aristellier

Hi Guys, anybody out there know the best way to convert my 394 single exhaust to a twin system. Can I just change the left hand manifold to one from say a Starfire or am I just making things too simple. Any help would be appreciated. Thanks

Big Joe P

I'm looking to do the same. Trying to find the manifolds has been difficult. It can be done without them, you'd have to cap off the passenger side maniflod where the crossover pipe connects, and some creative pipe bending on the drivers side. I'm going to keep looking for the manifolds, but am prepared to do it without them.

Big Joe P

Yes, both manifolds on a dual exhaust car are different from the single exhaust car manifolds. And they ARE hard to find...

Oldsguy

If you guys end up modifying yoru existing manifolds I encourage you. It can be done. I did it with a 455 in my '69 Delta. The Delta has the steering box behind the control arm and had to do that. I think I posted about this before, maybe I can find it and link it.

https://classicoldsmobile.com/forums...highlight=dual

Big Joe P

On the 63 passenger side, you'd just have to cap off the port where the crossover pipe connects. Oldsfan, would you share the part number for the 1963 drivers side dual manifold? Thanks.

OLDZGUY

I have a 1963 Dynamic 88 with FACTORY Single Exhaust converted to DUAL Exhaust.
It is like the newer years with the split out of the Right Side Manifold to Duals from there back. This conversion was available years ago and still is.
The Dealer I bought the Olds from had it done. It looks and sounds great and I still haven't disturbed the original Manifold set-up.

I did buy the LEFT Exhaust Manifold GM Group# 3.601 Part# 587793 in case I later decide to change to TRUE Duals. There are a few more parts needed to do the conversion:
A BLOCK OFF PLATE GM Group# 3.602 Part# 587576 for the Right Exhaust Manifold Cross-over Inlet from LEFT Side Manifold w/Gasket GM Group# 3.611 Part# 563689.
Left Side Manifold Heat Control Valve Assembly for DUAL Exh ( riser) GM Group# 3.640 Part# 588008.

Since any Muffler Shop can fabricate everything from the RS Exh Manifold back, this is an easier choice than the Parts Search. Since mine was done in Aluminized pipe, I'll leave it for now.

tiparosa

Just did the single to dual exhaust on my 62 dynamic convertable this past weekend. Caped off was easy, had to use 2" aulim pipe for the driver side as it is tricky bends to get from the manifold to the bottom of the car. Used 2/14 pipe once I got to the bottom of the car to the back tips. Sounds great, used summit all welded aulimin mufflers ($37 per muffler compared to $100 flowmaster muffler). Capped off the rear with polished alum tips. Cost me about $400 in parts to do the job right.