Hello all,


I know that there are threads out there already on this topic and I've read them, but I wanted to get some advice/opinions on some enhancements to my Oldsmobile. I've owned the car for 1 year and I'm pretty much a "keep it stock" guy.


Now that I've got just about everything sorted out on the car, I'm looking to do a few performance upgrades like an Edelbrock intake & carb and possibly a Magnaflow exhaust. I obviously want to get the most bang for my buck while keeping the car as original as reasonably possible. Thanks for your opinions and suggestions.

 

I would forget about the Edelbrock carb.

 

You have a heavy car with a low compression, emissions-choked, single exhaust engine and likely a rear axle ratio only suited for Bonneville. I suggest that you decide what your performance goals and budget are. Simply throwing bolt-on parts at this car will result in spending a lot of money for very little effect (though if you flip the air cleaner lid, the added intake noise will likely register as a performance improvement on your "butt dyno" ).

Biggest bang for the buck will be a better rear axle ratio and a true dual exhaust system. Changes to intake and carb will provide only minimal improvements until you fix things like cam profile and ignition curve.

 

Beautiful 88 ! I agree that a true dual exhaust makes a notable difference. I've upgraded both of my 76 Ninety Eights in that way and it was absolutely worth it. I was able to ditch the converter as well.

 

Building on Joe's post, I would say, not jokingly, that if you really want to improve performance, your best bet is to swap in a 1965-'67 Toronado 425 or a '68-'70 Toro 455 (or, failing that, a 425 or 455 from a 98) and install dual exhausts.

Most of the "usual" performance upgrades, such as higher revving cam profiles and the associated modifications to make the engine breathe better at higher RPMs, will not help you unless you significantly increase your numeric rear end ratio, which is very hard to do, as significantly higher gears are not available for your car's rear, so sticking with an engine that is designed for low-rev pull is your best bet.

Also, put real mufflers on those dual exhausts. Nice, full-size, smooth-riding, luxurious cars with muscle-car exhausts sound so low class.

- Eric

 

Definitely install dual exhaust. I installed all sorts of "go fast" parts on my 71 98. While it's been fun, it's sort of an exercise in futility. If I really wanted to go fast I should have bought a Fox body Mustang or late 80s, early 90s Camaro as a project. I can't afford or fit in an exotic.

 

Shingo - Your car looks Sick. I looked for details in your previous posts but didn't see any. Does it have A/C? Power accessories?

As others have said:

I sure would NOT move away from the Rochester carb if you're a "keep it stock" guy. I'm sure there are lots of places to get it rebuilt in San Antonio - I have a contact here in Houston if you're stuck.

Installing an aluminum intake of any kind is going to be way too much work for NOT a lot of performance gain (and only a little bit of weight reduction) without accompanying extensive internal engine modifications.

What rear end does your car in fact have? 7.5 or 8.5 ? Posi ?

What exhaust manifolds does it have on it now?

Does it have resonators after the mufflers?

 

Most likely a 9.3

Every single 1975 full size with 455 had the same single exhaust manifolds.

 

Really wild: Thx! and Joe P is absolutely correct about the rear-end and single exhaust manifold. It does have A/C and all power accessories. I'm getting the strong impression that changing the intake and carb aren't really going to amount to any substantial changes. Looks like a true dual exhaust setup is worth the effort though.

 

Dual exhaust available for $ 350. at a shop corner of Grant and Hildebrand and I know of someone whom will rebuild the carb for $ 100. labor, you supply the kit. or Lonestar Carb on South Flores.

 

The Performer intake is a good intake but does support the hot air choke and is taller. You could add the high performance W/Z manifolds and dual exhaust, 2.25" minimum. I think the W/Z manifolds that year Delta, I am sure Joe will correct me if I am wrong.

 

Another option for the exhaust is to use the original manifolds and have the crossover outlet capped. I didn't do this but I'm pretty sure it's a fairly commonly done option. Any good exhaust shop can make it work with or without the dual manifolds.

 

Considering that this is a low-performance, low compression, low revving engine, I'd say 2.5" maximum, myself.

Too large a pipe diameter might actually reduce performance.

- Eric

 

If you are ever of a mind to make substantial changes to the engine later (pistons, cam, heads etc) you'd need a decent dual exhaust system anyways.

This could turn into an expen$ive project but it looks like such a nice car to begin with...

You've got catalytic converters, right? You want to keep them (so you don't smell like a lawnmower and can pass emissions), right? Should you then go "dual cats"? I'm sure others will have their own opinions.

I'd determine for sure whether W/Zs will clear your frame/steering gear and start with a new (reproduction) set of those. You could keep costs down (new set of W/Zs is $275) by keeping the original manifolds + a crossover block-off plate BUT since you're going to want to replace those exhaust manifold gaskets regardless (with a new set of header-type gaskets, so you know for sure you don't have any leaks) AND since the manifolds will already be off you MIGHTASWELL replace them with sexy new W/Z manifolds too, paint 'em up nice...then go with a 2.5" aluminized steel exhaust system and probably three-chamber mufflers as others have mentioned.

Does that car have resonators (after the mufflers, before the tailpipes)? Will you keep them /get new ones?

What's the transmission cross member look like? Will it need modification to accommodate true duals? Will you be able to run an exhaust crossover ("X-pipe" or similar)?

Re: the 9.3 rear end - what ratio is in it now?

 

Yes, I mostly agree. I ran 1 5/8" shorty headers with 2.5" dual exhaust with compact X pipe with an Olds 260, since exhaust was already in the 88 CSC. I felt absolutely no bottom end torque loss, though 3.42 gears, negated slightly by 1.6" taller tires would help over 2.78 gears. This was compared to capped off 260 manifolds and 2" dual pipes.

 

Sorry taller tire lower the gear ratio response not add. A shorter tire on the rear will add gear ratio response.

 

You are correct. The W/Z manifolds will fit the 1971-76 full size cars.

 

Don't forget about the recently available ford 9 inch rear for our cars.
Single greatest thing made available to us from an acceleration from a stop point of view. Quickperformance.com Happiness has been attained.

 

Where on their website does it list a Ford 9" rear end for an Olds B/C body? All I can see is options for the Cutlass, 442 and Omega. Sorry if I'm blind.

http://www.quickperformance.com/

BTW, W/Z manifolds will work great on a 71-76 B/C body, just like Joe mentioned. I got a set from one of our members years ago and they were AWESOME! FWIW, I have 2.5" duals on my 71 98.

 

They have it listed on their e bay store. Or just call them.

 

http://www.ebay.com/itm/9-Inch-Ford-...item5aef32eec4

 

 

First tell us if there has been any work such as timing chain changed, valve job etc. How many miles are on the drivetrain? What are your goal? Ice Cream cruiser, street with an occasional full trottle, or all out National Record Holder? If your car has 70k or so you should check the timing chain. Everything will snowball depending on the answer. Jmo