My last motor only lasted 6 months.It has a 5" crack inside the cam tunnel.What kind of block is best Dart,merlin,gm bowtie :rolleyes:

just was reading an article in here someplace and some guy was saying dart is coming out with a new block next year so u may want to check it out says its only gonna cost 300 more

bb485 look for member yellow77 he says new dart block comin out

GM bowtie graemlins/thumbsup.gif

http://www.chevelles.com/forum/ultimatebb.php/topic/4/22975.html

How did it crack? Unless you are making big power or have a big stroke save your money. They still require machining.

If you are looking for a standard 4.250" bore and are contemplating a hyd roller, I'll tell ya the new GM block seems pricey at $900, but if you figure the $200-250 savings on hyd roller parts + the new guaranteed good deal, it's not so bad CONSIDERING 454 blocks are getting up near $500 for unknowns.

Just curious, but I've heard of older standard deck 454's being able to be over-bored .100"-.125", but what can a "new" non-Bowtie (standard) GM block be bored to?

In all my years of racing I never had a block crack just for the fun of it. The only ones I ever ruined were caused by broken rods dropped valves etc. The factory stuff is fine unless you are far more serious than 99.9% of the people on this site.

IMHO (and with plenty of problems to back it up) -unless you get a MarkIV block that you have the mag inspection report in hand or buy it on a contingency - go get a new GM 454 GenVI block. Comes machined, needs cam bearings installed, final hone and deck to desired height (not necessary but I am doing it on mine). Build it with whatever compression ratio you want. Use a Stef's performance #7036 2pc real seal adapter (87.00) and install any MarkIV crank in a GenVI block using the 2 pc. crank seal. These newer blocks are ideal for stroking also (oil galleries are moved up next to the cam instead of the pan rails). Another good thing I learned, the GenVI blocks can use all the old MarkIV heads as well as the new stuff.

If you add it all up - cost of block, clean/mag, line hone, bore - you are darn close to the new block cost - and one heck of a lot less aggravation and work.