I'm trying to do this right the first time. Your help appreciated. The last gen I small block I put together was 25+ years ago. I've done my research, but still have more than a few questions.

Proposed parts include forged pistons and rods with stock crank. Shooting for about 10.5 c/r. Block is a two bolt main. Strong enough for 450 hp and 6000 rpm? If not, is the block upgradable? How?

Top end to include 700 cfm carb, high rise dual plane intake and Trick Flow 23's at 195 cc intake ports.

I'm a little fuzzy on cam selection. The cams that I've used on my LS motors have had 112 to 117 LSA's. I like the manners of the wider LSA cams much better. However, just about all of the off the shelf gen I performance grinds that I've seen have very narrow LSA's. I want all the power I can get, but want "0" drivability issues. I know it's all a compromise. If this were a 400cid LS motor, I'd feel comfortable using something like a 226/228 .580lift on a 114LSA. Don't have a clue which way to go on a carbed motor. I'd like to see at least 12" of vacuum at idle. I'm trying to get away without using a real loose converter in front of the T350.

I'm hoping that with the extra cubes, this is doable. Is it? Am I on the right track or way out in left field? Help appreciated.

 

Some good info (not by me...) on this thread:
http://forums.corvetteforum.com/c3-t...questions.html

 

Hey thanks....didn't see that thread in any of my searches. Good stuff

 

I go to the comp cams lob catolog and pick the duration I want and have them make a cam with my LSA. MY 383 SR cam is a 112 and it is a sleeved distibuter gear billet steel

The Crane Cams street rollers are sleeved and come with 112 Their 232/238 might be a good choice.

 

Is a roller (I'm assuming hyd roller) necessary with 400+ cubes and a power goal of 450?

 

Sorry, buddy, but you're gonna have to forget most of what you know about camshafts for LS engines when you're looking at smallblocks. Most of us scratch our heads when we see the crazy splits and duration that LS engines seem to like. I've seen L92 headed engines with close to 20 degrees difference betewen intake and exhaust but they seem to like it.
I'd step up to hydraulic roller as well - it'll cost you a lot more than the difference if you have a lobe go flat on a cam and you have to pull and go thru the entire engine.
I have a 406 in the works for my '81. Two bolt block with ARP bolts, Scat cast crank, Scat capscrew rods, SRP reverse dome pistons should put my compression right at 9.8:1. The cam I picked should give me enough vacuum, at least that's what others have told me. It's a Crane grind, 234/240 with an 114LSA. I'll be using the new Bowtie Vortec heads with 225cc runners and a Performer RPM intake, topped with a 750dp. I'm looking for 475 - 500hp and about the same torque.
For pure streetablity, keep your duration in the range you quoted for your LS engines and keep the LSA around 112 - 114 degrees. That should make for a hoss with a mildly lumpy idle and tons of torque.

 

You LS has HR cam and you mentioned .580 lift. so I figured that is what you were talking about

 

With most of the other posters here. You are limiting your RPM to 6000 so a hydraulic roller is a great option. With 10.5 to 1 compression you will need around 236 duration @ .50 on the intake to safely run pump fuel. 112 LSA is a good choice. A split duration cam is also a good choice. Most cams you look at will be short of your lift goals so 1.6 rockers might be a good choice. Your trick flow heads might not flow much more over .500 lift. If so, no need to go with higher lift. The hydraulic flat tappets just aren't the answer anymore on a fresh build. Spend the upgrade $ and get a hydraulic roller. You will get more power and less chance of wiping a lobe with this setup. Your cost per HP gained upgrading to a roller is not a lot. The $ saved on high zinc oil and piece of mind not wiping a lobe and trashing your new engine will justify the initial expense. Good luck on the build.

 

Not trying to be a stick in the mud: But why the 400 sbc? Its siamesed bores make it harder to keep it cool. Its two piece rear main seal is prone to leaking. The retro hydraulic roller setup is expensive.

Why not go with a Gen2 350 or 383 stroked small block? It came with a factory roller camshaft so roller cams are much cheaper for it. The Gen2 will have the one piece rear main seal. And the Gen2 bores are spaced farther apart for a more friendly street motor on those hot summer days.

