Mean 318...or stroker....hmmm

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mini said:
I find it funny how everyone always say to build a 340 or 360 instead. And saying a 318 has a small bore,is laughable. You ever talk to an LS guy about small bores? Lol
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6 years ago when I decided to stroke my 318 it became quite apparent at that time that the Pistons cost $200 more than doing a 360... (I was at the time at any rate it was more common to do a 360 than a 318) the machine shop offered me a 360 block for $150 it became a no-brainer.. $50 less for 20 more cubes..
 
I personally I put all my money into the bottom and and then I've been able to play with whatever I want up top. Nothing like a solid foundation...
 
Here is the issue with 10:1 SCR and the 390..... the only listed kits from SCAT will get you in the low-mid 9's or 11 for SCR; nothing in between. I see some Diamond pistons that will get you to around 10:1 SCR but those run around $800 for a set. The quench supposedly will help overall combustion efficiency so is worth something even at the mid 9's.

So you could get the block square-decked, and get the pistons at zero deck and use the .028" thick head gaskets of you are brave or the .039" gaskets and have decent quench effect either way. But you are going to be at 9.6 or 9.4 SCR respectively with the 23 cc dish pistons, 63 cc head chambers, and those 2 gaskets. You need the 16.7 cc dish Diamonds to get to 10:1.

The above is probably the main factor that makes a 360 an easier choice to make for stroking: piston choices.

BTW, I would not personally sweat over .020 vs .030 vs .040 overbore if I was not sweating the 390 vs 408....
 
cawcislo said:
I have the flywheel which was attached to this 318 that will work on an internally balanced engine. The kit I was looking at from scat was the internally prebalanced one already. For main studs I figure if I do want to put better cylinder heads and a bigger cam down the road and make bigger power the bottom end will be solid. I realize my open chambers have no quench but again I was thinking down the road if I go with closed chamber aluminum heads do I need/want to achieve quench if I get compression up to 10:1 with aluminum heads?

I think the new pistons will be about 0.012 in the hole with 318 kB pistons or stroker 390 icon pistons. I will wait to see what the machine says about the bores. If they’re good to go with 0.040 overbore they make stroker pistons for that size. Otherwise I’d have to go to 0.060 over for stroker pistons (icon does not make a 0.050 over piston) not sure if my 1977 318 block can go that big overbore.

if I do the stroker engine my end goal would be to run 11.99 at the track which would need about 420isH hp with a 3000lb duster. I realize it’d need better heads, cam maybe bigger carb, etc... but that is longer term plans.
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Do the math on a zero deck piston and closed chambered heads. Pay attention to the valve relief cc amount and head gasket sizes. I run pump gas 93 @ 11-1. Cams under 250@050. Get all the quench you can.
 
OBTW, speak with SCAT in person. They sometimes have other piston options that they can sell you than just the listed kits.
 
how much do you want to spend...and how much power are you looking for?
Use all your parts on a used 360 with a good rotating assembly,you will save
a lot of work and money and make lots of power.If you have some attachment to
the 318 block well then that's the way to go.
 
A lot of it boils down to personal preference you can make a short stroke 318 pump out 400 horse fairly easily. Rod ratios piston speeds and sideloading are all in the favor of a Short Stroke motor. That being said there is no replacement for displacement, or is there? a nice Nitrous system on a bulletproof 318 could easily surpass 600 horses! It's very easy to chase numbers and theories ,nicely cammed well-built 318 with a set of 3 91 or 410s and the right Supporting Cast can haul *** without tearing Parts apart from extreme torque but then again you could just run street tires and do burn offs all day long? Many of 318 has sent a 360 with its tail between its tail lights
 
i would question easy to to get 400 horsepower out of a 318.
It would take a high revving 318 to make that number and would likely be a poor performer
on the street.
 
You can question it all you want but it has been done so many times I can go dig up the latest issue of mopar magazine where it was done with KB Pistons ported Factory heads and an extra high lift comp hydraulic 409 with a thermo quad 415 with a holly like falling off a fence
 
That's fine and dandy but sometimes there's nothing like the tire twisting torque of a stroker getting that instant under pedal power...
 
2 problems here.
what's your definition of easy?
Magazine articles...they can get those numbers but you can't.
Go with the expensive stroker or the 360.
 
