I am running a 350cu, LT1 pistons, 9.5 compr.,(estimated of course) Comp. extreme hydr. roller cam (I think it is a 262) not sure. 64cc ,202valves, angle pluged old style double hump heads, ported and polished. 69 Z28 Factory aluminum intake, 600 Holley carb., 1 5/8 Headman Headers, Electronic factory dist.,

Estimated HP is 375,?
700r4 trans. with stock converter.

I am running stock 336 gears.

Will there be any advantage to go to a lower gear ratio?
And what do you guys suggest.

This is just a street car, no racing, just for fun.
Daily driver.

I do get 17MPG on the highway.
At 70MPH I am tacking 2000 rpm's.

3.31:1 12 Bolt Posi I believe are Stock BB/SS Gears. That Cam if the Advertised Intake Duration is 262 should deliver plenty of torque for Mid Range Gear Ratios with a 9.5 Static Compression. It all depends what you want; a Drag car with say a 278 Intake duration and 3.73 or 4:10 Gears which is a useless daily driver or what you have that will boogy on the Street and HWY.

That 70MPH at 2000 rpm sound more like 2:72.1 Gears NOT 3.36:1 as you refer to; in which case, if you want to up your Gear Ratio to 3:31's you will have to change out from a 2 series carrier to a 3 series carrier. If you want to keep that 2.72 ratio for gas mileage and HWY cruising, you will not do better than that 262 cam for Hi-Speed. OOP's forgot that the 700R4 has OD and you may have 3:31's but I suspect 3.08"s.

Are you running a 10 or 12 Bolt rear end?

For Mid Range Road Race Performance with 3:31 gears and 9.5 static compression, I like using a Marine cam Profile say with a XM274H-12 Profile and 4 Spd.

I have to disagree, remember that tire size has a lot to do with rpms. I run 3.73 gears with a 700r4 and 27" tall tires (275 60 15) and run 2200 at 68 mph and it's perfect. I also get 17 mpgs last I calculated. I run a 327 with 284 advertised duration and 11:1 compression.

I wouldn't even think of running a lower (numerically) gear. Of course now with the t56 I will be going with 4.56 gears within 2 weeks :)

OD tranny, small block, I would run a 3.90 - 4.10. I run a 4.10 in my Avalanche w/ 31.5" tall tires. Cruises about 2100 at 65. My Chevelle runs 3.73's with a 28" tire and T400 tranny. Cruises at 3000 at 65.

You need more gear!

Thanks guys, I am running 275 60 15 also as far as tires go, I am sure I have 3.36 gears, I was just not sure if I was getting the most out of the cam and all the engine parts.
The car pulls very well through the low range and loves it around 4000 up to 5500rpm's.
just thought I would see if there was something I was not thinking of to make more low rpm torque.

Thanks again for the input.

No question a lower gear would give you more squirt. The combo you have now, the 200R4 has a much lower first gear than say a T350 (may not be exact but a T350 has about a 2.48 1st and the 200R4 is something like 2.84), then you have the OD. As a driver I would leave it alone, as a hot rod you would want 4.11s or such

rick , i dont mean to steal your post , im running 3.31 gears 12 bolt posi with 275/60/15 rear tires and a 700r4 trans . do i need to run bigger gears ? and at what rpm am i at 70mph (tachs out) ?

There is a formula to figure tire hight, gear ratio,rpm's, and mph. But I cannot remember what it is.
The only difference in my set up and yours is the gears, I 'm running 3.36 and your at 3.31, that is so close I would say @ 70 mph, you are taching around the 1900 rpm's.
As far as gears being too high or too low, like the rest of the guys said, depends on what you want out of your car, track time, mpg, street car, daily driver, what engine set-up, all these make the difference.

you say you have an EXTREEM COMP CAM in 350 so that to me COULD BE A LRG CAM in a hot350 with 202 heads etc and a 600 holley?

