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Some 350 questions.

nad

nad

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Okay, so I'm buying a carburated 350 for my Jimmy today, and I was wondering, how can I tell if the motor is for sure a 350 and not a 305? Also, since it's carburated, can I just swap my intake and throttle body from my 305 onto it, or will I need to swap cams and other parts?

If I just leave the carburater on the motor and use it as a carburated motor, what will I have to change? The guy I'm buying it from says the carb is bad because it cuts out at WOT. But if I rebuild the carb and drop it in like that, will I need to change fuel lines, etc?

Thanks for the help guys.
 
I don't know about the cam, but I have been told that the heads have to be swapped to use the TBI. As far as I know the casting numbers are going to be the only way to tell for certain that it is a 350. I don't believe there is any way to tell from the outside of the motor.

Fuel lines are a question for someone more knowledable than me.
 
best way to tell the difference between a 305 and a 350 is to pop off a head and measure the bore. but if memory serves, there should be a casting mark on the back of the engine that will tell you if its a GM 5.0 LG motor, i cant remember exactly where it is, but it should be there.

as for your induction questions, the easiest thing to do is rebuild or swap out the carb, and just run fuel to the mechanical pump and 12v to the ignition system and take off. if you want to run the TBI, you dont have to swap cams, as the TBI operates off of a mass air flow system which will adapt to the different cam profile. also you may run into prolems swapping the cam if the engines are on different sides of the 87 model year. if the tbi 305 is 87 or newer, chances are its a factory hydrolic roller cam, where as the carbed 350 is most likely pre 87 and therefore will be a flat tappit engine. the two cams are not interchangeable without a special kit.

youll also have to swap over all the nessesary sensors, electronics, and computers that are on the 305 to the 350, time consuming but not hard, especially if you have the motors sitting side by side. i would recomend running the tbi over the carb any day of the week. only upgrade you might want to do is to find a 350 throttle body or an aftermarket replacement to match the flow demands of the extra 45 cid.
 
You need to change the knock sensor, PROM, and if TBI has one, the ESC.

Injectors, not sure of, someone should be able to answer that. I *think* 305 were different than 350's.
 
i swapped my 89 tbi and heads from my 350 to my 76 400 sbc. all the stuff is swapable. 305 350 400 i had to drill vent holes in the block for my heads but that is it
 
Fitting and working right are entirely different animals. :)

Datalogs or a dyno session are the only ways to prove one way or the other, besides using a completely stock setup.
 
The motor is from a '78. It's a '78 carburated 350 and I want to somehow swap it into my Jimmy with a newer 305. The 305 is indeed 87 or newer. I want to do this with as little work as possible.

Should I just get the 305 rebuilt? I can get it done for a decent price, but I just didn't know if the power difference was that great between and 350 and 305. Plus I wanted the upgradability of a 350.

Any more advice would be great.
 
Piece of cake, ur truck already has all of the computer and tbi so all u have to do is use ur 305 heads and intake and the old 78 350 block. Ur gona need new intake gaskets, (when u ask the parts guy tell them they are for a 87 305 ) head gaskets, valve cover gaskets, water pump etc. all of ur assesories should bolt up.
 
you also might concider just putting some performance parts on the 305 for now depending on how much youre lookin to put into that older 350. i would personally prefer to have a hydrolic roller block over an older flat tappet, even if it was a 305. the 305 has a bad rap as a dog motor because of its small bore and 45cid less, but they can be built to run, and the parts will all transfer over to a 350 if you want to do that in the future. personally i would keep the 305 and play with it. there are several dyno tests after a head/cam/intake swap that added 150hp to a 305, putting it at around 350hp. i think that particular one was carbed, but it was definatly built on the cheap. 450 on a pair of heads, cam shaft kit (call it 300) and intake 300 and youre lookin at just a hair over 1000 bucks, and youve added at least 100hp to the base line. then add some headers, an exhaust, and that 305 will run just fine.

the big thing here for me would be the newer block with the roller cam and the much less leak prone one peice rear main seal.
 
I will probably just get my 305 rebuilt. It shouldn't cost too much more than getting a new motor put in and swapping all the stuff I have to swap...
 
Why don't you just buy a crate TBI 350 motor? It will cost the same or less than getting your 305 rebuilt. Everything will bolt right up. All you need to change is your injectors. You can get new 55lbhr injectors for a 350 for around $100.oo. IMHO that is the easist and cheapest route to more power.
 
The 305 is in the middle of being rebuilt, and I'm having people trying to convince me that I'm wasting my money because it's such an old truck and it's not worth putting the money into.

Will the 305 put out decent power if it's rebuilt to stock specs? I'm not gonna be using it as a rock crawler or anything, but mostly just a weekend warrior/dd. It'll see a little mud and some rough terrain, but nothing too extreme. What are some bolt on power adders I can get?

Thanks guys.
 
Glad to hear you're having the original engine rebuilt as there is alot of incorrect info in this thread. With the incorrect info you would have had a nightmare on your hands had you decided to use the 350 and listen to some of the advice that was given here.

As far as bolt on power, not alot of power to be had but there is some. I would start with the injector pod spacer (http://cfm-tech.com/catalog/air_intake_-_injector_spacer_549426.htm), then the air enhancer (http://cfm-tech.com/catalog/air_intake_-_hypertech_power_charger_-_4_3_5_0_5_7_full_size_truck_549430.htm), and also an adjustable fuel pressure regulator (http://cfm-tech.com/catalog/fuel_-_cfm-tech_adjustable_fuel_pressure_regulator_for_gm_tbi_549435.htm) and fuel guage (http://cfm-tech.com/catalog/fuel_-_cfm-tech_fuel_psi_adapter_2940807.htm). If the truck doesn't have headers that will probably be your biggest power increase if you also have the exhaust redone at the same time with a hi-flow cat and a good muffler.
 
Nevermind, found out the block on my 305 was cracked and it would take a lot more work and money to rebuild than I want to deal with.

So it's back to the drawing board. Any ideas? My buddy is still trying to sell me his carburated 350.
 
Casting numbers on the block will tell you 305 or 350.

Biggest problem for EFI is the cam, if it's a stock cam, it will probably bolt right in and run pretty darn decent, provided you get the EFI 350 stuff.

I drove my 305 for YEARS and although it didn't move the truck quickly, it wasn't bad.
 
cam swaps so long as they are somewhat close to the factory setup, (throwing in a crazy bumpy .6in lift cam wont work) the TBI setup will adapt pretty well to it. the mass air flow system measure airflow and taylors the fuel curve to match, its systems like TPI that are a speed density system that dont adapt well to changes in airflow (either heads, intake or cam)
 
K5dreamer said:
cam swaps so long as they are somewhat close to the factory setup, (throwing in a crazy bumpy .6in lift cam wont work) the TBI setup will adapt pretty well to it. the mass air flow system measure airflow and taylors the fuel curve to match, its systems like TPI that are a speed density system that dont adapt well to changes in airflow (either heads, intake or cam)
Click to expand...

ALL TBI systems are speed density.
 
Okay well I ended up buying a 350 TBI that will bolt right into my truck. Had 80K original miles on it, completely stock for $350. Hopefully now I can get some bolt on performance for it. Any suggestions?
 
tbi spacer
cam
heads
intake
holly tbi
checkout summit racing they have a bunch of stuff

as for mine it is all stock with a spacer stock heads and cam with good set of headers and exhaust. should run nice for you.
depends how much power you really want or need
 
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