Just got the new Summit Racing Catolouge in and noticed the Dart blocks......My question is what is the difference between Steel Mains and Ductile Iron Mains? And has anybody went with this 400 block? Pros & Cons? :cheers:

 

Why do you think you need this block. The stock bottom end is good for more HP than I have seen a TPI, even with a miniram and blower make!
If you are planning a 1000 HP motor, you might want to look into this.
Good Luck,

 

PS Throw that Summit catalog away. If it is in there or you can even think of it, you can get it from one of the Corvette Forum vendors.
Of course, I might suggest you pick one in particular. :cool:

 

While a stock L98 block MAY be good for lots of HP, it is not good for that long if you bore & stroke the motor. You can get lots of HP from a high-compression motor, but can't drive it on the street (unless you LIKE buying gas at $4-$5/gal.). And certainly I wouldn't try to push that kind of horsepower without splayed caps on the bottom end.

The cylinder walls on the stock blocks are good for .030" overbore, and if you go over that you are taking your chances. The life of the motor will be in question, and when a rebuild comes you'll be stuck getting a new block anyway. If you want to make HP with cubic inches, then a block that is designed for that is much better than a stock block.

I know you know your stuff Chris, but I think if he's looking at going 400+ cu/in, then the Dart, Motown or similar block would be the best bet. I kept my original motor complete, just so I'd have a back-up to put in if something went wrong. In my case a new block needed to be purchased anyway, so why not go with something a little beefier?

Just my $.02

 

Problem is that some of the other forum vendors have quite a mark up on stuff. Got to shop carefully these days to keep more money in the motor and not in someone else's pocket

Cory

 

Jay,

I built my SBC427 using the Dart Iron Eagle block. It is identical to GM's Rocket Block, actually Dart makes the Rocket Block for GM. The Iron Eagle is made using the same castings, material, machining etc, the only difference is that the IRon Eagle is can be either a wet or dry sump, whereas the Rocket Blocks are sold under two difference part numbers depending on whether you want a wet or dry sump.

I opted for the 4.125" bore, 400 main, BBC cam bearing, tall 9.325" deck block. AS you probably know it is a significant upgrade over any GM production or Bowtie Block. Here are some details:

Nomenclature: Iron Eagle Small Block
Part Number: 31122222
Price: $1,850.00
Material: Cast Iron
Cam Bearing Bore ID: BBC - 2.120"
Cam Bearings: Special Coated, Grooved, W/ 3 Oil Holes
Cam Bearing O.S.: +.010", +.020", +.030"
Cam Bearing Press: .002"
Camshaft Position: Raised .391"
Camshaft To Crank CL: 4.192"
Camshaft Snout: SBC On All
Cam Plug: 2.375" Dia. Cup Plug
Cylinder Wall Thickness: .300" Min. @ 4.185" Bore
Cylinder Wall Type: Siamesed
Cylinder Deck Height: 9.325"
Cylinder Bore Range: 4.125" - 4.200"
Deck Thickness: .875" Min. (Can Machine To 8.800")
Fuel Pump: Mechanical Pump Provision
Freeze Plugs: Press-in Cup Plugs
Fuel Pump Pushrod: +.200" Long Or BBC
Lifter Bores: .842"
Main Bearing Size: 2.650" (SBC 400)
Main Bearing Bore: 2.8401" (SBC 400)
Main Bearing Press: .005"
Main Bearing Cap Bolts/Studs: 4
Main Cap Bolt Orientation: Splayed 18o
Main Bearing Cap Type: Steel
Oil System: Wet Or Dry Sump - Main Priority Oiling
Oil Pump Shaft: BBC Shaft W/ Wet Sump
Oil Filter: No Provision, Remote Filter Required
Oil Pan: Pan Rails Spread .400" Each Side
Rear Main Seal Type: 2 piece
Serial Number: Left Front and Main Caps
Starter: Mounts On Either Side
Studs, Mains: #1: 7/16"(2)
#2,#3,#4: 7/16"(2) & 7/16" Splayed Bolts(2)
Rear: 1/2"(2)
Stud Holes, Head: Blind, Freestanding
Timing Chain/Gears: Must Use Raised Cam Components
Timing Cover: Can Use Stock Cover
Torque Specs: 1-4 7/16" Studs - 75 ft. lbs.
1-4 7/16" Bolts - 65 ft. lbs.
Rear 1/2" Studs - 100 ft. lbs.
Weight (lbs. - bare): 202





