I have a 1974 Sage Green Cutlass Supreme with a 350 I bought 2 years ago. I love this car so I’m throwing a little money at it to start trying to wake it up a bit.

Right now Im just looking to do some new manifolds or shorty headers (don’t want long tubes to create any unecessary clearance issues), dual pipes and an intake. Not racing just cruising and would like some more power and a better sound.

I don’t expect massive gains obviously but just wanted to touch base and get some info about good options and any problems I might encounter.

Ive searched some threads and made some calls and it looks like either

- Thornton manifolds or Hedman block huggers 58163 for the headers (I’ve got a good fabricator for the pipes and I like the flowmaster 50 series mufflers) My 74 did not come with dual pipes but does have dual hump crossmember.

And

- Edelbrock performer intake with the original Qjet

I’m not an expert. Does this sound like a good plan/place to start ? Any known issues, experience, pitfalls I might be walking into would be a great help.




74 Cutlass Supreme

 

I don’t think the intake will give any measurable performance boost. What will give the best performance increase is lower rear gears.

 

Ok look into this as well, any specific suggestions?

 

As Fun71 said and true dual exhaust will be your best bang for the buck. Without complications, and unnecessary expenses.

The Performer was the go to mod when the engine was born 2bbl. But is only good for weight savings on a base stock 4bbl 350. And the shorties are a worthless feels like you did something but you didn't, except waste money and time mod.

True dual exhaust will give you an extra 20 hp, real headers (full length) will give you another 20hp.

With the right gear swap will feel like you added 50 hp...

Your Supreme and my Supreme share the same cid and cam. Meaning our engines could sound similar. Here, is my 350, true duals, hi flow cats, and generic mufflers.


Sounds exactly as it does in real life if you have a stereo with subwoofer for audio.

P.S. your car looks great by the way.

 

Awesome thanks for the info and the car sounds great. We’re talking about rear end gears yes? Do you have any suggestions for what to swap in?

 

You will gain some power over manifolds with shorties but less than full length. The Hedman headers are more like a mid length header, you will probably gain the most with them. Another option is Sanderson but the welds are hit and miss. The big advantage is the larger outlet over the Thornton.The Stainless Thornton will last the best, long term. The Performer as said is basically a weight savings but does have a different runner design. Any 3.08 or 3.23 gears and 28 spline posi for a GM 8.5" 10 bolt rear will work for your 74. It depends on what you are comfortable with for highway rpm. A 3.42 or 3.55 are options if 3000+ rpm isn't an issue. A mildly built 2004R overdrive trans and 3.73 or 3.90 gears with just dual exhaust will gain more than any headers will for acceleration and cruising at low rpms.

 

Yes, you would need to confirm your current gear ratio. Assuming its 2.73 swapping to 3.73 will feel like you swapped in a big block. But thats extreme fill your head noise at steady highway speed. The single exhaust 180 hp 350 is turning 2500 rpm at 70 mph with factory height tires. And has a top speed of 119 mph. With 3.73s 70 mph becomes 3500 rpm and top speed gets limited to 90 assuming same rpm range as stock. If keeping her above 90 mph matters, go 3.42, now you can safely hit 100 mph, and revs at highway speed are a bit more reasonable 3200 rpm at 70.

For reference ideal stock 0-60 on base 350 is 10.4 , modded exhaust and gears, may knock that down 2 seconds.

👍

Cinnamon, Hot Rod was showing your ride some love, with this great illustration.


3rd question down coincides with Olds 307 and 403s suggestion. https://www.hotrod.com/features/tech...982-1561-118-1

Going 4 speed auto is the best of both worlds. And of course a very significant extra step. But it makes all those calculations above irrelevant. Now you can do everything the factory expected while being much quicker with no negatives.

 

It is a significant step but the 2004R bolts right in place, just move the crossmember, he will want a dual exhaust crossmember for ease of routing exhaust to TH400 position and done. The 2004R, unlike the TH700R4/4L60E and 4L80E are much more involved to fit and custom drive shafts or finding an application that works, like I did for my 4L80E. Also the better .68 vs .70 and .75 overdrive gears is another bonus, along with better gearing through out. I got custom 2.5" duals under the passenger side on my G body with the Sanderson shorties, so it is possible. The usual D9 2004R converter stalls about 300 rpm higher than his current TH350 and add a 2.74 vs his current 2.56 first gear, both off the line acceleration improvements. Add a 3.42 or 3.55 with the converter locked up, it drops about 1000 rpm, about exactly what you probably have with mid 2's factory gears at highway speeds. Also with his power upgrades, basically a stock build with a couple of minor improvements and a Transgo shift kit and servo and done. He won't even need the deep pan for a cruiser. The later B body late 80's/early 90's Caprice differential are a direct bolt in I believe and some came with the better gearing and posi like the SS and Cop cars. I say, a timing chain and gears, just duals, a 2004R and the gear/rear swap. With the $1000 saved on the intake headers goes a good way to the trans and rear. The dual exhaust will bump you from your whopping 165 HP to 180 and boost torque and sound as well, according to Oldsmobile factory single vs dual exhaust numbers. Good luck.

 

Thanks yall this is all great info to add to my list of options for this car!! And I love that cartoon 😁

 

Perfect. The code 9 drivetrain or its equivalent is the high-water mark for Olds RWD automatic efficiency.

1974 was a lucky year for Cutlass guys. No 2bbl. For the first time ever post 1970 base single exhaust was 180 hp. Oldsmobile's last hurrah before the bottom fell out in 1975.

Cinnamon incase you are not familiar, 1974s 200 hp dual exhaust 350 Cutlass as well as the 455 version. Is the last time rear wheel drive Cutlass was factory rated that high or higher. The last unadulterated Cutlass. A fact that we are always reminded of when looking into headers. "Headers are 49 state legal for 1974, back..."

Its very very fitting from what I wrote regarding headers, to honoring its namesake. Unfortunately not downloadable, not even complete in its open page. But when you forward the link via smartphone you get a glimpse of it entirely. Here is a magnified screenshot, sorry for poor quality.



And here below is the inspiration for the name and illustration as well, being catapulted at launch, September 28, 1954.


The Vought F7U Cutlass.

 

Great looking car!

Before trying to get a little more out of the engine, how are the timing chain and gear set? If they are marginal or worse yet original replacing them will improve both reliability and performance.

 

Yeah that’s what has been suggested and I appreciate it!! Definitely going to look into to it along with the duals 🙏🏽 Do you have any suggestions for a good timing chain? Are we talking an easy upgrade in quality or just a new one?

 

Anything/anything that's better than the piece of planned obsolescence that was installed at the factory.

I've had two timing sets replaced in my lifetime. The first is so long ago I can't remember the brand but it was literally bought over the counter at a local parts store on the spot. Worked out great. The 2nd time was my 69 in 2019, it is Sealed Power. It's been roughly 20,000 miles since and its worked out great...





P.S. Summit Racing Equipment is great to deal with.

 

Awesome thanks man!! Im researching now!!