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Theory question; cam/head related

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ReverendDexter

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Discussion starter · #1 ·
At what point is the stock cam limiting in building a 5.0 and should definitely be replaced?

I know this may not be the best crowd to ask, as the answer for every build question is "347 + Trick Flow top end + custom grind cam or GTFO", but I'm starting to think about building up the motor a bit in my car and looking at smog-legal options.

My primary concern as odd as it may be is reducing weight, so aluminum heads are the biggie. Is it totally retarded to run a stock cam under aluminum GT40s or TF Twisted Wedges? How much power would I be giving up to do so? Are there other cheap aluminum heads with CARB numbers that aren't junk? I'm actually NOT chasing power here, though making power for another 1k rpm over stock would be nice.

My knowledge of cams is pretty limited; I know that the key things are duration, lift, and overlap, and that those things determine at what conditions the cam is ideal. I don't really know just looking at cam specs where it would lie, i.e. I know that more lift and duration allow for more flow, I assume a higher-rpm cam would need more duration and overlap, and that if boost or passing emissions are involved overlap is bad. Other than that, it's voodoo to me.
 
#2 · (Edited)
a little rusty

New to the board, but I used to be very into the theory - even took a graduate level class on IC engine theory... However it's been some years.

I designed a cam for my 331 stroker (10.5:1) when I was into it, a lot of guys say it's a "blower cam" but I can tell you it runs excellent and sounds excellent N/A. The specs are .549/.549, 110/118, 138/138 (I think)

Before you worry about a cam, ask yourself what your end result is. ie. Drivability vs a little more power. I've heard that 114 lobe centers are as aggressive as you can go with a computer & F.I. but I can't say that's true or not. For a mild build, I'd consider the E,F,X,B cams. I hear the X is pretty driveable yet adds some performance. I remember .550 lift with 1.6 rockers is about as much as you want to go in lift for stockish motors (maybe clearance was the issue?). I did a bunch of flowbench testing and remember over .550" didn't really increase the flow that much on most heads, except AFR and a couple others. Therefore, the efforts to lift the valve are wasted energy. I do remember clearly that Vic Jr heads were the best "bang for the buck" for flow in my testing at the time. I got the BBK SSI intake, which is a good torquey 3 plenum (side-side-middle) intake which seems to work well for my cam. Look at the advertised power bands for the cams you consider with your intake, heads, and goals. Your duration is of course your lope, and at 138 my car runs like a carburated one when cold... jerky driving (the car, not me) under 1600 rpms. I would be selective certainly, research and read A LOT. Call the cam companies, they were happy to talk with me back when.

FYI, my setup put out 404 ft lbs and 345 HP at the wheels... but I run World heads, limiting my peak HP at 5600 RPMs. Also, the iron head doesn't give off heat as well limiting my ignition timing advance to 10 degrees. Sorry for the poor memory.
 
#4 ·
If you are worried about passing smog the only smog legal cam in the alphabet series (b, e, f, x cam ect) is the e cam. The trick flow stage 1 cam is fairly close to the e cam and a buddy of mine passed smog in california with it. It really depends on what you are looking for in the end. I know you said it already but the trick flow top end kit is a great kit. I just installed their street heat kit in my 92 gt. If you are looking to get cheap power and really don't care about going aluminum just yet you can run down to your local junk yard and find an explorer and get some gt40 heads and intake.(if you can find one) either way good luck!


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Discussion starter · #5 ·
96paxtonstang said:
If you are looking to get cheap power and really don't care about going aluminum
Click to expand...
That's actually the opposite of what I want, hahaha. Cheap is good, but I care more about going aluminum than I do about power :) Basically I just don't want to get total junk heads.
 
#7 ·
None. Trickflow is good ****. The top end kit will do you good if you're willing to spend that much. They advertise a 350hp street heat kit(or street burner, which is what they call it now) and a 360hp track heat kit. I'm pretty sure they are both smog legal but you'd have to research that yourself. I believe they are the same price so I recommend the track heat kit because of the better intake. I would also highly recommend buying and piecing together a kit by buying used parts off the corral, craigslist, and ebay. You can easily get a better combo for the same price by doing it this way, even though it probably wouldn't be smog legal anymore, lol. A Supercharger can also be added and remain smog legal if you're looking for more power.
 
#8 ·
^ Agreed! I pieced mine together and used a TFS Stage II Cam and the Race intake mani with the 75mm opening.. ran freaking great! ... don't no about smog though...
 
