wildbill99
New member
I'm looking to set up my gearing and tires on my 2x4 304 powered 67 1100b shortbed stepside and am wondering what the optimal operating rpms would be. Thanks
304 optimal RPMs
- Thread starter wildbill99
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kyleandhisIH
Member
Depends on what speed, and at what degree of load you plan on doing most of your operating. I've seen posts that claim 2500rpm @ 65mph works really well for whatever hills they pull. My Scout II is right in that area with factory gearing, though I have 33" rubber.
If you're going to be dragging trees/boulders/trailers around more often than the typical weekender, I'd say that shooting for a lower gearset can't hurt in the long run - these engines can definitely handle prolonged operation at higher rpm. If your shortbed stepside is just going to be a "dry cruiser" then I'd think you could shoot for a bit higher gearing, but that's putting you into an area where the next lowest gear becomes more necessary at highway speed hillclimbs.
Your peak horsepower will be somewhere in the area of 3000-3500rpm, and peak torque May be anywhere between 2000-2500rpm, so if you wanted to shoot for something...
Good luck getting it right the first time.
If you're going to be dragging trees/boulders/trailers around more often than the typical weekender, I'd say that shooting for a lower gearset can't hurt in the long run - these engines can definitely handle prolonged operation at higher rpm. If your shortbed stepside is just going to be a "dry cruiser" then I'd think you could shoot for a bit higher gearing, but that's putting you into an area where the next lowest gear becomes more necessary at highway speed hillclimbs.
Your peak horsepower will be somewhere in the area of 3000-3500rpm, and peak torque May be anywhere between 2000-2500rpm, so if you wanted to shoot for something...
Good luck getting it right the first time.
Kyle is pretty close.
The max net hp(horse power) is at 4,000 rpm.
The max net torque is at 2,400 rpm.
Even though they have a reputation as long lived at high rpms; I've found the best range for power, and driver comfort, is around the 1,800 to 2,600 rpm range whether it's in a loadstar, 1210, or a Scout. Some engine fans they used make a lot of noise over 3,000.
The max net hp(horse power) is at 4,000 rpm.
The max net torque is at 2,400 rpm.
Even though they have a reputation as long lived at high rpms; I've found the best range for power, and driver comfort, is around the 1,800 to 2,600 rpm range whether it's in a loadstar, 1210, or a Scout. Some engine fans they used make a lot of noise over 3,000.
wildbill99
New member
That confirms what my papa told me about it driving best at 55 which would be almost 2600 rpms thanks for the info.
Robert Kenney
Super Moderator
For all engines behind a 3 speed auto or non od manual trans (1-1 top gear) in a truck.
Cruise rpm should be at or just above peak torque rpm. How far above depends on loaded/towing capacity.
For a od auto or manual cruise rpm should be about 800- 500 rpm below peak torque for efficiency reasons. One downshift puts you in the sweet spot for hills etc.
A 304 as already posted is rated for peak torque at 2400- 2500 so best to be around 2500. Tow a lot, and you will want to be in the 2800 rpm range. Steep hills and stick her in 2nd and wined it up to 3800- 4000 max. Sv's will do that all week long in fact they are designed to do that for their entire life.
Cruise rpm should be at or just above peak torque rpm. How far above depends on loaded/towing capacity.
For a od auto or manual cruise rpm should be about 800- 500 rpm below peak torque for efficiency reasons. One downshift puts you in the sweet spot for hills etc.
A 304 as already posted is rated for peak torque at 2400- 2500 so best to be around 2500. Tow a lot, and you will want to be in the 2800 rpm range. Steep hills and stick her in 2nd and wined it up to 3800- 4000 max. Sv's will do that all week long in fact they are designed to do that for their entire life.
I would agree with what the others have already said.
In our school buses we never ran them over 3200 rpm's for a couple of reasons. The first, you really don't gain much in anything except noise faster than 3200 rpm. The second, when you run faster than that you use a whole lot more fuel for not a lot of gain.
Gearing your average top cruise speed in the sweet spot will return the best fuel mileage while still leaving enough grunt if you decide to load your truck or pull something behind it.
In our school buses we never ran them over 3200 rpm's for a couple of reasons. The first, you really don't gain much in anything except noise faster than 3200 rpm. The second, when you run faster than that you use a whole lot more fuel for not a lot of gain.
Gearing your average top cruise speed in the sweet spot will return the best fuel mileage while still leaving enough grunt if you decide to load your truck or pull something behind it.
I see that this is an old thread, but what I have found with my 304 powered 1210 3.73 gear is that it will easily do 60 on the highway (2500rpm) and have plenty of power. If I push it up to the 3000 rpm Mark, there isnt much power to spare and it does burn a ton of more fuel. Ideally, I would put 3.54 gears in it and a my t-34 od. I have also discovered that in the 2 bbl Holley carb, size 52 jets are ideal. Most of the other carbs I have seen had 60 or 62 jets and used more fuel. I think the additional fuel is a waste and there is no gain. I used to have a 78 Scout that had 31" tires, 345 2bbl and 3.07 gears. It would consistently get 17 and would fly on the highway, it would still tow, but it wasnt a great combo for that.
All of this is just my .02; possibly overpriced
good luck
All of this is just my .02; possibly overpriced
good luck
Scoutboy74
Moderator
While it is easy and commonplace to overjet carbs on sv engines, there are a number at factors that must be considered when determining proper jet size, such as average operational elevation, percentage of alky in the gazz and so forth. There are also several different Holley 2bbl carb models commonly found on sv engines...the 22xx smog-n-bog, the older side hung float 2300 with a million list numbers, and the aftermarket center hung float 2300 list 0-7448. All are jetted somewhat differently.
wildbill99
New member
Thanks for the new info. I still haven't got to do anything with it but will update when I do.