Comp cams xe268h for 318

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you can use one size shorter duration with the Howard (15) footnote cams or the Voodoo or a custom grind from Bullet, Engle etc- going for area under the curve not lift

in my mailbox yesterday
Valvetrain Geometry 101 With T&D Machine Products
same song different verse- note where they say machine work required...
B3 I think has a better answer for us MOPAR folks ( but this article takes some thinking but less confusing than a Jessel article I read and we know how screwed up some of the camgrinders articles are.
What I think is to ignore the talk about center of the valve stem and concentrate on narrow pattern and how to get there T&D is using mid lift
once you get the mid lift narrow pattern set then you can worry about center of the valve stem but remember a roller gives a straight line force in any case

Isky E4- dates from before 1957 if I remember correctly I think they came in the trunk with the dual quad for the T Birds...

A LOT OF DIFFERENCE IS SPRINGS SINCE THEN
a .904 grind may NOT be as radical as a .842 grind and as I said you can go one size shorter if you are short on compression
I know the DC, Engle and Crane .904 grinds are pretty easy on the valvetrain IDK about Comp HL, or Howard (name your poison but we are not doing hyd spec race motors here)
 
toolmanmike said:
Isky does that with their E-4. A pretty mild cam and dual springs are recommended.
Click to expand...
Not sure that comparing springs for a mechanical flat to a hyd flat cam is truly apples to apples as far as ramps, over-the-nose 'sharpness' of the profile, etc.

I 'try' to take the springs as an very general indication of the force on the lifter-to-lobe interface, but when a mfr tells you to use the same spring for everything, that idea goes out the window.
 
Just got through reading this thread.
Alot of great information. I had the xe268 in my "stock "340 and didn't like the soft bottom end. After reading this thread I figured that I needed a bigger converter and more gear. I ended up putting the stock cam in and I am much happier.
Hey AJ any pictures of that green couch?
 
Mike 340 said:
Just got through reading this thread.
Alot of great information. I had the xe268 in my "stock "340 and didn't like the soft bottom end. After reading this thread I figured that I needed a bigger converter and more gear. I ended up putting the stock cam in and I am much happier.
Hey AJ any pictures of that green couch?
Click to expand...
Already given away
 
Mike 340 said:
Just got through reading this thread.
Alot of great information. I had the xe268 in my "stock "340 and didn't like the soft bottom end. After reading this thread I figured that I needed a bigger converter and more gear. I ended up putting the stock cam in and I am much happier.
Hey AJ any pictures of that green couch?
Click to expand...
Or higher actual compression ratio..... Was that a later production 340, like a late '72 or a '73?
 
Stock 68 block .030 over 71 J heads with 2.02 valves. Wouldn't make good power until 2500 rpm then it came in .
I didn't like it as I want a street car .
 
With what stall? and gear?
This why the factory put 2400s and 3.23s behind them.
BTW, the factory cam was also a 268; but worse is, it was a 268/276/114 with valve events of : intake 22/66 and exhaust 74/22 Which sucks the pressure down further than a 268/276/110, given the same real starting points. The factory cam shoulddabin even a lil softer out of the gate; I'm guessing 5psi less at cranking speed.
But I totally get the softness.
Yet guys with 7.8 teeners rave on that cam. There is ZERO chance I would ever put a 268 in a 7.8 teener for street use. You are exactly right, it would require a hi-stall and minimum 3.55s, to be remotely effective and fun.And with those it's pretty much a Citycar.
>>Now a 340 has a few cubes on the teener to help it off the line, but it still likes it's pressure, especially with a 114 LSA. Installed straight up, the 114 cam loses 4* of compression; 114 versus 118, changing the Ica from 62 on the 110 to 66 on the 114. To make the same pressure as the 110 cam, one would have to advance the 114 those missing 4 degrees...... which would, relatively speaking, kill the overlap period, and the absolute power along with it
Never mind that these two cams from different manufacturers are not directly comparable anyway. The Comp shouldabin better in every way, shoulddabin.
>>Spec wise; the Comp should make more cylinder pressure, more low-rpm power,more midrange, more top-end with a higher shift-rpm, and better fuel economy; and with headers, a nice little power boost at the top. It Shouldabin better.
 
