318 Build suggestions
Ok
I've been thinking it over
if you really want to spend your money on a 318
and with the parameters as already stated ( see *1 below),then;
>the first thing you will need to do is get some airflow going at rpm, >and the second thing is get the Effective Pressure up.and
>the third will be in the tune.
(*1)
I still want this to be streetable with the occasional local weekend 1/8th mile.
Also what about cam specs? any suggestions?
try to build a good performing 318, without breaking the bank
an Eddy Airgap RPM intake topped with a performer 600CFM. Ignition is stock plugs with a Pertronix electronic distributor.
Transmission is a fresh rebuilt 904 with B&M shift kit, stock converter. Rear end is fresh rebuilt 8 1/4 with open 3.55 gears.
What would need to be done to run the 65cc heads on a 318 lower end?
I don't mind changing pistons out to boost compression,
I would still like this to run on pump gas.
I would like it so be streetable with the occasional weekend fun.But i've also thought about aluminum heads but don't really need 2.02 valves since this car wont see 5000-6000 RPM
Its nothing that has to be done in a hurry so im not worried about costs.
Just would like to know what some good recommendations might be with stock heads, rods and pistons.
I am not trying to build a 1/4 mile car, but maybe achieve 300 HP? Something reasonable out of a 318
Already have a excellent 318 core, already have a left over gasket kit, rings and some other 318 components. I would just be looking a some heads, cam, and decking on the heads.
>so the first thing you have to do is decide if the 3.55s are gonna do it for you; because,
65=3000@4% slip with 26.7" tires .
>This is gonna set the tone for the rest of the build, because the next thing to do is to choose the rpm of operation to work together with those 3.55s.
Here's what I mean; with 3.55s, and your TF904 (2.45-1.45-1.00)
your self-imposed rpm limit of 5000, brings the following;First gear tops out at 40 mph
and second at 67mph. These are good numbers. To shift at 5000, the power peak can be at 4700, so, I doubt this will get you 300hp. But you installed a "?" after 300, so lets forget about the 300, and concentrate on "good performing",on "pumpgas".
> So, having set the powerpeak at say 4800, we can now look to the cam as to intake duration. In this case, I'd be looking at
[email protected].
> to get the power with that small a cam, and limited to 5000rpm, you are gonna need a very specific head and a lotta pressure, more than IMO, iron can supply. You're not gonna touch 300hp at 155/160 psi. Yur gonna need 185 or more, and that pressure dictates alloy heads, and the
.039 FelPro head-gaskets. So now we have the second piece of data
8.8cc for the gasket, and the third;
185or more psi
> So now, lets choose fuel economy. How important is this to you? Ok so IMO, because I believe that the price of gas is gonna skyrocket in the coming months, I'm gonna go with "very important". And so we come to the cam's extraction cycle and overlap. In an effort to make power at 5000, with headers, that cam is gonna need a generous amount of overlap. Normally we can't get away with that, but cruising at
60@2780rpm, we can. So I'm gonna set the max to
50*overlap, because I already got 32mpg with that number, even at 2100. Next is extraction. We're gonna need to maximize this to, IMO,
greater than 114*
> so now we can begin to build a cam spec. So far we have intake of
[email protected], 50* overlap, and 114 extraction.I already know that I want a minimum TC stall of 2800, so, I can chose a tighter than "normal " LSA, so I'm going with 108. And I know I will need a solid lifter profile, so I can control the exact opening and closing points of the valves, so I can control the pressure. So that
[email protected] is gonna become about
258 @.006/.008, we'll finalize that later.
> because our heads will be fantastic, and because we have headers, and because we will have plenty of pressure, and because I want more than 114* of extraction; I'm gonna choose a tight split of 6*, so that makes the exhaust duration to be about
264*. I now have everything I need to generate a cam profile. And I get;
258/264/108+1/45* overlap/56*Ica/124* compression/119*power.
>Bam! now we have an Ica. But look, the extraction is a huge 119*, and overlap is only 45*, so it has the potential to make fantastic fuel economy; the stock 318 cam has 20*overlap and 122* extraction.
