350 or 400?

[landjhallmark]

go with the 400 but put a 350 crank in it 5'7 rods 400 pistons and then you will have a power house

[1fast71]

i like the 350's myself but then again im still young and have never felt the power of a 400

[67_C-30]

Originally Posted by Hittman

Wow guys, I was looking for opinions and boy am I getting them. I didn't realize there was such a debate between these two - glad I asked.

So unfortunately I am still torn - though I am getting increasingly leery of the 400 with all the comments on their longevity and reliability issues. At this point I am not in a position to rebuild either one due to the all so common lack of finances at this time. Thus my question as to whether to drop the original 58K mile 350 back in or the 60+K mile "tuned-up" 400 this guy never had any problems with. I get the idea the 350 Chevy was around so long due to its inherant ability to hold up just about anything. I had a '78 shortbox with the original 350 that was at 215K miles without a rebuild when I sold it and it was still running strong (wish I would have kept that one btw!). Just another reason to stick with the 350 in my mind.

With the long weekend coming up I am planning on putting in one or the other. Sure wish I could just buy the 400, try it out for a while then decide which to part with. Again don't have the cash laying around for that option. You guys keep throughing your opinions out there and just maybe I will make up my mind on this end!

Thanks again for all the input!

If you had the $250 to spend on the 400 (which is a killer price for a running 400!), I'd say get and try it if gaveproblems, put the 350 back in. However, to quote the Cowardly Lion, there's "Not Noway, Not Nohow!" I would sell the numbers matching 350 out of your truck to get the 400, especially if your budget is what as thin as you say. You'd be asking for the possibly of having your truck sitting not running for maybe a long time if the 400 did crack and you didn't have the money to another engine in it. JMHO

Another thing that surprisingly hasn't been mentioned is keeping a 400 SBC cool. We have established that some are prone to cracking, but alot of that is due to fact that most of the time they are harder to keep cool that the other small blocks. I couldn't tell you how many 70's van I've seen that either had 400's that were replaced or had a cracked 400 in them. I've also seen 400's that didn't run any warmer than the 350 or 305 they replaced. Like the cracking issues, it boils down to having a good block.

[slammed1]

No problems here with cooling with a 2 core radiator in my 67 Impala with solid 4 blade fan and shroud,nor my 72 Chevy it was in for a while with 4 core rad,shroud and same solid 4 blade fan. Yes they are known to heat problems but that is mainly because they are not being cooled properly.mine had double humps with 67 cc and I drilled the steam holes myself.

Again I neither prefer a 350 or 400 when they are brought in frt of me because I have built and ran them both,now choosing between 283 307 305 vs the 350 400......no brainer.

[prg machine]

Originally Posted by drivethechevy

if it were me i would stick with the 350, i have a 400 sbc in my old plow truck and its a good strong motor but no matter what i do to the thing it just eats oil it dont eat alot but enough to frustrate me althought ive never had any problems with my 350 and i have beat the snot out of both engines and the 350 perfored just as good if not better so it really depends on how reliable u want ur engine to be the parts or different for 400s and there built a little different so not as many parts can be changed from bore to bore when running a 400 were as a 350 is alot more versitile parts and cost wise, not to mention u can still go to any junk or scrap yard and pull a 350 for a couple hundred bucks good luck with ur truck

exactly my point!

[BurnoutNova]

Originally Posted by prg machine

exactly my point!

just another opinion, and you know everyone has an opinion


mine is to keep an open mind, not to close the door on somthing just becasue of stories, and b.s. bench racing people do. ive seen plenty of good running engines people talk trash about for one reason or another.

so all in all, yes i'll agree the 400 has been known to have its flaws, but does that make ALL 400's scrap? hell no

[prg machine]

Isn't it something that the simple fact that the title here is entitled "350 or 400 ?" and now there are almost 5 dozen posts!

[sleric77]

350 or 400 ? It' really simple, do what you feel comfortable with because hey it's your money , your truck , and your time . So no matter what any of us say the last opinion that ultimately matters is yours.
I' m a Chevy man and as long as it's Chevy you can't go wrong as far as I'm concerned.

[prg machine]

If you have a 350 now and it works.................why go to the 400 with no flywheel....................and the unknown potential trouble.

This is a no brainer to me!

[Gray Ghost]

While the 400's had trouble cooling there are solutions. I foggily remember certain heads/blocks that were drilled differently to help with cooling and those eliminated the problems.

All that said, if you want more reliability, stick with the 350 and toss in a cam kit for more HP.

[OrangeCrush1970]

Number's matching are hard to find these days. That gets my vote. Especially since that 350 hasnt been bored out, etc... you still have to oportunity to do so down the road and build it the way you want. Stick with the 350 unless you just want more torque.

