[70-406]

Hello all this is the first post to this forum. I Have a 70 Chevelle with a well built 406 but when I was putting it together I was torn between having a aftermarket crank or a stock. The motor went way beyond my budget and I settled for a stock crank. ARP, Balanced and all the rods were straightened ( I guess that is what they call it). I have read in many magazines and books that sb400's are good only to 6500 rpm's. I was told by the machinist/advisor that this motor would never need to go over 6500 rpm's. The problem i am having is that with my 3000 stall it jumps to 7000 rpm's very quick on the street tires I have. BFG's 295/50 TA's. I try not to let it get that high but it is almost instant when the tires spin. Does any one know if this will be okay on a stock crank or do I need to go out and buy a rev limiter. I would prefer not to put all this extra stuff in my engine compartment but if I have to keep this motor together I will. Thanks
Tony
This seems to be a pretty good place for info

 

[sschevellefan]

as long as the machine work was done right and you used quality parts for your rings bearings and rod bolts, 7000rpm`s should`nt be a problem. I know several guys with 383`s which have the same stroke and they spin to 7000rpm`s all the time without problems. One think about the 400 crank is it`s cast which generaly wasn`t inteded for high rpm`s and they are heavy and don`t really like to rev that high. You can take out a lower end pretty easy with any motor if not properly built. Just my opinion, others might have more info for you.

 

[greg_moreira]

With a stock 400 crank and stock rods...I would not want to let it get over 6000rpm. If your real confident in the work....maybe 6500.....maybe but not me. If you cant keep in under control on those street tires, Id probably put a limiter in there that wont let it get much over 6000rpm at best. the stock rods are the scariest part really.

 

[bracketchev1221]

I would definietly put a rev limiter on it. It's one thing to shift the car at 7000 but it's another to go to 7000 relatively unloaded. Also does this motor have the stock 5.56 400 rods in it, in that case I wouldn't go above 6500.

 

[DOUG G]

I stay below 6500 as a redline. My cam is only good to 6000 anyway and I shift at 6200 or so.

 

[67RAT]

First,what are your engine specs?---IF you know the ballpark rpm that it will produce max power--install a rev limiter and set it 100 rpm above that--done deal--your safe--also I know guys had run 400 stock bottom small blocks over 6500 rpm--the thing is rpm are only good if power is being produced---so why go there if nothing is to be gained--example---If your motors power is maxed at 6700 rpm, rev limit it to 6800--or 6900 rpm-----then your safe---my old 350 sb with total stock bottom end would make power to 7000 or so,and held up fine---Its all in how well it was put together----67rat

 

[Darracq]

My 406 had stock rods and crank. I turned 6800 or so though the traps. This was with 175 shot. I ran it that way for a couple years. Then went to 5.7 rods. Sold the 5.56 to a friend that put them in a 302 ford and he turns it 8000 all day long for a few years now, i dont know how they stay together.