I found a SBC 400 block that was running when it came out of the car. Its out of a 74 monte carlo, and i can get it for 300$. Its all there except carb. Would this be a good investment?

It could be a solid foundation for an easy 400+ hp engine. Were you considering running it as is or building a performance engine from this? If the crank and block are good I'd say buy it! Ask for a money back guarantee, teardown will reveal any problems. Also check to see if it's been bored or is stock bore size. 400 blocks don't like being bored more than .040 which means if it's over that it can't be cheaply rebuilt. 74 models were all two bolt blocks and are stronger than the earlier 4 bolt versions. The heads are usually 882's and I've sold them on ebay as rebuildable cores for as much as $175 per pair. Bob

Ok thanks alot bob, i was planning on rebuilding using stock crank and rods, with new pistons, and a bigger cam.

Man I'd sure like to have a 400 sbc

Originally posted by dirty_dawg:
Man I'd sure like to have a 400 sbc find me a nice 427 BBC and i will hook you up with mine. ;)

Anyone know what the good casting number 400 sbc are?

*509

I was thinking about doing a 400. But I just talked to my local machine shop, and he said that about 80% of these blocks turned out to be bad when pressure checked. He said they usually find cracks in the lifter valey area. Anyone else find that number to be accurate?

Seems high to me. Kinda discouraging, and really not worth the risk to spend money on a core, and then $100 for a pressure check, only to find out it's un-usable.

Originally posted by MarkM:
I was thinking about doing a 400. But I just talked to my local machine shop, and he said that about 80% of these blocks turned out to be bad when pressure checked. He said they usually find cracks in the lifter valey area. Anyone else find that number to be accurate? That is an SBC problem, certainly not limited to the 400s.

Originally posted by 79943:
</font><blockquote>quote:</font><hr />Originally posted by dirty_dawg:
Man I'd sure like to have a 400 sbc find me a nice 427 BBC and i will hook you up with mine. ;) </font>[/QUOTE]Ebay. Any why you wanna part with your 406?

Originally posted by MarkM:
I was thinking about doing a 400. But I just talked to my local machine shop, and he said that about 80% of these blocks turned out to be bad when pressure checked. He said they usually find cracks in the lifter valey area. Anyone else find that number to be accurate?

Seems high to me. Kinda discouraging, and really not worth the risk to spend money on a core, and then $100 for a pressure check, only to find out it's un-usable. That's what they all say! Machinist have a big time woody for 400 blocks! Then they take it off your hands for a small environmental fee :D turn around and make a bad arse cheater circle engine for cheap and charge large dollar. :rolleyes:

Had a buddy not too long ago needing a 509 done and the machinist told him he lost the block after about 3 weeks of run around. We both went down there and searched the shop......we found it graemlins/sad.gif

Originally posted by dirty_dawg:
</font><blockquote>quote:</font><hr />Originally posted by 79943:
</font><blockquote>quote:</font><hr />Originally posted by dirty_dawg:
Man I'd sure like to have a 400 sbc find me a nice 427 BBC and i will hook you up with mine. ;) </font>[/QUOTE]Ebay. Any why you wanna part with your 406? </font>[/QUOTE]dont really want to part with it but i have been thinking about swithching to a 427 mostly for a change and a higher rpm engine just to be different. regarding the comments above about propensity to crack i wouldnt argue with that. i went thru several (all two bolts) before i found a good one. another widely expressed opinion is that the 2 bolts are stronger. that may be true but in my case the only good one i have had is the 4 bolt i have now and when i bought it i could have bought a two bolt much cheaper. it is also true that machine shops drool over them because like anything else it is a supply and demand problem. for years the circle track guys, at least those in the northeast, were going thru these blocks like crazy. a few years later the amateur drag race guys start burning them up. voila they are now hard to find. actually like i mentioned in another post i think the best thing about a 400 sbc is the fact that it is such a natural for the hot rodder to play with. it was so tame when it came out of the factory, and can be made to be a such a sweet little thumper and that adds to its mistique.

I was thinking about doing a 400. But I just talked to my local machine shop, and he said that about 80% of these blocks turned out to be bad when pressure checked. He said they usually find cracks in the lifter valey area. Anyone else find that number to be accurate?

Seems high to me. Kinda discouraging, and really not worth the risk to spend money on a core, and then $100 for a pressure check, only to find out it's un-usable. Thats pretty much been the case for me. Out of 5 400's that me or my friends have found in the last couple years, only one was uncracked. Luckily that was the one I got, :D The rest were ALL cracked in one of the inside cylinder walls. Thats the chance you have to take when buying a 400. Id ask for a return if cracked if possible.

Bore it .030 over and throw a 350 crank and rods in er for a killer 377!!
VERRRYYY happy with my combination!!!
....another Brian with a 71Malibu graemlins/beers.gif !!!!