[TotalChevy1]

Originally Posted by Hittman

I am currently in the middle of tearing down my 1970 C20 to transfer the body/engine to a 71 3/4T 4x4 chassis. My plan was to just pull the original 59K mile 350, clean it up and give it the old puff can Chevy orange paint job and put it in the new frame since it is running fine. However I have an opportunity to get a hold of a good running 400 small block. A neighbor of mine just pulled it out of his 1971 Cheyenne as he replaced it with a fuel injected late model 350 he just had rebuilt. He is a GM mechanic who found this low mileage 1972 400 about 10 years ago. At that time he opened it up and replaced the bearings, re-ringed it put in a mild cam. He believes there to be about 60-70K on the rebuild and says it was running fine when he pulled it this winter. He thought he might have added a quart every 1K miles or so but nothing excessive. He is a stickler for maintenence and I don't believe it was ever abused really. I know it sounded really good when it was still in the truck but I never rode or drove it to compare to my current 350.

My question out there to you guys is what would you do? Keep the original, numbers matching, never gone through as far as I know 350 that I know runs fine and doesn't use much oil OR drop in the similar mileage rebuilt 400?

I have a guy who will buy mine for $250 and I can get this one for $300 so it's really a wash. I know the only thing I would have to do is get a flywheel for around $65 as the 400 I guess is externally balanced where as a 350 is internally balanced. Check me on that one - just what I hear.

Is a 400 going to be any more impressive than a 350? Are rebuild kits that much higher for a 400 when it does come time to rebuild?

Thanks guys,

If that thing is burning a quart every 1k, that is excessive, it's got more history than 60 or 70 unless he beat it to death, plus matching numbers on the 350 is work more than $250 if you every plan on selling. If you have to have the 400, pull and store to 350 until the 400 blows, which with the oil it's burning, it should take long.

[prg machine]

Originally Posted by TotalChevy1

If that thing is burning a quart every 1k, that is excessive, it's got more history than 60 or 70 unless he beat it to death, plus matching numbers on the 350 is work more than $250 if you every plan on selling. If you have to have the 400, pull and store to 350 until the 400 blows, which with the oil it's burning, it should take long.

It's already blown!!!!!!!!!!!!!!

[bad421]

Originally Posted by prg machine

This is the classic argument 400 vs 350 block

The reason they are siamesed is because the bore is too big for a reasonable wll thickness at the water jacket area. they cool unevenly and the cylinders go out of round.
The racing blocks you mention aren't even the same animal
The 400 was a short lived GM experiment that didn't last for a good reason.

Those are the facts!

I've had 350s and 400's, don't blame gm and say the 400 was a bad experiment and didn't last long for a reason man. If that was the case there must have been a bad experiment with the 396/402 also right? Since those motors were short lived also, and how bout the 302, 327, and 427. I've worked on the side in a all chevy machine shop for years now and yes you are right on about the cracking problems, but that is mostly cause some dumba$$ didn't know what a steam hole was and threw on a set of double humps or didn't think that 240* f was running hot, Fact is that the 400 is a great motor if you know what you are doing and what to look for, and the race blocks other than the main caps and a little reinforcemet, and improved water jackets are the same. The 350 and 454 based race blocks also are upgraded too. Don't put down 400s cause they were before their time with siamesed bores, everybody else is doin it now, more cubes in a smaller package, that what people want and with the high cost of the bbc a 400 fits the bill. Those are facts!

[67_C-30]

Originally Posted by bad421

I've had 350s and 400's, don't blame gm and say the 400 was a bad experiment and didn't last long for a reason man. If that was the case there must have been a bad experiment with the 396/402 also right? Since those motors were short lived also, and how bout the 302, 327, and 427.

Every engine you list was superceded by a bigger engine except the 302. The 350 replaced the 327 and and the 454 replaced the 396/402/427. The 302 wasn't really replaced by anything because it was of creature of comformity. SCCA rules mandated a 305 cu in rule limit at that time, and the 302 was only built to fall within those guidelines. That is the only reason it ever existed. The 305 cu in limit was raised after the 1969 season making the 302 obsolete.
The 400 SBC while loved by racers and hot rodders, was a nightmare for GM in fleet vehicles and commercial trucks.

Originally Posted by bad421

the race blocks other than the main caps and a little reinforcemet, and improved water jackets are the same.

You are understating the differences though. Those seemingly minor modifications make all the difference in the world. There is really no comparison between them. Yes, they are both siamesed cylinder SBC's, but the race blocks are FAR superior. In addition to those improvements, the race blocks have thicker decks, beefier main webbing and beefier casting around the lifter bores.

