Another Cam Question

I would ditch the 1.7 and use the X cam with 1.6 rockers. I have run an F w/1.7 rockers making .546 with stock heads and gotten away with it, I am not sure how much bigger your AFR valves are. Any plans for a power adder?

why not custom?? for the extra 150 dollars u can insure no ptv issues and you will be about to get the idle you want all while making the most power possible from your combo.... well worth it I would say..

Torked,

A custom camshaft is always the better way to go, but it cost a little bit more than a typical camshaft. But you get something for that extra $.

- Better driveability
- More power
- More manifold vacuum
- You will get the sound as well, it is just part of it
- Professional assistance

www.flowtechinduction.com

Ed Curtis @ edcurtisFTI@verizon.net

I have done business with the above a couple times with good service and parts. He sells your AFR's as well.

http://www.wighat.com/fcr3/camtruth.htm

Buddy Rawls contact is rawls1103@aol.com

Now, remember that lift is not a factor of piston to valve clearance. It is the period of overlap that causes piston to valve clearance.

The period of overlap is when both valves are open at the same time when the piston is at the top of the cylinder bore. The exhaust valve is closing and the intake valve is opening.

When a valve is at peak lift, the piston is well down into the cylinder bore.

Also, LSA (lobe seperation angle) is not set in stone from camshaft to camshaft. LSA is figured out by the individual timing events that can vary from camshaft to camshaft.

Two camshafts can have 112 LSA, but have different individual opening and closing events.

Let us take two common camshafts with the same advertised LSA.

B-303 Camshaft

224*/224* 284*/284* - .480"/.480" - .300"/.300" - 112* LSA - 107* ATDC /117* BTDC - 3,300-5,100 RPM
Overlap: 60 degrees.
1.6 Rocker Ratio
Intake Opening: 5* BTDC
Intake Closing: 39* ABDC
Exhaust Opening: 49* BBDC
Exhaust Closing: 5* BTDC

and...

Trickflow Stage 1 - 221*/225* - 275*/279* - .499"/.510" - .312"/.319" - 112* LSA - 108*/116* - 2,000-5,500 RPM
Overlap: 53 degrees.
1.6 Rocker Ratio
Intake Opening: 3* BTDC
Intake Closing: 38* ABDC
Exhaust Opening: 49* BBDC
Exhaust Closing: 4* BTDC

Do you see how the TIMING EVENTS are different between camshafts, although they have the same LSA.

So take the B-303 opening and closing events for the intake and exhaust:

Intake Opening/Closing - 5+39 = 44. 44+180 = 224* Duration.
Exhaust Opening/Closing - 49-5 = 44. 44+180 = 224* Duration.

224 is the answer on the intake and exhaust. If you look, this makes up the DURATION at .050", since the timing events were taken at .050".

So to find LSA divide the durations by 2 and average them.

Intake: 224/2 = 112
Exhaust: 224/2 = 112

Average: 112 + 112 = 224/2 = 112 LSA

As another example, you can look at the Trickflow Stage 1 opening and closing events.

Intake Opening/Closing - 3+38 = 41. 41 + 180 = 221* Duration.
Exhaust Opening/Closing - 49-4 = 45. 45 + 180 = 225* Duration.

Good Luck

Does the duration chage when bigger RR's are put on?

Duration at the lobe lift (cam) does not change, because the camshaft is, what it is. It does not effect valve events or ramp rate at the camshaft either.

But, say you are at 100* of a 224* duration, and you have 1.6 roller rockers, and then you add 1.7 roller rockers. At that very duration point, the valve will be open further, thus making the cam to potentially act bigger.

The increased ratio does speed up the valve opening and closing events.

Larger roller rockers do not just increase peak lift.

From the very moment the valve lifts to the very moment it closes will not change, but when you start getting some lift, the duration starts to increase at very small rates.

I would not buy a roller rocker to get more duration, so just get the right camshaft to begin with

Atleast, this is my basic understanding of it...

To add to what was said above, which is great info, check out this link. I read this thread three times before it started to click. I have it book marked, because I am a nerd.

LSA isn't the whole story when it comes to having a meaty idle. Heck you could tune one in, I did this on the stock cam as an exercise when I was learning the TwEECer.

http://bbs.hardcore50.com/vbulletin/showthread.php?t=40629

Adam

i'm a big fan of the comp xtreme energy cams. all the feedback i hear about them is very positive. you can go as high as the xe-262-hr without piston to valve clearance issues; i think the ex-274-hr will fit too, but i have not seen definitive info about that. i think they run about $250 or so

T0rk3d said:

Thanks for all the info guys. Cams are like another language to me at the moment. I would like to run a power adder, but at this time since im still waiting on my real job to become open and im going to college this is just my have fun not too crazy daily driver. I have thought about going custom cam, thats probably whats going to happen considering my lack of knowledge in that area.

