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Old 06-04-2013, 10:00 PM
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406 build....stock crank & rods?

So over last 2 years I have slowly been acquiring parts for a street/strip 406. I can't stand to see my camaro sit any longer and really want to get it on the road this summer. What I have in the garage is a 509 2 bolt block freshly punched .030, stock 400 rods, 2 stock 400 cranks (both need turned), stock 400 damper, trick flow super 23 195 heads (Valve springs for a solid roller cam up to .650 lift), howards retro fit SR cam 237/239 .585/.585 LSA 108, holley 750, HEI distributor (All new electronics), 1 5/8 long tube headers.

I guess my question should be what do you think about using the stock 400 rods, crank, and damper. The rods of course would have arp bolts. I'm thinking i should be around 450 horse. I'm a college student and dont have much money to blow on this, but dont want to be rebuilding it this winter either.

I've done research and have David Vizard's Max performance chevy small blocks on a budget. Everyone has a different opinion on this subject but i think a set of 5.7 rods with cap screw bolts and the stock crank and damper would suite my needs, But just looking for some input on this thanks!

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Old 06-05-2013, 05:33 AM
How fast is fast enough?
 
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I would reuse the crank but get new 6" rods and a new damper. Both if these items will have good returns in durability and power.

Building an sbc from scratch is not cheap you may want to consider other options.
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Old 06-05-2013, 06:19 AM
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If those parts are in your possession then use them for now.I agree with ap72 about the rods and HB.The 750 will work and the headers are a little small but will work
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Old 06-05-2013, 12:56 PM
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I have built several engine before and realize the cost that goes into them. I bought the 400 stuff for $100, heads and cam for $600, holley was already on the 350 in my car, headers $20. I wish i had heads with a bigger runner size, a hydraulic cam, 1 7/8 headers. I'm just trying to put together a respectable engine at small cost.

Now for a damper what would you recommend a stock replacement or something a little more spendy.
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Old 06-05-2013, 01:31 PM
How fast is fast enough?
 
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If you're going with a stock replacement then there's no sense in replacing it is there?

I had the wrong impression, I thought you were going after some serious power, not just putting spare parts together on the cheap.

for a cheap build you can probably reuse the stock crank, rods, and balancer, try to match the new pistons to the old ones (weight wise) and you can probably even skate by without a rebalance.

Its not the "right way" to do things but it'll work.
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Old 06-05-2013, 09:02 PM
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Are you saying that I can't make good power with what I have? Lets say i had a short block that could withstand 7000 rpm this thing would really rip. Will a fluid damper, 6 in. rods, stock crank, and a balance be the ticket. i've just never built an engine that made me question the integrity of the bottom end. You see people go all forged when it doesn't seem needed and then hear stories of stock crank and rod small blocks that put down big numbers. I just need a little guidance here. I would love nothing more to see my engine cross the 500 hp line in the sand mark. If it will cost more money than I can budget for at the moment, then I'll wait.
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Old 06-05-2013, 09:42 PM
How fast is fast enough?
 
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If you want 7000 rpm then you better add about 7k to your budget. A 400hp sbc 400 can be built with mostly stock parts. A 500hp NA 400 cannot. Now if you put a small turbo or supercharger on a 400hp 400ci engine then you can still use mostly stock parts and see 500hp. That may be the best approach for you to take, a mild 400hp now then add boost later when you can afford it.

7000 rpm is not cheap though, the rpm is a killer. You can make 500hp at 5000 rpm though if you build your engine right, and it will be cheaper and last longer but it will require boost, maybe 8-12 psi to be sure you hit the mark.