[prg machine]

Originally Posted by 67_C-30

Every engine you list was superceded by a bigger engine except the 302. The 350 replaced the 327 and and the 454 replaced the 396/402/427. The 302 wasn't really replaced by anything because it was of creature of comformity. SCCA rules mandated a 305 cu in rule limit at that time, and the 302 was only built to fall within those guidelines. That is the only reason it ever existed. The 305 cu in limit was raised after the 1969 season making the 302 obsolete.
The 400 SBC while loved by racers and hot rodders, was a nightmare for GM in fleet vehicles and commercial trucks.





The race blocks has thicker decks, beefier main webbing, beefier lifter bores You are understating the differences though. Those seemingly minor modifications make all the difference in the world. There is really no comparison between them. Yes, they are both siamesed cylinder SBC's, but the race block are FAR superior. In addition to those improvements, the race blocks have thicker decks, beefier main webbing and beefier casting around the lifter bores.

I think Bad 421 is outnumbered here by words of wisdom. Not trying to put anyone down. but fact is the 400 was a GM disaster.

[454_72_4X4]

I'm votin for the 400.
Why, because the term "numbers matching" makes me ill.
There's not a vehicle on the planet that is made better by what numbers are stamped on it.
And that, my friends, is the fact and only fact.

[bad421]

[QUOTE=67_C-30;2638568]Every engine you list was superceded by a bigger engine except the 302. The 350 replaced the 327 and and the 454 replaced the 396/402/427. The 302 wasn't really replaced by anything because it was of creature of comformity. SCCA rules mandated a 305 cu in rule limit at that time, and the 302 was only built to fall within those guidelines. That is the only reason it ever existed. The 305 cu in limit was raised after the 1969 season making the 302 obsolete.
The 400 SBC while loved by racers and hot rodders, was a nightmare for GM in fleet vehicles and commercial trucks.





Yes they were all replaced by larger motor but, thats not what i'm getting at here. What i'm saying is that people shouldn't put down a 400 just because they are far less common than a 350, 400 were the biggest of the small blocks so they wouldn't have been replaced during the bad smog years by anything bigger, this the time the 305s came out. With some people talking smack about the 400 it leads me to think that 1 they have never had one or 2 they were one the ones who destroyed one due to overheating, and yes the race blocks are alot better, but i've seen plenty of 550 to 625hp 400s with stock blocks and plenty of these lasted 5+ year in full race apps. so for some to say that a 400 is a gm failure i think they need to read a more into it. But, then the less people who like um the more i can collect!

[BurnoutNova]

Originally Posted by bad421

so for some to say that a 400 is a gm failure i think they need to read a more into it. But, then the less people who like um the more i can collect!

thats what ive been debating with pgrmachine about for 6 months!!!

and to say words of wisdom outnumber us IS a dis, i feel that i have much more experiance than most when it comes to doing machine work and biulding engines, as i said ive worked off and on in an automotive machine shop for years. and built HUNDREDS of engines of all sizes, from 265's to 434 small blocks.

the fact is, the 400 is a fine engine. ther have been some probleoms but several were self inflicted becasue of misuse of heads without steemholes and overheating. and the oil burning has been discussed and the real probleoms are evident: the rod length.

[67_C-30]

This thread had skewed WAY off topic. This has turned into a general 350 vs 400 debate, but the original poster simply wanted an opinion on whether he should sell his original 59K mile 350 to get a 400 that is burning a of quart every 1000 miles. He said with his financial situation that he could not have both, so he had to make a decision between the two. I recommended (and still do) to keep his perfect running, low mileage, original 350. I see no reason to take a chance on the 400 he really knows little about except its burning oil, because it sounds like in his financial situation that if the lunches the 400, he couldn't easily replace it.

Now, we can go back and forth for all day on the 400's, but the fact is that many have cracked, and the main reason is CORE SHIFT. Core shift is variation from specified dimensions of the block due to a change in position of the core or misalignment of cores in the casting process. All production engines have a degree of core shift, but the 400 is more prone to failure because of the already thin water jackets. This was the main design flaw. As I said before though, when you get a 400 with very little core shift, it is a great engine. There are tons of them out there that have little core shift, and are great platforms for HP engines. However, there are lot of them with significant shift. These are the ones that crack easily. Some don't even have to overheat. There were low mileage engines when almost new with a lot of core shift that cracked for no apparent other than the cylinder wall was less that .100" and just couldn't handle the stress of pulling, high RPM etc. If you know what you are looking for, you can even tell to some degree if the block has a lot of shift. You can pull the timing cover off and look at the machined area around the camshaft. If one side is or the other is significantly wider than the other, this is an indication of core shift. This of course is not an exact science, but I promise you if you have block that is .100 wider on one side of the parting line, it will sonic check very thin.

