Too much engine work at once

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Springs are in, they look great.

IMG_0487 copy.jpg
 
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AJ/FormS said:
Well, a 318, at 9.2, won't be that bad with that cam.The VP will be a little better than a low-C later 318.The math says about 7% better

But, for a 4speed manual; I'd get it on a 106LSA to punch up the pressure and the VP, and with headers, the overlap, at 47* will actually count for something, and best of all? you can get some fuel mileage out of it.
Yeah that's what I would do; an LSA of 106 and in at 105.
Here's food for thought
the Wallace says;.............................Scr./Dcr./psi./.VP
The original cam,a 240/112 looks like 9.2/8.15/164/136VP..in at 108
The new 262/112, in at 108 looks like 9.2/7.78/154/122VP
The...... 262/106,in at 105,looks like 9.2/7.93/158/128VP
But no matter how you slice it, 122 is soft.
with an Scr-bump ,the 262/112 looks like 9.7/8.19/165/130VP jus saying
howzabout a 268/104,in at102,looks like 9.7/8.19/165/130VP now yer talking. I would sacrifice 6 points of VP for the power of this cam.And to go from 9.2 to 9.7 is like 4.57cc...... so look; you're gonna loose compression anyway with the .039 gaskets over the factory steels,so you might as well shave the heads enough to compensate for both,(about .042) and stuff the 268* in there, then you only have to do it once;Cuz I'll tell you the 268/104 is gonna be a charger.... at 9.7Scr,lol.
Just remember, all that power is gonna be 800 to 1000 rpm higher than with stock cam, or 8 mph further up in first gear with 3.55s..... but at least your bottom end won't suck so bad.....122VP is pretty soft. Well I guess that depends on your idea of soft; a stock 8/1 360 2bbl makes about that.
Anyway
Just thinking what I wouldn't do. And 122VP is for sure on the list,especially when for a couple of bucks more, I could have 130VP and something like 20 or more hp,over the 262 the only downside being the lumpy idle, and a bit of lost fuel mileage over the stocker. But a possible gain at steady-state over the 262/112. The 268/104 wants headers to make those 64* of overlap to work.The 262/112 with just 35* won't hardly care
Happy HotRodding
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So do you think I should install the lunati at 106 or are you recommending a different Cam. You have to dumb it down a little for me:)
 
stumblinhorse said:
So do you think I should install the lunati at 106 or are you recommending a different Cam. You have to dumb it down a little for me:)
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Neither, if you already own the cam
And I see now, that you shaved the heads.So your Scr went up some.

But I was saying what I would do.
And that was a different cam,yes. I was showing that the 268Custom LSA cam could make a lot more power than the 262/112 , and with just a small adjustment in Scr(Static Compression Ratio) would actually have a stronger bottom end than the 262 and not lose all that much from stock.
And if you were willing to go to a solid lifter cam, well then, we could do a lot with that.
But if you already own the new cam , then .........far be it from me to tell you to ship it back,lol; that would be Whack.lol.

Oh I see why Imighta confused you; I kept calling your a cam a 262, when I shoulda been calling it a 256. All the math was worked out with the correct 256 numbers tho, so I went back and changed all the 262 references to 256.
My apology for the confusion.
 
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Marcohotrod said:
I have heard it before, but don't see how more overlap boosts pressure
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It doesn't......usually.
The pressure boost comes from tightening up the LSA,advancing the cam, and therefore having an earlier closing intake.
Heres an example; take the 268/110 cam and install it at split overlap. this would be at 108; and the ICA would be 62*
Now order same 268 but on a 104LSA and install it at split overlap.This would be 102, for an ICA of 56*.........................6 degrees earlier, and that is where the pressure boost comes from, slamming the valve shut earlier, on the mixture trying to go back up into the intake, being pushed in that direction by the rising piston..
Now order a 268/114 automatic cam and install that at split overlap. that would be an install of 112* and an ICA of 66*. This is 4* later than the 110 cam, and 10 later than the 104, and so a pressure loss compared to them. 10 degrees is a lot. A change in ICA of 3.5* is about one cam size, when installed at split overlap..In other words tightening up the LSA 10 degrees, allows you to run a cam about three sizes bigger with little to no pressure loss..... because the ICA remains or can remain, the same.

With an automatic trans and a hi-stall, this gets lost in the shuffle because as the rpm rises, there is less time for this pressure to be lost, and somewhere around 2200 or a bit this way or that, reversion is down to a minimum and nobody with a higher than 2200TC cares about it.
But with a manual trans,and street-gears like 3.55s, the engine is stuck down in that sub 2200 zone for a lot of the time,either in first; and especially in second this really sucks.
 
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If a cam is short on overlap for a certain rpm point, obviously more will help get air moving. The draw (vacuum) on the intake side can get VERY high from a combination of exhaust and intake tuning , and the overlap period is where flow really,really, gets moving!
 
if the cam is advanced more and there is a narrow lobe sep. angle, the intake valve opens early=more exhaust reversion-not helping intake flow into cylinder. overlap does help pull into the cylinder, and when the piston starts going down flow in really gets going. I like the Lunati cam mentioned in at 106*
 
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