Odmark

Hello. I just got myself a 1974 Oldsmobile Custom Cruiser with a 455 big block, and i was planning to up the horsepower a bit, as well as maybe get a little bit better fuel consumption and was hoping i could get some tips.
I am not removing the engine from the car at this point.


Is an Edelbrock Performer intake and a edelbrock 750 carb a good way to start? With a decent cam maybe and some headers. What hp gain should i expect from that?

I live in sweden and cant seem to find many performance parts for these engines, so im probably going to have to order from the states.

Appreciate all tips!

Thanks in advance!

pogo69

Headers have a guarantee in picking up horsepower along with making it sound good....induction might be your next step but you have other things to consider such as what tranny and rear you have now and most importantly how much you want to spend

oldcutlass

Welcome, post some pictures when you get a chance. The Edelbrock performer is a good 1 step over stock intake manifold. The Edelbrock carbs are a relatively simple and reliable swap. What is currently installed on your 455?

stressed1

Ive heard swaping to an edlebrock intake on a stock motor adds absolutely zero horsepower. Has anyone prven this on a dyno?
Now if you got the edlebrock heads, cam and intake, I can see it boosting power

MDchanic

I have no experience with the exact manifolds in question, but I agree that an intake manifold, alone, on a stock engine, is very unlikely to increase power.

I do recall back in the seventies we installed Edelbrock SP2Ps on a Suburban and a Blazer, and they definitely improved perceived torque, as well as fuel mileage, but they did that through smaller runner sizes that increased charge velocity.
On a dyno, they would not have increased power.

- Eric

Odmark

Thanks for all the answers!
I have a TH400 gearbox, no idea about the rear axle though.
I am currently off to work in another town and not driving the car, but i will take pictures when i get home. Just bought it but i think it is completely stock.

I was told the headers, camshaft, intake and 750 carb combo would get the car over 300 horses.
Another question, what is the stock torque of this engine (1974)? Preferrably in nM.
Thanks in advance.

cutlassefi

Eric, you're normally a pretty sharp guy, wanna rethink this statement?

If you increased charge velocity, at some point you just picked up torque, maybe at the expense somewhere else in the powerband. But at some point you filled the cylinder more efficiently, that'll make more power, there.

olds 307 and 403

I think he meant horse power. I ran a SP2P on my Olds 350 in my truck. With the small ports, the Qjet overwhelmed it at full throttle. I ran it on my 4x4 with TBI, being less cfm with better trans and gearing didn't have the issues.

cutlassefi

I hate to nit pic Christian but the hp calculation is the direct result of torque, more torque= more horsepower.

Thanks guys!!!

matt69olds

If the car has a catalytic converter then you will need to swap in a 73 or earlier trans crossmember to go to dual exhaust and headers. Definitely should add some get up and go!

Unless your interested in adding a little more camshaft I doubt that a aftermarket intake will add much to your "butt-o-meter" feel. It might show up on a timeslip but seat of the pants feel is unlikely. I would suggest adding a mild camshaft and a timing chain. Bad things happen when the nylon coating on the chain chips off and plugs up the oil pump pickup!

If fuel economy is important (with the price of fuel who isn't concerned!) I would have the factory Q-Jet rebuilt by a carb specialist. Its hard to beat a well set-up Q-jet for power AND economy.

olds 307 and 403

I should have said more very low rpm torque. Think swirl port 307. I would get a properly rebuilt Qjet over the Edelbrock 750. Performer intake is worth the 50 pound weight savings. Cutlassefi is the resident cam expert, get what he recomends. The Edelbrock cams are Ok but not great.

MDchanic

My point was not internally contradictory.

The old SP2P made more torque (and therefore more power) at lower RPMs than the stock manifold, and did so with improved throttle response (higher charge velocities), so the truck felt faster, and, under those exact throttle and RPM conditions, it was, BUT the smaller intake tracts reduced the maximum flow rate, thus reducing power (acting kind of like a governor) at higher RPMs and definitely reducing the maximum power output of the engine (which is what everyone talks about when they do dyno runs, and what the car companies talk about when they refer to a "310 horsepower 350").

So, yes, it increased power where most people actually drive, but it decreased total available power, which would only be noticed when racing, or, more realistically, when towing a heavy load.

