Thread: sbc 400 2-bolt main

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hay i just got this 400 sbc it is 60 over, afr 210cc 202 aluminum heads, with a long stroke rods all balanced and blue printed in side and out, with forged dome top pistons
i sill have to get a cam and in take, basically a top end i wanted to make it around 550 horses (this is my first hp engine) but when i flipped it over i found that it is a 2-bolt main, all the old school dudes have been telling me that i should of got the 4-bolt or make it a 4-bolt main, (ow and its a high nickel block at least when i looked up the block it said it was 2% nickel) so my ? is is this a good block for hp? i dont want dump a lot of $$$ in to it just blow it up with one good run... if you could help thanks..

Welcome and the best thing you could do is convert it to splayed 4 bolt caps----the outer bolts are angled out toward the pan rails which really helps tie the bottom end together

iv seen them and you think that would hold it to gether?

i was all so thinking of putting solid roller lifters with a lopy cam heavy springs but i dont know about the in take

Intakes are easy===themains will take a align bore/hone job

Welcome to CHR!

I’d be concerned about a .060 over bore in a 400 long before I’d be concerned with the 2 versus 4 bolt mains. As Jerry stated, they are a good candidate for the splayed 4 bolt conversion and I certainly agree with him that it would hold the lower end together however; but bring a bunch of money to your machine shop. Was the block sonic tested after the boring? The .060 over on the Siamese blocks is really pushing it as their design (two cylinders actually touching) is not as efficient in the cooling department and they are prone to “hot spots” where the cylinders touch. Removing .060 doesn’t leave a lot of cylinder wall.

That said – you didn’t tell us what you have in mind for the engine – when you say “one run” does this mean you’re going to drag race this engine? Why 550 HP? What is this engine going to go in?

Before cam selection it would help to know; rear end ratio, tire size, transmission (manual or automatic) and stall (if auto) would be good to know as well.

Give us a bit more info and there’s a lot of help on this site!

Again, welcome to CHR,
Glenn

well two more bolt holes in the mains of a weak block to start with . stud the two bolt main use a main girdle . splayed would work .but buy caps.. fit the caps . line bore block . then deck with BHJ tru-deck .then bore hone block with deck plates .now you want to push this block to ?? how many Hp 550 it should hold it but if your going to go with the block work you may want to look at a SHP dart block

To Pat's point - it will cost a boatload of money for additional machine work and splayed caps - get us the additional information I asked for above and we can help you with a cam and intake/carb and you may want to call it a day and run it as is.. Although as cold as it in in Northpole Alaska - ya may not have any heat issues

well like i said im new at this im a mechanic fresh at of collage i havent decided what to put it in , the guy i got it from didnt say if it was a long block or not , but i do have a 78 280z in the back yard, thay have lotts of kitts for those cars ,so what do you think im i going about this all wrong ? and with all the balancing and blue printing they would check the block (i have all the paper work with the engine and ive opened it up its had a lot of woke done) so some direction would help thanks....

It is possible with 400's and the best efforts to leak down one a number of times and get a number of different results because the cylinders do move quite a bit.The logic behind aftermarket blocks is the failure of the OEM stuff.When you start talking about 550 hp,there is a formula for dollars spent per each 1 hp.So it as always comes down to your budget.

I knew of a guy with a 406 in a Super Gas car.It had a cast crank,high stall convertor and tranny brake.He along with all of us called that a grenade with the pin pulled on each run.If it wasn't for fact he couldn't afford anything else at that point,he won't have tried that.Got to the end of the season and tore it down.Bottom end was trash.If your thinking of a big time spray on this,I suggest to limit that.

sounds to me like he has a lot of good parts and other work already done on the top side---these caps can be put on the 3 center mains and actually make the block a lot stronger because the outter bolts are angled(splayed) out inti the outter pan rail/main web junction. I do from 2 to 5 of these jobs every week and find that the eagle caps are cheap compared to the programs, milodons etc (well under c-note) and takes total of about an hour to install the caps and another hour to align bore then finish align hone block

Its all he needs to do , its simple (if the shop has the equipment) and about the only machine shops who won't recommend it are the shops who don't have the equipment or the knowledge/experience to do it.

it is what ever he wants to do and how much the shop gets to do the job your talking 150 in mich for line bore then caps 107to 170 milodons 222.fit drill for caps . so lets stay 400.?to 500. more hard to stay what they get for the job were he is at. as for saying the shop would talk you out of this and a better block if the shop did not have aline bore or line hone that can go both ways were a shop would talk you in to a job if they had aline bore ?

Pat the eagle caps are way less than $100----

My two cents worth(normally a dollar charge but discounted for here.),is now you have strengthen the bottom end and still have a cast crank.Sure don't have much of a future at 550 hp with that.

never look at them thats just prices out of comp for them caps