Hey guys, this is my first day on thirdgen. I have an auto transmission, 87 trans am 305 carbed. It's definitely on its last leg. So instead of grabbing another 305 from the same year, I decided on a freshly rebuilt, bored .040 over 350 that came from a 1991 chevy 1500 4wd so I'd have a better foundation for building if I wanted to do some more things to it in the future. So my questions are:

Does my car have any sort of ecu or chip or anything like that?

Will my intake and carb from the 305 bolt right onto the 350?

What all will i need? Trust me, I've looked at plenty of threads and all I found were tbi and tpi swaps.

This 350 engine is complete from oil pan, to heads, to valve covers, to flywheel, to serpentine belt and accessories. It has everything except the carb. It has a 2 barrel intake on it.

Take it easy on me, this is my first 3rd gen car, so my knowledge of them is very limited, and I need this engine swapped soon because I have to drive this car to school. I really need your help. Thanks guys!

 

Anything guys?

 

If your carb is stock, it is computer controlled.
Your intake and carb will bolt on to the 350.
From there, I am no help. I'm a fuel injected kind of guy.

 

Thanks Zane. Do you know if I'll need to change anything in the computer in order to make the swap work with my old carb?

 

I don't believe anything has to be changed with the computer per se.
It will probably actually run quite well as is(depending on the condition of the carb), but getting the carbed tuned at some point will help it run as optimal as possible.

 

OK thanks. The carb's in decent condition, but I could see a rebuild eventually. So i'll do the best I can with tuning it after the swap, but school's about to start so just getting it running decent and getting me to school is the priority. Will I need to use the 305 or 350 flywheel?

 

87 and 91 have the same 1 pce RMS flexplate/flywheel
The truck block may not have the ( inline ) holes for the 305 starter that goes with smaller 153 tooth flexplate so you may have no choice
but to use the larger 168 tooth flexplate and starter (offset holes ) that matches it

If there are 3 holes where the starter mounts to the block you have a choice

 

Well could I just put my 305's starter on the 350 and not even worry about flywheels?

 

The pic he posted has 3 holes. He's saying that your truck block may only have the 2 off set holes. If it has 3 holes use your 305 starter and flex plate, if it only has 2 holes use the truck starter and flex plate. Make sure if you use the truck flex plate that it has both bolt patterns which will be 6 holes.

 

Sorry I'm at work and it won't pull up pics, but I used my phone and I see it now. I hope it has 3 holes, the truck block didn't come with a starter lol. I'll check when I get home and let y'all know. Can you give me an estimate of how long this swap will take? Hours wise, asssuming I have all the parts and tools already

 

An experienced person ( usually persons) could start early one morning and be driving it by that night assuming all the parts are good and everything comes off w/o breaking, but most likely a couple of days if your not sure about everything.

 

Ok. I should have plenty of experienced help this weeked. So pretty much, just unbolt the 305, swap starter and flywheel if needed, swap 2 barrel intake and carb, and stick the 350 in?? Seems too simple... lol

 

It's that simple as long as everything unbolts decently easy. A 305 and 350 are identical in size, shape, whatever. It will be just like putting in another 305. The main thing you need to worry about is the flex plate/ starter problem.

 

I work at Volvo Penta and we use GM blocks for production so i know just how similar they are to each other. I just didn't know how that would transfer to a 3rd gen. Thanks a lot for your help guys, I'll be starting the swap soon and I'll keep y'all updated!

 

I would swap the compu carb for a regular Rochester or a Holley unless you have to have it for smog.

 

It's your car, but there are a lot of guys on here that advise against this especially with just a stock engine. The distributor has to be changed to a vacuum advance if you do.

 

I live in west TN and go to school in Tuscaloosa, Alabama, so no emissions to worry about. But with me being a broke college student, this is a budget swap, so I can't shell out that much for a carb just yet

 

So you should be aware Chevy have two different size flywheels with the matching starters I mentioned above that don't mix 'n match.
If you do end up with different size F/w then they can only be swapped with the matching starter

Because truck ,Ind and boat motors nearly always have the larger flywheel, GM saved $$ by only drilling the 2 holes required for that starter;
not 3 holes that allow you to fit either type

 

Well day 1 is down. All accessories are off, and the transmission will be unbolted Thursday

 

What do I do with all the smog pump junk? I don't want it

 

Well quick update since everyone is SO interested. Got the 350 in, it runs, but with kinks. First, my lights won't come on. Headlights won't open. Gauges in dash work, but their back lights won't come on. I checked all under dash fuses, they were all good. And the 305 had what i believe to be a mechanical fuel pump on the block, but when I hooked up the fuel line to the 350, it still got gas. So would I be correct in assuming there's an in-tank fuel pump? So we just stuck a piece of hose from the main line to the carb. Also, only the main fuel line is hooked up to the carb, the return line is still open. What do i do to close that off properly?

 

Some of these cars with carbs used both pumps. You probably should use both pumps as it was before.

 

The 350 didn't have the hole on the block machined for the external fuel pump like the 305 did

 

Ahh. Maybe it'll work w just the intank pump. Guess there's only one way to find out.