If thats the cheap 600 vac sec get the piec of crap off that motor,they are fine for a hot little 283/305/307 but threy are not very good for a hotter 350 with a farily lrg roller cam,202 heads,etc it needs a nice 3310 750cfm or 770cfm holley with vac sec set up correctly.

336 is high of a gear ratio with 700r4 and possibly lrg cam'd motor,for best perf & fuel economy i would run 373 since you have the o/d trans . But not more gear like 390-410 for all street & no racing which is more race oriented gear and will start to loosde fuel economy vs the 373 gear with 700r4 o/d trans.

If you get a 3310 holley(or 770cfm) dialed in correctly along with a correct perf ign curve (with huge cam then 20 base + 18 deg mech in dist in by 2800 rpm = 38 deg total by 2800rom) setup properly for you poss lrg cam'd 350 on the street (also need vac adv too) along with appropriate matching gearing like 373 the motor would really wake up motors/cars performance ,thats for sure. and 373 gear with 70044 will still have good cruise rpm of like roughly 2100-2200rpm @ 60mph depending on tire size.

If you tune the 3310 750 correcly/for leanest poss primary fuel calibration along with the 373 gear to put the motor in better operarting rpm for better trq at cruise the fuel mileage may stay approx the same or improve a 1 or so pergal .

But sine you have said IT's AN EXTREEM COMP CAM what are the specs,maybe the cam isnt that lrg & we would need to re-evaluate/revise the suggestions we are giving you.

But a lrg camed 350 with 202 perf heads and a 600 holley vac sec with an O/D 700r4 with 336 gears is mismatch for best street perf & fuel economy IMHO .

Just my 2 cents on that.

Scott

Thanks, Scott, yea I was not too sure about the Holley 600 when I bougt it, I was just going by the formula for CFM's and decided to go with the smaller carb. for the price.

I have lost the tech. sheet on the Comp. Cam.
I want to say it was the Extreme Hydraulic Roller 262, (X?262HR)?

I have never had a problem running out of fuel with the small carb, but I hardly ever wind it up past 5800rpm's.

I do know when running at 50-55 mph the car seems to lug and jerk just a slight bit because the rpm range is down low in the 1500 rpm range. The OD does not kick out the way I would like for it to. I usually just drop it down in to drive when I get to that speed.

Thanks for the information.
Ricky

I made a spreadsheet to help me work out my gear issues as I was going to a 3.36 700R4. I haven't drove my combo yet, but I think I'm going to be happy with how she cruises. I will be using a XE262 in my 350.
Please keep in mind these numbers assume no slip from torque converter (as if it were locked). I also assumed 27 inch tires. This does show the 700R4 with a 3.36 running very close to 70MPH.

http://s200.photobucket.com/albums/aa265/dauber65/?action=view&current=336.jpg

That is a very impressive spreadsheet, Randy.
Really shows what an OD can do for your engine needs and desires.
Thanks, I will have to keep that in mind.

If anyone wants the spreadsheet they can send me an e-mail and I'll give it to them. Just plug in you tire size and rear ratios you want to compare (you can use the same two like I did in the picture I posted and that will show you just what swapping the trans will do for you). I made the TH350 vs. the 700R4 have different gear options because I was changing from a 2.56 10 bolt with a TH350 to a 700R4 with an undecided 12 bolt gearing. I was basically wanting to see how changing the 12 bolt ratio was going to act. But then I found a 3.36 12 bolt for sale and decided it was good enough for now. I'm very interested to see how it feels. Something alot of people miss is they want to comparte the TH350/TH400 gear rations to a 700R4, but you can not. The 700R4 has a lower first gear so the rear gear will FEEL more aggressive that it would in a TH350/TH400. You can see that in my spreadsheet. I create a colum called "gearing". Basically I am multiplying the rear gear to the trans gear. I think when I crunched the number a 3.36 in a 700R4 will act like a 4.08 (4.11) in a TH350/TH400 in first.