I have a completly stock, but completly rebuilt IH 304 with a 2barrel carb, again stock. I have a 4 speed close tranny with a Dana 20 tc, 1 ton Ford differentials from an f-350 with 3:73 gears and currently 37x12.5 tires, but looking to upgrade to 38x15.5 new tires. This will mostly be driven on the road with very light off road use and I am looking to do some minor engine modifications to boost up the low and mid range torque. I am thinking of going with a 4bbl carb, minor cam upgrade and if necissary changing the gear ratio. This is for my son and I do not want to do anything radical. I would be interested in hearing any suggestions that you might have. I have not yet dropped the engine, tranny and tc into the vehicle yet and would like to make any modification before I do. Thanks for all of your suggestions.
Stock IH 304 cam upgrade
- Thread starter waltrobak
- Start date
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
The only four barrel intake manifold for an ihc 266/304 engine is the aluminum unit manufactured by IH only and sold both through IH only and IH Parts America. Occasionally a used unit becomes available also.
A decent carb for that manifold runs about $325 new with electric choke.
We have the camshafts in stock now, some thing around a 262.
3.73 gears with tires that size are a real bummer, I'd run 4.56 if it were my rig.
There are tons of engine performance tips and how not to do things included in this sub-forum!
A decent carb for that manifold runs about $325 new with electric choke.
We have the camshafts in stock now, some thing around a 262.
3.73 gears with tires that size are a real bummer, I'd run 4.56 if it were my rig.
There are tons of engine performance tips and how not to do things included in this sub-forum!
What was the ratio that came stock in the Scout II from the mid 70's on? Is there a simple way of determining what ratio to use to try and make it ride as close to how it did before the modifications? I am trying to find that balance of good around town and not making the engine screem at 65mph.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
The actual axle ratios could range from 3.07 through 5.18 on selected models. There is no "stock" ratio, the ordering dealer specified the axle sets desired and then the vehicle was produced.
There is a bill of materials (bom) number stamped on each axle housing. Find that number and post it, we'll tell you what was originally supplied in the tubes.
This question has been asked many times and we've answered 'em all in the "axle tech" sub-forum.
There is a bill of materials (bom) number stamped on each axle housing. Find that number and post it, we'll tell you what was originally supplied in the tubes.
This question has been asked many times and we've answered 'em all in the "axle tech" sub-forum.
Scoutboy74
Moderator
Obviously, someone has made some major suspension modifications to this Scout in order to accommodate the beefy axles and ginormous tires. And you've mentioned going to an even larger tire size. As mayben stated in his first reply, that's a lot of rolling resistance for a 304 engine with 3.73 axle gearing to overcome. However, seeing how your stated intentions for this vehicle involve mostly highway use, your tire size and axle ratio combo, while a bit sluggish off the line, will actually make for pretty fair cruising rpms once you get up to speed. Now it May sound to your ear like the engine is screaming at 65, but in reality it isn't. The IH sv8 engines were over-built in order to run continuously at their maximum rating (redline) for long duty cycles, day after day. Yes, 3800 sustained rpms from a 304 is pretty dang noisy. But I'm willing to bet that if you had a tach connected, you'd see your engine running well below that figure at a true 65 mph. Still plenty loud, for sure. Which brings up another point. Speedometer accuracy. Until your ancient speedo has been verified against a gps, you don't really know how fast you've been traveling.
It takes some getting used to when your previous frame of reference is likely some modern hoop-d with tiny engine, muted exhaust, overdrive transmission, and tall highway gears. Once you're accustomed to bombing along at 72 with little to no perceived engine noise and the tach needle resting below 2k rpms, hopping into some obsolete truck with a noisy truck engine and trying to drive it the same way makes for a rude awakening.
I don't see how you'll get this Scout to drive like it did before the modifications short of reversing them. Those mods are the very reason why it behaves the way it does now. You want lower engine revs at top speed? That takes taller gearing (numerically lower). But taller gears will make it even more sluggish. I'd strongly advise against going in that direction. Lower gearing would certainly make better use of available power, but it will also mean higher revs at top speed. You can make some minor performance gains under the hood, but those are unlikely to be felt in the seat of your pants. If it was me, I'd want to know exactly how fast my engine was turning at the true speed I like to drive. Then I could decide if that was acceptable, or if I needed to make a drastic change somewhere. Knowledge is power.
Edit...just went back and re-read. I initially missed the point that this truck isn't currently a driver. That fact doesn't invalidate my observations.
It takes some getting used to when your previous frame of reference is likely some modern hoop-d with tiny engine, muted exhaust, overdrive transmission, and tall highway gears. Once you're accustomed to bombing along at 72 with little to no perceived engine noise and the tach needle resting below 2k rpms, hopping into some obsolete truck with a noisy truck engine and trying to drive it the same way makes for a rude awakening.
I don't see how you'll get this Scout to drive like it did before the modifications short of reversing them. Those mods are the very reason why it behaves the way it does now. You want lower engine revs at top speed? That takes taller gearing (numerically lower). But taller gears will make it even more sluggish. I'd strongly advise against going in that direction. Lower gearing would certainly make better use of available power, but it will also mean higher revs at top speed. You can make some minor performance gains under the hood, but those are unlikely to be felt in the seat of your pants. If it was me, I'd want to know exactly how fast my engine was turning at the true speed I like to drive. Then I could decide if that was acceptable, or if I needed to make a drastic change somewhere. Knowledge is power.
Edit...just went back and re-read. I initially missed the point that this truck isn't currently a driver. That fact doesn't invalidate my observations.
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