Rpm sounds nice but it can be very costly. There are other ways to make power.
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Old 06-05-2013, 10:11 PM
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cant believe I agree with AP twice in a row,lol.
after 400 ish HP the costs of ponies goes up.
The stock oiling system is good for 500 hp,some cranks and rods are good for 500 hp.Cams get more expensive and so do heads and valve train.,,,machine work becomes more precise and costly,,,and so on
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Old 06-05-2013, 10:25 PM
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I'm not interested in FI, Ill save that for the time when i get a 5.3. One of the cranks I have is a gm cast steel crank. If i get the crank cut, a decent damper, 6 in. rods, KB performance pistons, and a balance...what would be holding me back from making nearly 500 horse with the cam and heads I have. Might be slightly optimistic but not a pipe dream.
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Old 06-05-2013, 10:32 PM
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vinniekq2, I already have heads and a cam that i bought from a guy I knew he had them on a 383 but upgraded to some afr's and a bigger cam. Other than the fact that I need lifters and rockers, I feel my valvetrain is pretty stout.
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Old 06-06-2013, 06:07 AM
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how much power did the 383 make that the parts came from? your 400 should be slightly better at a slightly lower RPM if all else is equal.
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Old 06-06-2013, 12:34 PM
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Well it was pushing a 77 nova into the mid 11's, so I think 500hp would be a fair estimate. What size tires, gears, and stall speed i'm not sure of. I would assume he probably had a forged rotating assembly as well
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Old 06-07-2013, 07:04 PM
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Stock 400 crank reground is fine at 7000 rpm, done it many times and I never even worry a second about it. 5.7" or 6" capscrew rods , sportsman type, no need for H-beams(your choice on length), KB forged pistons, stock 400 balancer is fine IF?!!! (and only if) rubber is good and you don't think you will need the SFI spec for racing (faster than 10.99 ET).

You will need to get the block deck machined however. real important on the 400 block with it's narrow space between the big cylinders.

Should get close to your 500 hp goal no problem , I'd say 470hp minimum. 6400-6500 rpm shift point with your cam, maybe as high as 6700-6800.

Similar to the last engine I did with a friend this spring and had dyno'd - 377" destroker from an 509 casting block, Scat cast 350 crank, 5.7" rods, KB flat tops, 10.7-1 comp, same Trick Flow 195's heads, cam Herbert Solid Roller 247/252 dur @ .050", .590" lift, 106 lobe separation, Victor Jr, 750 Holley Double Pump, 1 3/4" long tube Vega swap headers___ made 571 hp on pump gas at Roush in Livonia, Mi. Goes 10.50's in a minitubbed all-steel Vega wagon 2900 lbs.

Only reason it was a 377 is because we bought someone else's partial project, we would have built it as a 406 had we bought the crank and rods and expected 20-30 more hp.

I thought the small (in my opinion) heads would hold it down to 500hp or so, was pleasantly surprised it made 571hp.
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Old 06-08-2013, 12:30 PM
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Agreed, the Chevy nodular crank is good. Best "cast" crank availble, IMO.

Replacing the rods is a good idea. 400 rods are just too short. For the 5.7" rod, Speed Pro offers a decent hyper-eutectic piston, not afflicted with the issues surrounding the KB H-E pistons. 6" rods are better yet, but piston prices go up. Icon (fka KB) are about the best for the money. Good forgings.

If you want 6,500-plus RPM, by all means, use a good balancer. The Pioneer SFI unit is a good buy. You should also consider an SFI-approved flexplate (if auto trans). Converting to "internal balance" isn't cheap, but not a bad idea for such a revver. It involves adding "heavy metal" and using 350 balancer and flexplate/flywheel.

377s were an "after-thought" using leftovers from building 383s. I first saw the bearing spacers around '75, MAYBE '74. Now that's a small block that can REV! GREAT drag engine, especially in a light car.

Jim
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Old 06-10-2013, 01:00 PM
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Thanks for the responses. I think I'm going to go with some 6.0 I Beam rods given they are the same price as 5.7's and it seems piston selection for 6 in. rods is better as well. Budget wise I think I better stick to some hyper. pistons. So I messed up with my cam specs. its is actually 247/249 .585/.585. How I messed that up Im not sure. How does that change your opinions on this build. I just figured the dynamic compression assuming i shoot for 11:1 compression with my correct cam specs and my elevation I get about 8.4:1. I really don't wont to put additive in my fuel, does this cam need that much compression, and compression is a cheap way to make a few more horse. I'm in a limbo here. What do you think?
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