Engine Block Notes: All block dimensions are machined to +/- .001". Minimum cylinder wall thickness of .300" with a 4.200" bore. The outer water jackets are scalloped to enhance coolant flow. The reinforced deck has a minimum .875" thickness. The head bolt holes are blind-tapped and the head bolt bosses are freestanding to minimize cylinder bore distortion. The three steel 4-bolt center main caps have splayed outer bolts. The 2-bolt front and rear bearing caps are retained with studs. The block uses 2.650" SBC400 main bearings and a two-piece rear main seal. The camshaft is raised .390", for a 4.912" camshaft-to-crankshaft centerline. The relocated camshaft will clear a 4.125" stroke crankshaft without interference, eliminating the need for a small base circle camshaft. The block uses Big-Block Chevy V8 cam bearings. The block has a "priority main" lubrication system that directs oil to the main bearings before the cam bearings. The oil pan rails are spread .800" (.400" per side) compared to a production small-block V8.

Machining Notes: With BBC cam diameter, camshaft snout must be machined for SBC size to accomodate SBC gear or sprocket. Special Timing gear is required for raised camshaft. Cam bearing OD should be deburred before installation. A sealant/antiseize must be used on the head studs. Studs should never be torqued into the block. They should only be finger tight. Press-in cam plug diameter is 2 3/8". When a mechanical fuel pump is used, a +.200" SBC push rod is required (BBC shaft). When a wet sump oiling system is used, a BBC oil pump driveshaft is required. When using a wet sump you must plumb oil into inlets at front or rear of block. (1/2" NPT).
With some intake manifolds, the distributor will not fit into the block. The distributor hole is at 5o instead of the stock 4o for extra clearance for the larger oil pump driveshaft. Solution: Machine hole in manifold, then remachine top surface to match. Use collar on distributor if possible. Do not use o-ring on distributor to seal it. Always remove the o-ring. Ensure that the distributor groove is lined up with lifter supply hole. If distributor is too high or too low it will expose the oil galley at the bottom.

Main Priority Oil System Notes: Oil feed can be directed through the front or the rear oil inlet. Oil is directed to the main bearings first, then to the cam bearings. If lifter oiling is restricted, restrictors must be installed in the front and rear lifter galleys to prevent oil from bypassing and feeding from the opposite end.
If a dry sump oiling system is used you must plug the oil inlet hole in the rear main cap or in the block,underneath the rear main cap (1/4" NPT). The block has provisions for dry sump scavange in the valley area. If no scavange is used at this location, or a wet sump is used, a 9/16" oil drain must be drilled to insure sufficient oil return. For Drag Racing the hole should be just left of the distributor hole. For Oval Track the hole should be in the right rear corner of the valley.

 

nice block but heavy. go with an aluminum block. ive seen em as light as 92-95lbs for a sbc, i have no clue if they have an aluminum small block for big displacement like the rocket block

 

Depends on what you want, I suppose. There are aluminum Rocket Blocks, and Dart offers their blocks in aluminum as well, even an SBC with a 9.500" deck height(!). Rodek, Donovan, etc also offer aluminum SBC's.

However, the iron blocks are much more rigid, stronger and durable than the aluminum blocks. Additonally, the iron blocks typically make more power, especially as rpm increases, due to the fact that they are more rigid and stable, and thus the main webs and cylinder bores don't move around as much, providing better ring seal.

Add to that the fact that aluminum blocks are typically around $4000, compared to $1800 or so for iron. These blocks are meant for heavy duty racing use and for big strokes and bores. A side effect of all that extra material to strengthen the webs, decks, bores, and bulkheads is a little more weight. An average production SBC block weighs around 175 lbs or, depending on what year it is and it's alloy content. So for an extra 20 lbs or so, you get alot more strength and the ability to run a 4.00" stroke crank if that's what you want.

The only benefit of the aluminum blocks is a 100lb weight savings. Unless you're into professional road racing, I couldn't see justifying it considering all you lose in terms of durability, strength, and possibly power, plus the extra $2200 more than the iron block.

 

i am actually wanting to build something like a 406 cubic inch engine....i wished i had the L98 but 84 came with the L83...My question was what is the differnce in the Ductile Iron Mains and the Steel Mains :flag

 

Steel is stronger than ductile iron, but the iron is a little more 'forgiving'. Which is better? - Depends on who you ask. Steel is certianly stronger, more rigid, and better resists bearing bore distortion. World Products likes to claim their ductile iron caps are better because the nodular iron expands at the same rate as the block, but most high-performance engine builders, as well as manufacturers of high performance blocks, will tell you steel is the way to go. In reality, for a street or street/strip, either is more than sufficient.

Sorry for not addressing you inital question completely.


[Modified by Monty, 7:19 PM 9/19/2001]