[willrace]

I have a 70 model .040 400 sbc 3.75 stroke and a 6 in rod what is my cubic inch displacment?

 

[techinspector1]

I have a 70 model .040 400 sbc 3.75 stroke and a 6 in rod what is my cubic inch displacment?

Multiply .7854 x 4.165 x 4.165 x 3.75 x 8 and find 408.73 cubic inches. The length of the connecting rod has nothing to do with figuring the cubic inch displacement of a motor.

 

[ericnova72]

Formula is: Bore x Bore x Stroke x 2PI for an 8 cylinder engine. PI is 3.1416. Use just PI for 4 cylinders and 1-1/2 PI for 6 cylinders.

Your engine = 4.165" x 4.165" x 3.75" x 6.2832 = 408.73 cubic inches.

The fact that it has 6" rods does nothing to change the cubic inches :nono: , it just changes the rod length to stroke length ratio compared to the shorter stock rod.

 

[Torque454]

The 400 SBC didnt exist in 1970. I dont envy you running a .040 over 400 SBC tho if thats what you have. Sounds like it will be prone to overheating even worse than a stock 400 is. Anyways its 408.73 CI. Since you round to the nearest inch, id say you have a 409 SBC.

Bore x Bore X Stroke X .7854 X # of cylinders = Displacement:

4.165 X 4.165 X 3.75 X .7854 X 8 = 408.73 (rounds to 409 since it is over 408.50)

 

[techinspector1]

She's so fine, my four-oh-nine.... :thumbup:

 

[ericnova72]

The 400 SBC didnt exist in 1970. I dont envy you running a .040 over 400 SBC tho if thats what you have. Sounds like it will be prone to overheating even worse than a stock 400 is. QUOTE]
Yes, it did, 1970 was the first year for the 400 SBC.

...And the 400 overheating myth lives on, I've run them .020, .030, .040, and .060 over, and with half fills of block filler, none of them have had an overheating issue, neither have the ones friends have used. It's all about the cooling system, since it is a big block sized Small Block, it needs a cooling system to match. Factory high flow air conditioning spec water pump(it has a better impeller) and clutch fan and at least a 3-core factory rediator with a shroud. Put it behind a radiator meant for a 307 and with a plain sheetmetal impeller pump of course it will overheat, just like a 396 will with the same radiator. You are cooling tha same # of cubic inches.

I'm getting tired of people repeating the same old "overheating 400" BS just because of their lack of knowledge. If your 400 overheats, it's because you don't know what you're doing.

 

[Torque454]

All I can say is it must have a FLAWLESS cooling system. Large squeeky clean aluminum radiator, high volume pump, and a large fan with lots of blades and a d*mn good clutch. The 400 SBC has half the ability to cool itself than any other SBC has. There is NO water jacket between the cylinders. That means half of each cylinder doesnt get adequate cooling. Oil changes are probably more critical too because half that cylinder will be alot hotter than the rest, causing some thermal breakdown. The cylinder heads were also steam cooled in alot of places rather than coolant cooled. And why do you think the 400 SBC was only produced something like 5 years? (i thought it was 9 years, ending in 1980 but i cant find any application that had a 400 early than 75, and later than 80 so it must have only been made for 5 years). If it was so great, the 400 would be the choice engine of most people rather than a 350, and the factory would have continued to produce it. That alone convinces me that they are problematic and having no water jacket surrounding the cylinders and steam cooled heads sounds like the problem to me. For racing only it might be ok, but i wouldnt expect to put it on the street, daily driven, sitting in traffic, on long trips, towing trailers, etc and certainly not expect it to live a long full life.

You may not have problems but the 400 didnt get that overheating reputation for no reason. It is an overheating prone engine and thats why its not made anymore. Thats why no one runs them, they take a 400 crank and stuff it in a 350 block and IMO thats probably the best way to go.

 

[lg1969]

The 400 SBC didnt exist in 1970.
"Wrong" 400 started 1970 to 1973 as a 4 bolt main motor. P/N 3951509. From 74 on up 2 bolt main

 

[Torque454]

The 400 SBC didnt exist in 1970.
"Wrong" 400 started 1970 to 1973 as a 4 bolt main motor. P/N 3951509. From 74 on up 2 bolt main

OK I just looked it up and you are right. I have never ever seen or heard of a 1970 400 SBC tho.