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Mike 340 said:
2200 stall with 3:55 gears.
It was a slug off the line.
Click to expand...
I believe you.
Allowing 800ft for your elevation, and a true 10/1 Scr, that Comp, in at 108 is predicted to make 162psi@ 132VP.These numbers are really good.
But the 3.55s hobbled her and the 2200 chained the engine to low-rpm operation for waay too long, giving the slug-like off-the-line performance.
But now, the factory 340 cam, with the 22/66 specs is in at 112, and is predicted to make 155psi@122VP.

So that makes it hard to understand how the factory cam runs stronger off the line. I said understand,Mike, not believe. I'm learning too, so I always wanna investigate the enigmas, that don't conform to common thinking.
My own car is one of those. Given the relatively mild build, it should not have run the miles per hour that it did.
 
So I was just reading comps instructions on cam break ins and it says to remove the center coil during break in. Does anyone actually do this or is this just a way to cover thereself in case of a flat cam? If so that is gonna be a pain in the butt. I'm gonna have to either get another spring compressor or pull the heads after break in.
 
SSG_
You need a worster avatar, I can't get any work done with her around; how about a picture of a rock, lol.a pet rock. a sleeping pet rock, with moss growing on it. Or a lump of coal. jus one mind you, an ugly one, with no identifying features
 
Mike 340 said:
Stock 68 block .030 over 71 J heads with 2.02 valves. Wouldn't make good power until 2500 rpm then it came in .
I didn't like it as I want a street car .
Click to expand...
In the rebuild, I'd bet something like the Felpro standard head gasket were put in, which are quite a bit thicker than the originals. Just that change would make the Static CR drop from the ACTUAL 9.7-9.8 from the factory down to around 9.2. So AJ's numbers are likely higher than what you really had for cranking pressure and V/P.

I gotta root around Wyrm's info on how the factory actually measured 'advertised'....IIRC it was at .008" lift?? (Wish I could get his info on that matter memorized.) Meaning that at .006" it would be more like a 274-ish cam and driving more towards being sluggish in the lower RPM ranges. And if the stock cam had no ground in advance like almost all of the aftermarket hyd flat cams do, there is another factor; it would go in retarded typically 4 degrees versus most aftermarket cams if installed dot-to-dot.
 
nm9stheham said:
Both for this tool.. the height for retainer clearance and the outside for the non-stock type of seal. If you don't want the different seals, I suppose you could just grind down the guide tops a bit with a grinder... not what you want to do 'on-engine' however! And there are several different tools available.

Spring seat cutters are different:
http://www.compcams.com/catalog/COMP2012/pdf/COMP_Catalog_2012_362.pdf

Got those heads off yet? Inquring minds want to know....
Click to expand...
I'm using the seals that came with the felpro gasket set. Factory style. So it's ok to just file down guides to allow for more clearance?
 
The truth is I broke my Hughes HE3037AL in with fully assembled 1129 springs. But I did some oiling mods to dribble oil on the lobes, the engine was oil-primed, and I had everything set just right, so that when I hit the key, I just sat down for twenty minutes and had a beer. HUG1129s are pretty stout springs, allowing my .549/.571 cam to rev to over 7200 without drama of any kind....... and since it can do that, guess what, I go there as often as I can.

Your results may vary............
 
dartfreak75 said:
So I was just reading comps instructions on cam break ins and it says to remove the center coil during break in. Does anyone actually do this or is this just a way to cover thereself in case of a flat cam? If so that is gonna be a pain in the butt. I'm gonna have to either get another spring compressor or pull the heads after break in.
Click to expand...
Yes, it is done by some, in some cases. It helps lower the risks. But, in reality, you can mess up a cam lobe in many ways. My philosophy: if it is a low lift cam, and the spring pressure at max lift stays under 300 lbs, then I personally would not bother. But that is my personal view; YMMV.

Use a moly loaded cam lube and that will help reduce risks too.

There are plenty of lever type spring compressors to do this while the heads are on the engine. Do searches here and you can find some homemade ones.