Click to expand...

Hey ... don't feel like you are all alone on understanding cams and all that
goes with them

I do feel I got a good bit of general knowledge when it comes to modding
sbf's but most of my experience was back in the 60's and 70's.

When I got back in this hobby things had changed so much with the long
runner intakes, roller cams, and the like

A thought or two for you on my experience with a Custom Guy

I went with a hired gun to kill my cam concerns for several reasons
but
Proven successful results was the main reason

You can tap into that fellows knowledge database
and
Not have concerns about your lack of knowledge in that area :Word:

Those guys have the ability to listen to what you want and based upon
what you tell them ... they basically will tell you three things

1) You need a cam with such and such specs
2) You will need these specific parts to go along with that cam
3) Expect your Stang to behave like this

Here is where most peeps don't understand a benefit of this method

You tell the guy what you ... THINK ... you want at the time

When you get the ... STRAIGHT SCOOP ... form him

You may find what it takes to make that happen
is not what you can deal with

Quick Example

You tell him you want 400rwhp NA using your OEM block

He comes back and tells you .....

It will need to idle at 1000 to 1200 rpm
It will have a very soft low end
and
To counter act that soft low end ... you'll need 410's or better yet 430's
You'll need big headers ... something like Kooks, etc
It will not have drivability anywhere close to a stocker
etc etc etc

After hearing all that

You QUICKLY realize ........
Your lowered dd Stang ain't gonna be practical for a combo that radical

The outcome and benefit of all that is

You amend your first plan to one that is more practical for your dd
AND
You can be confident that he is guiding you with accurate experience :Word:

My reason for not going straight there, is that I was not even planning on buying this expensive of a head combo but the deal was great so I jumped on it. Problem is that im already way over budget and I was hoping for a off the shelf cam to suit me well and save me 150$. I also already feel weird not rebuilding my engine and strange not putting new cam bearings in with a $160 cam. I think it would be risky doing it with a $325 dollar cam. Or am I wrong? The car has 117k

Click to expand...

My young friend ... Your thinking is slightly flawed here :Word:

What you DON'T have here is ........... a problem
What you DO have here is ............... an opportunity

You now have heads in the best category
as opposed
To heads that would be considered to be in the good category

Another thing you have going for you is .........
Great heads but at a price you can most likely get your money back out of

I know you are college bound and money it tight

Just relax and save up a bit more
and
Make a plan that is worthy of those quality heads :Word:

I assure you ... It will all be worth the wait to do it right

If i dont decide to go custom, what are the typical guidelines for as far as max lift max duration. Like is only 500 lift with 220 duration the max or is 530 with 218 usually safe? That kind of thing.

Click to expand...

You should be able to find an ots cam that will work pretty good

Look at some of my old posts to see what others have done with those
heads and using an ots cam :Word:

Just remember this ..............

If you change your mind after doing an ots cam ...............

You gotta do gaskets, oil/filter, coolant, and all that work ... TWICE
and
If you don't do your own work ....
you gotta pay for the labor all over again as well

I've said more than enough for now but if you have any more Q's .......
I'll try to help ... if I can

Grady

Torked - Since money is tight, be patient College comes first, play comes second...

Remember, lift is not a factor for piston to valve clearance, but it can be one of the factors that causes valve float (lose control of the valve) and coil bind (the spring becomes full compressed and can break).

Duration is a bit more accurate in terms of piston to valve clearance, but not all of it. There is many combinations of opening and closing points that can determine how long a valve is open, which is duration.

Do not worry about cam bearings, many do the swap with 150k plus with the stock cam bearings. I swapped mine at 142k and I used that combination until 162k, and daily drover with no end in sight...

The trickflow stage 1 camshaft is a great budget camshaft for the foxbodies. The sn-95 computer (94-95 cars) have a pickier computer so I am not sure how the valve events with respond to the computer's wants. This is something that hopefully someone can help you with that is running the Trickflow Stage 1 camshaft.

You have great heads, and a good intake.

If you can swing for a custom camshaft, you need to be thinking that you will need a spring upgrade and they are incredibly well engineered and need some better engineered parts.

If money is tight, I would not worry about it. Just keep hitting the books...

Therefore, it will lend you better opportunities in the future to get 1, 2, or even 3 custom camshafts, for the many vehicles you may own

Adam - Good post, I have not read over that in a while, so it was good to get a refresher