Fun with main caps, what to do?

[VETDRMS]

I'm building a 406, and am having some difficulty on deciding on how to approach the bottom end while still fitting it into my budget. The block is a "509" 2 bolt, I have ARP studs for the mains, but am somewhat concerned about the strength. I should be at ~500/500 hp/tq.

These are the options i'm aware of, but not sure of which one to do.

1.) Check registers for proper alignment and just use studs with stock caps.

2.) Same as above, but machine block and caps and install locating dowels.

3.) Install support straps on the mains.

4.) Install steel caps

5.) Install Splayed Caps

4 and 5 are a bit out of the budget, but 1-3 are doable.

At this point I would like to go with 1, and if the registers aren't quite right, go ahead and install the dowels. I do not intend to run this motor over 6000 rpm, and will only see rpm's above 5500 for brief amounts of time. I will probably install the support strap over the rear main, as the 400 is kind of weak there.

Any help or clarification is welcome!
Thanks.

 

[69MyWay]

Take this for what it is worth...as only my past experience.

I have been involved with, and or owned/seen/built plenty of two bolt main street cars that see limited real track duty. In fact, I helped my buddy put a roots blower on a sbc build from a 2 bolt main. We built that motor nearly 7 years ago, and it is still running quite well and pushed hard every chance the new owner gets to nail it!

The C4 is a two bolt block, and Callaway and others have had no problem getting major hp out of them, and they live a good long life.

So, my point is....spend the extra $$$$ on a better stereo system, etc, and don't go overkill at this point...because you are not building a professional race car that will be living at 6K plus every time you fire the engine.

 

[patsnitrovette]

i agree ,as i mentioned to you before in my instant message,ive had several 2 bolt blocks handle it,if its only gone to be a street motor on the occasional run at the strip then youll be fine.At least use main studs.

 

[VETDRMS]

69MyWay
Thanks, that seems to be the general consensus, it will get fairly abused (1/4 and autocross), but I doubt I will actually run the motor for more than 10-15 thousand miles before I do something else with it (2 summers). The extra money will go straight to the heads. Having a hard time deciding between getting the AFR's, or some Dart Pro 1's and having some light port work done on them.

patsnitrovette
Got your message, thanks!
Oh, and I already have the studs. I read that the rear main cap is the weak point on the 400. I could reinforce this with a strap, I'll be using a 7qt pan so I should have the extra room to move the pump down a little. Sound reasonable?
How much is it usually to have the dowels installed?
Thanks again.

 

[vigman]

Do what I did for my 327

ARP studs
Forged crank
good balance job
Good harmonic balancer
windage tray

The studs are stronger and if you want to go a little further.. do Helicoil inserts.. they are actually stronger then the casting so you get a better bite.

Forged crank is stronger then a cast.

A good balance will reduce your side load stresses ( short of winding up to 6K and sidesteping the clutch)

A balancer will keep the nose of the crank centered better.

And the windage tray will keep the oil from sloshing into the crank path.

end of story.

Vig~

 

[VETDRMS]

vigman
Thanks:

ARP studs : Got them already
Forged Crank: $ SCAT Cast 9000 series lightweight (48lbs) internally balanced for 6" rod.
Good Balance Job: Yes. Fully balanced internally.
Harmonic Balancer: Yes, nodular iron 8", can't remember brand
Windage Tray: Yes, in pan, with crank scraper and baffle.

I've heard that with a forged crank it is more of a priority to run steel or 4 bolt caps due to the additional "flex" of a forging. The cast gives a little less so it puts less load on the caps. This correct?

The crank is knife-edged too BTW.

Thanks again

 

[vigman]

Sounds like your 100% there

Any thing else is OVER KILL...

Oh the amount of FLEX were talking about is a JOKE.. do not worry about it.. you have 4 times the amount of MOVE in the distance between the bearings & oil film then you do in the actual CRANK flexing.

Show Pix's as your building it.....

Vig!

 

[VETDRMS]

vigman
Thanks, without the splayed caps and additional machining, I can use the money to go into the heads/fuel system.

Thanks for clearing that up a bit, never was the "amount" of flex mentioned, yes, .0002 is bigger than .0001

I'm going to be building a website similar to Monty Williams'
Everything will be there, including parts list, and lots of pictures.
My machinist is going to let me harrass him with a camera and take pictures of all the machining operations! ;worship