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Discussion Starter #1
68 vert came with the 400. Smokes a bit, but starts right up and compression is OK. As a first project, I'm thinking I should go with a 350 instead of the 400. Seems like there is more info on the 350 and the 400 has some quirks that I may not be up to dealing with. What do you guys think? Anyone in N. VA want to swap?
 

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The 400 is a good motor and since you have a running one then you have all the pieces to put it back together. They are different because they are balanced different than a 350 other than that they are pretty much the same. I believe they are externally balanced and require a flywheel made for 400's and since your car is running, you have all of that.

If you have a two bolt block then those are considered stronger than the 4 bolts.

I would rebuild it because 50 cubes are 50 cubes and that's horsepower/torque. Just get bored out .030 over to make a 406 and a real stout motor.
 

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hmmm, ya, we talkin a camaro wit a (non-orignal) 400 SBC? or a bird?

Assuming a Camaro, by all means, do up dat 400, they run great. Lots of guys here runnin 400's or 383's, I'm sure they'll give ya all the help/advise you could wish for. 400sbc is a torque monster.
 

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Indeed, the 400 sbc is the way to go if this is really what you have on hand. Since your car is apparently equipped with the 400 out of the box, the rad will naturally be enough to cool the unit, which can sometimes be a problem when putting a 400 where a 350 used to be. I didn't think they started making the 400 sbc until the mid 70's though, so either your engine isn't stock, or you are perhaps referring to a Pontiac block?
 

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400 all the way!


They are a little more expensive to build than a 350, but not much (especially depending how you build it) and make WAY more torque.
 

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Go with the 400. Lots of torque is what you want and need.
 

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Discussion Starter #8
Thanks for the advice. Car is a Camaro. As you guessed, it's not the original motor. VIN says it started life with a 6 cyl. I checked the numbers from the block and the heads and it's a 400. Don't know about the cooling system. Radiator has an outlet for the overflow bottle, but no bottle. Looks like it was thrown together to sell it. It's got a 2bbl and stock ex manifolds. Where do I look (other than inside) to check for 2 or 4 bolt? Other issues I won't go into here. I guess I'll keep it either way and rely on you guys to take me through it. I don't plan to build it too much, just enough to smoke the tires a bit. Thanks again.
 

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I can try to lookup the casting number for you in this book I have beside me, just let me know what it is and I should be able to tell you the year of the block and whether it is 2 bolt or 4 bolt main (if you can spot the casting number that is).
 

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Hey Shredder, welcome to the club! I am just south of you in Richmond.

I agree, go with the 400... I would of if I could have afforded the extra $ at the time.
 

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Discussion Starter #11
Blocl is 3951511. Heads are 8973493. As I think about it, I seem to recall reading that the block isn't the best to have so it may be a 4 bolt. Heads are just average heads I think. Thanks
 

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4-bolt? Who cares! When we say that a 2 bolt is stronger than a 4, it's on the way of splitting hairs. It's gonna hold up, unless if maybe you're running lots-o-boost or nitrous. Build it and have fun! You wont regret it!
 

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#3951511 is a 1970 - 1973 400 c.i.d. block, 4 bolt main, used in heavy duty trucks and passenger cars.

Don't worry, the 4 bolts will hold up just fine. David Vizard mentions nothing about 2-bolt mains being superior, and actually hints at the 4-bolt main blocks being stronger if the caps are in good shape. I for one doubt it matters at all, despite rumors that the 4-bolt caps tend to break. I have not seen this personally.
 

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actually i've got a 511 block thats a 2 bolt, some were made, i belive they were replacements or something.
and even though vizard doesn't mention it, 2 bolt 400's are preferred in performance applications, and the best way is a 2 bolt drilled for splayed 4 bolt caps, but thats only if your looking at lots of horsepower ( over 500, and higher rpms imo) or nitrous. with the larger bore of the 400, the extra holes (drilled straight, as factory) just weaken the main web, since there isn't much meat left there with the 4.125 bore. you end up with the main caps moving around and flexing, with bearing failure not far behind. ask around with guys that build 400's a lot, like the 410 class sprint car guys and such.
but really, as silver69 says, the 4 bolt is just fine to certain horsepower levels, but if you start exceeding 450+, a 2 bolt with studs, or a splayed four bolt is the ticket with a stock block.
and oh yeah, there is no way i would consider anything but the 400, you will make more power with all else being the same, and the torque is awesome
 

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Actually, yes, he (David Vizard) does metion here (in this book) that using 4 bolt caps on a drilled 2-bolt block will work. He seems to stay away from judging between 4-bolt, 2-bolt, and hybrid blocks, but he does make it quite clear that the 400 is his choice; in more sections of the book than one. Interesting how so many of us revere David Vizard as a teacher of sort, and no doubt we have all learned a lot from his wisdom. With this in mind, I feel it is safe to advise other to go out and buy some books by David Vizard. The books are undoubtedly of great help!
 

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vizard definately knows what he's talking about, no doubt. i dont have that book, but from the sounds of that he is referring to splayed caps on a 2 bolt block, which is definately the best bet. he wasn't talking about using 4 bolt stock caps and fitting them on a 2 bolt block was he? that just wouldn't make any sense to me. just curious, like i said i dont have his books, so i dont know.
 

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Well, he was going on about how rare 400's are, so he mentioned that if you had a good 2 bolt block, and a bad 4 bolt block, you can use the 4-bolt caps on the 2-bolt block, but it needs to be machined, drilled etc etc. I think he is mainly stating that in a pinch, you can make 1 good block out of two if you are absolutley determined to have a 4-bolt main 400 for some reason.
 

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Regardless of all this somewhat irrelavant 2 bolt vs 4 bolt discussion...any 400 that runs is worth keeping... just a question of what to change to get more performance... so....

We need a condition report on this motor... do a compression check, and post the numbers. Check the plugs while they are out, let us know how they look. Pay particular attention to differences from plug to plug, or if any pairs next to each other look "funny" Does the motor start easy and idle smoothly? Does it smoke? If it smokes, is it when you're on the gas, or when you let off? Does it use oil? Does it leak oil?

IF it passes all these tests, then it's solid. Heads, intake, carb and headers will give you near 325 HP / 400 Ft-lbs torque. Change the cam too, and pick up another 50 easy.

Have fun!

P.S. since you gave us casting #'s, this don't matter... but if in doubt, a 400 sbc has 3 freeze plugs per side, evrything else has 2.
 

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Discussion Starter #19
Compression on all is between 160 and 170. Squirting oil in cylinders doesn't change it but a couple pounds. Smokes a bit. All the plugs looked the same, black from oil. Changed the valve seals and that cut it down some. I can see the play between the valves and the guides so I'm thinking that's the problem. Starts right up and idles smooth. At idle, the exhaust pops a little. I think it's a solid motor. Drove it a couple hundred miles at a stretch with no issues. It'll be a while before I get into it. Going to try to do some body work before it gets too cold. I'll be in touch. Thanks again.
 

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seriously, go with the 400 regardless, unless there is a serious problem with it, a crack etc. even if it needs rebuilding. most factory 400 heads are crappy for performance purposes also, so i wouldnt worry about them either.
and another piece of "irrelevant" information, all 400 do not have 3 freeze plugs, in fact, my 511 block has only 2, so dont base identification off of that info. if it has 3 plugs (and a smallblock), its a 400, if it has 2, it still could be a 400. but regardless, the numbers you gave make it a 400, which is a very good thing, imo
 
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