O.K., I need all the opinions you can give me on this one.
I'm looking to purchase a '69 Bird with a 350 2 barrel. Horsepower around 265 as you know.

If I changed out the intake manifold on this 350 engine for a intake that would take a 4 barrel carb., would I gain any horsepower and if so how much?

Could I bring the HP up to around 300 or wouldn't it be possible? What if I also added headers? Would that boost the HP?

Or, would it be better to find a 400 engine with a 4 barrel
and replace it with the 350?

If the new intake manifold idea would work, then what manufacturer would you suggest and also what manufacturer of the new 4 barrel would you suggest?

It seems like 350's are fairly common to find, but 400's are a little more difficult to come by. That's why I'm considering a 350, but I want to boost the horses. I'm not a hot-rodder by any means, I just like to have some more engine response when I start out and passing on the freeways.

Anyway, would appreciate anyone's feedback on this. Thanks.

Upgrade your carb to a stock Quadrajet and get a good stock 4-brl intake. Upgrade your cam and replace timing chain while your at it. Put on the long branch Pontiac exhaust manifolds or put on headers. If you have a Auto then put in a shift kit.

IMO

Great timing. If you do not already have a subscription, I suggest you pick up the latest copy of High Performance Pontiac.

There was a detailed article in it about "hot rodding" a Pontiac 350.

Headers (or long branch manifolds), properly designed exhaust and 4bbl conversion should get you close.

Best to choose the carburetor that you, or someone who will be helping you, is comfortable tuning. Either a square bore 500-670 cfm range or a spreadbore 600-750cfm would work well (vacuum operated secondaries). If going with a Qjet, a stock 4bbl intake would be cheap and effective. Otherwise you could go with an Edelbrock Performer (inexpensive used).

Headers, do not use larger than a 3" collector (some have 3.5"). Exhaust should be a 2.25 to 2.5" dual system with H-pipe or crossover.

Agreed with most of this. In particular, replace the cam. A 2-bbl. engine with a 4-bbl. carb will "pick up" only a minor amount, and may actually HURT overall performance. If compression is "high" (over 9.5:1), use something like a Melling SPC-7 (068 Pontiac cam) or SPC-3 (744 Pontiac cam). If compression is lower, use Comp XE256H or (a little "bigger") XE262H.

The factory Q-Jet intake is excellent. Unlike other engine families, Pontiac did a good job engineering their manifolds. The 350 doesn't "need" the 800 CFM carb, so an earlier Q-Jet (pre-73) would be ideal. One with "notches" cut in the secondary air valve are intended for "performance" use, and may be the best choice.

Jim

Gus nailed this one dead on. All of the above is the answer you are looking for. Even just a stock Q-jet and stock intake will help tremendously...

O.K., guys, I couldn't ask for more than these answers.
Your help is greatly appreciated!

Frank S.

Stupid question, but will the intake manifold off a 400 fit a 350?

Should bolt right on. Just make sure you have the right gaskets for the heads that you are bolting to. I think the only differance is is in the exhaust pre-heat area. The guy that rebuilt my 350 put the wrong gaskets in and it sounded like crap.

Yes! I put the intake off my 400 from the Bird and bolted it right on to the 326 in the LeMans. No issues at all and a MASSIVE improvement...

i saw this reply & bought the new issue of HPP . my bird is a 350 2bbl also i bought a 4bbl pontiac intake off ebay , & i am tempted with converting mine later to 4bbl . that is a good article on the 350 hop-up.

Well, as I mentioned before, adding a stock 4bbl intake and a stock Q-jet to my 326 was a HUGE upgrade and a HUGE success! An upgrade this quick and easy and fairly affordable doesn't come along too often. This one is a breeze with resounding benefits!

So Frank... how did it work out for ya???

Frank died of necropostalia.

To think, I could have healed him with ressurectopostation

Six posts since 2002. Frank, we hardly knew ye.