J1MMY
Well-Known Member
Well I’m guessing these aren’t KB167s like the now folklore surrounding this engine once suggested. I’ve done some searching but the eyebrows and centre relief doesn’t match anything…
No that just the basic summary of those 4 400 hp 318 builds.When you said ‘magazine’ I thought I’d put the wrong link!
Your mostly there depending how well your heads are ported.Headers - tick.
Air gap - no problem, will order.
750 - no problem, will order.
Cam - happy to make what I have work
Here's all the 318 plus for the 318 guys
318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine
Mopar 318 Engine - Car Craft Magazine
Chrysler 318 Engine - Popular Hot Rodding Magazine
318 Small Block Build - How To - Hot Rod Magazine
318 Long Block Bolt Ons - Tech Articles - Mopar Muscle Magazine
https://www.hotrod.com/articles/0901phr-mopar-318-magnum-engine/
https://www.hotrod.com/articles/mopp-0311-318-engine-buildup-and-dyno-test/
How To Install A Hotter Camshaft - Mopar Muscle Magazine
https://www.hotrod.com/articles/mopp-0009-1985-dodge-dart/
Vintage Mopar Power! 550HP Chrysler Poly 318 V8 on the Dyno
318 head porting for the average joe
Porting small block 915 j-heads
Magnum head porting for the beginner
360 Engine Head Porting - Mopar Muscle Magazine
https://www.hotrod.com/articles/mopp-0002-porting-exhaust-smog-heads/
https://www.hotrod.com/articles/mopp-0507-cylinder-head-porting/
https://www.hotrod.com/articles/mopar-small-block-intake-manifold-flow-test/
https://www.hotrod.com/articles/0601em-intake/
https://www.hotrod.com/articles/10-critical-mopar-engine-building-specs/
https://www.hotrod.com/articles/mopp-0309-mopar-engine-rebuild-intro/
https://www.hotrod.com/articles/mopp-0308-adding-magnum-to-a-360-short-block/
Sealed Power. Good slugs. They look real close to zero deck.Well I’m guessing these aren’t KB167s like the now folklore surrounding this engine once suggested. I’ve done some searching but the eyebrows and centre relief doesn’t match anything…
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Well that’s nice to knowSealed Power. Good slugs. They look real close to zero deck.
I am not knowledgeable enough to judge in all honesty and I’ve not seen a set of unported ones up close to be able to compare meaningfully.No that just the basic summary of those 4 400 hp 318 builds.
Your mostly there depending how well your heads are ported.
I was looking at the cost of heads on the Summit app this afternoon. I did notice that Trickflow are quoting higher flow rates than Edelbrock so could be more of a goer straight out of the box?having built the fabled 400hp 318 (twice, natch) your make or break is going to be the heads. to note, that 400 was just barely and everything has to be dress-right-dress to get there. and i honestly don't know if the air gap will do it over the single plane. i can tell you that i took the single plane off and wound up putting on an airgap the second time (it wasn't available the first time i built one) and that made the car much more driveable.
anyway, onto what you've got cooking. if you're not looking to spend a ton of dough or re-engineer the whole enchartio, i'd say you probably have enough cam to get there. those sealed power slugs aren't a bazillion miles in the hole and are up to the task.
so, heads. either you work the F out of your 915's or... flip for some eddy's, speedmaster or trick flow. given your locale i think by the time you splash the pot for some magnum heads you're pounds ahead just biting the bullet and getting something aftermarket that'll support your cam (or the air flow requirement) needed to hit the number without a bunch of additional work.
with that combo, plus an airgap and 750 i say you'll tickle just shy of 400
I was looking at the cost of heads on the Summit app this afternoon. I did notice that Trickflow are quoting higher flow rates than Edelbrock so could be more of a goer straight out of the box?
Flipped the block and pulled #1 piston and rod this evening, noticed the big end and the big end bearings are pretty scratched up, the crank is also .010 undersized. Rods are the usual 318 items the part no. now escapes me but there have been plenty of posts discussing them (not bushed at the little end). The crank has been ground, I can’t find any numbers of meaning, 616 on the end of a counterweight, 5389 on the side of the counterweight at the balancer end but nothing else.
This has given me some uncertainty and perhaps increased the shopping list.
