Waterloo is at 1000 ft elevation according to Wiki.
That cam, in at 108, has an Ica of 59*.
To make an average pressure of 141psi, your compression ratio is estimated to be about 8.85 to 1.
Those are facts,
Here are my opinions, and I'm sortof thinking it out as I go.
> This makes your bottom end fairly weak.. Coupled with 3.23s, and a 2.66 low gear ( a starter gear of 8.59), I imagine taking off briskly takes a lotta clutch. The Wallace calculator estimates your V/P index to be just 110....... A peppy V/P target is ~135 minimum.
However;
Even at 10/1 compression ratio; the pressure while rising to 165psi, the V/P is still only 129. While this is a 17% improvement; a stock 5.2 Magnum@1000ft, has a V/P of ~124. That means, that even if you pumped your cylinder pressure to the max, your engine would still only have the bottom end of a stock 5.2M, from idle to about say 3300rpm.
With an automatic, this is no big deal, you just stick a 3300 stall on her and call it done.
But
with a 4-speed, and 3.23s, probably 95% of the time, you're gonna be at under 3300, so bottom end is a really big deal.
Your tires are about 25.7 tall= 80.74 roll-out, thus
3300, will get you to 29mph in first, 41 in Second, 56 in Third, and 78 in Fourth. So, until you get to those speeds yur teener is sucking wind.
Am I right so far?
>Your only solutions to this are
1) way more cylinder pressure, or
2) an earlier closing intake event
3) a bigger engine, or
4) supercharging.
You can bandaid the situation with a higher starter gear, or bigger rear gears, this is true, but eventually, the low-pressure 318 just runs out of steam.
So from your question sheet, I'm gonna read between the lines and answer thusly;
1) I do NOT disagree with anything that has been said in earlier posts.
2) You have already spent a lotta time and money on the current combo. Which is actually a pretty good combo, except for the lack of cylinder pressure.
3) so, since the engine has to come apart anyway, the cheapest bang for the buck, IMO, would be a new set of pistons, fitted to make about 160psi.
4) and I agree that a stroker kit is a great solution, but it requires additional monies to bring it on line.
5) the simplest solution, if hiway travel is NOT considered, then, is to leave the engine as is, and go with a lil more rear gear. The current combo would like a starter gear of at least 10/1, which, with a 2.66 low gear, means a rear gear of 3.73s.. That will increase your torque multiplication in every gear by ~15.5%, nearly equaling the 17% earlier talked about. The downsides are the higher cruise rpm, higher fuel consumption, and sooner or later the low-pressure 318 is still gonna run outta steam.
6) another other option is to get a Commando trans with it's 3.09 low gear. Thus, to get a 10/1 starter, you only need 3.23s, which you already have. Unfortunately, the other gears are the same, and 3300 now only gets you 25mph in first, and on the shift, the Rs fall down to 2050, so there you are stuck back in lo-performance mode.
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>Ok so now; what would I do?
Well, I've been driving Mopar 4-speeds all my life,(since 1970) and currently have one of every SBM box, except the 2.47 T/A which I have no use for on the street. So I am very familiar with them.
and my current combo is a 68 Barracuda, which as you probably know, is at least 150/200 pounds heavier than a similarly equipped Dart, and Ima thinking your wheels are plumping that up a bit too. My 68 is 3450/me not in it; with an all-aluminum top end, all aluminum 4-speed and a GVod, so I can't get much lighter.
So, if I was in your shoes, and
if I was looking for more performance on a budget,
The first thing I would do is pump up the pressure,
But I wouldn't stop at 160/165 psi.
Nope, I would install some alloy heads and target 190/195 psi. That would take an Scr of about 11.2, and would yield a V/P of 150(sweet)
Lest you think 11.2 is impossible, I ran 11.3 in my 367 for quite a while, the only trick is to run a tight-Quench (I ran 028).
>My opinion is;
that at a V/P of 150, you will never complain of a soft bottom end again. This is about where big-blocks of yester-year ran. At a V/P of 150, you can run the 2.66 trans and 3.23s just fine.
But this is no longer budget friendly. Yur looking at both heads and pistons, and eventually a carb.
But the bonus is that you can move up a camsize , with very little loss of pressure. Plus, if you went to a stroker, you'd need better heads than you now have, anyway.
The 3.23s are still a bit of a handicap, but that V/P of 150 will power thru it.
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With your new found pressure, you have an ideal opportunity for transformation with one of the the A833od boxes.
Your current trans should have ratios of
2.66-1.92-1.40-1.00 with 3.23s the roadgears are
8.59-6.29-4.52-3.23
If you drive like me, then you are mostly using First and Second. and occasionally fourth. Third is mostly used just to get to Fourth. Am I right.
Your 262* cam power-peaks at about 4800, and you can shift that at say 5200 on the street.
Thus that 6.29 Roadgear will get you 60mph@4940/perfect. So you don't want to stray too far from that number.
Say you had the A833od with ratios of;
3.08-1.67-1.00-.73od, then 3.73s, will get Roadgears of
11.52-6.23-3.73-2.72. Compare that to the current
' 8.59-6.29-4.52-3.23
As you can see, from 6.29 to 6.23 is near enough to be perfect. Your starter gear is now in tire-frier/parade mode, Third gear is 17% worse but that overdrive is dropping your Rs from 65=2750 to 2320, and since Third is mostly used just to get to Fourth, that 150VP will power you thru that. IMO that is a fair trade, even if First gear is pretty low. My 367 ran that overdrive box with 3.55s pretty good. With 3.23s First was better, but Second was worse.
Ima thinking ;
Your current heads, with the right pistons and Quench, at 160psi, would do pretty good with those roadgears.
Thus you are trading a set of alloy heads for an overdrive box, and 3.73s. Great deal. the budget is back! But you still gotta ditch those pistons.
With iron heads and a hydraulic cam, IMO this would be as good as it gets for the money spent.
If you ever buy another cam Consider a fast rate of lift, tight lash, Solid lifter type, if for no other reason than to preserve the pressure.
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So to recap, what I would do is;
1) Increase the pressure to in the window of 160/165psi together with a tight Quench of less than 040. It doesn't matter how you get there.
2) install an A833 od
3) install some 3.73s or if you need a better parade gear, then 3.91s
4) leave everything else as it is. except you might have to tweak the power-timing to come in a lil later. It's a 4-speed and that is normal.
5) speaking of parade gears
Your current combo, at 550 rpm, the slowest it can drive is ~4.9mph. Since nobody can walk that fast, to parade, you gotta ride the clutch. This sucks for the clutch and sucks for your left leg, so you tend NOT to parade, am I right.
Well, with the 3.09-Overdrive and 3.73s, 550= 3.65 mph. But, if you install a High-Volume oil pump while the engine is apart, you can idle that 262-cammed engine down to 500 pretty easy, and your new slowest speed is 3.3mph, and parades are now possible. For me, that was a happy day. Idling thru the parking lot at 500 rpm at the car shows, was a rumpidy-rumpidy good time.
Ok so, those are my opinions.
