I have a 91 rs with a 305 throttle body I want to a 350 in it...I kno I can just swap intakes an stuff but I want to put a little bigger cam into it an do a little head work....can I still keep it throttle body with the factory unit or not? thanks

 

i would stay thorttle body, better fuel economy more reliable, plus if you have emissions testing they want to do a visual check, u can use the 305 throttle body but it wont be as powerfull may run a little lean, but it wont be an issue, u can use any throttle body from any 350 tho, well u just need the injectors but i just swap the whole thing.

 

Depends on your definition of "a little bigger", and your tuning skillz.

No you can't really keep the 305 TB. You need AT LEAST a 350 one, with its injector pod. Which is no biggie; there's like BILLIONS of em in junkyards on trucks & Caprices. You'll also need the 350 knock sensor, "chip" (if you want to try the stock route), and ESC module. The B-body (Caprice/Roadmonster) ones are said to be better for the purpose.

 

iv ran several 350 tbi motors with 305 top end and ecu, u shouldnt have an issue but u wont get the full potential out of it...

 

I just want a good loopy cam an shorty headers...I thought bout going to carb but I don't want to do that ive done it before an I like the ease of the throttle body...I kno id need to change the chip in the computer an knock sensor bcz of the bore size but the injectors...do I need to change injectors or just change the whole thing out...and whats the esc module?

 

yea if your going to do all that then your definatly going to need a 350 throttle body

esc is the electronic spark control module


and you can change just the injectors but id do the whole thing i beleive 350 throttle bodies boring is slightly larger, meaning higher CFM

 

The 350 an the 305 throttle body is the same damn thing .. The only difference is the injectors all u gotta do is get some 350 injectors and put them in ur current injector pod on the throttle body u already have and poof u have a 350 throttle body ... And if u wanna get technical u really don't even gotta do that u can get a fuel pressure regulator and bump the fuel pressure up to give it the fuel it need and u can just use the 305 injectors .. All u need is the knock sensor and a tune

 

^ what he said, if u skip the cam step or keep it a mild cam u may not need a tune, to bad your not mass air flow

 

Right:

Which means, you gotta get a 350 TB w injector pod. Generally anyway, as that's how the buzzards will allow their nest to be robbed.

So why take apart 2 throttle bodies and exchange some parts? That's EXTRA EFFORT: ya gotta pop th eTB off and clean it up ANYWAY, why not just swap the whole thing out? I'm lazy, ya see; no point in doing a bunch of unnecessary work. There, I said the dirty word, now my momma is going to make me wash my keyboard out with soap.

And on top of all that, why take the risk that they're NOT the same? Just stick a 350 TB on your 350 and be done with it and move on. No worries about whether it's "the same" or not.

Can't really bump the FP up that much. For a wimpy stock 350, maybe sometimes, just barely; anything more, won't be enough.

A cam with lots of "lope" is going to be hard to tune. Unless you're sure of your mad tunning skillllzzz, best to avoid that.

 

I don't want not 600 lift cam I just want a lope...I kno just sticking a stock 350 in it an swapping the injectors knock sensor chip an esc will get the car running but how much can the throttle body do with any motor work?or how much cam can I run with the throttle body an computer handle without a custom tune or anythimg?

 

they have a slight lope from the factory, well tpi's do, how much of a lope are you looking for maybe we can point you in the direction of a cam, post a link to a vid of how you want your car to sound

 

well whats the best kind of cam to run? I mean ive had a 89 Camaro that I built a 350 with a 520 lift thumper cam but it was carbureted can I run something like that an keep my throttle body?

 

uhh how do i put this, no, unless u have an AMAZING tuning guy, speed density efi systems dont seem to like giant cams, altho my knowledge on this is limited, if you were mass air flow it wouldnt be much of an issue..... something to do with the vacuum at idle and such.

theres alot MORE you can do to get the same hp then throwing a giant cam in it, a GOOD cam with a GOOD intake manifold (yes you can use a single/dual plane intake for a carb with ur throttle body, you just need an adapter plate) some head work, and headers, and such, can get you in the same power range your probably lookiong for.

speaking of which, what kinda power are you trying to make? do you want a giant cam just for the sound? headers make a hell of a difference in sound, especially if you have exhuast cuttouts

 

my exhaust right now is manifolds ypipe cat then after the rear end ypipe then 2 pipes off the ypipe out the back ill be keeping the same setup once the 350 gets in it except putting shorty headers on it....I just really want to kno how much I can do to the motor before I cant use my throttle body....an what cam is a good cam for throttle body ive never built a motor with throttle body before

 

The throttle body doesn't care; but the chip programming (aka "tune") does.

Anything that upsets the relationship of vacuum, throttle position, and RPM, will confuse the computer.

In a 350, about as far as you can go with the cam on the stock TBI tune without running into MAJOR driveability problems like surging idle, dying at red lights, impossibly bad gas mileage, etc. etc. etc., is something in the 212° @ .050" range; and that, only if you keep the lobe separation above 112° or preferably 114°.

The ABSOLUTE WORST way to buy a cam, GUARANTEED to cause problems, is for the "sound". I guess it's just built-in punishment for poseurs.

I'd suggest this one right here. http://www.summitracing.com/parts/cca-08-416-8 Ignore the "marine" designation; it works GREAT in street cars. Guess how I know.

 

did u use stock lifters an rockers?

