Looking for a torque curve chart on stock 401 Nailhead. I’ve looked everywhere and maybe it’s me but haven’t been able to find this info. Little help please?
I’m looking to see what the power curve of a Nailhead looks like. Dyno sheet of a stock 401 would be good. I’ve been able to find ones for later model Buicks but not for the anailhead.
The only way you are going to find that would be someone who rebuilt a 401 to stock specs and had it dyno'd. Most guys modify them so that wouldn't be very representative of what you are looking for. I don't think you would find that in any of the Buick manuals.
Thanks Roadrunnernz, that’s what I was looking for. I wanted to see how much torque a Nailhead was producing around the 1600-1800 range. Over 400 ft/lbs, not bad for a stock 400 ci engine.
the curve might be close on them factory charts, but the peak TQ and HP in reality we all know are lower then the charts show. take 10-15 % off those numbers.
Another thing that is forgotten is that any dyno sheet or chart shows torque at WOT at a particular RPM. The motor doesn't make that torque anytime you are at ----- RPM.
Hemming's Muscle Machine mag's Nov 2013 issue did a mild 401 rebuild. They got 329 hp at 3800 rpm's! and yes 500 lbs at 2900 Not much tweaking on the dyno according to them and the factory dual quad was only using 2 500 cfm carters. If you haven't seen it it's using some very small tube temporary shorty headers.. Sorry for the bad pic..
Look at the charts that roadrunnernz posted. It indicates about 400 ft. lbs. of torque at 1800 RPM. Say you are tooling down the road at 50 MPH at 1800 RPM. Throttle angle is small and the engine is ingesting just a partial fill of air. The engine isn't making 400 ft. lbs. of torque under those conditions. When an engine is operated on a dynamometer, the dynamometer places a load on the engine (water brake), and measures the amount of power the engine can produce against that load, it measures the torque, and torque is converted to HP by multiplying by RPM, and dividing by 5252. Go back to the video I posted in post 7 and listen to the motor. You'll see the carburetor go to WOT and seemingly stay at the same RPM for a second or two because it is up against that huge load. The RPM then increases. That's when torque is being measured, at constant WOT through whatever RPM range the operator decides on. JW told me the dyno stresses a motor more than anything you can do to it in the car. It is easy to understand why listening to that video. Here is my engine on the dyno,