Bob,
I've built many SB400s over the years, and I've NEVER seen one which was not rebuildable. NOW, UNDERSTAND THIS, I'm not saying that bad blocks are not out there, I'm saying that I have not yet run across one which is not rebuildable.
Also, regarding the heads. The LAST GOOD PRODUCTION SB heads (400, 350, whatever) were 1974. Starting with 1975, GM started cutting corners with their SB heads and they are either cracked, or will likely crack after spending good money on them at the machine shop. GENERALLY speaking, the 70-74 SB400 heads make really good street/performance cores. A good valve job, open the intake from 1.94 to 2.02, open the ex from 1.5 to 1.6 and add hard seats, stainless valves, guide plates and screw-in studs, and you have a very nice set of heads. If you like, you could have them port matched and the bowls cleaned up for a little additional money. Of course, if you want a REALLY killer set of heads for a SB400, then you will need to go with aftermarket heads such as Dart or World.
When it comes to boring a SB400, I like to only bore it .020, IF it will clean up at .020. This leaves the cylinders as thick as possible and room for a future bore and rebuild.

if your machinist is any good and not trying to steel your block he can fix the crack its fairly easy and cheap just drill a hole on both ends of crack and pin them then good old jb weld will do the rest .ive had some 35o blocks fixed this way and had no poblems out of them.the other thing to look for is cracks between the steam holes and bolt hole.now the other way to go is 400 crank and 350 block as most know 383 very little difference in horse power

These blocks really do much better with some block fill in em. That is the only way I have gotten a 4 bolt block to live in a serious performance application. If you fill em mid way it will live past 500 hp and I have never had a cooling problem on the street with one done as such as long as you have steam holes drilled in the head.

I'd also recommend going to a 6" rod as well. Helps with rod angle which decreases side load and cylinder wall deflection (the block filler also helps this).

Buy it, tear it down and have the block and rotating assembly inspected. Get a money back guarantee if possible. Most of the 400's I've torn down were fine for rebuilding. When the power level goes up the bores will crack, overheating will cause the steam holes to form cracks to the nearest cylinder head bolts. A friend of mine used 400 stock blocks in his 10 second chevelle for years, 600 hp is about where they fail according to him. He now runs Dart. I built an engine with a block that had the steam hole cracks and never had any problems. I think the stock 400 block is an excellent base for 400-500 reliable HP.

My father in law passed on last year, leaving behind 2 70 Impala's, both with 400 sbc's and TH400's. Both run well, but have been sitting in a pasture since he died. His widow will not part wiht them for senimental reasons, but she is also letting them rot away out in that pasture. Dang.

If all else fails and the block is still sound except for the cylinders themselves the just sleeve all of them back to stock size and continue!!

PAW is doing it now as a motor kit block option but you can't buy just the block..

pdq67

Originally posted by MarkM:
Anyone know what the good casting number 400 sbc are? Originally posted by clean7t:
*509
So are the '509' castings the ONLY good 400, 2 bolt block?

If so, what's wrong with the '817' casting 400, 2 bolt blocks?

A few months back, I found myself with 6 2-bolt blocks, all standard and would clean at .030. After measuring cam and lifter centering in bosses and quick sonic checks, the only 817 block I had turned out to have the thickest walls and least amount of core shift, so that's the one I went with. Sold the others to local drag racers. I'll buy most any 400 I find, just to keep it out of the hands of the roundy rounders. The circle jerkers I've been around have absolutely no respect for an engine, less for one that was made for only 10 years. Plus, I have a soft spot in my heart (and in my head) for 400's.

Originally posted by MyBoTy:
A few months back, I found myself with 6 2-bolt blocks, all standard and would clean at .030. After measuring cam and lifter centering in bosses and quick sonic checks, the only 817 block I had turned out to have the thickest walls and least amount of core shift, so that's the one I went with. That's really odd because I bought my 400 from the machine shop. It was the only core that they had didn't have exessive core shift was a '817' casting, plus it was the only one that cleaned up with a 0.020" overbore. So, that's the one I bought.

Honestly I didn't even know at the time that the '509' casting is the prefered casting.

They have another '817' that hasn't been checked yet. I might have it mag's and if it good to go, pick it up too.

Its funny though. My 400 is a '74 casting with 2 freeze plugs on each side and the 'bump' in the middle where a third freeze plug would be. Now the other '817' they have is a '73 casting and it has 3 freeze plugs on each side.

Was there any advantage to having 3 or 2 freeze plugs?

I could be wrong on this, but I thought the blocks with 2 core plugs on the sides were 2-bolt blocks. I've also used a block with a crack between the steam hole and head bolt in a mild build-up in my C-10 for the last 30,000 miles. I'm not saying it's guaranteed, but it worked for me.
-------------
Jeff

What's ya'lls experience with 400 rods? What can you turn them to reliably?