To clarify my quoted statement, "On the dyno, they would not have increased maximum power [which is what everyone loves to talk about], but it would have shown a small bump of power lower in the rev band."

- Eric

Odmark

Does anyone of you know a good place to buy like headers and such? Not very easy to find in sweden. And do the headers from another olds fit?
A company called Hansen Racing in sweden and they supply headers, when i search for 1973 Custom Cruiser it says they have it in stock, but when i read about them they say they are for Oldsmobile Delta 88.

MDchanic

The intake manifold does not vary by model but by engine.

Big blocks have one size, small blocks have a different size, and some later small blocks, such as the 307 and the 260, have yet other different sizes.

- Eric

oldcutlass

I would look at Jeggs or Summit racing for headers, manifold, etc.... I don't know what shipping would cost.

oldsman72

+1 Summit or Jegs should have what you need for the engine....BUT

My 2 cents....if the motor runs well, maybe spend the $$ on rebuilding the rear (probably an open rear anyhow). Get a posi carrier and a nice set of 3.73 gears in the rear. That will wake up the performance a little, especially with that 400 turbo.

Whatever you decide, best of luck with it!! Welcome to the site!

MDchanic

Remember, he is in Ornskoldsvik, Sweden, so rebuilding a rear may be a very different proposition for him over there.

- Eric

Odmark

I actually was thinking about rebuilding the rear at a later point, but as MDchanic just said its not the easiest thing where i live.
But the main question, do the headers from a delta 88 455 fit the custom cruiser? Those are the only headers i can find, atleast in sweden. Summit doesent appear to have any either.

joepenoso

Odmark:
Here's your "Pisano's" experience with a low cost header and he comes from your neck of the woods. Maybe contact him and see what he says and if it's still holding up
joepenoso
https://classicoldsmobile.com/forums...ce-header.html

https://classicoldsmobile.com/forums...ce-header.html

Odmark

Will check it out! Im starting to think this engine is not stock, clocked it 0-62 mph and its about 6.6-6.8 seconds, with wheelspin up to 40mph on dry tarmac. All i installed was the HEI distributor

MDchanic

I'm starting to agree with you.

With an original 230HP 455, a '74 Custom Cruiser, at 5,400 pounds (2,400kg) shouldn't be able to do any better than 0-60 in 10 seconds.

To get 0-60 in 6.7 seconds, you'd need at least 365HP, which is an increase of over 50%.

What else can you tell us about this engine?

- Eric

Odmark

Its actually a -73, i was wrong in my first post, just bought it ^^ But makes no difference in power. Here is a video: , actually when i look closely 0-62 is about 7 sec, but still pretty fast, with proper traction i think i could easily get a under 7.

I really dont know much about it, its got stock exhaust manifolds, stock intake, an unknown edelbrock carb, and the thunder hei distributor. And its a bit of a junker really, far from mint condition but not really a wreck either. And sorry for the video quality, it was dark and i hade to use the cellphone light.

Edit: Also should add that the gauge is working fine, GPS checked it, less then 2 mph off.

MDchanic

Yup, that's a '73.

That didn't sound like a stock '73 motor to me, though.

Two questions:
What is your rear-end ratio (it sounded numerically higher than stock to me)?
Are you sure that your speedometer is accurate?

If someone had installed a numerically-higher rear and not changed the speedo gear, the car would accelerate faster, but the speedo would read falsely high.

- Eric

Odmark

Far as i know, the rear-end is stock, although it is imported from the US so someone over there could have rebuilt it.
But as my last edit said, i checked the speedometer with a GPS and its about 2 mph off.
And in daily traffic the speedometer also seems accurate according to the speed of the other cars, if you know what i mean.

MDchanic

That's one fast wagon, then.

- Eric

Odmark

Haha well i guess it is. Something must have been upgraded, though. Anyway, im pleased, still could do better though Thinking of making a large order from summit this summer, pistons, rods, heads, headers, intake, carb, cam everything. Would be pretty cool with a street/strip -73 estate.

Octania

I was going to suggest timing advance and perhaps vacuum advance routed to the manifold with mechanical advance and vacuum advance mechanisms altered to compensate, for improved economy and seat of the pants power feel.

Inexpensive and effective.

But, it appears you already have the thing pretty well optimized.

That's beasty fast.... for what it is