70olds455

Does any one know if the Offenhauser Intake #5822 (Square-bore) is any good for performance? It is a flat looking intake and says offenhauser 360 on it. My brother has this intake on his 71 cutlass. The car has a rebuilt 1970 engine with #6 heads and a mild cam. He says he cannot spin the tires and that the car does not feel as fast as it should be. The car also has 600 cfm Edelbrock carb with electric choke. Do you think the intake is hurting performance or maybe the carb is the problem?

Nasty455

I doubt the intake is at fault,they are simple in operation,
As long as it's dual plane and the rpm matches the engine output.
If its a single plane manifold they come alive about 3000 rpm.
I'm guessing if he is using the stock carb,it may need too be re jetted or tuned.
I was inspecting my new manifold,and the carb plenum is at least twice the size as the stock intake.
Vacuum secondaries will adjust fuel flow per airflow,but the carb may now be too small.

jag1886

Nothing wrong with that intake, just Offy's rendition of a dual plane high rise.

joe_padavano

No, it isn't. The Offy 360 series is a single plane intake. Flat, just a big plenum. Won't help torque and won't help top end. I would not recommend it.

Rickman48

Stack 4" of open spacers on it - good for both ends!!

70olds455

So it sounds like that intake might not be good for performance. Do you think that carb is a good match for that engine. I am under the impression that the 600 cfm Edelbrock carb was made more for fuel economy than performance.

cutlassefi

Thank you Joe, you took the words right out of my mouth.

What gear is in it? And that small carb, in theory, should make it more responsive not less.

70olds455

The car has the stock 2.73 gears.

Nasty455

Single plane intakes have one large plenum and feed all 8 cylinders through it.
Low end suffers,but once the motor is turning some rpm,performance should be better.
Low compression,stock rear and converter,and city driving all add up to a uninspiring experience.

Run to Rund

like Joe P said! Whether the single or dual 4 configuration, the runners are too short and the plenum is too big.

oldsmobum

Your car is a slug because of the way its geared. Not much will roast tires with a 2.73. I would track down a lower rear end preferably posi...

jag1886

In my own defense that intake isn't really a single or a dual plane manifold (or as I said Offy's rendition of a dual plane) it's some sort of Hybrid (if you can call anything Offy built a Hybrid). They did work well back in the day, I know I sold them for quite a few years in the 70's, as far as not recommending them today I have to agree with all the new manifolds that are available these days but he already has one and I really doubt the manifold has anything to do with not being able to turn the tires on his car.
If you don't have much money and you find one cheap they allow you to bolt on a Holley carb and they work fine, just not optimally.

joe_padavano

Sorry, but you are confusing the Offy 180 with the Offy 360. The 360 is a single plane manifold, period. The Offy 180 is the hybrid you are thinking of. That manifold was essentially two single plane intakes stacked one on top the other. On the 180 intake, the upper single plane intake was fed by the primary side of the carb and the lower was fed by the secondary side.

joe_padavano

Here's a picture of the ports on an Offy 180 (for a BBC)

jag1886

I'm sorry but an Offy 360 is divided down the center it is called an divided open plenum there is a plenum for the left side of the engine and a plenum for the right side. If you don't believe me maybe you should look it up before making your period statements.
That goofy look dual port manifold was called the Dual Port not the 180.
I realize you know a lot but you don't know everything.

captjim

Not true, it is all about the combination. My wife had a 77 Supreme (heavy at 4100 lbs) with a mild 350 and 2.41s and it would roast the tires. Same for my G-body with a 355 which had a similar, if not higher, gear.

oldsmobum

A 3 foot skid after a neutral drop is not roasting tires. I know enough to know what you just alleged is not likely. If you are suggesting that he should do anything but change the rear axle ratio you are wasting his time and potentially his money.

Nasty455

The RPM Of engine,cam and torque converter can be made to smoke the tires pretty good,if they are matched.
The car just wont have any top end.
The offy photo does show how modified intake ports can be tailored,but it's still feeding only one cylinder,probably just to smooth the airflow.
How about a plenum photo?
A carb spacer should make for better performance,if you have the hood clearance.

captjim

Exactly.

captjim

Calling me a liar? I promise you both cars would fry them from an idle. I did not suggest he do anything, I just disagree with your statement.

Run to Rund

Here is a regular Offy 360 deg. as Joe P described:
http://www.ebay.com/itm/Offenhauser-...item2a1778b04e

and here is an Offy "dual port"
http://www.ebay.com/itm/offenhauser-...item43b0137c33

another 360 dual port:
http://www.ebay.com/itm/Offenhauser-...item53eb646e0f

here was an article on the Offy 360 dual port:
http://www.ebay.com/itm/HOT-ROD-MARC...item231626d629

I don't recall Offy advertising their dual ports as 180's

70olds455

He is going to be replacing the offenhauser intake with a better intake. Most likely he will get a edelbrock performer intake for it. His car also has a high compression engine so it should be faster that what it currently is. Even my 71 cutlass with a stock engine and 2.73 gears will spin the tires from a stop.

jims2000lt

Edelbrock performer= big block. Edelbrock RPM performer= small block.

oldsmobum

Sorry its been a rough couple of weeks and I've been a dick.

Fastback71

will a performer rpm respond well with stock everything except headers and exhaust? its my daily driver and want to squeeze as much as i can out if it with bolt ons. future plans include eddy 600, HEI, Converter, posi, then later on I'm going for the whole RPM kit w/ aluminum heads port matched to my intake

Run to Rund

For your application, just find a pre-egr stock quadrajet intake (1966-72 model years). Cheap, seals easily to the heads with the stock gasket. I doubt you will feel or get any noticeable gain from an aftermarket intake.

L69

Agree. Low compression and Low (number) gears, a stock pre egr 4V is the best and most cost effective way to go. If you want an after market dual plane I have a performer 350 from Edelbrock for $150, and also a 350 68 stock 4V for 60.00. Let me know if your interested.
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