Main caps

I’m in the process of building my first all out race engine and am looking for the advantages and disadvantages of running aluminum caps. This is for a stroker big block.
Thanks.

If this is a stock block Rb, i would definitely run the BRC cap and girdle kit. This is an all out race motor and the caps will help and the girdle should help strengthen the lower main area that is prone to cracking Even on a low deck 400, i am using the cap and girdle system for my all out race motor. I try to overbuild as I def don’t want to drive over the crank and/or oil down my slicks on a pass.

I agree with Chargerfan, run the BRC kit in a stock block. A lot of people will say that it doesn't help, but my take is that it won't hurt anything. And don't run a stock forged crank if you're going to make any horse power at all. The savings are not worth the cost. I just freshened my engine because I wanted to look at the block (mostly the main webbing) after running 4 1/2 seasons of mostly 1/4 mile racing with the BRC set up in my engine. The block (and bearings also) looked just like it did when I built it. I am pleased.

Brian

Aluminum main caps are a very nice upgrade. Don’t buy into everything you hear on the web.

Mopar BB, RB and B,mopars V8 have a very strong design that really is a lot stronger than blocks like the early hemi and current LA type SB with two bolt mains. I'm assuming the 440 blocks had the main webbing thin down for costs and maybe weight saving, hence the tendency to crack the main webs between the bottom of the cylinders down into the main cap webbing
The 400 blocks are a better choice to build due to them having thicker main webbing than the 440 blocks and the 383 blocks also.
As far as adding a main girdle take a very close look at all of the them and then see if you can see where they add material or strength into the main webbing
I have used the Mopar brand of Ductile iron main caps when they still sold and stock them, they are not available anymore so I use aluminum main caps instead now to help keep the stock cast iron block from cracking under drag racing conditions. EDITED: Do NOT use steel main caps, they will hasten the block cracking
There are a lot of people believe if they have a certain race part in their motor and it hasn't broke yet they assume it is the best part like that so it must be good

I wouldn't build a Stock block, 600+hp engine without aluminum main caps. I've never had a oil pressure issue, and the caps are 5lbs lighter that stock caps.

This is what Herb McCandless told me many years ago, if you build a maximum effort big block Chrysler and want it to hold together, either use aluminum rods or aluminum main caps, to help dampen the internal harmonics to keep it together. I have built several with both combinations, only one that broke was an aluminum rod engine, that by my mistake, I did not replace the rods when they were over time to do so.
I have never ran a girdle with aluminum main caps, seems like they would work against each other. Have built a couple with steel caps, and girdle, with aluminum rods. My experience with block failures that I have seen are in the number 2 main area, either the cap breaks, or the area between the main and cam bearing above the number 2 main cracks. I had one engine around 700HP level that I used the four bolt main conversion, water jackets had block filler, and a girdle, with aluminum rods, ran for several seasons. Started losing some ET, did a leak check and it was terrible, took the engine apart, the cylinders had barrel shaped and pushed so hard against the filler that it had hairline cracks between the freeze plugs on the outside of the block. That engine was bored .055 over, and I never had it sonic checked. But again it had around 600 runs on it. I look at it this way the original 440 block was engineered for what 400HP? When you bump an engine up to 750 HP or 800 HP , you are doubling the rated capacity of the block, the foundation of the entire engine. I finally learned and just purchased an aftermarket block, best decision I ever made. I know there was a shortage for a while, but I see several companies are now making and selling blocks again. With the machining cost of prepping a stock block, aftermarket caps, girdle, etc. then compare to the cost of the aftermarket block. Then realize that even if it holds together, when it comes time to freshen, will the block be a throw away?

I've ran stock caps and a stock forged crank at the 6-650 hp range. Engine lived for 8 years at 10.0 before I tore it down out of curiosity. It's all about timing control. Detonation will destroy the bottom end.

That being said, I always run aluminum rods, and my latest motor is the first with aluminum caps in addition to the rods. It's too new to tell how it is holding up.