318 with 360 crank

Posted By: Anonymous

318 with 360 crank - 10/08/08 07:42 PM

hi i have a 318 in my cuda as we speak. and i also have a 360 that i want to make a 408 out of. but since that is really out of my price range right now i was wondering how much work it would be to make my 318 a stroker with the 360 crank, heads...ect. how much work is it actually? and what would i be looking at spending?

Posted By: 70AARcuda

Re: 318 with 360 crank - 10/08/08 07:54 PM

actually i would make a 390 out of the 318,

KB makes forged pistons for this combo...flat top and dish..

you couse use stock rods or get a set of scat i-beams...

pick up a 4 inch cast crank for 250 bucks...about what it will cost to cut the 360 crank to 318 journal size.

just something to look at...

also Mahle makes 318 3.58 stroke pistons...seen them on ebay a couple of days ago...not cheap...around 550 bucks..

there is probably a cheaper route to go on that combo also.

Posted By: Reggie

Re: 318 with 360 crank - 10/08/08 08:06 PM

If money is tight, I would just build the 360 rather than mess with the 318/360 crank combo. You will only get 349 ci by turning down a 360 crank to 318 main journal size. Bottom line is that you will end up doing a lot of work to end up with 10 less cubes than you already have with the 360.

Posted By: patrick

Re: 318 with 360 crank - 10/08/08 08:18 PM

yeah, I looked into the possibility since I have a roller 318 block and wanted to build an engine without any chinese parts.

places here quoted me from $80-320 to turn the 360 crank to 318 main bearing size & SB chev journal.

doing the math, you can get 0 deck with a 360 crank, 6" rods, and KB167 pistons. howards racing components have some real slick powdered metal 6" chev rods for a decent price, but you'd have to rework the little end for the mopar pin size, as KB won't do anything custom (i.e. doing a SBC pin size in the aforementioned mopar pistons), which I got quotes of ~$250 to do.

overall, if running a flat tappet cam, build the 360 with stock rods, crank, and KB107 or speed pro H116CP pistons.

a 318 bored .030 over, stroked with a 360 crank ends up being a .060 underbore 360....

Posted By: Anonymous

Re: 318 with 360 crank - 10/08/08 10:55 PM

I don't understand why you don't just build the 360. I'm not "into" custom engines anymore, but you will have to do a lot of expensive work to fit the 360 crank into the 318 block.

Posted By: 69Cuda340S

Re: 318 with 360 crank - 10/09/08 01:43 AM

Here is a write up about putting a 360 crank in a 318. Also, the 3.58" crank with 318/340 mains is available:

http://www.forabodiesonly.com/mopar/showthread.php?t=19556

Posted By: roe

Re: 318 with 360 crank - 10/09/08 03:07 AM

Quote:

actually i would make a 390 out of the 318,

KB makes forged pistons for this combo...flat top and dish..

you couse use stock rods or get a set of scat i-beams...

pick up a 4 inch cast crank for 250 bucks...about what it will cost to cut the 360 crank to 318 journal size.

just something to look at...

also Mahle makes 318 3.58 stroke pistons...seen them on ebay a couple of days ago...not cheap...around 550 bucks..

there is probably a cheaper route to go on that combo also.

This is probably going to be the route I take. I already have a 318 and if necessary I can get another b/c they come a dime a dozen. I originally wanted to go w/ a 408 but a 390 will more than do what I want and make a fun driver. Even throw in a a set of ported magnum heads and you've got a pretty powerful little engine. It should be no problem to get 375hp/400tq or more from a good build.

Posted By: 70dart360

Re: 318 with 360 crank - 10/09/08 03:13 AM

Quote:

It should be no problem to get 375hp/400tq or more from a good build.

But thats alot of money and custom stuff. I got more than that at the rear wheels in my Dart with bolt on's on a used bottom end and lasted 7 years. Why do all that modifying when a 360 is cheap and more cubes.

Posted By: roe

Re: 318 with 360 crank - 10/09/08 03:26 AM

How exotic do you think it would need to be in order to get that type of power? Also, if I had to purchase a 360, motor mounts, flex plate, converter, for a 360 build, what would the total price difference come out to be in building the 390 versus the 360?

Thanks
roe

Posted By: copchaser

Re: 318 with 360 crank - 10/09/08 03:32 AM

Dude 390 are cool, just ask any ford guy.

Posted By: patrick

Re: 318 with 360 crank - 10/09/08 12:58 PM

Quote:

How exotic do you think it would need to be in order to get that type of power? Also, if I had to purchase a 360, motor mounts, flex plate, converter, for a 360 build, what would the total price difference come out to be in building the 390 versus the 360?

Thanks
roe

you don't need motor mounts, $1 in washers used as spacers will allow the use of a 318 drivers mount. pass mount is the same.

B&M flex plate is $80 to be able to use a neutral converter.

around here you can get core 360's for about $300-400. you probably can find a core (not running) mag 360 for about $500-600.

on the 390, if you're going cast crank, you'll probably want to balance it to 360 specs anyway so you don't have to spend a boatload of money on mallory to balance it, so you'd need that weighted flexplate anyway.

IMHO the only reason to stroke a 318 is to use a hydraulic roller cam cheaply, especially with LA heads. 318 roller cam blocks are easy to find (any 85-up M body in a junkyard) compared to 360 blocks. if you're planning on running a flat tappet, just start with a 360. pistons and rings are cheaper. if you plan on a hydraulic roller cam and mag heads, you're probably money ahead just picking up a core mag 360, again, pistons & rings are cheaper, and if you stroke it, cast cranks and stroker pistons are cheaper than a 318.

according to comp's camquest software, a mag 360 with KB107 pistons at 0 deck (10.8:1 comp), a little port work as outlined by dulcich in a 2005 article in mopar muscle, headers, an RPM air gap type intake and a comp XR265HR hydraulic roller cam should be 400-425 HP and ~440 lb/ft tq, and plugging the info into the dynamic compression ratio calculator at kb-silvolite.com, it should still work on pump premium.

heck, 375hp/400tq should be possible with a mag 318 with the same recipie as above, but use KB167's at 0 deck.