Looking for a set of 1 3/4 headers for my swb 1/2 ton truck, was wondering what other vehicles with headers would fit my truck besides 73-87 trucks.  What is a tuned header worth compared to one that is not tuned.

Thanks

I guess my first question is why 1&3/4? These typically work best with engines 383 and over, and those that regularly turn over 5000 RPM, etc. If this is a racer that size can be of some advantage when the engine is held a constant high RPM. For the street, even with a 383, they will hit cruise torque negatively. So as usual everything is a compromise, but the vehicle works better when the compromises maximize torque and power where the engine spends most of its time.

Typically 1&5/8s is a pretty good compromise for a street driven vehicle that spends most of its time at or below 3000 RPM.

Tuned headers typically pull both better mid range torque and top end horsepower than non-tuned. But the expected range of performance is quite wide. Shorties are a bit better than factory cast iron by 5 to 15 hp, but not as good as long tube tuned units which will typically run from 10 to 25 hp. In the end a lot depends on the the head and tail pipe size and number of bends as well as muffler and if equipped catalytic converter flow capacity.

For a 350 with duals I like to run 2&1/2 head pipes off the collector, I like to get a H-pipe crossover in the head pipes as soon as its possible to get around the transmission and ahead of the cat converters or mufflers if they're mounted forward. If you're running converters they produce a lot of reheating of the gasses so I come off a 2&1/2 converter with a reduction to 2&1/4 to the muffler. If the mufflers are forward I come off them at 2 inches for the tail pipes. If the mufflers are all the way to the rear I run 2&1/4 all the way back. The thing here is that as the exhaust gasses are heated they expand and need more space, hence not so big a pipe reduction coming off the back of the cats. As the gasses cool they loose volume and require a smaller dia. pipe to keep velocity up so the flow doesn't stall in the pipe. If no cat converters you can drop to 2&1/4 around the transmission rear crossmember and carry that to rear mounted mufflers. If the mufflers are up front just behind the cross member, you can drop the pipe to 2 inches coming off the mufflers because they take a lot of acustic and thermal energy out of the gasses making it necessary to use a smaller pipe to speed the gas flow up. For a 383 add a 1/4 inch to these sizes.

If you use 1&3/4 tubes on your headers and feel the need for more mid-range torque you can extend the collectors by 10 to 12 inches, this increases the pull on each pipe and makes them act a bit like their 1&5/8s pipes thru the mid range. However too much of this stalls the flow at higher speeds. Another trick is to wrap the pipes with insulation to keep them hotter. This causes the pipes to pull harder but significantly reduces their life span..

Bogie