Perkolator

I've inherited my dad's Delmont and it's getting some last items addressed on a list of things my dad paid an auto restored to do for him before he passed away. I've been talking with the restorer and he had an issue that if like some advice on since I only know enough about cars to get in trouble.

The Delmont is one with a 350 (rocket?) and my dad had the guy do a rebuild and get a few more ponies out of. I recall them saying something about an Edelbrock carb, a cam upgrade, and cylinder heads off a 455. My dad also requested dual exhaust and I know this car didn't have or was even designed for this. They were also going to put mufflers from a 442 on it to flow yet be relatively quiet at least at idle.

What I've been told is the hangup for the last few weeks has been an issue finding the right exhaust manifolds that will allow for the upgrade, and that they went through at least 3 sets before finding set that had the right configuration...but is in VERY a close proximity to some giant high-torque starter they put on. The true solution proposed to me was to replace the starter with some high output compact race started, but it will be a while to get that part if they order it. It's so close that they can't get any form of heat shield between and it will kill the starter sooner than later.

Since we have been tired of the restorer dragging his feet over the last 6mo my mom wants it out of there ASAP - so I suggested that perhaps we keep the big starter in place for now, install the "L-shaped" manifold on the passenger side where it clears, put the stock "y-shaped" manifold on the drivers side for now and run the dual exhaust. When I get the car up to sacramento I can get the smaller starter, swap the manifolds, and only have a short section of pipe that needs to be tabbed up.

Does this sound legit for a temporary fix?

Fun71

I am wondering what manifolds they are attempting to install? Most all SBOs used the same manifolds for single and dual exhaust versions. On the dual exhaust versions (N10 option) the passenger side crossover port was blocked off with a cap and the drivers side pipe was run to the rear instead of under the engine to the passengers side manifold.

2blu442

From what your describing it sounds like it may have the A and T castings from a big block engine. Either the small block or big block manifolds will bolt up to the heads. I'm not sure what kind of starter you have, but the factory had the crossover pipe running from the drivers side to the pass in a location that shouldn't touch a factory starter. The aftermarket starters I'm familiar with are smaller than factory. So... can you put a factory starter back on, drive it home and then figure out what they did to it?

John

2blu442

Here's a couple pictures of common manifolds for the factory single exhaust on the 1968ish full sized cars. The first is the A and T and the second is the #1 & 4 I would suspect they used something like these on your car. As Fun71 said its common to block off the crossover port on the passengerside and run two pipes to the rear of the car for dual exhaust. John

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Octania

Letters are BB manifolds
may or may not work on SB in same chassis

What year Delta/ big car?

'65-70 requires the "S" LH casting to clear the steering and whatnot, and a U shaped equalizer [frame to trans rod] to clear the exhaust pipe.

Not sure if you can fit an S on a 350 in that Chassis

"S" manifold is on epay all the time, Thornton reproduction, $230 typically.

joe_padavano

I'm pretty sure the 330/350 was only available with single exhaust in the 1965-70 full size cars. I do not know if the S manifold will work with an SBO, as it will be lower and closer to the steering box and shift linkage.

MDchanic

Note that installing big block heads on a small block could be a Bad Idea, unless proper steps have been taken to maintain compression.
Even then, the larger tracts will hinder mid-throttle response, and will not match up, height-wise, with the small block intake manifold without additional work.

- Eric

joe_padavano

I missed this in the OP's original post. Admittedly we have only a limited amount of info, but from what was posted, I would not recommend following that shop's recommendations. This is a heavy car and needs torque, not top end HP. Note that even the factory W-31 cars only used standard small block head castings. They did install big block valves in those castings, however.

Perkolator

Thanks to all who've replied. The pics will help me know what I'm looking at. I'm used to toyotas and 22res only, this oldsmobile stuff is new to me to those who asked, it's a 1968 Delmont 88 convertible.

I guess I just need to see what has been done in person, which is later this week. I'm sure they had a plan when they decided to keep and build the 350 instead of put a BB in there, since I know the suspension and brakes were upgraded from stock. In regards to the dual exhausts, not sure why they needed new manifolds - only that it's taken several different versions to get one that fits the setup.

I did some reading on the BB heads on a SB and I see what you're saying about compression. I will have a build sheet of what was done to the engine, but I can't imagine this car guy would not know about something like this without putting the proper fix in place. Who knows though...

joe_padavano

Our collective experience has been that machine shops that really know how to build Olds motors are unfortunately few and far between.

oldolds88

by any chance did they put a diesel starter on it?