> With the Ica known, we can now generate, using the Wallace Calculator, the Scr/Dcr numbers, and get an idea of how much fun this engine will be, looking at the VP. I'm gonna jump the pressure up to 185, because I know with a tight-Q and alloy heads, you will be able to run 87E10 at full load/full timing. And since Indio is near sealevel, that's what I'm gonna input. So here's what the Wallace says
Static compression ratio of ................... 10.5:1.
Ica of 56*/sealevel
Effective stroke is 2.74 inches.
Your dynamic compression ratio is ................
8.85:1 .
Your dynamic cranking pressure is ...............
186.51 PSI.
V/P (Volume to Pressure Index) is ................
149.
BadBoom!
VP of 149 puts you solidly into the funzone, so I am downgrading the TC to stock, or use what ever you have. You can upgrade later if you feel the need.
> now, all we have to do is build your 318LA up to 10.5Scr, which at .020 o/s, will require
69.36cc.
The gasket was earlier selected at
8.8cc, so that leaves 60.56 for the total of head plus piston. So lets use a
58cc closed chamber alloy design, leaving 2.56cc NET for the piston plus deck clearance.. This design calls for no more than .050 less .039= .011 deck clearance, and up to .028 less .039= .011 pop-up , but has to end at
NET 2.56cc, sounds pretty easy.
You could try this with an .028 gasket, allowing up to .022 deck clearance, and maybe save the cost of decking, BUT, I have not had long-term success at 185psi with those; the one-time I used them, they blew the fire-ring into the valley. Of course this will change the NET volume so you would have to re-calculate.
If you can't get a flat-top piston with a high enough cd to get you up to the minimum .012 deck height, then you will need to either lower the decks (I don't like doing that), or get a piston with a dome or step or a reverse dome step-D cup, whatever it takes. At 185psi, you can't afford detonation.
> in a nutshell this build will satisfy your every dream.
You can use the stock crank and rods.
But you will need some way to adjust the lash on your solid-lifter cam. This doesn't need to be fancy with the modest 5000 rpm shift speed. You can use the 273 stuff, or IMO, even just adjustable pushrods, if you can find some adjustable with the intake still installed.
You can use everything else that you already own; namely the TC/3.55s and bolt-ons, and all your current support-works should be fine. And she's an easy to tune combo.
> of course it is highly unlikely that you will find an off-the-shelf cam as detailed. Not to panic, you have lots of pressure to burn, so you could use a fast-rate hydro of similar .050 numbers, and readjust your Scr as may be required, to try to maintain the minimum 185psi spec. Yes you could even go back to iron heads and 165psi; but then you will need to pull the Scr back to 9.5.... which reduces the V/P to 131, still a bit better than the stock 318, but really a ho-hum number; Say goodbye to roasting both tires. To get the bottom-end back, you will need that 2800TC now. Also, at V/P of 131, your fuel-mileage is slipping away. And at 165psi, you will need best pumpgas. If you drive 10,000 miles a year like I used to, the fuelcost difference between 87 and 91, is gonna rapidly eat up the equivalent cost of alloy versus iron heads.
Do you need alloy heads?
At this power level no; not for power gains. But it allows you to run the pressure, to make big-engine, down-low torque, and to make decent fuel economy, so you will want to put the miles on it instead of complaining how expensive it is to drive..
As to VP, for comparison, the 340 of 1970 had a VP of 131, and NOBODY I know, ever bragged about how much torque the 340 had. So we know that 131 is nothing to brag about, lol. The 440M made about 137, and out of the gate, they never impressed me either.
But 149 is a real ripper.
Furthermore, alloy heads will, by virtue of their assumed to be better flowing ports, OOTB, will be worth about one cam-size at peak power, so there is that,lol, getting you closer to 300hp.......
>So there you go; power with economy and a chitload of torque, not usually all mentioned in the same sentence, concerning a 318.
> BTW, if you find some traction, hang the heck on, cuz when she spits the driveshaft out on the 1-2 shift with those puny 7260 joints, things get a lil crazy; hope the back one lets go first. VP of 149 tends to break stuff. Don't even think about peg-legging that 8.25, the spiders will not take it for long either seizing on the crosspin, or simply shattering on the shift. Order your "posi", and your driveshaft loop .....today. In your camsearch, PM
@Wyrmrider, to get the skinny on fat .200lift cams.
Now, I leave the task of choosing the components in the hands of my very capable fellow FABO members, who like to paint me a 318hater.
Happy HotRodding
