why is the 350 so popular compared to most other engines. you can do the same thing to all small block chevys regardless of the size so why wouldnt you go with a 406 or something big like that? if you look at the 305 (which i hear is deemed a horrible engine for power) it is only 45 cubes short of the 350. however the 350 is say 56 cubes short of a 406 (which i wanted to build). however it seems to be much more of a sin to own a 305 when you can have a 350 than it is to own a 350 when you can have a 406 just the same.

 

350's are very plentiful and have THE BEST aftermarket. The avftermarket is a direct result of their abundance, especially in performance cars. They are very good motors and are very versitile. They work great in anything from a blown strip vehicle, a small tow truck, or even a full size sedan.

The 350 is based on the same block, but is not as strong and cannot make quite as much power as a 350. Plus parts for a 305 will be harder to find, have less choices, and more expensive. You can get a 350 block for around $50 if you look hard enough. 305's can be fun to play with if you want to show that they can make power, but you can do more with the 350. A 406 is a very nice motor, but not as plentiful as the 350.

 

The 350 was close to ideal for the external dimesions of the SBC. The 400 requires siamesed cylinder walls, which isn't all bad, but the factory blocks had other weaknesses, and there were never nearly as many of them made as 350's - not even close. 383's are becoming more popular, and because of that the aftermarket has responded with new cranks. Aftermarket blocks for 400's are available, but new cranks are a lot cheaper to make than new block castings.

The 45 CI shortcoming of the 305 costs more than 14.7% of the HP, because the small bore of the 305 limits the valve size that's effective in a 305. The extra bore of the 400 isn't that much more than the 350, so the HP ratio is about the same as the CI ratio - although torque will be higher at a lower RPM.

BTW, a 406 is a .030"-over 400. So, if you're comparing that particular displacement, you need to compare to a 355. If you are starting off with a new 40x-bore block, you should start with 4.125" to leave yourself with rebuild room down the road.

 

also from experience the 350 is alot more reliable than a 400, 400's tend to overheat, they have small cylinder walls which create higher cylinder temps, etc. for instance, i had a 406, when right it was alot faster then the 350 i had now, however i couldnt keep it right, it would overheat and go through pistons, my 350 keeps on running, just my 2 cents, also the 400's are hard to find
Russell

 

A properly built 400 will not have any more overheating problems than a 350.

 

A 350 has an Optimum Bore/Stroke ratio. It's the perfect balance between torque, horsepower and Reliability. A 383 has a really long stroke which limits it's RPM range unless you do major things like 6.0 rods and get it perfectly balanced. Another excellent combo is a 327. It seems to make as much horse power as the 350 but less torque. It's all about big bore short stroke motors. Even the 60's 302 would Murder even the wildest 305 motor's. A 4.00 inch bore seems to work really well in the chevy smallblock. If you destroked a 400 to 377 it makes nice high RPM power but the 400 blocks are known to be weak.You could get an aftermarket block but you would run into some seriuos cash.Bottom line is a 350 makes the most horsepower for the cheapest and is the most reliable.

 

what do you consider "properly built"? Ive talked to various machine shops, along with people that have had the motor and all have the same problem of overheating.

 

I believe the main reason (at least for 3rd gen owners) that a 350 is more popular than a 400 is that you can get 350 blocks with provisions for a factory roller setup.

 

The 4" bore blocks (302, 327, and 350 all large journal) used by far the strongest blocks the factory had cast. The 400 small block does not overheat if you build it properly, like many people here will tell you.

The problem with the 400 block is just that it was a very weak design. Proof of that is that the 2-bolt 400 blocks are actually stronger than the 4-bolt 400 blocks! Thats because there is not enough metal on the main webbing inside the block.

400ci engines, at least with the stock crank and rods, are usually more prone to wearing out cylinder bores faster because of the very long stroke and the very short rods (the shortest GM ever put in a SBC)

The 400 also cannot use some of the otherwise generic small block parts too, like for example, a 350 crank, because the stock crank has larger journals.

The 350 does not have any of these problems. It has the stongest block design, a great bore/stroke ratio (unlike the 305) and it is compatible with basically any other SBC part, whether it is off a 302, 327, 350, 305, 267 or 307.

Basically, the 350 is the best engine to use because it was the biggest engine GM made out of the original small block design without drastically altering the basic design of the engine, like they had to do with the 400.

 

my 400 never overheats. None that I know of around me do. I think you just heard that they do.

as for the 350 yes they are almost every where cheap. and the pistions ect, can be had very cheap as well.

the 305 is not bad at all just alot of people set them up bad. as stated before the small bore only shrouds the valves and creates another problem to overcome, the already cheap and easy to find 350 does not have this. the 400 is harder to find. see the easy choice

 

Well lets see.

Anyone can find a 350. Flex/fly/starter interchange, less overall cost and makes plenty of streetable power for most.

A larger engine is much better for making more power easy and I'll agree that its a better platform then a 350 for making easy power finding a 400 that doesent need to be welded, sleeved or freshly cast is the hurtle most dont want to cross.

 

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it's the largest for the least idea. 400's aren't readily available everywhere and are quite often no good if you do find one. there is a reason they stopped making them and it wasn't because they were just too good to keep around.

 

The 400 small block is definitely an interesting and unique engine. I dropped a stock one in a 77 camaro I used to own years ago in place of the oil burning 305 it originally had. I finally ran the 305 too low on oil and killed it, which I considered an act of mercy! The one thing I can say about that 400 is that it had enough torque to drag the local church down the road! Probably due to the large bore and shorter connecting rods I'm sure. I had a stock th350 and 2.73 gears, and I could start powerbraking it in first and shift it all the way into drive standing still with the tires just roasting! I loved the pulling power of that motor. The end came for the 400 when a piston skirt disentegrated at the wrist pin. As far as the overheating myth, I've always heard that it mostly arises when you bore them more than .030 over. These guys are right about the 350 being a better overall choice. The 350 in my 69 camaro probably doesn't have as much torque as the 400 did, but it's far superior in horsepower and rpm cabability. Plus, like everyone has already pointed out, the price and aftermarket parts availability for the 350 is unlimited. Just my .02.