Quote:
Originally Posted by RANDY COX
I had a gentlemen do it for me.Alot of people just add another downtube,but the correct way is to actually cut the manifold,I think it's 4 and 2,the front 4 cylinders are up front and the rear 2 cylinders are on the rear.cut a small section out and block off so that there 2 separate exhaust manifold pieces from the same one you just have to watch what angle it needs to be before welding so that linkages will clear.it gives it a distinctive sounds that's for sure...If you like I will try to get a pix of the cut....Thanks Randy...
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These were called "split manifolds" in yrs. past. One caveat: from the back, weld a plate over the inside passage to the rear THREE--exhausting NOT 2 and 4, but 3 and 3! It will not run right with merely an additional ex. pipe/opening. (And only on the "straight 8"/inline-8 cylinders did you have to run unbalanced # of cyls.; due to manifold design, you could not 'reach' inside to get 4 and 4, yet it had its distinctive sound also.)
On stock manifolds, we did not have to actually cut the manifolds in two--altho' it would make for a more 'tuned'/symmetrical system at the expense of considerably more labor. Also, if you cut them in 2, you'd need to run some type of heat source to 'burning chamber'--where the ex. manifold bolted to intake manifold. Easiest, by far, to merely block inside and weld 2nd pipe to new opening. Really makes for a sweet sound in addition to giving a power increase you can feel in the seat of your pants!