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

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cawcislo

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My other thread got out of control. So I’ll start another. 70 duster - vehicle use street fun some drag racing a few times annually. Current setup. 4 speed, 8.25 rear with 3.73 gears 750 holley, Weiand action plus intake, dougs headers, 360 heads 1.95 intake Valves have some porting done 63cc chambers, bored 30 over Stock low compression pistons 0.102 in the hole giving poor compression around 7.8:1. Cam Crower Hyd flat tappet 224/224 .465 lift. Crank was ground 0.010 on mains and rod journals.

I started out looking to change timing chain as it was lose/worn and went deeper to find out the story on the engine as it was new to me. So I end up looking to do a bit of a refresh and get some higher compression pistons. I hope the block can cleanup with 0.040 waiting on machine shop. Rod bearings were to the copper so crank may need more grinding. I started adding up costs for my 318 bottom end refresh and someone mentioned stroker which got the gears turning. With the machine work on possible cutting crank down, balancing etc A scat Pre balanced stroker kit may only be $500 more. Although a stroker engine will require other upgrades like better intake (the action plus has tiny 318 ports) Edelbrock air gap would be much better, cam upgrade to take advantage of more cubes. Clutch upgrade likely. But upgrades aside. What else would a scat stroker 390 kit require.
I think main studs (I’m sure the stroker will make 375+ hp fairly easy) So I’d like to keep it together, align hone as well. Any block clearancing for 318 stroker (minor or major work?), does the scat stroker crank need machining for pilot bushing for my 4 speed? Is zero decking the block necessary? Was looking at the dished piston option to keep it pump gas friendly. Compression likely around 9.5;1 with my current 63 cc heads. The zero deck will help with quench but not sure if quench is critical at my compression ratio or not. Okay let’s try to keep this on the rails this time boys.... lol.
 
Do the 318! Id go down that road myself but im too busy playing with 6's. Do it so I can live vicariously through your build lol.
 
How happy are with the performance you have now ?
If not, where would like to most improvements idle-3000 rpm, 3000-5000 rpm etc.. and do you want 0-50 hp above what you got more?
 
To me if I was going the expense of a stroker, I'd go to the trouble of getting a 360 block.
But if I was gonna build a 318 I'd want stock stroke, to me thats the point of doing a 318 bit of a revver, plus you got decent gears and a 4 speed.
 
How happy is your budget? Getting into a stroker can quickly escalate into big heads, big carburetor, huge headers........all of which can add up quickly. If you think you can be happy with 325-350 HP ( I know I could be) then by all means build a 318. I'd kinda like to see where you go with it.
 
318’s can be a lot of fun. Many will argue that the rotating assembly isn’t much more than just rebuilding the stock bottom end. As RRR said, everything starts adding up.

The longer stroke adds a lot of torque and hp. Despite what others think and say. (I don’t know how they come to this conclusion when proof of it otherwise is widespread for decades!) The question is, is it worth the expense to you?

@RustyRatRod

This is what I was saying earlier about the wife’s new coffee mug! Even more so perfect since she works in a jail with crazies!
1039D0AE-A45A-4EA3-8FA6-D9945F02AA48.jpeg
 
Yes, except that small notch on eh LA block. That bore notching is pretty minimal and extend down into the bore about as far as you see on the bottom of the bore. You can do it with a Dremel (or maybe even a rat-tail file LOL).

On the stoker kit, 390 is darned close to 408 or 416. But if you have to bore a block, then getting a 360 block might make sense. I personally would not sweat a lot over it for the use you state. You're gonna be roasting tires either way!

On the stroker, you need to look into internal balance or external balance, especially with the lower cost cast crank. You ought to be looking at a new damper anyway, so you can get either that you need. If you go with the kit as-is, then I am pretty sure you are looking at finding having it balanced locally. If you go internal balanced, then you can stick with what I assume is the neutral balanced flywheel that you possess. (What did that flywheel come out of, or do you already know it is neutral balanced?) SCAT can internal balance for you, but it is a higher kit price IIRC . So account for balance work somewhere in the costs; the cost differential just got larger again.

IMHO, at 350-375-400 HP, studs on the mains are not mandatory.

Upgrades to induction and heads can always come later. You already have 360 heads so that helps.

BTW, quench on the milled 360 heads (which still retain a shallow open area) is not going to happen with the standard pistons in the SCAT kits. There is no piston with a quench pad on top for the 318 (that I am aware of), like for the 340 or 360. To do that, with his present heads, the OP would need to go to a larger bore block. Quench is desirable for 2-3reasons, but not mandatory; IMHO, if your static CR is down in the 9.5 range, you'll be able to tune it up for pump fuel OK.

Since you cannot get quench here with these heads and no quench pad available on the 318 pistons, then zero-decking does not get you anywhere.
 
To me If your building a stroker it's mainly to gain torque why give up a bunch to use a 318 bore. Most builds make around 1.15-1.25 lbs-ft per cid.
So on 0.030 overbores a 318 = 390-400 lbs-ft, 360 = 420-455 lbs-ft, 390 = 450-490 lbs-ft, 408 = 470-510 lbs-ft. 416 = 480-520 lbs-ft.

If it was me I'd rather spend the money on a killer top end and put on a 318/360, than a stroker, if you can afford both no reason not to do that then.
 
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
 
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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To me it comes to incremental steps, like torque every 20 cid is like 25 lbs-ft, If your looking for a streetable 0.9-1.1 hp per cid about 20 hp per 20 cid, gearing .25:1 per 20 cid, rpm 200-300 rpm every 20 cid.

At a max end build the issue would rpm need and block strength more the the bore no allowing the air flow needed.
 
BTW, here is the pix I put on the last thread, giving you an idea how much you would have to notch the bores. With the SCAT rods and 4" cast crank; it'll be less than this as this is a smaller bore 273 block:

DSCN2611.JPG
 
273 said:
To me If your building a stroker it's mainly to gain torque why give up a bunch to use a 318 bore. Most builds make around 1.15-1.25 lbs-ft per cid.
So on 0.030 overbores a 318 = 390-400 lbs-ft, 360 = 420-455 lbs-ft, 390 = 450-490 lbs-ft, 408 = 470-510 lbs-ft. 416 = 480-520 lbs-ft.

If it was me I'd rather spend the money on a killer top end and put on a 318/360, than a stroker, if you can afford both no reason not to do that then.
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I agree.
I build engines from the top down.
There are many strokers under performing do to not enough cylinder head.
 
RustyRatRod said:
How happy is your budget? Getting into a stroker can quickly escalate into big heads, big carburetor, huge headers........all of which can add up quickly. If you think you can be happy with 325-350 HP ( I know I could be) then by all means build a 318. I'd kinda like to see where you go with it.
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325-350 hp is arguably all you need on the street anyhow. Thats a low 14 second car if it is geared right and not too heavy.
 
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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Talk to some slant six guys. We would kill to have the bore of a 318.
 
/6 Matt said:
325-350 hp is arguably all you need on the street anyhow. Thats a low 14 second car if it is geared right and not too heavy.
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If that's all the OP wants, his 318 is already a decent build, rebuild with decent pistons 9:1 cr and call it a day.
 
I did a 318-390 stroker. Very happy with results. I notched the bottom of the cylinders with die grinder and got the clearance within their tolerance. The mancini kit was like 2100 or so. It’s a totally different animal compared to the 74 318 it started out as
 
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.
 
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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Sounds like a solid plan, I would zero deck and buy pistons that are gonna give you quench and Cr you want with your future head and cam choice.
 
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