Swapping intakes

[oldwhity]

   I was reading the thread on dual plane intakes and thought down the road that it might be a cheap upgrade for an unmodified crate 305. Maybe I would even notice a difference in mpg's and or a little umph. My question is, if your just swapping intakes, will the carb need to be readjusted? Thanks

Rob

[Captkaos]

If it is running ok now, you probably want have to mess with it. 

[Russ130]

What Capt. says is true however it doesn't mean you can't gain anything by tuning it up with the new intake on. But unless you really know what you are doing I'd leave it alone.

[VileZambonie]

Changing intakes without doing any other modifications would be kind of a waste. I agree I'd leave it alone.

[oldwhity]

If it is running ok now, you probably wont have to mess with it. 

So it's ok to change intakes if I find one and just put the untouched Quad back on? It runs fine carb wise now.

What Capt. says is true however it doesn't mean you can't gain anything by tuning it up with the new intake on. But unless you really know what you are doing I'd leave it alone.

By the last statement you mean tuning the carb right or swaping intakes? I can tear down and reassemble, it's the fine tuning where I lack.

Changing intakes without doing any other modifications would be kind of a waste. I agree I'd leave it alone.

No benefits? What would you suggest? A bigger carb? I do plan on doing the exhaust down the road.

Thanks fellas
Rob

[eventhorizon66]

Exhaust is a great place to start.  Headers to tailpipe.

What Vile meant was on a bone stock engine an intake swap will yield minimal gains.  But if you had a 350 with good flowing heads, some compression, and a healthy cam, then you would be foolish not to run an good aftermarket intake.  But as it stands now your biggest restriction in the intake system is the cylinder heads not the intake manifold.

[oldwhity]

Yeah, i'll probably try to find a cheap set of full length headers and 40series Flows with 2.5 pipe like I did for the 81.

[eventhorizon66]

Well don't go too cheap or you'll just give yourself headaches.  Look for 3/8" thick flanges and quality welds.

[Russ130]

I was referring to the fine tuning aspects of a carb. Tearing apart and rebuilding a carb does not qualify you to fine tune one and I don't mean this in a bad way either. Fine tuning requires a knowledge of what the engine wants and needs at several different points in its operating range and adjusting the carb to meet those needs at those times.

[Marc]

Aren't the stock intakes dual-plane intakes anyway?

[VileZambonie]

Yes they are dual plane. If you are going to make the engine breathe to increase volumetric efficiency you need to be able to get more IN and more OUT in the same amount of time. So if you are going to modify the intake you need to modify the exhaust etc.

[oldwhity]

I'm familiar with the whole "more in more out". I was just going to take baby steps getting there.

As for the stock intake, they are dual plane?! Well if it is then I'll just get a better breather and save for the exhaust.

Are they really On a 305?

[Russ130]

On a typical smog engine the main restriction is the exhaust not the heads or carb or intake.

Just because a factory engine comes with a dual plane doesn't mean they are on the same level as a good aftermarket intake.

Going to a bigger carb would be a huge mistake and also the most common mistake followed closely by too much cam.

Changing the breather is not going to do anything for the engine. Thats not what he meant. What he meant was that air comes in through the carb then intake and then into the head and finally into the cylinder. You have combustion and that air which is not burnt gas goes through the exhaust port of the head and into the exhaust manifold then through the pipes then through the cat if you have one then through the muffler and finally exits into the outside air. That is the process of an engine breathing. In order to build power you have to eliminate any bottle necks in this path. The exhaust side is always the first place to start since the manifolds, mufflers and cats are serious bottle necks.

The best bang for your buck is going to be headers and free flowing mufflers and upgrading to true dual exhaust. You will see more gains here than any carb/manifold combo at or around the stock level.

So you have a performer intake? Put it on, leave the carb alone or get a small squarebore carb. You aren't going to realize any real power gains but when you upgrade the exhaust you will realize even more of a gain than if you did the exhaust first. After that it may be time to think about a cam swap.

[oldwhity]

Changing the breather is not going to do anything for the engine. Thats not what he meant. What he meant was that air comes in through the carb then intake and then into the head and finally into the cylinder. You have combustion and that air which is not burnt gas goes through the exhaust port of the head and into the exhaust manifold then through the pipes then through the cat if you have one then through the muffler and finally exits into the outside air. That is the process of an engine breathing. In order to build power you have to eliminate any bottle necks in this path. The exhaust side is always the first place to start since the manifolds, mufflers and cats are serious bottle necks.

I'm also familiar with that. What I probably should've said was that I needed a new air filter. That was something that I didn't replace when I got the truck. I know that's not what Vile meant.

So you have a performer intake? Put it on, leave the carb alone or get a small squarebore carb.

Thanks Russ, that's what I was looking for.This was just a thought, if I should happen to run across an intake, would it be worth it in the long run(turns out not too beneficial)? I wasn't looking to make a powerhouse or try to make a 305 something that it's not. If I can squeeze a little mileage out of it then great. Maybe one day i'll replace it with a 350 so i'm not looking to put too much into it that I can't swap over. Thanks for you help guys