 

[ericnova72]

All I can say is it must have a FLAWLESS cooling system. Large squeeky clean aluminum radiator, high volume pump, and a large fan with lots of blades and a d*mn good clutch. The 400 SBC has half the ability to cool itself than any other SBC has. There is NO water jacket between the cylinders. That means half of each cylinder doesnt get adequate cooling. Oil changes are probably more critical too because half that cylinder will be alot hotter than the rest, causing some thermal breakdown. The cylinder heads were also steam cooled in alot of places rather than coolant cooled. And why do you think the 400 SBC was only produced something like 5 years? (i thought it was 9 years, ending in 1980 but i cant find any application that had a 400 early than 75, and later than 80 so it must have only been made for 5 years). If it was so great, the 400 would be the choice engine of most people rather than a 350, and the factory would have continued to produce it. That alone convinces me that they are problematic and having no water jacket surrounding the cylinders and steam cooled heads sounds like the problem to me. For racing only it might be ok, but i wouldnt expect to put it on the street, daily driven, sitting in traffic, on long trips, towing trailers, etc and certainly not expect it to live a long full life.

You may not have problems but the 400 didnt get that overheating reputation for no reason. It is an overheating prone engine and thats why its not made anymore. Thats why no one runs them, they take a 400 crank and stuff it in a 350 block and IMO thats probably the best way to go.

I guess it just shows what you know. Nothing more than a factory copper-brass 3 row rad, an AC application waterpump and a 7 blade factory AC clutch fan, and the factory shrouds. Never get hot even with a half block hard block fill. These are Street/Strip engines, circle track may be a different story. Racers who know more than the average ******* shade tree mechanic actually go looking FOR the 400 smallblocks because bigger cubes is bigger power. That's ok though, stick to the smaller small blocks, that just leaves more of the coveted 400's for me. I don't like building a small block smaller than a 400, only do a 383 if I can't find a good 400 block core.

The 400 got it's bad rep undeservedly from people not keeping the cooling system clean and replacing water pumps and radiators with incorrect application parts only adequate for the smaller SBC's. Part of that is the fault of the parts stores listing almost all SBC parts as being the same. The 400 was made for 10 full years and got phased out due to emission regulations and corporate downsizing, not because it was a problem engine.

The Dart blocks are just 400 blocks with more metal everywhere and priority main oiling revisions. They have siamese bore waterjackets too, even the ones with a 4" bore. Are They junk and "overheaters" too for that reason??

I just hate bogus BS second hand shade tree information that has no basis in real facts, not trying to jump on you Torque454, just setting the record straight for others. :thumbup:

 

[Blazin72]

I'm with ericnova72 on this one. A friend and I pulled a 400 out of his GMC truck and when we pulled the heads the pistons had .060 stamped on them. He had that truck for a few years and even made a trip to Los Angeles from Western Washington with no cooling issues. The engine ran great until it dropped a valve and trashed one of the pistons.

I'd be willing to put money on why the 350 is so much more popular than the 400. The 350 was factory installed in production vehicles from 1967 until sometime in the early-mid 2000s in many different car and truck models. The 400 was largely a truck engine in the 1970s, though I think it was installed in a few cars. That means there are probably millions more 350s out there than 400s. I think the 400 is the choice engine for people that can get their hands on them.

My 511 casting 406 is from 1970.

 

[Torque454]

I guess it just shows what you know. Nothing more than a factory copper-brass 3 row rad, an AC application waterpump and a 7 blade factory AC clutch fan, and the factory shrouds. Never get hot even with a half block hard block fill. These are Street/Strip engines, circle track may be a different story. Racers who know more than the average ******* shade tree mechanic actually go looking FOR the 400 smallblocks because bigger cubes is bigger power. That's ok though, stick to the smaller small blocks, that just leaves more of the coveted 400's for me. I don't like building a small block smaller than a 400, only do a 383 if I can't find a good 400 block core.

The 400 got it's bad rep undeservedly from people not keeping the cooling system clean and replacing water pumps and radiators with incorrect application parts only adequate for the smaller SBC's. Part of that is the fault of the parts stores listing almost all SBC parts as being the same. The 400 was made for 10 full years and got phased out due to emission regulations and corporate downsizing, not because it was a problem engine.

The Dart blocks are just 400 blocks with more metal everywhere and priority main oiling revisions. They have siamese bore waterjackets too, even the ones with a 4" bore. Are They junk and "overheaters" too for that reason??

