406ci SBC

[richie 2]

I can aquire a 400ci factory chev block, hardblock filled, billet caps, bored .030'' making a 406ci unit. safe enough to last w/proper internals in a #3200 10.50 et trans brake/bracket car motor? anybody got one/results? tks.

[Adger Smith]

Sounds good to me. The caps tie the bottom end together and help hold the long stroke crank. The block fill makes the weaker cylinder walls stronger. A shop that puts on caps and block fills will usually be doing the other thing that is a common problem with a 400 block. Blocks bored and honed "Without" stress plates are prone to cylinder wall distortion and bad ring seal. There can also be cracking out of bolt holes if plates aren't used. I think that is the most common complaint of the 400's when they were first being used as race engines. A shop that takes the time to do the right things to a 400 block will probably be using plates. Run a leak down on the engine before you buy it and see if it is healthy. don't treat it like a 302 SBC and try to make it an RPM king. They are Torque engines. Gear and converter it and keep the RPM well below 7,000 and it will make you a strong bracket engine that should last a season or two before freshening. I've done quite a few of them over the years and am doing one for myself at this time. I plan on putting it in a former Comp Street Roadster I have to run some local Index classes. Another issue with big SBC's (until lately) has been heads. You can never put too big a head on one. That is why you shouldn't try to RPM it. I've got one customer that uses one in a S/G style Monza that has Track 1 heads 11-1 compression and (FT) Eagle rotating assy , Small comp solid roller. (264/272) 830 carb. He runs foot brake/NoE as well as some 6.50/7.00 index classes and is deadly consistant with it. He is seen quite often in the last couple of rounds and at the winners circle.
You would be surprised at how tight his PTC converter is.
I don't think twice about using a well prepaired stock 400 block for a good mild bracket application.

[richie 2]

tks adger...how about a centre inlet 850cfm q/jet carb (454ci truck) be enough for that motor? love to stay S/SS style on top...

[Adger Smith]

Yep, done right those are or can be good carbs.

[richie 2]

they probably run those on the SS/GT Chevrolet 400ci motors.

[riv187]

I race a 400 bored 60 over. 509 casting.I built it with a tight budget but am making 565hp and turning 7200. 14.1-1 compression,,scat 5.7 pro rods,eagle 3.75 crank,icon ft pistons,regular 5/64 gapped total seal rings at .020. EQ iron 220 23* heads, elgin1090 mech flat tappet cam,msd,and hilborn on methanol. Block is filled to front freeze plug holes,stock caps,studs top/bottom. Std volume m55 pump. Felpro MLS gaskets. Transbrake leaving at 2500 with 5100 stall convertor. We where unable to use torque plate at my friends shop 'cause his didn't fit the large 4.185 bore. I finished the cylinders at .005" for the icon pistons. Didn't want them loose and banging cylinder walls.The engine has about 100 passes now. Runs well and beating Big blocks costing $10,000 more than the $3000 invested and a leftover 400 block this cost me.
Pay attention to details,,Mine is .003 on mains,.035 rear,.027 on rods.The deck is .000-.004. Current gaskets.051. Timing 34*. torques 70lbs heads and mains. The studs up top hopefully are taking the extreme pressure off the common thread cracking places. The cement is good for bottom end but the 2" of water at top is still keeping it cool enough on methanol/injection and small radiator in our hot FL heat. The deck clearance and timing are aimed at preventing detonation. too much deck is bad,,and too much timing is too.
I've read over and over..that about 600hp is safe limit of the 400. That was part of the plan. I pushed the compression at 14-1 and have 250lbs compression..but she's working and Wallace calculators show 550-565 from my slips and weight.
Brian

[Geerhead55]

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

[John Kelley]

I've got a 400 block 4 bolt main block never bored, been sitting in the garage for over 10 years.......I guess I'd better look it over !! Stock heads and crank.........hmmm,,,,