I want a big displacement engine that doesn't weigh a whole lot. I understand that you can enlarge a 350 to 383. I have also heard of 406s. How much heavier is the 406? Can the 350 be larger without a whole lot of machine work?

Thanks,

 

406, 350, 355, 383, and 400 are all SBCs and weigh the same

 

The 406 block is different though, right? 350s can be found without to much effort. Is it the same with 406s?

 

you can find any SBC you want, just a matter of looking in the right place and how much you want to spend.

 

I would like to spend less than $500.00 for the block. I expect to replace the internals.

 

Because of the popularity of racing in your area, a 400 might be harder to find than most parts of the country. Look for standard or .030" bores. The safe max overbore for a performance build is said to be .040" but have the block sonic checked if you must bore over that. You might get lucky. You might also prefer the 2-bolt main blocks. They are stronger. The two bolt blocks can be converted to splayed 4-bolt blocks for the strongest of all factory based set-ups.

As far as big motors go. The simplest and least expensive probably is the 415/418 kit from Speed-o-motive. It is a 400 crank offset ground for more stroke. The journal, as you can imagine, is now a smaller diameter than the standard large journal. They use a 5.7" long small journal rod, forged or hypereutectic pistons, and quality bearings. Last I check, the kit could be purchased for less than $1100 with hypereutectic pistons.

http://www.speedomotive.com/500_hp_maxi_mouse.htm

 

how much power do you want? just get a big block if you want some serious displacement the benefits from it will make up for the weight.

course thats only if you want realiable 500+ horse... id go 355. keep it simple.

 

I really don't have a power number yet. I think I want as much as can be generated without having to do major machining as that escalates the cost big time.

My goal is a street legal car that outperforms any stock new car under a vette.

If I end up with 1.1hp/ci lingenfelter's book says that's ideal, yet GMHTP just claimed that they made 480hp without a power adder on a 383.

I anticipate a SuperRam Intake with appropraite engine management, AFR 195cc heads, Hydraulic Roller Valvetrain, Ross forged pistons, Oliver connecting rods and cranshaft, and Dynomax exhaust system.

I am more inclined to work on a broad power curve rather than peak numbers.

If it wasn't for the fact that iron big blocks cause a huge weight gain I would go with that. I am trying for boths 12s in the 1/4 mile and 1g on a 200ft. skidpad (I ordered a vanity plate thats says "1G 12SEC"). I think a big block would make one part easy, but make the other part very hard. Too bad Donovan blocks are so expensive.

 

You don't get a "406" block. It's a 400 block. The "406" is nothing more than the CID you end up with when you perform routine maintenance on a worn-out block by boring the cylinders. It's still a 400, just bored .030" over. It's not some special size built out of special parts that need its own special number to indicate how special it is.

At 450 HP out of a 400 CID motor, you don't need a $3000 crank and rods to survive. The stock ones with ARP rod bolts would be adequate, although that's about the limit.

I'd strongly suggest a MiniRam instead of a SuperRam, if you really want max power. The SR, while it can run strong, is such an incredible PITA to work on, you'll hate it from the minute you start trying to put it on there. The MR is alot like the LT1 intake; or rather, the LT1 intake is alot like the MR, since the MR had been around for several years before the LT1 was introduced. It's small and compact, with very short runners and great flow, with everything easy to get to.

As far as weight, a 400 weighs the same as any other small block Chevy.

 

The only reason that I picked the SuperRam was because it has an EGR provision. If I can pass the sniffer test without it I am all for it. I am not concerned about the visual inspection as they didn't even look under the hood of my car when I took the test in October.

I have heard (upon further reading) tales of 400 blocks getting too thin. Do you absolutely have to bore it out? It would sem to me that 400ci should be enough on its own, right? And since I would already be using the 400 crank there's no stroke capability I guess.

Is there a crank and rods set less than $3000 that has a higher capacity to it than the stock units. I would like a bit of a safety factor.

 

you bore it out if its worn.

because they were made in the 70s, chances are, its worn.

you overbore it to the next over bore, and get pistons to match.


and yes on the crank and rods.... heh, you could get the whole upgraded rotating assembly for around $1000 easily.

 

Passing the sniffer test depends on exactly how it's administered. If it's at idle, it won't matter. If it's on the dyno, as long as you have a functional cat on it, it should be just fine.

The bit about 400s getting thin is an old wive's tale. Ignore it. No block you get should have problems going out to .030" over.

Almost any block made since 1970 is going to have a chance of hitting water, or at least porosity, if it has to go to .060" over though. Try to find a block that's still std bore.

There is essentially no difference in power between std bore and .030" over. That overbore produces just about 1% CID change, so that's about what the power change is. About 4 HP if it's a 400 HP motor. Negligible at best.

There are dozens of better-than-stock bottom ends that you can buy. I'd recommend Eagle, if you're looking for a good reliable setup, with trouble-free installation. I don't think they have a web site right now; but you can call them, they're in Memphis (or at least available to the Memphis directory assistance). Or, look at any of the vendors that carry them, such as Thunder Racing (top of this page).

It is possible to stroke a 400. I've built a 434 myself, so I know it can be done. Again, Eagle is someone to check, as they do make a 4" stroke crank for 400 (434 = 4" stroke + 4.155" bore). But it's not just a drop-in kind of thing; if you don't have lots of engine-building experience, or are willing to pay someone who does, I wouldn't suggest trying it.

 

A 350 is easy on the wallet, and generally a very reliable engine, parts can be cheap, and even well made parts still wont break the bank so to speak. I would build another 350 if i had the chance, just cause I had the 305, the 350 dropped right in, and she runs awesome... Old 350 tho, Everyone says get the newer fuel injected 350, or get the old school 350, I hate fuel injection, So old school I went, 1969 i believe
Good luck