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Old January 11th, 2017, 03:28 PM
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Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
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Default Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton

Quote:
Originally Posted by Dazzoman View Post
OK and yes I except your offer to visit ifI ever go thru S, Oregon .
I was thinking this :
My buddy is a truck driver in Weed CA and an mechanic Chevy nut for 40 yrs .
He swears by ( and I drove in it to see this ) putting an modern rear end (they have more higer gears ) in his 72 chevy half ton with I think an 307 in it and leaving the SM450 in it because you can't break those really and he is into towing . His truck gets up and MOVES I mean that high rear end did something for it (but I gotta see what he gets gas wise maybe you arent into that ).
The 66 Dana Spicer rear end I have only will go up to 356 or something whereas it had the original 411 when I got it . I was into gas milage and the combo of the 292 and the 356 made things nicer for me since I wasnt pulling tree stumps , only an camper .
Now I have no camper and Im still searching for the perfect win win situation where I have the gas mileage and the power IF I NEED IT I can call upon it !
With a taller rear gearing it'll move better in lower gears because the driveshaft is turning less revolutions per revolution at the tire.
That's another reason why the v6's don't seem so fast, the torque is there, but the gearing is not. Put a 3.73, 3.42, or 3.07 gear behind a GMC v6 and it'll move! I guess GM didn't understand that low gearing and low rpm engines Don't mix. haha
With my 66 c10 I kept the 3.73's and I went with a 30 inch tire and put a TKO600 behind the 292. It'll do 65 at 2500 all day in 5th. And still have plenty of power to pull 5th if I want to as 2500 rpm is in the torque curve! I built the engine to handle 5000 RPM with ease, and doing so brought the torque curve to the mid-range with the new cam.

in my experience, the Best cruise RPM for an engine is to find its peak torque RPM or just below.

With a v6 for instance, bone stock they peak torque at 1600. So finding the gearing to cruise 65 at 2000 RPM would be optimum. You are close to the engines peak torque, RPM's are low, and fuel consumption and engine wear is decreased.

With a v8 350 the torque tends to be more mid-ranged...somewhere's between 2500-3300 as from the crate they are capable of 5000 RPM. So the win win to me would keep the rear gearing fairly low and put in a 5 speed, that way you won't have to down shift all the time.

I think the best win win would be fuel injection. haha
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1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
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1964 Chevy C20 292/SM420
1966 Chevy C10 292 hotrod 6/TKO600


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