Quote:
Originally Posted by Nobighurry
So I have a 1970 c60 with a 366, 4 speed with 2sp rear. Truck weighs 10800# empty with a gvwr of 24k. I can legally carry around 6.5 tons. Truck only has 34k miles. My problem is it falls flat on hills. I'm in mid-South Carolina, so I'm not talking mountains. Truck runs good, just powerless on hills. I try to avoid full loads just because of the weakness. I can drop from 53 mph to 25 mph on hills. It really isnt safe with that much of a drop.
I have changed it to electronic ignition, new edlebrock 650 carb, plugs,wires etc.
I found a new/remaned 427td but it's going to take $4700 to get it. If I knew the 427 would give me what I need (power wise) I wouldn't have a problem doing it.
I'm hoping someone here has experience with both engines. Any ideas?
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Nobighurry,
I cannot help with comparing engines as I have not driven a 427, but the performance of your truck does sound a bit sluggish.
What I can share with you, is the new carb you installed is not the best for your engine, for initial and maintaining torque. Much too large.
My 1976 C60 weighs 14K empty and has the 366/5-spd, and 2-spd rear with 8.85/6.50 gears.
Pretty gutless when I first got it and performed similar as yours. I live in the Ozarks with a lot of "hills" and it was a struggle to maintain any speed.
I went thru a very similar process as you - updating and repairing/replacing what was needed to help the truck become drivable.
I first performed a compression check and all cylinders were between 110-115.
I replaced the VERY worn distributor with a non-governed / non-vacuum advance electronic along with plugs and wires. Made a noticeable difference.
I replaced the carb as it had an Edelbrock of some flavor on it. The install was a bit of a mess and parts were missing. I ordered and installed a new 600 cfm holley (0-80451).
The C60 did run better, but did not like initial acceleration whether taking off from a stop, or even the initial accelerating at the bottom of a hill. The truck would "stutter" really hard and seemed to have no torque. The engine also seems to be idling rich on fuel.
Frustrated, I knew this was not acceptable, so I sat down at the computer and hit the web - and read, and read....
When I ordered the carb, I did not do any research. No reading, no asking, no calling. I just ordered from a vendor and installed.
I chose a 600 cfm because it was a familiar carb that I had used hundreds of years earlier on hotrods and it was popular then.
What I learned was - I failed to do any research prior to purchasing and bought the incorrect carb for a 366 bigblock.
I did finally go to holley's website and after much reading, and watching one of their videos, I found I needed nothing more than a 425 cfm carb after using one of their formulas.
The formula -
cubic inches X maximum rpm, then,
divide by 3456 =
cfm.
366 (ci) x 4,000 (rpm) = 1,464,000 / 3456 = 423.6
I believed (and still do) I have no reason to go above 4,000 rpm, so that is the formula I used.
I have since bought and installed the holley 465 cfm (0-1848-2) and the performance has made me happy.
The truck will gain or sustain speed going up
most hills with a 8,000 pound load.
KC