exhaust suggestions

[blkmonday]

i have a 66 olds dynamic 88 ragtop with a modified 425 (crane cam,30 over, edelbrock performer carb and manifold...about 10k miles on rebuild)
my question is i still have a stock single exhaust (which for obvious reasons besides the gaping hole in the sears muffler has to go) they do not make headers for this vehicle. i still have the single exhaust manifolds and want to bolt on a dual exhaust. any suggestions on where to start looking for parts. did dual exhaust ever come on these vehicles. the dynamic88 and delta 88 are virtually the same. did the delta come with a dual exhaust? can i modify my stock manifolds to run dual exhaust and still get the performance that i need? i do not have access to a welder which is why im hoping somewhere out there is a bolt on kit. thanks in advance

[MagicRat]

Good questions.
First of all, several header companies seem to make one Olds 455 header. Your 425 uses the same heads so they should fit, provided the rest of it clears.
Generally the larger Olds cars have enough room for headers to clear. I used these headers in an Olds powered Caddy Fleetwood. You may have to roll the dice and locate a set, then see how they will fit. You might have to heat up and bend a pipe a bitm, but this is commonly required for lots of header installations.
If you must use the stock maifolds......I believe your exhaust has a cross-over tube which routes the left side exhaust under the engine and into the right side exhaust manifold. You can weld up the entrance for this corss over tube on the right side manifold. Then you can run two exhaust pipes from the outlet of both manifolds in the conventional manner.
Alternatly you might be able to locate a set of Olds 442 manifolds, all of which were a dual design.
As for the routing of the exhaust, any muffler shop which has a custom pipe bender can easily install dual exhausts. There is lots of room under that car for pipes and mufflers. Realisitcally, it does not matter whether the car was available stock with duals. Underneath it is virtually identical to several other GM models, all of which came with duals.
The trans cross member might have to be notched on the driver's side for clearance of the pipe. Sometimes you can get away with just running a pipe underneath the cross member, it depends on how low the car sits.

[blkmonday]

i got my hands on a set of blackjack headers for a vista cruiser (i actually had a set i never tried from back in the 90s)...the left side does not fit. the steering box is real tight to the leftside exhaust on these cars. after some tiresome research...they do not make headers for this car. i found several conversion kits for the single to dual exhaust systems. about 300 bucks in steel with classic smitty mufflers and a blockoff plate for the stock manifolds. hopefully this wont effect hp too much and let the big block breathe like it wants too. im in ct and the snow on the ground is buying me time right now...ill probably get the kit within a month or 2. ill post my results as soon as i bolt it on. ill also post a link to where i got it from for any fellow full size olds performance enthusiasts.

camaros,cutlass's and mustangs are already fast...imagine a world of 2 ton rockets.....god if we could only get them to turn!

[MagicRat]

If you have the headers already, at least use the right side, since it fits. Also, a good welder /fabricator may well be able to modify the left side to fit.