Guys I am in the process of building a 383 stroker motor and I ordered a complete rotating assy.that includes an Eagle ESP cast internal balanced crank,Scat Pro Series 6" I Beam rods with 7/16 arp bolts,SRP 5cc flat top forged Pistons, Moly rings, Clevet ,rod and main bearings,Pro Comp Aluminum 210 runner 64 cc Heads,Edelbrock performer RPM Air Gap Intake, 650 Dual line ,vaccum sec,electric choke carb and the whole bottom end has been balanced.When I called the guys that I bought the heads from and talked to them about what kind of cam I should use he scared the h>>> out of me by telling me that I would more than likely be running some where around 11.00 to 1 comp,and now I don't think that the cast crank will stand up under the stress of a stroker moter with 11.00 to 1 comp.I think I will go with the 4130 Eagle Steel crank,Now comes to my ? about the 400 block,I have a 509 standard bore block and my ? is will the Eagle ESP cast crank fit the 400 block and can I get adapter bearings to go from the 350 mains up to a 400 crank and also can you run an enternal balanced crank in a 400 with say 5.7 rods and a decent set of pistons,and I have a fresh set of 186 heads with 194 valves and a weiend Intake and Edelbrock 600 carb,would it be feasable to try Thanks Camaro BOB

Eric68,

Where are you GUY!!

Heck, a stock 400 crank will handle in a GOOD set up 383" motor, what is it guys?? -- 600 hp???

A 1/4 mile at a time.....

pdq67

That kind of compression isn't gonna bother the crank at all. It's higher RPM's that'll eat it up, not compression. If you zero decked the block, you'll be running about 10.9:1 and it all depends on the cam as to whether or not you'll be able to run on straight pump gas without mixing. Since you have everything ordered, go ahead and build this one, hang onto the 509 block for a higher performance build. Have those heads checked really good, some of 'em take a lot of $$$ to make 'em work right. And pdq's right, the GM 400 cranks can handle a lot of power, they're nodular iron just like the Eagle ESP and Scat 9000 series cranks

If you're worried, trade in the pistons for a set of SRP's D-Dish forged pistons, they'll knock the compression down a point.

Bob let me get this right. You have a +.030 350 block and a cast 400 crank you want to build a 383 with. You also have a 509 400 2 bolt block and a steel 4130 crank.

No question what I'd do in your situation. Build the 509 block here's why.

First off the larger bore will breathe better since the valves aren't as tight against the cylinders, even a little makes a big difference that's why GM flycuts the heads that they put 2.02 valves into unshrouding them, it leaves the chambers around 66 or 67 vs 64 on the 2.02 heads.

Second cubic inches, why settle for the .125 smaller bore motor if you don't have to. The 509 block is the strongest 400 GM made.

Third with the larger bore it will you can build more compression with a flat top piston, I know you currently are using flat tops on the 383. I also understand you don't want to run 11:1. I would not worry about it as long as I had flat tops, and forged, forged, forged! Not hyper, not cast, forged is the only choice. Also the right cam and aluminum cylinder heads.

That's why I'd also use the 210 aluminum cylinder heads they'd be great on the 509 block, allow you to run a point more comp than the iron heads did and if they aren't already I'd move up to 2.02 valves and have the chambers cut to unshroud them, again it'll drop your comp slightly which is something you are concerned about.

I'd also most definitely use the 6.00 rods in the 509 block. You'll load the cylinder walls less, and the rods won't swing quite as far on the crank, albeit slightly it may help with some clearance issues on the pan rail if you have any. Just pick up a set of forged 400 pistons for the 6 inch rod, they'll have a comp ht of 1.125 which is stacking the rings fairly tight, but still greater than the 1 inch minimum, it'll probably put the wrist pin up under the oil ring, but they supply rings with a steel support ring to go underneath the lower oil control ring wiper for this application. I used them in the last long rod motor with no problems at all.

The cast crank would work to about 500 hp, above that I'd go steel variety. The alloy in the 4340 steel crank is IMO the best choice for strength and durability, 5130 is stronger but more brittle, GM 1053 is the least desirable of the steel alloys, but still a nice crank. The longer the throws on the crank the less material there is between the rod journals and the main centerlines which means it is weaker the more stroke you build into a crank. Also the torque applied to the crank from the rods is multiplied as the throws become longer and this all means the cranks is subject to more stress.

If Eric68 chimes in he's got a lot of experience and has been sucessful with his 400, he'd be a good one to talk to.

The 509 you can add splayed caps to or run it as is with the 2 bolt config, either way it's stronger than the GM 4 bolt version in the webbing.

Yes you can run the thicker spacer bearings to use the 350 mains in a 400 block. Just don't run the standard 350 bearings with bearing spacers. I know many of done this without a problem, but why risk another interlaying surfaces ability to transfer heat properly and quickly from your crank into your webbing of your block so the coolant can perform it's job. If the heat doesn't transfer well you're in serious trouble very quickly. I just hauled what was a nice steel crank to the scrap yard that the journals turned blue from overheating. These bearings run about $200 bucks a set so you've got to compare that against what a 400 main crank will cost and decide which way you want to go.

Just my thoughts, I'm building a 509 block myself this winter. Good Luck.

Once again I would like to point out that static compression is for motors that close the valves at BDC which no motor does. I have a zero deck 10.8:1 forged flat top piston 406 with 72cc aluminum heads and I run 87 octane without a problem because the cam (224°/230° duration) bleads off the static compression down to a 8.48:1 dynamic compression. That low dynamic compression along with a 125 horse shot of nitrous and a fuel cell fuel of 108 octane gas keeps me very happy.


Larger Dave

Hey, Big Guy!!

What cam is it??

pdq67

Most aftermarket small-block cast iron crankshafts are rated at 550hp/6500RPM by the manufacturer. The president of SCAT told me that this is for a circle track car with a higher duty cycle vs. a street car, so you could likely get away with a bit more in the HP department. Vizard has built some high-HP engines with cast crankshafts with good results.

I too have a 509 converted to splayed caps and 6" rods. If I were to do it over again I'd opt for 5.7" rods and better off-the-shelf pistion availability.