carb'd 4.9L improvements?

Whitelightning

Actually the first thing you need to do is check the rear axle ratio. A friend of mine had a truck just like that a while back and it was really a slug with a heavy trailer in 4 th gear. Hauling my 4000 pound tractor on a trailer to borrow it, it basically stopped accelerating once you shifted to 4th and we never hit even 50. (I offered to tow it to his place with my old Jeep truck with strong V8 and deep gearing and that tows well but he wanted to see what his ford would do with load) It had a 3.08 in rear axle ratio which killied it towing in 4th. No engine mod you do to that 300 is going to fix your problem if you have a 3.08 rear axle but a 3.73 or 4.10 axle ratio would help out towing a LOT. Even something around a 3.55 if you are worried about non towing MPG would help you out a lot. If you have a 3.08 you are turning just under1800 RPM at 50 in forth and there is not enough power to be had to take load faster at that RPM. (you would have about

80 flywheel HP at that RPM IF your engine was still tight and strong and that is not much). At 60 MPH about 2000 RPM assuming 30 inch tires. That engine was rated at 125 HP at 3200 RPMs which means it would still have about 205 ft lbs of torque at 3200 RPM down from rated peaks of 245 so you see there is not much to work with. A 3.73 would yeild about 2500 RPM at 60 and if we split the torque drop in have we figure on about 225 ft lbs at 2500 RPM which equals about 110 HP availble (or maybe more depending on haw fast the torque curve falls off) vs about maybe 90 HP at most at same speed with 3.08's. Also remember that this it with a new tight engine. One a bit worn with more leakage and blowby will tend to make less torque at a lower RPM than a tight one. With enough gear behind it, even a six can move a lot of weight. You just need deeper gears or in effect a "bigger longer pry bar" instead of trying to pull even harder on your current short one.

----------------- TheSnoMan.com

Thanks for the input, I'll definately look at the rear end gears and move 'em on up when we pull the bed off. Not sure about headers and tuned intakes. I think we'll try the rear gear, clean her up and such, replace the suspension with a bit beefier stuff, and see how she does... Thanks again OldIron

Headers will not help lower RPM power at all in your case. Tuned intake is not going to help much either here. You are on the right track to consider regearing it first then maybe consider some other engine mods after it is regeared because no mod short of a supercharger is going to give you a big low RPM torque boost and even with a super you could still have engine and clutch issues with your tall gearing pull a load.

----------------- TheSnoMan.com

A decent 460 will improve low end torque:)

Al

Go out and measure the length of your engine, front to rear at the intake manifold. That is a long Muthu. Ford 4.9 liter inline 6's with carburetors suffer from fuel starvation in the furthest most front and rear cylinders. The best bang for the buck would be to buy a pre-94 Electronic (PORT) Fuel Injection change over, Engine, Intake, (New MUCH IMPROVED style split) exhaust manifolds, wiring harness (including fuel shut-off), fuel tanks w/sealed fuel lines (oh and the fuel gauge.

Go out and drive a fuel injected 4.9, the run vastly better than any carbureted on will.

If you are really serious about doing such a change over, I can take pictures of the '82 I did with a '92 EFI setup, as the guy I sold it to is storing it at my place right now...

Be advised, If I had it to do again, I would have sold the carbureted trucks (yes I did the same to a V-8 Bronco too) and bought factory EFI trucks.

BTW: The Low RPM torque of that 4.9 is incredible, you don't need any lower gears in the rear end, they already crap out soon enough on the highway. I have towed cross country over 10,000 pounds with that 4.9 EFI converted truck and it's gear ration is 3.00/1. Before and after the EFI made a night and day difference in highway speed power, with the same gears.

Good Luck

And likely improve fuel mileage as well....

>

You are a real good BSer too. 10K trailer with a 300 and a 3.08 would flat out SUCK towing wise and would have a lot more trouble at higher altitudes too. The 300 is not a bad motor but it does need more than a

3.08 rear axle to move a lot of weight effectively. It takes more than EFI to fix this problem. Back in 70's I towed a fullsized car on a trailer from Ohio to near North Carolina border with 66 chevy 3/4 P/U with a 4 speed and a 250 six which as I recall was only rated at around 150 HP. Back then that model came standard with a 4.57 rear axle ratio and it was a stump puller for a six. It had no trouble obtaining and holding highway speed then even through hills of KY and TN. Rear axle ratio made all the difference in the world then and as I recall we got around 11 MPG on that trip too. It pulled it well not because it was a GM truck but because it had a serious rear axle ratio. My neighbor has a even older 1 ton with a 6 and a standard 5.14 rear axle, talk about stump pullers.

----------------- TheSnoMan.com

Listen Blowman you IDIOT the 250 Chevy 6 doesn't hold a candle to the Ford

300 I-6. And any straight six one barrel from the 70's is like comparing a model-T to a 4.9 EFI I-6.

When you actually have some applicable experience go ahead and tell us your experiences, until then STFU. You can come drive this truck, try it yourself you fool.

Unlike you my experience is not some misguided ledged in my own mind, I STILL have the truck sitting right here.

Piss Off SnowBlower you fool.

which as I recall was only rated at

Great maybe you should be posting all this irrelivant Bullshit in the OLD.HASBEEN.CHEVIES Usenet group.

I was pointing at the intake more than headers. There are two barrel adaptors on the site for use on the four barrel manifolds. Going from a 4 barrel to a two barrel with an adaptor works a hell of a lot bettetr than slaping a two barrel adaptor on a one barrel carb manifold. Those are the only two options to get a 2 barrel on a 300 CID today. Course he could go nuts and go with the twin weber dohc side draft set up, which will take care of the end cylinder starvation issues brought up in a later post as well. But I was aiming for his request, ie a two barrel set up. Of course a spread bore 4 barrel carb if he can keep his foot out of the secondarys would work wonders on that rig as well.

Whitelightning

The problem is that this will not boost lower RPM torque any and may reduce it a bit because of reduced mixture velocity in bigger throttle bore area. It would help it above maybe 2500 to 3000 RPM though but not enough to solve his problem of tall gears. Deeper gears and a different intake would wake it up a lot though. 3.08 gears are okay if you never realy ever tow anything serious.

----------------- TheSnoMan.com