I am in the stages of building a 406 using the 817 2 bolt block for a bracket car. I had a machinist who builds alot of dirt track motors suggest using hypereutecic pistons and the stock crank w/ aleast an I beam rod w/ 12-1 comp. ratio using Dart cast or alum. heads.
I would like to spring for forged(srp,wiseco,speed pro) pistons and some decent I beam rods. The hopes are to use it for a few years w/o any major issues.
Any ideas???
Thanks

12:1 compression? Where are you going to drive this car?

For the most part at the track. I should be able to go to cruises and blend cam2 and pump gas, its not a daily driver-more like a bracket race car

do your plans include a splayed four bolt conversion on that two bolt block? cuz dude that is a lot of compression for a cast crank, cast piston, two bolt block.

Your two bolt block should be good to around 600 HP (I have a couple of books written by famous small-block builders that say 600 is the magic #.) I would definitely use some ARP Main Studs. The problem would be with the crankshaft, if anything. Definitely go with a better and longer rod, but think about a steel crank. A lot of guys get by with it, but for piece of mind and longevity, a steel crank would definitely be your best bet.

the machinist brought up using the stock crank- he builds alot of circle track stuff and uses them w/ good results. I not totally sold on that,thinking of 4340 stuff, but he is open to what ever I choose.
About splaying the block is the best set up, even on a four block 400 block. He claims that the four bolt factory 400 blocks the outer bolts don't have alot support-gets pretty thin in the block, and are trouble some.
He thought for my use I should use arp studs on the bottom end and for the heads.
Caru68- are you saying go w/ the 6" rods over the 350 5.7 rods?
Thanks To all!!

rb-69- I was just saying that if you are going to be buying aftermarket rods, then why not go with a longer rod for a better rod/length ratio? You would have less side loading on the cylinders and longer life out of the bottom end if assembled correctly. I figure you would be buying new pistons, too, and the new pistons would not be much more $ than a regular rod length piston. The longer rod needs a piston with a higher pin height (obviously).

rb69,
I'd opt for some decent forged pistons first because they are stronger & second because they can be lighter.

Nothing wrong with a cast crank as long as you keep the RPM down. What are your intenions??

The two bolt 400 block is a lot more stable in the mains compared to a 350.

The reason for this is the surface area that is being clamped.

The four bolt 400 has some issues with the outer bolt area tending to crack when leaned on.
There is no magic HP limit on a two or four bolt, cast crank, rods you use etc.

These parts rarely break because of HP, they break because of being overstressed & the biggest killer after detonation is RPM & weight.

As for rod length,,, I have posted this before but here it is again :D


I'll probably catch all kinds of flack for this but here's my opinion.
First let me say I normally prefer a longer rod but,,,,,
Rod length is one of the most over rated, over discussed parts of engine building.
I favor a rod long enough in strokers to be able to clear the needed counter weight as it normally makes balancing easier. If the rod is too short you can't get enough counterweight on the crank to balance it.
If you were to take the crank angles differences between say a 5.7 & 6" rod & overlaid them on a graph you probably wouldn't be able to differentiate between the two lines on the graph!

In a longer rod engine the piston dwells longer around TDC & less around BDC which can be argued both ways.
If it is moving away from TDC slower it isn't putting as much power into turning the crank but it gives the charge more time to build pressure.

Ok, if it's a "short" rod it is moving away from TDC faster it will put more power into turning the crank sooner. :confused:
My basic opinion of rod length is if you don't have a good reason to change that actually makes sense,,,, leave it alone.

This was summed up real good at the Superflow Advanced Engine Technology Conference this year in a round table discussion with some of the very best in the business of engine design in NASCAR.
This ain't a direct quote but it went something like this:
You decide on a stroke, design a piston to fit your needs, measure the deck height of the block & then make something to hook them together ;)
That was pretty much the consensus on the importance of rod length in overall engine design.

Here is an excellent post on two & 4 bolt blocks that was done a while back & hopefully will be archived as it has some excellent information in it.
Block Post (http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=9;t=016286)

Go with 6.0" rods, all else being equal, the pistons at least will be alot lighter.

Thanks to all who posted!!!
It sounds like for a solid piece I should use a forged piston & a steel crank along w/ a 6" rod.
Not sure if I will use splayed caps ($$$) issue, but will use studs in the bottom & top ends.
I have been pricing rotating assy. @ flatlander & Herbert's, Jegs & summitt, are there others w/ decent prices that I am missing?

Thanks Again!!