You are running almost the same HP and weight as my 61 poncho and it has run a best time of 10.37, so if you can hook you are going to need the roll bar. Other safety gear too. The car sounds awesome.
Thanks for doing that! I'll discuss this with Sandersons when I bring the car over.I ran your specs through my header program.
For street use it recommends an outside diameter of 1.843 or about 1 7/8" and a length of 34.1 to 36.9 for the primaries.
It also recommends a 3.375" collector with a length of 19" (3 1/4" would probably be the closest but either 3" or 3.5" should be fine)
For race use it recommends an outside diameter of 1.846 to 1.971 so about 1 7/8" to 2" and a primary length of 34.1 to 36.9 (same primary length as the street headers)
It recommends a collector outside diameter of 3.375 to 3.625 with a length of 19"
They say not to loose too much sleep over getting the primary lengths right but it is nice to have a number to aim for.
Apparently the collector length is the most important thing to get right. If you're running full exhaust it won't matter but if you are building headers that can be uncorked aim for a collector length of 19"
If you're putting in a crossover or cut outs, putting them in at 19" will give you the best results.
You will absolutely love thast HR636. If you have a stroker, idle will be no problem. Idle at 1000 to 1100 no need...........600 will be smo0th. ............
I can relate to that!OK.......i lied.........at least my memory did.Went out and started the "64" and let her warm up. It is idling at 850RPM according to the tach with the mufflers on. Probably could go down another 100 rpm, but not any lower, never get down to 600. Sorry for the mis-information. Might have killed to many brain cells eariler in life...