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I want to add dual exhaust to my '70 98. I know they didn't come from the factory with dual exhaust but I saw Fusick has full size car dual exhaust manifolds. I'm assuming these were designed for either a Delta 88 police car or the W33 option. Is there a way to change just the LH and leave the RH original? Can the cross over pipe on it be capped off like on the SBO? Does the valve at the base of the LH single exhaust manifold need to be transferred to the replacement dual exhaust manifold? Thank you.
Duals was an option on the 70 98. You only need the driver's side manifold from Thornton, probably cheaper than Fusick... the rt side remains and gets capped on the crossover port. Don't really need the heat riser butterfly in the left manifold...
Actually, it was not in the 1970 model year, but it was in prior years. As we've discussed in the past, any dual exhaust conversion on the 1965-70 full size cars MUST use the correct factory style LH exhaust manifold, which is fortunately reproduced. All the repro houses sell this, so shop for the best price. You don't need the aftermarket RH side manifold, just cap off the crossover port, which is what the factory did. Note that the repro cap sold for the small block manifolds will NOT fit the full size manifold - the port is larger in diameter. I just welded one up from a section of the old crossover pipe.
Look under the car and see if you have a double hump trans crossmember. You need the space for the second pipe. Other wise you'll have one pipe hanging lower than the other. You can look for a Delta crossmember from a car that had duals or go aftermarket.
You find an increase in fuel economy if you rejet after ward.
So if I read this right, my 72 D88 will allow dual exhaust without the manifold? I do have the dual hump cross member,455, single exhaust, muffler is shot, damaged it when removing for floor repair above it.
Plan to replace with duals.
So if I read this right, my 72 D88 will allow dual exhaust without the manifold? I do have the dual hump cross member,455, single exhaust, muffler is shot, damaged it when removing for floor repair above it.
Plan to replace with duals.
The 1971-76 cars are completely different from the 1965-70 cars being discussed in this thread.
Depending on how correctly you want to reproduce the factory solution, you may need to fabricate or acquire the special “half-moon” horizontal shifter rod which transmits motion from your column shifter to the TH-400.
I believe it’s documented somewhere here on CO. If I recall someone made some pretty decent drawings which would allow you to make one. I don’t have the fabrication skills, but it’s welded and bent steel rod, not super exotic weirdly shaped stuff.
The difference is that single exhaust cars used a straight shifter rod, and the dual exhaust cars used a semi-circular horizontal rod to clear the LH pipe and connect to the transmission. The “half moon” rotates over the pipe for gear selection. The straight shifter rod would have to go right through the LH exhaust pipe which just ain’t gonna work.
If you want to source factory parts, you’re now looking for a dual exhaust 65-70 big car. That’s a fairly rare animal. Up to ‘67 that would be the “Starfire” engine option.
After 67, I don’t know how they marketed the dual exhaust option, but it would have had to include these fairly rare shifter parts to make it work mechanically.
Dual exhaust cars have a different shifter linkage?
Actually, they do. The equalizer bar that runs from the frame to the trans has an offset in it to clear the LH exhaust pipe. I did not have one of those when I put duals on my 67 D88 and it cleared, but the pipes I have are not factory, so all bets are off.
I did not realize that, there is no mention of it in the parts list for 1970.
You are correct, the parts book shows 403090 for all 1969-70 column shift AT full size applications, despite the fact that the RPO L32 390 HP 455 with dual exhaust was an available option in the D88 line those years. Maybe the 69-70 equalizer was redesigned to clear? Can you shoot a photo of yours?
Does anyone know if anybody makes replacement hangers for the W33 exhaust? It shows one across the transmission cross member that holds both pipes but I can't find a part number for it. The other two are identical to the right, rear muffler support (407232) and tail pipe support (394400).
Does anyone know if anybody makes replacement hangers for the W33 exhaust? It shows one across the transmission cross member that holds both pipes but I can't find a part number for it. The other two are identical to the right, rear muffler support (407232) and tail pipe support (394400).
It's not needed. I have run duals without that cross tie hanger for the last 35 years. Never had a problem. But if you want to be 100% original, you'd probably have to fabricate something.
Does anyone know if anybody makes replacement hangers for the W33 exhaust? It shows one across the transmission cross member that holds both pipes but I can't find a part number for it. The other two are identical to the right, rear muffler support (407232) and tail pipe support (394400).
No one makes new ones. I had to adapt generic hanger parts to run the duals on my 67 D88.
Has anyone ever been lucky enough to get the exhaust manifolds off without breaking the bolts? She's developed a leak at the back of the right exhaust manifold. Of course, the one I didn't need to take off to add duals. The bolt lock is completely broken out and it's ticking like valve noise through it. I want to do the work myself but I'm afraid of snapping bolts off in the block and having to drill them out which could require removing the engine. It's never been out of the car.
I can't say that I've ever broken any exhaust manifold bolts on an Olds. Note that except for the center bolt, all the exhaust bolts are in holes that are open at both ends. You can spray penetrating oil in the end opposite the head and let it work for a while before removing.
It's well above my automotive pay grade, but Joe's right on target to start with penetrating oil, a few days of patience and if that doesn't work, I believe the traditional solution is fall back to torch heat.
Personally, I'd farm out torch use to a professional. I haven't the skill to be the least bit confident of not blowing up the car.
See picture below. The bolt goes through the head and is exposed. The exhaust bolt on the right rear (passenger) side has exactly the same configuration.
I’d start spraying penetrating oil weeks before attempting this project. A torch to apply heat is also a good idea. A little prep work now can save major headaches later.
I had to do this job recently on the drivers side. I did the penetrating oil and six pointed socket. Try to use a sharp yank or rap with a hammer on a breaker bar to get it moving. In my case the center one was stuck firm. So I bought a pneumatic hammer set (typically used for body work). I used the long hammer from underneath the car hitting the bolt head as straight on as possible. Between that and penetrating oil I was able to get the bolt out. I did not use heat (it's very hard to heat up cast iron significantly and you want to heat the head not the bolt).
Prep work as mentioned above. After the soak period, I like to run the car for a few minutes to get everything hot, then break the bolts loose, you can come back to it after things cool down and do the removal. Never had much, if any difficulty doing it this way, especially on an Olds.
I just got a closer look at the bolt lock, turns out the rear most bolt head snapped off and is still attached to the dangling lock. Guess I will be having that drilled out.
I just got a closer look at the bolt lock, turns out the rear most bolt head snapped off and is still attached to the dangling lock. Guess I will be having that drilled out.
When the manifold comes off there should be, may be, enough of the stud sticking out to heat and try to turn out with a small pipe wrench or weld a nut on the stud and turn out.
Which Remflex gasket is for the B/C body S Manifold? Does it have a center split or a solid hole? 11-001 has a split center and 11-002 has an open hole.
Which Remflex gasket is for the B/C body S Manifold? Does it have a center split or a solid hole? 11-001 has a split center and 11-002 has an open hole.
It really doesn't matter. The manifolds have the open hole, but that little center divider will burn away in no time.
Quick question, are the pipe flange springs and bolts the same on the B/C as the A body? I can't find any specifics and even the part catalog isn't very helpful for 1970. I was able to get repro flanges and a manifold from Thornton and Fusick just no flange bolt/springs. Also, is there supposed to be a manifold to head gasket? It doesn't seem like there is one.
If the mating surfaces are clean and the manifold isn't warped it shouldn't be prone to leaking. That's the way they came from the factory. But some people prefer to add a gasket. Whatever your more comfortable with.
May 28th, 2022, 01:07 AM