 

Yea I'm putting a regulator and a gauge in the line to be safe though. Everything should be done by tonight though, and I'll put up some pics

 

Did you get the light problem fixed? That seems like an odd problem to have with just an engine swap.

 

Oh I forgot about that. Yes I did, just had a couple wires not connected to the starter properly. Only thing left is connecting the fuel lines properly (using a Y for the main and return lines)

 

Does the fuel come out of the supply line all the time, or only when the key is on?

If the latter, then you probably have an in-tank pump. You need a proper regulator, like a Mallory 4309 or other return-type equivalent. A cheap $25 regulator will burn up the in-tank pump.

A "Y" will simply return the fuel to the tank.

 

Sorry I didn't jump right on...

The smog pump can be left off. Plug the fittings on the exhaust. Of course, this is completely illegal...

 

Well five7, the best things in life are usually either free, or illegal haha. And to answer your question, only when the key is on. I definitely have an in-tank pump.

 

Okay, be forewarned that the in-tank electric pump for carb'd vehicles was a "pusher" pump, intended to just help get fuel up to the mechanical pump and prevent vapor lock. It may or may not be sufficient to feed the carb by itself. If it doesn't, then it's a simple matter to change out the pump to one with more umph, like a TPI pump, or even a TBI replacement pump. Many would say if you're going through the hassle of replacing the pump, you might as well put in an upgrade aftermarket pump like the Walbro 255.

Regardless, you absolutely need a return-type regulator to control pressure to the carb, and keep the in-tank electric pump alive.

 

I hope the OP updates about this. I'm curious if the "pusher" pump will suffice or need upgraded.

 

Odds are I'll just get an electric in-line pump and return style regulator when I get the chance. But so far, the in tank pump has worked fine. I have an in-line gauge and it's running about 6 psi

 

I believe if you end up running an in-line pump you'll have to take the in-tank pump out and modify your pickup tube. It would probably be better to just replace the in-tank pump when/if necessary.

 

Does it stay at 6 psi under full power?

 

Update fellas. Well it did stay at 6. But she wouldn't start last night. I believe it's the in-tank pump. I'm getting an in-line pump because I REALLY don't want to drop the tank and mess with it, plus it's completely full of gas. And I'm running out of time and resources before school starts back

 

I might be wrong, but I still think you are going to have to drop the tank. The new pump is not going to be able to pull through the old one. I believe you have to remove the old pump and replace it with a line or otherwise modify the pickup tube.

 

Well I hate to inform you AGAIN that you are REALLY going to have to drop the tank anyway. Five7 kid, ZaneM, and myself have said in previous posts that you WILL have to address the in-tank pump regardless of what you do, whether its removing it and modifying the pickup tube, or putting a better pump in it. IMHO I'd put a FI pump in place of the carb "pusher" pump.

 

Actually that is not true. What is true is that it will run better with a vac advance dizzy but that is true with the compu carb too. And don't use a FI electric pump on a carbed motor you will have way too much pressure. Either go with a mechanical pump or replace your carbed in tank with another carbed in tank. A carb only needs to see about 6 psi of fuel pressure a FI pump will put on 30 to 45 psi

 

You are correct about the FI pump having too much pressure, but if he uses any kind of in-tank pump he needs a return style regulator, so he can turn the FP down to only have 6 psi at the carb.

 

What is the in-tank pump's job?

 

The in-tank pumps job is to push fuel ( in your cars case its job was to push fuel to the mechanical fuel pump on the side of the block that you no longer can use ). You would be so much better off if you would still use an in-tank pump becaus 1) you have to drop the tank regardless. 2) if you put an in-line pump in you have to hack up your fuel lines. 3) if you decide to still use an in-line pump you will have to remove the in-tank pump and modify your pickup tube or you'll quit picking up gas around 1/2 tank.

 

To um..uhh..pump gas?

 

I modified my 84 T/A with an In-tank 255lph electric pump. My electric pusher pump died and my new motor didn't support a mechanical pump. I dropped the tank and completely replaced the pickup and pump while leaving the sender on the car. thankfully the wiring was already in place, I just had to find out why it wasn't working. I then installed a return-style 4309 Mallory regulator to bring the pressure down to 6 PSI. It's been running clean for 3 years now.

 

This made me laugh hard enough my wife wanted to know what was so funny!

 

Funny man Ozz. I didn't know if it was designed to supply just to the next pump, or all the way to the carb. But why would it stop picking up gas around 1/2 tank?

 

Because if you remove the in-tank pump and dnt't lengthen the pickup tube it'll be too short to pick up gas much deeper than 1/2 tank.

 

So what stops me from using the in-tank pump and an inline electric pump in unison?

 

 

The in-tank pump pushes fuel which is easier than pulling fuel through. I burned up 3 in-line pumps. They pull the fuel up and out of the top of the tank then down to the puller pump. When the pump StopsThe fuel retreats into the tank so be very time you start the car the pump runs dry thus heating up the pump possibly burning it out. After 3 pumps it was cheaper to install a factory style in tank pump.