318 X block

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Sedanman

Sedanman

67-9 Valiant specialist
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I have a 79 X block that I will be posting in the "For Sale" as soon as the shop cleans it up,mag's it,checks the cylinders and tells me which mains it is. What is a fair market value since I doubt I'm never going to use it? It is 2 bolt mains.
 
Sedanman said:
I have a 79 X block that I will be posting in the "For Sale" as soon as the shop cleans it up,mag's it,checks the cylinders and tells me which mains it is. What is a fair market value since I doubt I'm never going to use it? It is 2 bolt mains.
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It's junk. PM me NOW and I will make plans to get it out of your shop. That thing is a paper weight.






























Ok. Now the real deal is about a year ago, I paid $800.00 USFRN's for mine, but I consider that a smoking deal.

Honestly, I've seen them sell for $1500.00-2000.00 USFRN's pretty often.

That block is still just as good as any new equivalent R block today. I've sonic tested several and every one of them would go 4.125 pretty damn easy.
 
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BTW, all those blocks had under a 3.910 bore by about .030-.040 and all of them are 340 mains. Just an FYI.
 
Ok fellas, this thread just turned into a sale thread. Sedanman can send me a message if he needs something different.
 
Thread open. Conversation about the item only please. No offers. Sedanman will open a for sale thread when he is ready to sell. Thanks guys. tmm
 
Or PM me. I wasn't offering it for sale yet since I don't have the actual specs yet,just trying to get an idea. Thanks
 
mopar56 said:
Ok, just curious, school me...what is the 318 "x" block I didn't think any motor made in that 79 vintage was anything more than a smogger?
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The X block was the over the counter race block that obsoletes the former TA block. It had thicker decks, partially filled pan rail, some came with 4 bolt caps, some with 2. Could be either straight or angled outer bolts. It came with a bore that measures about 3.870 or so, with a rough bore so you could finish it at 3.910, but I've sonic checked a few and most would take an over bore of 4.125ish.
It also had 340 mains, takes OE cam bearings and has OE tappet bore angles.


It's a nice piece. Its biggest PITA is it has the 318 drivers side motor mount, which is not the same as the 340-360 drivers side mount. Passenger side mount is the same.


Thanks tmm for keeping the thread open.
 
318x block...mopar race block before the R series with thick cylinder walls...filled in web in the mains....

block is base on 318 block with 3.91 bore
 
They rough bored it 3.79 if I remember right. The info about them has gone the way of the DoDo bird but you can find tons on production stuff. When I took it to the shop he was suprised that a small block block weighed so much. He's a GM racer so he's not hip on Mopar stuff but did race along side Dick Landy and even rebuilt his Dana at the track when one of his guys didn't put his power lock back together right causing him to roach his ring gear. When he took the gear out and saw 5.13 on it he asked if he could get him one he said "No",I have to turn back in to Chrysler. That gear wasn't available to anyone who wasn't Chrysler sponsored.
 
Sedanman said:
They rough bored it 3.79 if I remember right. The info about them has gone the way of the DoDo bird but you can find tons on production stuff. When I took it to the shop he was suprised that a small block block weighed so much. He's a GM racer so he's not hip on Mopar stuff but did race along side Dick Landy and even rebuilt his Dana at the track when one of his guys didn't put his power lock back together right causing him to roach his ring gear. When he took the gear out and saw 5.13 on it he asked if he could get him one he said "No",I have to turn back in to Chrysler. That gear wasn't available to anyone who wasn't Chrysler sponsored.
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The bore you say is about right. It's substantially under 3.910 to start.


I actually have the original paper work for the X block. It came with my block. If you want a copy of it to seek with yours, I think I can scan them and send you the file.

Let me know.
 
Got big X in front of block

5432965-xmotor006.jpg
 
Cool,can you post it on here too so the next person that ends up having one can find the info by searching threads?
 
not production it was a race block and a nice and desired part in my world!700ish
 
Sedanman said:
Cool,can you post it on here too so the next person that ends up having one can find the info by searching threads?
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Absolutely....if I can figure out how to scan and post them!!

Guess I'll have to get my kid to do it for me.


Damn technology.
 
Sedanman said:
Cool,can you post it on here too so the next person that ends up having one can find the info by searching threads?
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Google .....Mopar X block....lol

just remember the x block shares the same casting number as the standard 318 block.....so look for that X on the passenger side of the front of the block
 
In 1979, Mopar Performance started selling their “X block,” a heavy duty racing small block which would displace 340 cubic inches used as is, or could be bored out, as Larry Shepard suggested, to 355 cid (Shepard also warned against using a used Kasper prototype block). These were painted orange and a large “X” was cast into the end. It had standard and four bolt versions. The same block was used in Pro Stock during 1979 and in NASCAR racing , as well as ARCA oval track racing in the 1990-91 seasons. There were numerous features in this block to add strength.

The engines were also used when Chrysler sponsored the IROC (International Race of Champions) series, which uses identical cars; drivers ran with Dodge Daytonas converted to rear wheel drive, with the 355 under the hood.
 
I'll scan them in the AM and if I can't post them, I can email them to some one who can. I've never found that info online.
 
My search didn't turn up much again. This was why I made this thread. I knew many more would have answers the internet couldn't provide...for once. Thanks,I wish I still had my old MP catalogs and price sheets.
 
Sedanman said:
My search didn't turn up much again. This was why I made this thread. I knew many more would have answers the internet couldn't provide...for once. Thanks,I wish I still had my old MP catalogs and price sheets.
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I'll find my docs and scan them. Maybe they can make it a sticky so everyone can have a copy.
 
yellow rose said:
BTW, all those blocks had under a 3.910 bore by about .030-.040 and all of them are 340 mains. Just an FYI.
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Ryan J told me that there is also 360 main x-blocks available, but it's rare. You can find this info on his sites also.
 
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