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#9 ·
Well I can tell you that the track heat and the "R" series intake are not smog legal and their cams aren't also (though as I said before im running their stage 1 cam and so is my buddy and he passed smog fine). Plus the track heat intake changes your power band higher so if you are looking to use it on the street also the street heat intake will start your power band around 1500-2000 rpm. Which in my experience my car dosent see 7000 rpm on the street to often.


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#10 ·
People always think you loose low end grunt and all this and that when you go with to bigger heads, TB, Headers, Cam, yada yada.. I used this combo on the street just fine. I wish I was home and could post my dyno sheet, but my tq curve was pretty flat and right at around 3K it stayed pretty solid.. it had plenty of low end grunt and with the added benefit of not dieing off in the upper RPMs, "I shifted the car at 6800 at the track and still pulled hard up to that" If it won't pass smog then yeah don't do it. But the Race intake mani doesn't kill the streetability of the car, neither does the stage II cam.. And if I could do it again I would go with the TFS 190's...
 
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#11 ·
96paxtonstang said:
Well I can tell you that the track heat and the "R" series intake are not smog legal and their cams aren't also (though as I said before im running their stage 1 cam and so is my buddy and he passed smog fine). Plus the track heat intake changes your power band higher so if you are looking to use it on the street also the street heat intake will start your power band around 1500-2000 rpm. Which in my experience my car dosent see 7000 rpm on the street to often.


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Click to expand...
Well, I can't do all the research for the guy. BTW the street heat intake operating rpm is between idle-5500rpm where as the track heat is 1500-6500 rpm. I don't know about you but my car idles at 900rpm and with one tap of the throttle I'm at 1500rpm already so the street heat over the track heat is really pointless unless you have to pass smog unfortunately. OP, The smog **** will really limit what you can get for the car. Why do you want to have it smog legal? There are many ways to beat the system you know.
 
#12 ·
^ Good point.. The op being from CA I know they are crazy with emissions, hell even with how loud your pipes are... But back to the other debate, I would not waste my time with the street heat... I even skipped the Track heat and went to the race. I had great results.. AND the big and here "ROOM TO GROW" kinda important to me to have that.. Thats why I say I shoulda woulda coulda got the 190's... that would support a 347 just fine.. But its not my car any more lol.. I got the Notch now..
 
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#13 ·
Gregg@TrickFlow said:
Either intake will work very well for you. You will not lose as much bottom end grunt with the R-series as you think plus it will give you room to grow.
Click to expand...
Here is a quote Directly from the horses mouth that confirms what I have been saying....
 
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#15 ·
Strokerupper said:
New to the board, but I used to be very into the theory - even took a graduate level class on IC engine theory... However it's been some years.

I designed a cam for my 331 stroker (10.5:1) when I was into it, a lot of guys say it's a "blower cam" but I can tell you it runs excellent and sounds excellent N/A. The specs are .549/.549, 110/118, 138/138 (I think)

Before you worry about a cam, ask yourself what your end result is. ie. Drivability vs a little more power. I've heard that 114 lobe centers are as aggressive as you can go with a computer & F.I. but I can't say that's true or not. For a mild build, I'd consider the E,F,X,B cams. I hear the X is pretty driveable yet adds some performance. I remember .550 lift with 1.6 rockers is about as much as you want to go in lift for stockish motors (maybe clearance was the issue?). I did a bunch of flowbench testing and remember over .550" didn't really increase the flow that much on most heads, except AFR and a couple others. Therefore, the efforts to lift the valve are wasted energy. I do remember clearly that Vic Jr heads were the best "bang for the buck" for flow in my testing at the time. I got the BBK SSI intake, which is a good torquey 3 plenum (side-side-middle) intake which seems to work well for my cam. Look at the advertised power bands for the cams you consider with your intake, heads, and goals. Your duration is of course your lope, and at 138 my car runs like a carburated one when cold... jerky driving (the car, not me) under 1600 rpms. I would be selective certainly, research and read A LOT. Call the cam companies, they were happy to talk with me back when.

FYI, my setup put out 404 ft lbs and 345 HP at the wheels... but I run World heads, limiting my peak HP at 5600 RPMs. Also, the iron head doesn't give off heat as well limiting my ignition timing advance to 10 degrees. Sorry for the poor memory.
Click to expand...

Like this one :shiftyeyes
 
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