Anyone done this?

Has anyone here throw a carbed 350 into a 4th gen, replacing either the LT1 or LS1.

I was thinking about going carb in my 4th. What kind of complications might I have?

one will be the fuel pump, as 40 PSI is useless for a carbed setup.

Can I use my LT1 block, or will it be easier to get a whole new starting point?

as far as the wiring goes... Most of it will not be needed, what kind of stuff will i need to keep?

Could I just take out the Engine portion if the harness and wire it up myself?

And last question.. Could you fit a Big Block underhood without cutting the firewall?

[JoeliusZ28]

John (wasjo with some number following it) on this site put a gen 1 SBC in his firebird so its definitely possible.

i would just gut all the wiring and re-wire what you need.

[esoteric18]

Ive heard of it done, but what is the reason? is it to less complicate a upgraded engine swap

[Derek]

I'm sure its been done, but I'm not sure why you'd want to? seems like a lot of hassle, time, and money, to put in a motor that could be more unreliable and less fuel efficient. I guess I just hear of lots of people having trouble keeping their carbed cars dialed in, while on EFI the computer does the work.

[Phantom409]

It's possible but a lot of work.

[98blackbeauty]

If you have a stick it would be easier. An auto would be a lot of work since the shift points are controled by computer.
Like Derik said why would you want to do this? the long engine life we enjoy is because of the electronic controls and can be more powerful than a carbed engine.
It definately would be unique.

[wasjo6431]

Ive done the SBC gen 1 350 carbed swap with alot of photos. when running a carb you have to cut into the cowl in the engine bay. i havent seen one yet without it cut into. The big block will fit without cutting the firewall GM had 572's in three 4th gens to show it can be done. they used to keep them at the tech center. I used wires in the original harness the first time around for my engine. and for my guages rather tahn running new ones. since ive removed most of the harness and re ran the wires. You cant use the stock gages at least i wasnt able to . you might be able to find a signal amplifier to use the stock ones as the signal was fed threw the ecu. The 4l60e can be used but you will need a piggy back computer to run it and tune it. I went with a TH350 id suggest a 700R4 though unless your giong straight drag setup then the th350 or th400 depending on your engine if you go big block def the 400. Wiring is simple. i used orignally the stock v6 fuel pump i had in my tank. you can tone it down with a regulator make sure you run a good sized return line from the regulator throught he stock return as its what makes sure the pump stays from overheating depending on the power your putting yeah the pump is 40+psi to start with but its low GPH i have since sumped my tank and im running two pumps one dedicated for motor and one dedicated for nitrous.
When going with this engine swap its also smart to use an aftermarket or make your own Engine cradleyou can modify engine mounts to mount to the oringal LT1 or LS1 k member but weight savings and strengthening id go with a tubular K member from bmr or somewhere else. i used bmr's along with a torque arm no longer mounted to the trans as you kinda will have trouble finding a way to maintain one on the TH350 or Th 400 also you will need to have a new driveshaft cut for the TH350 even with the long tailshaft. I used BMR trak Pak for my rear setup. along with now a moser 9 inch built by Scott from the site. with 4.58 gears. i also have Offset tubular LCA's fully adjustable. a 10 pt cage. but this is all extras you wont need mostly for the engine the K memeber and cutting into the cowel and part in to the hood you have to remove some of the support from the hood. even if you go with the cowl hoods they have the strengthening crash support going across them with a carb you will need to remove it as it will bump into hte carb adn restrict airflow depending on what intake height you are sitting on. If you want to talk more in dept about it Msg me on here and ill give you my number.

[wasjo6431]

If you have a stick it would be easier. An auto would be a lot of work since the shift points are controled by computer.
Like Derik said why would you want to do this? the long engine life we enjoy is because of the electronic controls and can be more powerful than a carbed engine.
It definately would be unique.

i Did it And youve seen and heard mine As far as fuel efficiency if your thinking of doing it your not planning on making a fuel efficient car. something tha ttakes about a gallon to two to go down the track possibly if you are thinking big block. I could make it from my house to lapeer about 50 miles on a tank of 15 gallons with my th 350 and have about 5 gallons to race and get back to a gas station in imlay city for the ride home.

Performance wise its much much cheaper. and so much easier to trouble shoot. theres three things it needs air/fuel/spark. timing is controlled by where you set it and can even still be digitally controlled depending on how much money you want to spend. personally i only dumped a few okay maybe more than a few K in mine but i also have done two engine builds. and a ton of other upgrades since my first 350 i put in. the last time i dumpmed money into a build was about 10 grand in the engine rebuild after spining a bearing. then the heads were the most recent and i only had to pay for the parts as the shop took two months to do them when it was promised within the week. and the cage and the nitrous and the tires and the rear. ive dumped about 5k this time around and need another 1k. but hte orignal setup including the 3400 on the motor and 1000 on the trans was about 1200 in parts from BMR all labor was done by me and chris. and about 700 in other parts needed. but i also didnt go the super cheap route on everything. also to use a th350 or 400 id suggest not using the stock trans brace that holds it order one trough bmr you might have to modify it i had to slot mine slightly it was off they gave me credit with them for it being off but i never ended up using it. like i said any other questions or you wanna go more in depth with everything send me a PM on here

[Clutch_Z28]

Thanks for the Info man, I have been reading a ton of stuff on LS1 tech, and I am liking the Idea of doing this swap.. The only thing that may make me think twice is if I can use my T56.

If I change the bell housing can I get it to bolt up to a big block?

[ITSSLOW]

The only way you can get away without having to cut the cowl is to use a SBF 5.0 or 5.8. I know its dumb but I have seen a 302 in a 4th gen Formula. I might have one picture somewhere around here.

[81DaytonaPaceCar]

If I change the bell housing can I get it to bolt up to a big block?

Yes, should be able to, although I've not seen what packaging restrictions might evolve (i.e. headers).

A carb vs. FI swap should be zero issues...'course I'm a dusty old fart that (in some cases) prefers carbs anyways...lol...

EDIT: Don't get me wrong...you will have to cut the cowl...not going to be able to avoid that...

[rcazan10]

Sounds like this is going to be a sweet project!