Will a 400 Small block fit a Chevrolet 1500 truck which has a 350?

Question

If conversion is possible what modifications must be made? Does this mean a switch from Fuel injection to Carb must be made?

Answer 1

400 SMALL BLOCK was the SAME block as the 350, it was bored, and stroked, (in a nut-shell)originally, it was called the 350M(for MODIFIED), this was, I believe 1975 if memory serves me correctly. what is this stuff about heavier mounts, frame bracing and so on? Same mounts as 350. biggest difference was the crank journals were different size. you guys really should brush up on chevy vehicles, and chevy performance before you spout your knowledge. beefing up transmission is for serious performance. Best tranny for that,-200r4, it can be built comparable to the turbo-400, only it has over-drive, 400 does not.( I have a '400 with an old manual over-drive out of a 1962 rambler adapted to fit, and it gets somewhat incredible mileage(considering what it is in, and what the vehicle is expected to do for me)

Answer 2

The fuel injected 350 was used up until they changed the body style in 2002 (or somewhere around there). If you're doing a swap you want an "R" motor. The R is the engine code in the VIN, 8th digit from the left when reading the VIN. They're the most common motor and very reliable (and easy to fix when they break). The newer trucks have 4.3L V6, and 4.8, 5.3, 6.0 and even 8.1L V8 engines. They're good, but for ease of installation I'd go with the R motor from a '98-'99 silverado or suburban. There are many aftermarket companies who make parts for the swap, and can even program the computer for you. EDIT: The R motor will also bolt up to many of the older transmissions, like the 350/400, 4L60, etc. Makes the installation that much simpler, since almost all 350's are based on the same engine block.

Answer 3

You can put a F-111 Jet Engine in it. But that is not the answer you are looking for.
Yes, with some Heavier Duty Motor Mounts and Frame Bracing, may want to upgrade the transmission, rear end, Suspension, and fuel lines, but sure, it could work good.
The Trucks are built for Small or Large Block, almost every American Auto is. a 327 might be better, I know those are screamers. Drop weight gain HP/Torque. That is the magic code that makes performance, Weight,Horsepower,Torque , get them balanced out and anything will work.

Answer 4

It will bolt right in with same tranny and motor mounts, it's a take out and install. I would go with the carb on the 400 and an hei ignition as this way you won't be getting into computer problems trying to put the fuel injection on the 400. If you know somebody good with the computers you could probably put the fuel injection on if you really wanted to.

Answer 5

Lots of 400 S/B engines suffer from over heating problems and cracked heads as a result of the siamesed cylinder design, which reduces cooling efficiency. I had one in a '65 Nova, and finally replaced it with a good old 350.

400's have a lot of torque, but are not that reliable in the long run.

My advice is to build the 350, get a new crate motor, or maybe go to a 383. You will be much more satisfied in my opinion.

Answer 6

Yes, the block is the same for those 2 engines. Just the bore and stroke are different. The 400 has a very long stroke and IMO isnt that good of a motor, it dosent rev high enough when compared to the 350.

Answer 7

Physically, it bolts in. All the mounting holes should line right up to attach it to your motor mounts and transmission. I'm not 100% sure the accessory mounting brackets are the same, but probably. You could even swap the EFI hardware onto it if your truck is injected, although you would need to retune things.

Answer 8

the 350 and 400 will interchange no problem , the Chev small block had the same external dimensions from 1955 on up , the vortec engines are a bit different , if your truck is a pre vortec your intake will swap no problem , good luck