Most of the 509's don't even have the center core plug boss - looks a lot like a 350 block. Most '70 - '71 blocks are 4-bolt, most '73+ are 2-bolts. I have an older bowtie block to do with what bluerebl wants to do. It's now at 4.155 and will clean at 4.165. It has 350 main journal size and I had studs installed and the block has been align honed. I'm trying to decide between the 327 and 350 crank, actually leaning toward the shorter stroke so make a nitrous engine out of it. My machinist tells me that the big bore short stroke is absolutely ideal for spray. The other block I have is also at .030, will clean, and it had billet splayed caps installed before I bought it. I have a repaired Callies 3.875 for this one.
Dang, I just realized I have quite a bit of small block stuff for a guy who's committed to big blocks.

if you can get a money back guarantee on a used engine, good luck! for what it's worth, i've had 7 different 400 small blocks and i've built 5 of them for either myself or a buddy and i have never had one that was cracked. most were 2 bolts but i personally have a 4 bolt in my car. this 4-bolt had a couple hundred thousand miles on it and it cleaned up easily at .030 over. all of the 2-bolts i've built had far less milage on them but still would not clean up until .030 over. the 4-bolt i have in my car right now is a motor that i've had for almost 15 years. been rebuilt twice, the first time it didn't even need bored at all and it had over 100,000 on it. i say buy the 400, you won't be disappointed with it.

Originally posted by bluerebl:
</font><blockquote>quote:</font><hr />Originally posted by MarkM:
Anyone know what the good casting number 400 sbc are? Originally posted by clean7t:
*509
So are the '509' castings the ONLY good 400, 2 bolt block?

If so, what's wrong with the '817' casting 400, 2 bolt blocks? </font>[/QUOTE]=
Absolutely nothing.
If it's a good block,, it's a good block regardless of casting number.
As for 80% being junk??
I have built a lot of 400's & very few were junk.
I bought 6 of them about 4 years ago & out of the six one was junk (cracks in the mains as I recall) one was a four bolt .030 over & the others were both 817 & 509 2 bolts which are my choice for building.
Some were thicker than others but all were completely usable
Every 4 bolt I have seen had 3 freeze plugs & every 2 bolt had two freeze plugs. Some had the boss for the extra freeze plug & some didn't

I have three 400's in the shop right now, one four bolt & two two bolts & they all magged good & the thinnest one tested at .186 on the thrust side.
So out of these 9 blocks, I had one that was junk,, hardly 80% graemlins/sad.gif

Originally posted by Wolfplace:
</font><blockquote>quote:</font><hr />Originally posted by bluerebl:
</font><blockquote>quote:</font><hr />Originally posted by MarkM:
Anyone know what the good casting number 400 sbc are? Originally posted by clean7t:
*509
So are the '509' castings the ONLY good 400, 2 bolt block?

If so, what's wrong with the '817' casting 400, 2 bolt blocks? </font>[/QUOTE]=
Absolutely nothing.

I have three 400's in the shop right now, one four bolt & two two bolts & they all magged good & the thinnest one tested at .186 on the thrust side.: </font>[/QUOTE]Mike, the 509 casting I'm running now checked at over .200" on the thrust side. Of course, it has the nice little cracks between the plugged steam holes and adjacent head bolt holes (which all showed up after an overheating incident), but it seems to be of no consequence and is still running strong. I check torque on those particular studs periodically and all have yet to lose torque.

My 400 was out of my Dad's 80 3/4 ton truck and it probable had way over 100,000 on it. My machinist said we had to go .040 over because the cylinders were way whipped. It has 2 freeze plugs and is a 2 bolt main block. I hope it is a runner soon.

I'm in total agreement with Mike and John.
In 35+yrs of building engines, 4spds, rears, Vette FI units, I've probably built about 25 SB400s. So far, I've not run across one that wasn't rebuildable. I've built 3-4 that had the cracks between the steam holes and head bolt holes. As far as I know, they still don't leak. I've HEARD of cracks between the cylinder and the bolt hole, but never seen it. Now that would definitely be a problem.
Regarding main cap bolts, 70-72 blocks were 4bolt only (no 2bolts). The 73-80 blocks were 2bolt only. Supposedly, and I rather agree, the ideal choice is to use a 2bolt block and replace the main cap bolts with aftermarket studs, or, add splayed caps and studs. I also agree that the blocks with 4bolts may not be quite as strong as 2bolt blocks. I PERSONALLY HAVE NEVER SEEN A FAILED 4BOLT BLOCK. In my family, there are four 4bolt SB400s. One is a 420 in my boat, which we flog unmercifully at the lake. So far, so good.