with the car!

I was thinking I should be around 400 horsepower with the new heads.

Thanks again

Yes the motor was balanced!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top