I just hate bogus BS second hand shade tree information that has no basis in real facts, not trying to jump on you Torque454, just setting the record straight for others. :thumbup:

So you are saying the world is wrong and you are right? The word on the street is the 400 sbc is overheating prone. Just because you yourself have been lucky enough to not have problems with one doesnt mean they are the GOD of all small block chevys and that everyone else is wrong. The stopped making them because they were prone to problems. Im sure there were other reasons, but id say thats the big one. Its an oddball engine with overheating tendencys. As for running them with block filler, alot of race engines have filler in them. Some of them are filled completely up and have no cooling system at all. You can run an engine down the track and not have overheating problems. But put that engine in a truck, pulling a heavy trailer on a 100 degree day with AC on in the mountains and tell me it has no problems whatsoever staying cool. The damn 400 got a reputation for overheating for a reason. If everyone has problems keeping cooling systems working properly then why arent 350s and other SBCs having problems? Whats the difference? The siamesed cylinders and steam cooled heads. That alone says that the 400 has a problem with overheating. You shouldnt have to keep everything perfect all the time in order for it to stay cool. You are pushing the cooling system to its max with little room for problems and thats simply put, a bad idea.

With all this said im sure the 400 is probably fine for racing only and maybe daily driving but forget making it WORK in the heat and be reliable. Thats what matters to me and the majority of people that want a truck. Even people with a car that would have a 400 in the real would would be sitting in traffic in the car in the heat with the AC going and probably easily have issues.

 

[techinspector1]

Studying human nature for as many years as I have, I'm betting that the bad rap was started and kept alive by backyard mechanics who bolted 350 heads onto 400 blocks and then spit out the head gaskets from overheating because the heads were not drilled for steam holes. Well, that and using a low performance water pump.

 

[ericnova72]

So you are saying the world is wrong and you are right? The word on the street is the 400 sbc is overheating prone. Just because you yourself have been lucky enough to not have problems with one doesnt mean they are the GOD of all small block chevys and that everyone else is wrong. The stopped making them because they were prone to problems. Im sure there were other reasons, but id say thats the big one. Its an oddball engine with overheating tendencys. As for running them with block filler, alot of race engines have filler in them. Some of them are filled completely up and have no cooling system at all. You can run an engine down the track and not have overheating problems. But put that engine in a truck, pulling a heavy trailer on a 100 degree day with AC on in the mountains and tell me it has no problems whatsoever staying cool. The damn 400 got a reputation for overheating for a reason. If everyone has problems keeping cooling systems working properly then why arent 350s and other SBCs having problems? Whats the difference? The siamesed cylinders and steam cooled heads. That alone says that the 400 has a problem with overheating. You shouldnt have to keep everything perfect all the time in order for it to stay cool. You are pushing the cooling system to its max with little room for problems and thats simply put, a bad idea.

With all this said im sure the 400 is probably fine for racing only and maybe daily driving but forget making it WORK in the heat and be reliable. Thats what matters to me and the majority of people that want a truck. Even people with a car that would have a 400 in the real would would be sitting in traffic in the car in the heat with the AC going and probably easily have issues.

Have you ever owned a 400 SBC?? You revealed your lack of intelligence on this subject with the "steam cooled heads" comment. Who's "word on the street", because everyone I know knows that the "word on the street" (according to your version) is totally the result of operator error and lack of knowledge. Go ahead and believe what you want, I can see providing you with real information on this is like talking to a fencepost. I bet you'll turn down a free 502 if it is ever offered to you too because it is a siamese bore engine and prone to overheat !!! Your being born in 1985 puts you on the wrong side of the learning curve here.

To the OP-- run, race, and have fun with your 400 engine, it is no more failure prone or hotter running than any other small block. Just realize that it is 4 cubic inches bigger than a 396 BBC and needs a cooling system to match.

 

[Torque454]

I've never owned a 400 and never will. I have a 305 right now and have had a few 350s in the past and quite honestly I think they are all junk. I've blown up one 350 without even trying. Guess what? it over heated. It had a new radiator in it and it was a low mileage rebuilt 350. I was just cruising on the highway at 70mph, temp gauge was inaccurate but i didnt know how far off it was. Turns out half way up the scale was way too hot. Dont know what the deal was, but the cooling system was dirty when i pulled the engine, but i had only put that engine in a few months prior to that and i used clean antifreeze and water. New water pump correct for my application as well.

Quite honestly if i was going with a Chevy engine for myself it would be a 454. More cubes, more power. And not prone to overheating just because I let a few leaves get between the radiator and condenser, or because I let the cooling system go a year or two without a flush and fill.

