Posted By: migsBIG
318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 12:14 AM
So long story short, was told this guy has a TA/AAR block and turns out to be a 1979 dated Mopar Performance over the counter block and has been sitting in his shop since the early 1980’s. Now I know a little something about the ‘R’ blocks produced later on, but nothing on the ‘X’ ones. It looks to have a standard bore set of 340 pistons, but the guy will double check the bores when he gets back home tomorrow. The 4-bolt mains look super beefy and dang, it felt heavy like a 440 block.
So my question is:
Are these desirable?
How much hp/tq are they good for?
Is there a value to owning one or just sell it?
Thanks in advance.
Posted By: migsBIG
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 12:18 AM
Posted By: B3422W5
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 12:40 AM
Ultra desirable
Come 2 or 4 bolt
Come 3.91 bore, have seen them check good for use at 4.125 bore. But each one can be a bit different. So, to get to a standard 4.04 340 bore, need lots of metal removed and sonic checking, imo, is a must
Beefier bottom end, filled pan rail, etc
Standard 340 type top end, so unlike 59 degree r3 blocks, roller lifters drop right in.
They can take a lot of punishment. They are my favorite LA 59 degree block
I Ran one at 4.100 700 horse years ago, that block is still in use
Virgin block like you have is worth 3k + all day
Posted By: LA360
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 05:09 AM
The 360 has 273 style rockers on it. Nothing uncommon there, as they were an alternative to buying roller rockers. Check that it has a solid tappet, rather than a preloaded hydraulic lifter.
The main selling point for the X block is that most roller lifters are a total drop in. Otherwise they're very similar to the early R blocks that came much later. Both blocks were machined with factory type tooling, just the casting had a lot more material where it matter.
You shouldn't have any trouble selling the X block, they're defintely sought after by the 59* crowd.
Posted By: J_BODY
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 01:10 PM
That casting number was on standard 318 blocks back in that era too. Just not the “X” on the front along with the other cool features.
Posted By: migsBIG
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/26/23 08:47 PM
So I talked to the previous owner and was told it was bored out to standard 340 piston size and looks to may be a non-ran engine and just sat in the garage since 1981-1982. The block has 340 mains and he has a time to clean it up when I need something for it.
Posted By: migsBIG
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/29/23 03:03 AM
Will post more info Tuesday. By chance, how would someone build up a block like this? High compression? Turbo? Blower? Nitrus?
Posted By: LA360
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/31/23 01:10 AM
They're an early race block, they're not siamese bore, so they're not going to handle a bunch of boost or a bunch of nitrous. Having the extra meat around the crankshaft will certainly help.
The builds I have seen have usually been W5 or Indy headed strokers that make around 700hp
Posted By: migsBIG
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/31/23 03:18 AM
Went to get the block today and my back was not up to the chore of moving it and my garage space got loaded up from the weekend, so I have to make room for it. Will bring it home in a week or two when I’m able to accommodate it.
Posted By: CMcAllister
Re: 318 small block ‘X’ block. Give me the dirty little details. - 05/31/23 08:26 PM
Useless junk. Contact me, and I'll do you a solid and take it off your hands for a fair price. I need a boat anchor.