Trying to convert the single crossover exhaust to duals on my 394 Rocket. Told I need to find a set of "Rear Drop" exhaust manifolds that typically come off of truck engines. Can anyone point me in the right direction on sourcing these truck exhaust manifolds that work for converting olds rocket single crossover exhaust to a true dual set up? perryproductions@hotmail.com
Thanks

 

First I have ever heard of any truck exhaust manifold being able to be utilized for the purpose of converting from single to dual exhaust?

Generally what is needed is a driver side dual exhaust manifold and a crossover pipe cap for the passenger side exhaust manifold. The proper manifold is out there, but hard to find.

 

And exactly what truck ever used an Olds 394 motor? (yes, I am aware that GMCs used the 371 - those manifolds will not work on this application) I would suggest that you need to stop listening to whoever told you that, because clearly they have zero knowledge of Oldsmobile motors.

The RH manifold is the same for both single and dual exhaust - P/N 587510. The LH manifold is unique to the 63-64 394 cars with dual exhaust - P/N 587793.

 

As Dave stated there is a correct dual exhaust manifold for your car. The manifold is for the 63/64 Starfire and 63/64 98 custom sport coupe. They show up every once in a while and you have a blocker plate on the passenger side where the cross over connects to the manifold. Google the manifold and you will see what it looks like GM # 587798 ( the picture of the one on the red sheet is mine so I know it's right) look under 64 OLDS STARFIRE 98 DUAL EXHAUST MANIFOLD.
Steve

 

the 50's gmc's used pontiac engines.

 

I think the exception was the 57-58 GMC when the Olds 371 was used. Some people claim it was the 370 Pontiac in 57-58.

 

But it was a 371 for sure.... Tedd

 

GMC used both the Pontiac and Oldsmobile engines in the 1955 thru 1959 period .
In addition to their own line of six cylinder engines .
The Pontiac engines were used in the pickups thru the two ton trucks . Models 100 thru 450 , 287 in 1955 , 316 in 1956 2 , 347 in1957 , and 336 in 1958 & 59.
The latter two years were smaller bore versions of the 370 and 389 .
The larger two and a half ton , series 500 and up , used Oldsmobile engines . 324's in 1955 & 56 and 371's in 1957 thru 59 .
GMC did however refer to the 371 Olds engine as a "370" .

 

Charlie, Thank you for clearing that up.

 

Been a bit of a digression from the OP's question about dual exhaust manifolds...

 

Having a heck of a time finding the correct exhaust manifolds to convert my '63 Olds Super 88 with a 394 to duals.

Do not need the blocker plate for the passenger side manifold.

I just need to find a set of correct exhaust manifolds for this 394 so I can complete my dual exhaust project.

Appreciate any help anyone can offer.

 

E-Bay is probably your best source .
Set up a perpetual search for " 1963 64 Oldsmobile exhaust manifold " on E-Bay , and they will e-mail you when one turns up .
Expect to see all kinds of gaskets , studs , etc . in that search too .

You will only need the left manifold . The right one you have is used with a block off plate . That's the way the factory did it . There is no special RH manifold for duals .
Expect to pay several hundred dollars . If you find one for cheap , you are truly blessed .

This is what you are looking for ;

 

I'm desperate.

 

Sorry , That manifold is not for sale .
It's going to be installed on my car .
Keep looking , you will eventually find one . They were on all 63 & 64 full size cars equipped with dual exhaust . Not just Starfires and 98 Sport Coupes .

 

Could you just have a set of custom headers made? Maybe buy a set of header flanges from this company ( http://www.headersbyed.com/index.htm ) and have a whole new exhaust made all the way to the rear of the car.....

I was looking around at this site and wondered if this could be a possibility.

Does anyone have any insight/thoughts?

 

The frame and steering gear are your biggest obstacles .
If you study the picture of the stock LH manifold above , you will see little clearance around the steering box .

 

Here you go williewonkadude ;
https://www.ebay.com/itm/OLDSMOBILE-...YAAOSw1pZdJVxe

Grab you piggy bank and a hammer .

 

Didn't last long on ebay.

 

Like an ice cream cone in Hell !

 

Here's another one that just popped up ;
https://www.ebay.com/itm/1963-1964-O...AAAOSw-ZZdOOuA

 

Hi,I would have headers made for it instead..my 2 cents..lol

 

"Just make headers . " Sounds easy , doesn't it ?

 

It's always easy for the person who doesn't actually have to do it...

But hey, ignorance is bliss.

 

Just chasing down an old thread about the left side dual exhaust manifold... there's no a lot of room there. That's a tight fit