 

bcz I want a 350 that I can use my throttle body an computer....I want to run shorty headers a cam I just didn't kno if the throttle body an computer "chip" would handle it

 

It's easier to replace injectors than it is to remove the throttle body ... And the injector pod don't need to b changed to put 350 injectors on a 305 TB ... And yes the FP can b increased significantly ... I'm running 30psi fuel pressure on 350 injectors on my 305 and I might still need more fuel pressure

 

I can use a fuel pressure regulator instead of getting 350 injectors? or is it beter to get the injectors? sry for askin these questions ive never done nothing with throttle body ive always went back to carb...lol....

 

no its not better to use the fuel regulator, do like somone prev posted "use the whole 350 tb, save urself time and unneccessary work"

 

how much power will the stock throttle body injectors an computer handle without it needing more fuel?

 

Power comes from fuel. Power IS IN fuel.

The reason your car only makes however much power it does, is because that's all the fuel it burns.

How much more power do you expect to make? That's how much more fuel you will need.

But what's holding you back isn't "fuel" itself, that is, you can't accomplish much just by jamming bigger injectors on it; it's the engine's ability to BURN it. Burning fuel requires air. THe more fuel you want to burn, the more air you need to go with it. Likewise, you can't just put more fuel and air INTO the motor; in order to get more IN, you have to get all the by-products OUT. Enter, EXHAUST. Even before you put in a 350, your FIRST modification to your car should be the exhaust system. EVERY PIECE from the heads to the bumper. No, I'm not talking about "cherry bombs" or "straight pipes" or hacking off the catalytic converter; the best way is, a set of chassis-specific headers FOR THESE CARS (NOT "universal"), WITH the Y-pipe that comes with them; a new cat; and a complete boxed cat-back. All for one of these cars, BUT NOT for a TBI 305. I'd suggest ordering the stuff for about a 89 350 TPI. Then get the headers and Y-pipe ceramic-coated (or buy them already done). It makes HUGE difference, not so much in "power", as in, the longevity of EVERYTHING ELSE; not having everything under your hood (wires, connectors, plastic things, sensors, hoses, etc.) being baked by 1000° headers all the time, makes a BIG difference in the operating cost and the reliability of a car with headers.

Without fixing that, the crap you have now, will strangle a 350 even worse than it's already strangling your 305.

 

You need to make a list of everything you want to do and figure in what your budget will be.

You want to go with a 350 with a cam. Well here's a couple tips for you. If you expect to make power gains with a cam you need to open up the heads. The most power will be had through an aftermarket set of heads but for a street car ported heads, new valve seals, and a valve spring that will handle your cam will make good power.

Now for the cam. You have options. Personally IMO you will want to go with something in the neighborhood of the LT4 hot cam. What I would do is call a company like comp cams tell them the application IE its a gm TBI 350 with ported heads headers back exhaust and your looking for a good street able cam that will make power and they will suggest an off the shelf cam or a custom grind.

You should also look at either porting your TBI lower manifold OR picking up a highflow unit. They can be picked up used for a decent price.

You will need to get a decent set of shorty headers with a y pipe. I suggest hooker 2055's. Get a high flow 3 inch in 3 inch out cat and a cat back exhaust. Which ever brand cat back you like will be fine. Just make sure your inlet is 3 inch. Try to avoid the OBX exhaust as it fits like crap and IMO is way to quiet and doesn't flow all that well

 

Yup; gotta have a cam; won't run without one.

First and foremost though, gotta make sure the compression is somewhat correct, which starts with the short block. NO "rebuilder" deep-dish .020" deck clearance smogger turd replacement pistons!!!! Then, the one thing most responsible for power output: HEADS. Reason being, all that big shiny stuff sitting up in top of the motor that's eeeeeeeezie to un-bolt and re-bolt, and gives you all that spank-off satisfaction of opening the hood and seeing BLING, is NOT the ultimate limit to how much fuel you can move through the motor. The HEADS are.

Don't mess with any stock ones, especially not if it involves putting money into them. Reason being, by the time you work up a set of heads to be "competitive", i.e. cut the pockets for larger springs, machine the bosses for screw-in studs & guide plates, cutting down the valve guides for clearance and to allow GOOD seals to fit, replace the stock valves with something decent, and port them, you'll have basically 80% of the cost of aftermarket ones ties up in them; except instead of having GOOD heads, you'll still just have stock ones only with too much money tied up in them.

ANY "TBI" heads are THE ABSOLUTE WORST for a "performance" application. Well, maybe it's a tie for "worst", the other candidate being, 70s smoggers like 882, 993, or 624. That includes 350 TBI heads as well as TBI 305 heads. They are not suitable for improvement. Don't spend a penny on them.

TBI doesn't have a "lower manifold"; only, "the" manifold. I'd recommend strongly against messing with a stock one. Also, against buying a "TBI" one. Instead, buy a good 4-bbl one, and put a TBI adapter on top. It'll cost less than a "TBI" one and will run circles around it. TBI ones are for people who don't know any better, not for intelligent people such as those who LEARN from what they see here on this forum.

 

ive got a edelbrock performer air gap intake ive had for another project.....with that intake work? an ive got stock exhaust except for i took the muffler off put a y pipe there an dualed it off the y pipe.....an that's wut i want is to port the intake an exhaust runners on the heads an port the intake runners....im just afraid that i wont be able to use my throttle body once im done with the engine bcz don't get me wrong i love carburetors i just like the kinda ease of throttle body