What springs are you looking at?
 
dartfreak75 said:
I'm using the seals that came with the felpro gasket set. Factory style. So it's ok to just file down guides to allow for more clearance?
Click to expand...
When short on $$, I don't see why not.... filing is awfully slow.... borrow a small grinder maybe?
 
nm9stheham said:
In the rebuild, I'd bet something like the Felpro standard head gasket were put in, which are quite a bit thicker than the originals. Just that change would make the Static CR drop from the ACTUAL 9.7-9.8 from the factory down to around 9.2. So AJ's numbers are likely higher than what you really had for cranking pressure and V/P.

I gotta root around Wyrm's info on how the factory actually measured 'advertised'....IIRC it was at .008" lift?? (Wish I could get his info on that matter memorized.) Meaning that at .006" it would be more like a 274-ish cam and driving more towards being sluggish in the lower RPM ranges. And if the stock cam had no ground in advance like almost all of the aftermarket hyd flat cams do, there is another factor; it would go in retarded typically 4 degrees versus most aftermarket cams if installed dot-to-dot.
Click to expand...

I adjusted the comp to match the Mopar cam, as best as I knew how. I used 10/1 as you noted because I was comparing each cam to the other, so the base compression used is relatively unimportant. The factory cam,with the 114LSA, no matter how you slice it,will puke pressure back into the intake, 4 extra degrees over the 110LSA-Comp, when installed as described. While the numbers may not be dead nuts accurate, I believe the comparison is.
I did not take the headgaskets into consideration because the heads don't have to come off for a cam change.I agree that a 4cc change in headgaskets, would skew the results a half a point of compression on a 10.1 340-engine , so the Mopar cam would finish at 160@126VP still less than the 162/132 of the Comp (post#284)
You won't hurt my feelings if you rework the comparo, just keep an eye on the percentage VP change; that's what's important here. Per post #284 that would be 122/132 = .924 or the Mopar should be 1-.924=7.6% weaker on the bottom, from stall to about 3000rpm. I have no idea what that 7.6% would feel like, but I could guess, lol. The difference from 3.23s to 3.55s is 9.9%, and from 3.55s to 3.73s is 5.1%.
Just remember that VP is a diminishing ratio number that may start out at that 7.6% loss, but somewhere between 3000 and perhaps 3500, that VP disadvantage number may have shrunk to zero; I have not studied out how that works. But the 2psi pressure difference, while quite small tells more about what the power difference might be from peak to peak, which in this case looks almost insignificant. However, we don't know what these cams are doing between closed and open. I suspect the Comp will be faster, and trap more mixture, and then the 2 psi might be worth something as it increases the EFFECTIVE compression ratio which is a third way of measuring compression, and is constantly changing with throttle position and rpm. This is the most meaningful compression ratio, as it most closely relates to what the operator is experiencing.
Scr is fixed mathematically, and so is the Dcr. But Ecr is constantly changing just like VE.
 
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Yep, I was just adding in some other factors as to why the 340 mentioned seemed soft to Mike..... one thing adding to another. Not to invalidate any of the comparative numbers.
 
Ok guys I had a min to run outside and I pulled one head off. And I have found a problem alot bigger than cam selection. I'm not sure how this happened because the engine has been inside covered in a tarp for the last seven years before that it was driven daily. But anyway two of the four cylinders had moisture in them and are rusted/pitted. I snapped a few pics it looked like it was covered mud it's not its greasy muck where I used a greasy rag to wipe off the piston tops. Kind of a mute point at this point but measured the pistons they where right at .064 in the whole without the gasket and the gasket miced at .043. Must be aftermarket? Here are some quick pics I took. I had to run in the mosquitos where carrying me off.

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You can seen in this pic the rough spot. There is one cylinder the whole cylinder is like that.

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nm9stheham said:
Yes, it is done by some, in some cases. It helps lower the risks. But, in reality, you can mess up a cam lobe in many ways. My philosophy: if it is a low lift cam, and the spring pressure at max lift stays under 300 lbs, then I personally would not bother. But that is my personal view; YMMV.

Use a moly loaded cam lube and that will help reduce risks too.

There are plenty of lever type spring compressors to do this while the heads are on the engine. Do searches here and you can find some homemade ones.

What springs are you looking at?
Click to expand...
Comp cams 901-16 the ones that comp recommends for the xe262h
 
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