64Rocket

I don't understand the need to change exhaust manifolds. A competent muffler shop would have cap the cross over connector. Then just run the pipes.
Sounds like they are just running up the dollar bills.

What is your location here in Calif. ?

Maybe I can help a little.

Gene

joe_padavano

Gene,

Keep in mind that the O.P. has a rear-steer Delmont 88. The steering box makes for creative pipe routing on the driver's side without the factory "S" manifold.

The other option might be to run the driver's side pipe under the oil pan, like a single exhaust crossover, then run two pipes on the passenger side. Not pretty, but it might work.

Perkolator

I got to see the car today. It's been years since I've seen it in person.

Seeing it in person, I agree with the mechanic that the car needs the new manifolds to do it right and make it look clean. The issue is in the drivers side - the stock manifold is a "Y" like the first manifold pictured above. The new manifold is one off a 68, 442 with auto trans and a 425 I think is what he said -- it has the correct shape to clear steering and point the pipe where it needs to be, but the giant GM starter they installed is rubbing. He showed me the style of starter needed to make it work (it's a tiny race application starter with a gear reduction on it) but I need one for left hand since I guess Olds had to be different.

As for using the stock manifolds to make dual exhaust - yes it can be done, but the pipe would end up lower than the oil pan in order to clear the steering box, crossmember, and suspension control arms. Pretty crazy how olds decided to put these motors so low in a huge car like this, with starter on wrong side, but oh well

Car is back to single exhaust and I have the restored $300 manifolds to do the duals at a later time once I get the starter resolved.

Oldsmaniac

There are only 2 starters for this engine to my knowledge, the stock style and the smaller gear reduction one. The only giant ones would be for a diesel and would be stupid to put on there.

Its not the wrong side its the side Olds chose.

joe_padavano

Again, your first problem is that you are trying to use big block manifolds on a small block. The shorter deck height of the SBO is why these manifolds are hitting the starter.

Second, as pointed out above, the rear-steer configuration of the 1965-70 full size cars requires a specially-shaped manifold on the driver's side to clear the steering. That manifold is the "S" manifold, used only on the big block cars. Olds did not build a dual exhaust version of this car with a small block. That's why you can't get a manifold to work.

Your only option is to have a stock manifold cut up and welded to fit. Some folks have had success using a Toronado driver's side manifold and had the exit port cut off and rewelded to change the angle. Pipe routing will be ugly.

Perkolator

Yes, manifold they have is the "s" version to clear. I'm just dealing with what has fallen into my lap. I would have put a 455 in there personally but they didn't. I do know a PO had installed mismatched heads in the past - 455 on one side and 350 on the other. They saw the 455 head code and thought it was a 455, ordered parts and sent the motor to the machine shop - they called back and were like "um this is a 350"

Perkolator

Dual exhaust has been completed on the Delmont!
It was not a straightforward task since this car never came with the dual exhaust option - but it was something that my dad expressed he wanted on this car, so I felt obligated to follow through with it despite the challenges.
The main challenge seemed to be regarding the 350 vs 455 heights difference (mine is a 350 block with 455 heads) with where it outputs the exhaust manifold nearby the steering box, starter and upper control arm.
The special "S" manifold got installed on the driver's side - had to lift engine about 5" to shoehorn it in there, even still it barely fit.
Starter got replaced with a Powermaster 9610 compact starter and covered with heat shield material to hopefully not kill it with heat.
Used a Summit 2.5" universal header-back pipe kit (SUM-680146), paired with some 25" Dynomax super-turbo mufflers (#17748). Not a show-quality install, but it works.


Can try and take more/better pics, but here's a few showing how it got routed on the driver's side to help inspire others attempting it:

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64Rocket

now how does it sound?

👍

Gene

Perkolator

Sounds pretty good to me. I didn't want it "loud" which is why I went with those particular mufflers, definitely deeper and throatier than what it was before, feels like it breathes a whole lot better that's for sure

olds 307 and 403

That manifold would also work great on anyone doing an Olds powered 4x4, the pointed down outlet on most manifolds and shorty headers mean pipe routing is super tight and a mini starter is necessary. Thanks for finishing this thread, glad you got the car finished as well.