Hopefully tmw I’ll get the remainder out and have a good look at the bores.
BTW, I’m grateful for everyone’s input and patience - the continual ‘oh and today I found….’ is a bit tedious but I don’t get much time outside of work on weekdays.
Dang, now I'm going to need to look around for the out of the box Speedmaster flow numbers.
that begs the $56,000 question: if it does make the same juice, then where and how?I agree with Junkyardhero that heads with 220-230 cfm will get you there but if you want to run less cam I'd be shooting for 240-260 cfm.
stock magnums flow okay, but they have their limits. if you're going to port something stock the mags have quite a bit more upside than stock LA heads. but then you're talking about the incurred cost of heads, rockers and that work. the other side of that coin is some aftermarket heads which should (in theory) flow at least or better than magnums all across the board. so there's that?
i'm gonna use some very loose numbers here, but on that particular 400hp build the magnum RT heads used have an intake runner of 180 and flow about 220-230 out of the box, so a wild *** scientific guess would say you need "about that", so there would be my target range for deciding aftermarket heads. well, that and rocker gear-- i don't know if you've got something decent you can reuse or if you wanted to upgrade.
if you can get away with a polish, then i'd just slam bearings in and ship it. but if it's beyond that or needs another cut, then it's decision time. i can't wholly make a recommendation because i don't know what availability is like over yonder, but if you've got a crank requiring work and those bores hold unexpected surprises then it may be time to rethink the path forward, especially with the block already being 40 over.
babies n' bath water n' all that.
that's just the way the scone crumbles homie. set out to do it one way and the script gets flipped on ya. we fully expect an update on the bores and i look forward to help spending your money for you!
that begs the $56,000 question: if it does make the same juice, then where and how?
more compression? more carb? more duration with super aggro ramps? what happens to the curve? how's the driveability?
if I have any more unwelcome news when the bottom end comes apart I’ll be fitting a 400hp BMW I6 diesel engine but seriously, I will know more later. If I cannot reuse much of the engine in its last guise I will need to prioritise replacement of bad before replacing currently usable which will draw things out. It’s not the end of the world, I’m in no hurry.I feel like at your current power level, significant gains could only be had with a "complete package" rebuild, at least in regards to cam/heads/intake. IMO going from cleaned up and milled J heads to unported Trick Flows will give an incremental boost, maybe 30 HP? If it were mine I'd go for some heavily ported Speedmasters, get that intake flow up in the high 200s CFM range (at least). You're at the point in the "Cost vs. Power" curve where it starts getting a lot more expensive to make solid appreciable gains in performance.
Yep and I initially dismissed it as I want to keep it a screamer. If the bores cannot be honed and the spare 318 I have isn’t economically worth the work I will consider the options.has anyone mentioned a 390 (392? at your 40 over) stroker kit yet? it'll get you to 400hp easier, again with decent heads of course.
neil.
Here's video kind of showing what I'm talking about.Yep and I initially dismissed it as I want to keep it a screamer. If the bores cannot be honed and the spare 318 I have isn’t economically worth the work I will consider the options.
Mad isn’t it that big blocks are everywhere over here but try finding 360s…that said I’d still put the same effort and money into one.
Here's video kind of showing what I'm talking about.
who told you a stroker won't rev? at 3.95" bore and 4" stroke it's pretty much 'square' after all. revs are down to cam, heads, induction and exhaust as you know. the limiting factor with a higher hp/revving small block mopar is heads not stroke. the reason some say strokers won't rev is they don't know what they're talking about. yes a stroker can make the same power/torque at lower revs as a stock stroke motor, but you then have the potential for more hp/torque if you build it for revs.Yep and I initially dismissed it as I want to keep it a screamer. If the bores cannot be honed and the spare 318 I have isn’t economically worth the work I will consider the options.
Mad isn’t it that big blocks are everywhere over here but try finding 360s…that said I’d still put the same effort and money into one.
he's already mentioned finding a 360 here in the uk is much harder than in the states, hence the 318 build.You can definitely make larger displacements rev, a 408 is about 28% bigger than a 318 so it needs to be able to move about 28% more air flow to rev the same and that would reward you about 28% more power and a 318 could do similar power but it would need to turn about 28% more rpms, if efficiency were similar for each.