<BLOCKQUOTE>quote:</font><HR>Originally posted by 1NAST69:
Please pardon my ignorance, but what are merge collectors?
These are merge collectors by S&S headers, about $60 each. Burns Stainless also makes some pricey ones. http://www.burnsstainless.com/MergeC...ollectors.html
1-3/4" headers will work fine, it's the little details that make the difference. We bought some Stahl primaries for a road race car last year and they were flawless. Brazed header flanges, perfectly matched ports, equal-length primaries, etc. A lot of off-the-shelf headers need finishing, like brazing up the outside so you can grind the inside to match the port, or adding tube to the primaries to better match your engine's torque curve. You can build a much better set of headers than you can buy off-the-shelf.
One of the major shortcomings of the ordinary 1-5/8" headers is the collector size, usually 3". A 1-3/4" header with the same collector will work better in most cases due to the increased scavenging ability. Another shortcoming is the port shape, usually round and unfinished, providing a large discontinuity in the exhaust flow.
Ed Henniman has a fairly extensive package on header design, and one of the points he dwells on is 'peak power and peak performance are usually not synonymous'.
1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.76 @ 116 thru the mufflers
18 mpg on the road