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Geerhead55 · 05-24-2014, 10:53 PM

I agree with Adger in using a 400 block in a MILD bracket application. I picked up a standard bore 509 block a few years back for a "future project". When the 355 gave up the ghost in my '68 Nova,, 3150lbs,,10.5x29.5 tire, full cage, ladder bar- leaf spring rear setup with 4:88 Dana 60 and a Coan glide,, I started doing some research on the 400. I was told by several builders that with the combo I had floating between my ears I'd be over 600hp and I should really think about an aftermarket block for piece of mind,, so I bought a Dart SHP block for the build. I got Manley H-beam rods and crank, Probe pistons, a Comp Cams roller setup and a Moroso pan and oiling system for the bottom end. Up top, I freshened the Motown 220 heads that came with the car, they'd been previously ported, and with new 2.08/1.60 valves, they were good to go.
I picked up a 2925 Edelbrock Super Victor intake and had it matched up to the heads. I'm running the Comp SS rockers,,1.5 and 1.6 split set. I also run a 2 inch spacer.
On the dyno, I had 3 carbs to play with, so we broke it in with a decent 850 DP, and after finding that this motor too liked 34 degrees, our best pull brought us 605hp. I had a "good" 950 DP that we tried next, and the engine didn't like it losing 12 hp. That carb didn't belong to me, so I didn't want to mess with it and off it came. The dyno operator asked what the other carb was and I told him it was a Holley- Proform hybrid 750 that I'd used on my 355, and he said lets try it. The difference was immediate, even at idle the engine sounded crisper and revved effortlessly. We made a pull(7400rpm limit) and we got 625hp! I was shocked! They asked what jets were in the secondaries and I had 82s in there, so we went up to 84s and the engine lost 9 hp,, so back in went the 82s and the last pull of the night it went right back up to 623. I was thrilled.
The car has run a best of 10.33 @ 128+ and Adger is right about the over revving as my car goes through at 7400 and its done well before that. I'm looking into finding a 4:30 gear to get the RPM down. I also agree with him on cylinder head choice.
I'm thinking about something like the AFR 227s with a shaft rocker steup for extra insurance. Good luck with your project which ever way you go
Danny Durham

05-24-2014, 10:53 PM	#7
Geerhead55 VIP Member Join Date: Sep 2002 Location: Tacoma, Washington Posts: 1,632 Likes: 0 Liked 5 Times in 5 Posts	Re: 406ci SBC I agree with Adger in using a 400 block in a MILD bracket application. I picked up a standard bore 509 block a few years back for a "future project". When the 355 gave up the ghost in my '68 Nova,, 3150lbs,,10.5x29.5 tire, full cage, ladder bar- leaf spring rear setup with 4:88 Dana 60 and a Coan glide,, I started doing some research on the 400. I was told by several builders that with the combo I had floating between my ears I'd be over 600hp and I should really think about an aftermarket block for piece of mind,, so I bought a Dart SHP block for the build. I got Manley H-beam rods and crank, Probe pistons, a Comp Cams roller setup and a Moroso pan and oiling system for the bottom end. Up top, I freshened the Motown 220 heads that came with the car, they'd been previously ported, and with new 2.08/1.60 valves, they were good to go. I picked up a 2925 Edelbrock Super Victor intake and had it matched up to the heads. I'm running the Comp SS rockers,,1.5 and 1.6 split set. I also run a 2 inch spacer. On the dyno, I had 3 carbs to play with, so we broke it in with a decent 850 DP, and after finding that this motor too liked 34 degrees, our best pull brought us 605hp. I had a "good" 950 DP that we tried next, and the engine didn't like it losing 12 hp. That carb didn't belong to me, so I didn't want to mess with it and off it came. The dyno operator asked what the other carb was and I told him it was a Holley- Proform hybrid 750 that I'd used on my 355, and he said lets try it. The difference was immediate, even at idle the engine sounded crisper and revved effortlessly. We made a pull(7400rpm limit) and we got 625hp! I was shocked! They asked what jets were in the secondaries and I had 82s in there, so we went up to 84s and the engine lost 9 hp,, so back in went the 82s and the last pull of the night it went right back up to 623. I was thrilled. The car has run a best of 10.33 @ 128+ and Adger is right about the over revving as my car goes through at 7400 and its done well before that. I'm looking into finding a 4:30 gear to get the RPM down. I also agree with him on cylinder head choice. I'm thinking about something like the AFR 227s with a shaft rocker steup for extra insurance. Good luck with your project which ever way you go Danny Durham Last edited by Geerhead55; 05-24-2014 at 10:56 PM.