Okay so what you're saying is it's easier to go get another motor a360 totally rebuild it with performance parts get upgraded heads do all the same things you will basically have to do to the 318 yes you will probably gain 40 to 50 horsepower and about the same in torque is it necessary it's definitely not easier, and maybe you can't but I know I could
 
Don't get me wrong I love the 360, but for a street motor a stroked 318 or a sprayed 318 or a normally-aspirated 318 can deliver quite a punch enough to get the front wheels off the ground if built right running to a 360 isn't always necessary
 
ir3333 said:
i would question easy to to get 400 horsepower out of a 318.
It would take a high revving 318 to make that number and would likely be a poor performer
on the street.
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I also dsagree with this. A decent compression ratio, I'd use the KB slugs at zero deck, good flowing heads, Edelbrocks OOTB port is GTG for that, headers, cheapies work here, and a typical street cam at about 230 @ .050 will do it. It may take the next gear ratio up to perform best, but these things are known and excepted. IMO, an OD would be excellent tpo use.
 
my definition of easy is a stock engine with a few hundred dollars of external bolt ons' AKA..a used 360
Complete machining and rebuild with aluminum heads and new everything is not easy
or economical. ( unless you get someone else to do it )
Not questioning the potential of a custom rebuilt 318 or 318 stroker.But i do think the high revving rebuilt 318 will be torque challenged on the street but may sparkle on the strip with converter and gears..
 
I'm pretty sure the Op has already made his decision on a 390.
 
and he already has nice bolt ons as well as mildly ported heads...but i wonder if they have been cut to 63 cc's? If so he will have to be careful with pistons, cam and or head gaskets.
'gonna make some torque!
 
UPDATE My machine shop got back to me that 0.040 overbore will clean the cylinders up nicely which is good. I would need to rebalance the crank with kb’s and no one in my city does it so it has to get shipped out for this which adds to costs and time. So after rechecking my costs it’s less than $200 more vs my 318 rebuild to get the complete scat stroker kit which is already internally balanced. I pulled the trigger today. Looking forward to build a 390 (actually I think it will be a 392 since I will be 0.040 over instead of 0.030). Now I’m just waiting for my parts to show up. I’ll take some pics and maybe throw a video up once the scat kit shows up.
 
Perhaps I’ll share what I have planned. For phase 1 - I will reuse what I have as in reusing my current Crower Cam@0.050 224/224 .465 lift, my mildly ported 64 cc chamber (yes they’ve been milled) open chamber 360 heads, Weiand action plus intake (small 318 ports), 750 Holley carb and dougs headers. I know this will leave lots of ponies locked in the stable. Phase two I will address the intake with a Edelbrock air gap with ports that match the 360 ports, a larger cam not sure yet if I want to go mechanic or hydraulic flat tappet, and better cylinder head (probably 60 cc pro maxx aluminum closed chamber heads - I called and they will mill the heads for free to get me to 60 cc chambers (they list 63 and 65cc heads on their web page). So those are my tentative plans... but first I have to get a solid foundation we can tinker later with the other stuff....
 
good moves
what"s yor taarget compression with the stroker?
use your crower for awhile
do a compression test
before you change cams
air gap is canada???
 
Similar questions: Which pistons are you ending up with in the kit?

We just need enough info to tell you that you are wrong LOL... just kidding! IMHO: Very good advance-planning on milling the later heads.
 
Future intake is the Edelbrock rpm air gap. Pistons included in the kit are icon Forged dished pistons. It’s scat kit #1-98007bi040. They have the 23 cc dish as I want to run premium 91 octane pump gas. I need to zero deck to get me to 9.4:1 with 64 cc heads and a 0.039 head gasket. With a 60cc aluminum head I get to 9.8:1. I’ve planned this thing to death. Time to make it happen. ;-) any recommendations on a fuel pump. I don’t think the stock looking mechanical is qualified for the job.
 
Fuel pump recommendation? The intended or Max HP of the engine would be good to know for this. In order of power supply ability.....

Carter (super) street strip pump

Holley mechanical pump, may require a regulator

Walboro Electric fuel pump.
 
cawcislo said:
UPDATE My machine shop got back to me that 0.040 overbore will clean the cylinders up nicely which is good. I would need to rebalance the crank with kb’s and no one in my city does it so it has to get shipped out for this which adds to costs and time. So after rechecking my costs it’s less than $200 more vs my 318 rebuild to get the complete scat stroker kit which is already internally balanced. I pulled the trigger today. Looking forward to build a 390 (actually I think it will be a 392 since I will be 0.040 over instead of 0.030). Now I’m just waiting for my parts to show up. I’ll take some pics and maybe throw a video up once the scat kit shows up.
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It’s actually 393 inches but it gets incorrectly rounded down.
 
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