You can stroke a Gen2 with a 400 crank and you will get a lot of that torque that you are seeking from the Gen1 400 block.

I have a Gen1 block in my vette and when it goes you can bet a Gen2 is going to replace it.

Again, not trying to be a dick. Just curious and I want you to know that you have lots of options.
Good luck with any build you choose.

 

Theres pluses and minuses, I like the bigger bore of the 400, it likes to breathe with a good head . Minus is they arent the strongest block but if he can find one that mic's out Ok it will handle 450chp without issue.

Now if he went with a 350 block he could always put a 3.875 crank and make it a 396, that would be fun. Nice ring to the 396 also He could use a late model mid 90s truck block which is 4 bolt main and equipped for roller cam already saving cost of retrofit lifters. Its a one piece rear main so all hed need is a different flexplae, those are cheap enough.

 

Well said Cuisinartvette.

And if he did go with the 400 block, he could always have a machine shop install splayed mains.

Done correctly, those are the best.

 

400's aren't hard to cool, you just have to build your cooling system accordingly and make sure you have steam holes in the heads if you're gonna be subjected to a lot of idle time. 565's are hard to cool - if you don't plan and build accordingly. The bigger bore unshrouds valves better and can take advantage of bigger runner (read: more power) heads that the 383 can't. Big block power in a smaller, lighter package. If you have a good block, there's no reason not to go with the 406.

 

Hi L88plus,
All good points. But the retro roller is expensive and with the rear main seal hassle to deal with, in my humblest of opinions, the Gen2 seems like the better bang for the buck. The OP only wants 450HP. Easily obtained with a stroker and REALLY easily obtained with your 406.http://images.ibsrv.net/ibsrv/res/sr...milies/lol.gif

 

on the question of needing a roller to make 450hp, the answer is no.
However youll get better manners/idle and more power under the curve with the roller plus the peace of mind you dont have to worry about the cam going flat. HR's are super reliable, set and forget type thing unless youre getting real wild with it.

 

Been watching the several 400 CID build threads lately...

Now I KNOW (and have read) the "discussions" on the forum about Sk1p Wh1te, and I have no opinions one way or the other, but he does offer a 400 with splayed mains, roller rockers, one piece rear main seal, either in a built motor or in a short block.

http://cgi.ebay.com/ebaymotors/SBC-C...item3ef5a7a919

http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

Can you engine guys at least comment on his product, without rehashing all the negatives regarding aftermarket heads...

I am not an engine guy (though I'm learning!) but what about the short block?? Would this be a good basis for a 400 build, with the right cam and a quality set of heads?? I dont pay much attention to his HP capability claims, but for a 500+/- hp motor....?

Price is not an issue with me, though it probably is to the OP and many others.....

Just asking....

Rob

 

I havent used any of his motors but have spoken with him many times and seems to be a decent stand up guy. Takes a lot of flack from the net, Ill say that.

 

He lost me here "These heads will out perform a set of non cnc'd Dart Platinum Pro 230's" . He no longer names the Pro Comp heads in his ad.

If the short Block is properly built and balaced it is a good basis for a 400 build. That is a big if though.

I would still go with the SHP Dart Block and a good Forged rotating assembly and have it built locally.. This will cost a little more but you get what you pay for.

 

Like this...??

http://cgi.ebay.com/ebaymotors/Dart-...Q5fAccessories

 

Why does he know the manufacturers name for everything, even the cam bearings but not the pistons ?

I see PBM under the pic and that could be the piston you get, not saying they are good or bad but why not put the name in the body of the ad ? Most of the parts in the ad are acceptable just don't like the omission.

Go to a track near you, ask the guys coming down the return road that still have their motors running where a good machine shop is around your area. I like to have the shop within sharp stick poking range if something goes wrong

Oh almost forgot 400's don't overheat and you can run a Holley double pumper with single plane and solid roller on the street

 

I have a stock 75 sbc punched out to a 406. I chose flat top pistons that will give me 9.8 comp. with stock 76cc heads and my cam will be 220 Dur or low @.050 . I'm more of a torque kind of guy,more than a HP screamer. Blown too many engines over the years
I'm shoting for a 110,000 plus miles on this one:o I hope