572 engine update
Secrets of the Mopar Aluminum block
When we started to put together a plan to replace our cast iron Mega-Block we kicked the rods out of last season, we called everyone we could think of that either built Mopar blocks or was using them as the foundation for the big-inch Mopar race engines.
I had heard that getting an aluminum block would require a lot of patience as they are always on backorder. I had also heard the aluminum blocks are always leaking and are not a good foundation for a bracket engine that might see 300 runs per season. After a lot of phone calls to other racers and calling the companies that make them I was pretty sure that I knew NOTHING about aluminum aftermarket blocks.
In the end my choice was to go with the newest block on the market, the World Products Mopar aluminum block, manufactured by the Bill Mitchell’s World Casting Company. Theirexperience in casting aluminum blocks for big-block and small-block Chevrolets as well as their huge selection of aluminum heads tipped the decision scale in their favor.
Here is what I found out in building my first aluminum-block Mopar.
1. The quality of the World Products block was outstanding. When Ohio Crankshaft prepared to do the final hone to 4.500” bore they “probe” the block to check for core shift, cylinder centerlines, deck alignment, deck height, etc. The block was as near perfect as it could be.
2. The World block has two sets of bell-housing bolt patterns. One for standard Mopar and the other is a Chevrolet so the Powerglide bolts right on.
3. The block accepts standard Mopar accessories and components. Crankshaft, oil pump, fuel pump, oil pans, timing chain and cam location are stock Mopar.
4. Setting valve lash: Now this was a little surprising to me. The aluminum block and the aluminum heads expand when they are subjected to heat. When I asked Stan at Ohio Crankshaft about setting valves he said to set them cold the first time at about .006 to .007”. He said to check them when the engine was thoroughly warmed up. I did and they were .021 to .023”. WOW! I had no idea they would move that far.
5. I now set the valves cold so the entire engine is a consistent temperature. I set the intakes at .008” (ends up .021”) and the exhaust at .010” (ends up .023”).
6. All the gaskets have performed just like they did on the iron blocks, no problems at all.
7. I did have two head gaskets fail on the fifth run. Both failed on the same run. They blew the wire out between cylinders 3 & 5 and 4 & 6. I was lucky, I think they failed just as I hit the chip on the start line and lost power, so I just shut it off.