I have also built engines for drag cars, street/strip cars, circle track, light truck diesels and even some speed boat engines along with I couldn't tell you how many mild or stock engines. Building engines paid my way through college and has supplemented my income as long as I have been working. I have been a machinist for 12 years and currently program/operate a Mori Seiki SL-35 and SL-25 CNC lathe as well as a MH-40 horizontal mill along with experience of the manual mills, lathes, boring machines, surface grinders, and a Hitatchi wire EDM machine. I have seen and built good 400's and I've had to chuck several boat anchor 400's.

A good thick 400 is a great engine, but you have to be careful when buying them, especially if you can't hear them run or be able to check the oil for water. Swap meet 400's have broken a lot of hearts!

[BurnoutNova]

Originally Posted by 67_C-30

I have been a machinist for 12 years and currently program/operate a Mori Seiki SL-35 and SL-25 CNC lathe as well as a MH-40 horizontal mill along with experience of the manual mills, lathes, boring machines, surface grinders, and a Hitatchi wire EDM machine.

as you surely know, that also is a completely seperate topic form automotive machining, none of those machines are used in the automotive field, except maybe to mass produce parts.

my father has been a machinist for 30 years started on maunual bridgeport milling machines and old school leblonde lathes, and runs similar CNC machines daily and has no experiance doing atomotive machinig, and if asked to run the CK-10 that i run almost every weekend, he would have trouble.


but yes, this has strayed a LONG ways from the original topic, and should be put to rest.

[stllookn]

Geez...at that price buy the 400 and keep your 350. Always have a spare for these old trucks...it is easy to swap them out.

[67_C-30]

Originally Posted by BurnoutNova

as you surely know, that also is a completely seperate topic form automotive machining, none of those machines are used in the automotive field, except maybe to mass produce parts.

my father has been a machinist for 30 years started on maunual bridgeport milling machines and old school leblonde lathes, and runs similar CNC machines daily and has no experiance doing atomotive machinig, and if asked to run the CK-10 that i run almost every weekend, he would have trouble.


but yes, this has strayed a LONG ways from the original topic, and should be put to rest.

I have run the Sunnen CK-10, as well as a Rottler and a couple of times I've done some work on my buddie's Kwik Way. I have also run Van Norman and Sunnen 3810 head and block surfacing machine. Not to step on toes, but automotive machine work is child's play compared to the type of work we do at the shop. I'm not saying that just anybody can do automotive machining, and you have to be good at it to produce quality work, but the type of work we do is on a whole different level. The tightest tolerances on automotive work is mile on die and especially mold work. We don't do production machine parts. We do custom order molds, dies, jigs, fixtures, test gauges a lot of which 3-D work on multi-axis machines. The seal molds I completed last Friday of last week had a metric .005 tolerance on the cavity which is equivalent to .00019". We've also had parts many parts that had tolerance in microns. You can't even measure those types of parts with a mic. We have to optical measuring equipment, as well as air gauges and Talorond and Mitutoyo surface measuring equipment. We are an ISO 9002 certified shop.

You're right that it is much different that automotive machining, but I have experience in both. The bulk of my automotive has come doing work on the boss' Super Late Model dirt engines. I have done boring/honing, align boring, decking, angle milling heads and intakes. fly cutting valve reliefs, you name it. A few weeks back I even put a fuel pump push rod hole in newer engine block for one of his buddies so he could run a mechanical fuel pump on a hobby stock car. He has the equipment I listed above just for his toys! (it must be nice, huh?) The only work the Sunnen and Rottler stuff gets is on his engines and couple of buddie's engines, but he won't do automotive machine work commercially because he says there is not enough money in it. I would love for him to let me do on it the weekends like you do, but he will only let me do my and my brother's stuff and occasionally a buddie's. He won't let me do it for many people because of liability, and he doesn't want people to think we do that type of work.

[Chevyholic]

I have to vote 350. If money is that tight, why take the chance. The Chevy small block 350 is the most successful racing engine in history for a reason. It is durable and reliable, the two hallmarks of cost effective driving. It will be better on gas mileage, cheaper to rebuild, easier to find parts, so on, and so forth.

I look at like this. The 350 is a good, loyal, attractive wife. The 400 is the siren next door trying to get your attention. The 400 would really make you go, but for how long, and at what expense. Stick with the good woman by your side and enjoy a long happy life together.

Best of luck to you!
David

[prg machine]

I have been a machinist since 1970............that's 38 years my friends! What I have realy enjoyed watching through the years is when "Captain Engine Lathe" jumps up and turns the conversation into "machinistvsmachinist".................

so now we are doing that and yes we missed the point didn't we of this whole topic...

kinda like the weekend BBQ and someone can't get the BBQ to light up- ...............................someone jumps up "I'm a machinist!!!!!!!!!!!!" and off we go!!!!!!!!!!!!!