straight eight header how to?

I looking at having a header made for the 263 in my 51 buick special. I have seen some with the front four ports grouped together running into one collector and the back four into another. I have also heard about grouping the front two with the rear two together, and the four ceter ports into another. Anyone know what the prefered method is? Would one of these methods sound odd through dual exhaust due to the firing order? Any info you might have would help? thanks in advance

 

I know nothing about straight 8s, but I do know that connecting the right cylinders via Y-pipe to each other can have a good scavenging effect due to vacuum. That allows more A/F mixture to flow into the cylinder resulting in more hp.
I can´t tell in which way that relates to the firing order...

 

Grouping the front four,and the rear four,makes it easier
to fabricate,and might look better to some people.

The "correct" pairings are based on the firing order.

 

If someone has the exhaust scavenging theory on hand I'll yield.
I would treat the engine as though it was two simultaneously running 4-bangers. That would mean two groups of tubes, alternating the firing order. If order was 1-8-4-3-6-5-7-2 for example, then I'd group 1-4-6-7 and 8-3-5-2. This is just based upon simple intuition, as I'd prefer to have equally spaced pulses acting to scavenge adjacent cylinders.

 

Even spacing on the pulses is the idea.

 

I just built a header for a 263 and there is a practical consideration you need to think about. All 8 cylinders worth of tubing are going to be located directly under the carburetors. That is a LOT of heat. I would suggest building headers with a simple and direct routing.
They don't sound cool at all when they are vapor locking all the time.
Actually straight eights sound very unique. No matter what the configuration is, it will sound quite different from anything else.

 

thanks for all the replies. I have visited a few exhaust shops in my area and they either want nothing to do with it or their price seems to be way to much. Has anyone had a set for a stright eight made by an exhaust shop and if so what did you have to pay? What would seem like a fair price? Does anyone know of a reasonable shop in San diego?

Well due to these problems I will probably just get the stock manifold split(5-3) and have an extra flange put on. THis wont look nearly as cool, or have the performance gain, but I will be able to run dual exhaust wwithout going broke.

 

Find a pair of '41-'42 factory dual manifolds. The engine mount will need some clearance work, but it's very easy. They're still selling for a lot less than headers will cost & are trouble free once installed.

 

I already have an edmunds intake but will probably start looking for the 41-42 set. What exactly needs to be done to the engine mount to make the exhaust clear? does anyone have a good description, picture, or drawing of what needs to be done? I am going to visit a few more exhaust shops while I try to hunt down a factory set of duals.

 

any of you guys have a good description,drawing or picture of what to do to the motor mount to make the stock 41-42 exhaust fit a 51? Amy info would be appreciated.
thanks in advance

 

If you have access to a light weight oxy/acy torch, then I'd see about getting a flange made to match up with the exhaust ports. Then buy (2) 4-into-1 collectors and some 1-5/8 tubing and either 90 degree elbows or some 360 degree donuts. You can gas weld a custom set right in place on the car! Its easy to arc weld the header flange "tubes" into the flanges, then start learning torch technique. You won't regret it! Get all combustibles/fuel out of the compartment, and go to town.