 

[327NUT]

AHHHHH yes, the infinite wisdom of youth, you should really sit back, smell the roses and TRY to listen to what some of these older guys are saying. As said before, you showed a fine example of your knowledge by stating..... no 400's in 1970, along with .... I think they are all junk.

Then after you acknowledge that you were wrong you go on to argue with these guys about the 400's over heating problems. These were TRUCK ENGINES! do you think Chevy would have made them that way if they were prone to over heating?? Do you know (obviously not) how many 1970-on up 400 sbc were installed in motor homes that pulled boats w/o an over heating problem?

Any engine if not built, tuned and the proper cooling system installed will have heating issues. Anyway you go ahead and think what you want, but making statements like that and then trying to justify them by arguing will give you ZERO credibility on this forum.

 

[Torque454]

They didnt make them very long, if they were worth a damn they'd have been used longer than 10 years. The 350 and 454 engines were built for 30+ years.You cant argue with common sense. Common sense says that the way a 400 is built it cant possibly cool as well as as other SBCs. Im sure it could be adequately built to cool just fine (as mentioned the aluminum radiator, high flow water pump, etc etc) but it absolutely will never be able to dissipate the heat that the rest of them can because of its design. The 400 should never have been built, the bore size is just way too big for a small block. I think the 383 would have been an excellent factory engine.

I am sick of all the old folks who think they know it all and that their fecal matter doesnt stink just because theyve been around the sun a time or two. Yes maybe youve had alot of experience. So maybe a dozen of you have had great luck with a 400. Good for you, I'm glad. Obviously more people have had trouble with them than people that have not and that is where the overheating so-called "myth" comes from.

I happen to own a GM 6.5L Turbo Diesel, also known to some as prone to overheating and some people have lots and lots of trouble with them and think they are junk and all that BS but you know what? 250,000 MILES on mine and never been opened up. Just got back from a 2000 mile trip to colorado and back about two months ago and wouldnt be afraid to do it again.

My point is, we all have an opinion and we all know what my opinion is and we all know what your opinion is. My 6.5L has been great to me and your 400s have been great to you. Some people think both are junk and we are all entitled to think what we want. I haven't dealt with a 400 but if you really think about it, and i mean sit down and think of every little aspect of it, its just not the best choice. Here again that could just be a matter of opinion, but I really dont think so.

 

[bondo]

The 400 SBC has half the ability to cool itself than any other SBC has. There is NO water jacket between the cylinders. That means half of each cylinder doesnt get adequate cooling. Oil changes are probably more critical too because half that cylinder will be alot hotter than the rest, causing some thermal breakdown. The cylinder heads were also steam cooled in alot of places rather than coolant cooled. That alone convinces me that they are problematic and having no water jacket surrounding the cylinders and steam cooled heads sounds like the problem to me.

Ayuh,... Just What the 'ell are you talking about,..??..??
Obviously you have No Clue....

The ole 400s have a full Wet cooling system, pretty much like Any other motor...

 

[SSedan64]

No 1970 400?? Only made 5yrs?? Steam cooled??
Man this 632 Merlin I have with siamese cylinders must not be worth anything either. :thumbup:

 

[cobalt327]

She's so fine, my four-oh-nine.... :thumbup:

Stewie to Brian, as Brian sings a line of a song, "Who sings that?"

"So and so", says Brian.

"Let's keep it that way."

LOL

I'm betting that the bad rap was started and kept alive by backyard mechanics who bolted 350 heads onto 400 blocks and then spit out the head gaskets from overheating because the heads were not drilled for steam holes. Well, that and using a low performance water pump.

I'm with TI on this. In apps where a 350's cooling would have been marginal- a 400 would naturally be over taxing the cooling system . It's no fault of the 400- a 400 cid engine needs the cooling that a 400 cid engine needs - not the cooling system designed for a 350 (or smaller) engine!

The idea that "nobody runs 400's" is just plain wrong. There are MANY 400's, and if I were to buy an aftermarket SBC block, personally, I would be using a 4-1/8" nominal bore size- w/a stroke larger than 3-3/4", however. All AM blocks from Dart and WP, etc. are gonna have siamesed bores- even on the 4"ers.
Siamesed bores are used on everything from ricers to the Hemi.

I think the whole "400's always overheat" deal ought to be submitted to the thread about 'Myths' that was started here a while back!