Thread: engine swap (350, 383, or 400?)

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Some things to consider:

It is getting increasingly more difficult to find a good 400 block, and they are much more prone to cracks than a 350 block. A 2-bolt main 400 block is stronger than a 4-bolt main block. Don't be surprised if the first couple of blocks you find will be unusable.

The cost of building a 400 or 383 is about the same. But you will have to drill steam holes in whatever heads you use on a 400. People that don't, or fail to use a 400 head gasket, will have cooling issues.

It is better to use 5.7 or 6 inch connecting rods in a 400 as there will be less side load on the cylinders, and you can get a more efficient combustion chamber burn with the longer rods. For ultimate performance Smokey Yunick recommended stuffing the longer connecting rod you can fit into an engine.

Heck.... go for broke

Get a second job....work the whole year....Order one of the big bore Motown small blocks....build a 454cu in small block....with good heads (Motown) you can get near 700hp....or shoot max it out to 470 plus inches and just go nuts....

did I type that out loud.....?

Not to mention the 400 Has major cooling problems sence the bore is so large that there is no place for cooling passeges between either 2 or 4 of the cilinders so it creates uneven cooling and power... or so ive heard.

not true....I have done a lot of 400's....you just have to factor that in when selecting the cam to build less cylinder heat where you don't want it....

has anyone read hot rod mag's dream engine winner article yet? i think it was well chosen

no do you have a link.....?

Originally posted by CIzA5IHIOvIzId3
Not to mention the 400 Has major cooling problems sence the bore is so large that there is no place for cooling passeges between either 2 or 4 of the cilinders so it creates uneven cooling and power... or so ive heard.

Yes you are right.Because of the different cooling effect from one cylinder to another it creates problems with ring seal.The 400's even seem to have problems when you run a 6 inch rod.If you take a look at the cross hatch after 30 nights of going in around and around circles you will notice some cylinders look good others you can hardly see it.Also if you perform a leak down test these inner cylinders seem to have less compression.Is it due to these cylinders running to rich because the runners are a little bit shorter I don't know but I would think it had more to do with these (hot spots).

Originally posted by dr_bowtie
not true....I have done a lot of 400's....you just have to factor that in when selecting the cam to build less cylinder heat where you don't want it....

Are you refering to cylinder pressure.The comp. ratio is an easier way to control the heat.Changing the lobe seperation from 106 to 112 will help to build the cylinder pressure and yes this change will tend to build more heat but not as much as changing the comp ratio.

go 4 a 350 .60 over. they are a great engine for racing/street driving. i am currently building a 350 .60 over with a cam that has .551 lift, eagle forged rods, vortec heads, KB pistons, eagle crank, edelbrok vicotr intake, holley 750, MSD ignition system. 10.5 compression. its able to shift at 6500-7000 rpm and use premium pump gas fuel. use a 4 bolt main block.

It is getting increasingly more difficult to find a good 400 block, and they are much more prone to cracks than a 350 block. A 2-bolt main 400 block is stronger than a 4-bolt main block. Don't be surprised if the first couple of blocks you find will be unusable.

p.s. 4 bolt is better, the main caps are bigger, and the block itslef actually has more steel 2 it.

Originally posted by Ross
go 4 a 350 .60 over. they are a great engine for racing/street driving. i am currently building a 350 .60 over with a cam that has .551 lift, eagle forged rods, vortec heads, KB pistons, eagle crank, edelbrok vicotr intake, holley 750, MSD ignition system. 10.5 compression. its able to shift at 6500-7000 rpm and use premium pump gas fuel. use a 4 bolt main block.



p.s. 4 bolt is better, the main caps are bigger, and the block itslef actually has more steel 2 it.

In all the years I have built engines I have never seen a broken cap in a street driven car.If you it makes you feel better run a 2- bolt with a stud kit.

i wasnt getting at a broken cap, studs really arent gonna help anyway since like u said, caps dont break. just the block itself is actually stronger. and ive seen block break many times.

Originally posted by Ross
i wasnt getting at a broken cap, studs really arent gonna help anyway since like u said, caps dont break. just the block itself is actually stronger. and ive seen block break many times.

That depends on the year of the block.Something else to think about you have 6 more holes in the block when you go to the 4- bolt main.

ok if u think a 2 bolt is better go 4 it. just ask yourself one question. y do all the high performance sbc crate engine builders (scoggin dickey, edelbrok, gm's crates etc) all use 4 bolt blocks?

Originally posted by delmar6189
i currently have a stock 305 in my 1986 pontiac grand prix and i was wondering what would be the best engine swap for my car. its going to be a daily driver but also occasionally raced (weekend racer). im trying to choose between a 350, 383, or a 400. i thought a 400 would be the best because its the biggest chevy SB but i have people telling me to get a 350 because its a great street engine and theres also people telling me to build a 383. i never got a real straightforward answer on what to do so im hoping someone can give me good advice and help me with this desicion. i would appreciate all advice and suggestions. thanks.

BTW, this is the link for my car... http://www.cardomain.com/ride/727012/2

He states it is going to be his (daily driver) but occasionally raced.Do you really think you need a 4- bolt main for the trips to work and to the store.Better read his first post again.The big parts house's have been selling people on the 4- bolt main idea for years.It is called marketing.

haha nice.

u would find a 4 bolt at a wrecker for the same price as a 2 bolt. i was just stating its something worth looking into.