406 smallblock advice needed

[bigvinnie]

There's a 406 shortblock for sale in town, here are the specs:

511 casting, 4 bolt mains
.030 overbore
Performer plus cam
double roller chain
stock 400 rods (5.56 inch)

comes with balancer and flexplate, has been sitting covered in this guy's garage for a year, machine work was done by the best shop in town, he assembled it himself, which would mean I'd have to re-check everything or have someone else do it...

He's asking $800... I realize the 4 bolt main blocks are less desireable, but I've also researched on the net, and opinions seem to vary widely on the subject... I do know the 511 casting is one of the better ones, with the 817 casting being the one to stay away from.

I'd probably not try to get more than 350 hp/ 450 torque out of this motor, and not spin it past 5500 rpm

I'd appreciate any opinions on whether this sounds like a good purchase...


thanks all...

[Green Machine]

Cast pistons or ? Will the pistons give the compression you want with heads you may want to use ? Balanced or not ? Cast rings ? Moly rings ? With the short rods, might just be a stock rebuild. I'm not saying good or bad just things that can add or subtract value.

[bigvinnie]

thanks for the reply... pistons are hypereutectic aluminum, slightly dished (no valve cut-outs) not sure about the rings... motor is balanced. I'm flexible on heads, I'm guessing a 64cc head will get me at least 9:1, but I can check that out.

How detrimental is it that the rods are the stock length vs. 5.7 or longer..?? I know about the egging problem...

thanks for any input.

[JimKshortstep4x4]

I have two of the 400 engines. Both are 4 bolt with the stock rods. One is in my short step side with automatic and the other is in my 65 SS Impala with a M-22 in it. The compression ratio on the stepside is 9.5 and the Impala is 10.2. I keep the revs down below 5500 and have not had any problems. They are a blast to drive and the Impala has surprised some big block Chevelles.

Since you have to check out the work, I would try to buy it for less money.

Jim

[manimal]

Find out where the machine work was done and if it was magnafluxed. I havent seen too many 4 bolt 400's that werent cracked in the main webs.IMO I dont like the 4 bolt 400 blocks. I do however like the 2 bolt.JMO

[manimal]

By the way the rod angle on those stockers arent the greatest,but if you keep the revs down it'll be fine. But for not too much more money you can build your own short block.Find a 2 bolt block,stock crank,and EAGLE SIR 5.7 rods and get your pistons,rings and cam set.Then YOU will KNOW what you have.

[bigvinnie]

block was magnafluxed, and machine work was done by the best shop in town, I've used them for some of my rebuilds so I'm confident that the block is in good shape...

Not sure about anywhere else, but the 400 blocks in SoCal are getting super hard to come by, especially the 511 and 509 castings.

I'd probably take it back to the machine shop and have them re-check everything and get all the info on it, maybe have them tear down and re-assemble as well just for peace of mind.

thanks for the input.

[HevyChevy42]

I need help.... I have a 406 that im looking to put in my 87 pick up. currently the truck is my daily driver. im looking for a cam thats gonna still hit but still be able to cruise around the city. Something like a mild chop sound to it...... Thanks in advance