cam question (duration and lift)

[D.W]

Hello newbie here . I have a question on cam lift and duration I am having trouble with.I am in the collecting process of building my stroker 400.let me list what I have and maby it will helpwith the question I have.
1-400 block
going with a good forged pistion shooting for 10 to 1 comp
440 rods and crank
intake is a torquer may be changed
906 heads ported mildely with 2.14 and 1.81
750 holly dp mechanical
727 cheeta rev v- body
8 3/4 -410 sg
time to pick a cam.I am looking at several grinds but am confused.I see some grinds with 2 diff lifts and durations intake and exaust.then some are the same intake and exaust.I have been told that the grinds with more exaust lift are better cause they get more of the trash out ,then I am told that they loose compression and that one with equil lift is better. Is this merely a preference thing or is one really better? Hope this question isnt too stupid but it is my first build and I am learning as I go.

thanks

[zij576ca]

Welcome to Moparchat, D.W.

I know there are members who will disagree with me, but here are a couple of choices for you. The 292 degree/.509 lift Mopar Performance cam is a good one. There are 2 cams (diferent part #'s) with this same lift/duration, though. Difference is one is ground on a 108 degree center line (lobe separation); the other on a 114 degree center line. If you are going to do more street driving than drag racing go with the 114 C/L cam; more drag racing than street, go with the 108 C/L cam. Another good choice for a street cam is the original Purple Shaft 284 degree duration .474 lift cam from years back.

Again some members may disagree, but the Torquer (original, not the newer Torquer II) is still a good intake for the street.

You will also need a torque converter that will work with your cam and intake/carb selection for your intended use of the car.

[MOPARMANJAMES]

I'm guessing that this will be a street/strip car so you'll want something a bit drivable.
It's true that if you have more exhaust duration, more exhaust should escape at a given rpm, but as you stated, this is usually accomplished by opening the exhaust valve earlier, thus reducing the cylinder pressure at that time.
If you open the exhaust valve later, and keep the same duration, then you increase overlap, not good either for a street machine.
Mopar Big Block heads flow reasonably well on the exhaust side, especially with porting as long as you don't mess with the short side radius, unless you build it up.

For example I loaded your combo on my Engine Analyzer program and used a elgin hydraulic that is .510" lift 244@.050" and 108 lsa single pattern, 5degrees advanced from the manufacturer.
Peak torque was 505@4500, HP was 505@5750.
I then added 10 degrees of duration to the exhaust and .015 extra lift.
Peak torque was 498@4500, HP was 506@5750.
Torque was down until around 5500 when it exceeded the previous grind briefly.
I then ran a cam that was 234@.050 and .480" lift, 108 lsa staight up.
Peak torque was 513@4500, HP was 493@5750.
I then added 10 degrees of duration to the exhaust and .03 extra lift.
Peak torque was 507@4500, HP was 499@5750.
I then moved the exhaust lobe centerline to 112 for a LSA of 110
Peak torque was 507@4500, HP was 496@5750.
Bottom end torque on the my graph was up but after 3500, it evened out a bit.
Have I confused you enough? If not, you can see that the single pattern is the way to go if you have decent exhaust flow.
Get a simulation program and start testing, it'll save you money in the longrun.

[MOPARMANJAMES]

Originally Posted by zij576ca

Welcome to Moparchat, D.W.

I know there are members who will disagree with me, but here are a couple of choices for you. The 292 degree/.509 lift Mopar Performance cam is a good one.... Another good choice for a street cam is the original Purple Shaft 284 degree duration .474 lift cam from years back.
Again some members may disagree, but the Torquer (original, not the newer Torquer II) is still a good intake for the street.
You will also need a torque converter that will work with your cam and intake/carb selection for your intended use of the car.

All excellent choices, I for one agree since I run a cheap copy of the .509 in my car, I just had it weighed again(the first scale was off 200#!, rock scale)
and it's 3700 with me in it, I have a 440 10:1, 3500 stall, 727, 3.23 gears and have run a best of 12.45 here in Las Vegas at 2100ft., 90 degree weather, 35% humidity.
I'd like to make it to a sea level track and see what it'll do!

[Chucksdart]

Good information all. What is a good , resonably priced simulation program? And where to buy it? Thanks

[quietdad]

Call Racer Brown , tell him what you want and let him grind a cam just for you. It's the usual "reply" to a "What cam" question here and for a good reason. I have one of his cams in my 383 and I'll never get a cam again anywhere else.

From the ultimate phone book......
Company: Racer Brown
Contact: Jim Doyle
Phone Number: 410-866-7660
Email: None
Web Site: OLYP
Specialty: Custom Cam Grinding
Location: Baltimore Maryland

[zij576ca]

Originally Posted by Chucksdart

Good information all. What is a good , resonably priced simulation program? And where to buy it? Thanks

I use both the Dyno2000 & Drag2000 programs. Got them from Summit for $40 apeace. The programs are older versions but way cheaper in cost than a current version; fine for my purposes. Their web site: http://www.motionsoftware.com/products.htm

[zij576ca]

Originally Posted by MOPARMANJAMES

...and it's 3700 with me in it, I have a 440 10:1, 3500 stall, 727, 3.23 gears and have run a best of 12.45 here in Las Vegas at 2100ft., 90 degree weather, 35% humidity. I'd like to make it to a sea level track and see what it'll do!

I have pretty much the same combination as you do - 3600-3700 lb RR. I'm running 4.88 gears though (want to switch to 4.30's) and 29.5 tall slicks. Here in San Diego I ran in the low 12's before the engine went bye, bye. Now though, new engine and no 1/4 track - 1/8 mile only. I have no idea what I'll run with the new combo; hoping for 12.0's but we will see

[MOPARMANJAMES]

I too am going through my engine right now, but it's because I had bad ring seal problems. I'm going for a rehone, putting 2.14/1.81 valves in, 1.6 ratio rockers, and that's about it. I also hope to get 12.0's since I am running in street class and that's all they allow!.
Good Luck zij!

[rumblefish360]

then I am told that they loose compression and that one with equil lift is better

Bullshit, No, I'm sorry, I ment to say BULLSHIT!!!!!!!
Build a 451 just like a 440. There close enuff to be built the same. But the big thing between them is the lighter rotating assembly/ It'll rev faster, make more power, and be easier on parts.
The intake selection on big blocks is very wide. The best part here is they all make the close to the same power. MoPar Muscle did a intake shoot out a few years back for the big block. Everybodys stuff did really nice.
This is an area where I give up on advice and send you to a place that excells in this area. Go click a link.
http://hughesengines.com/

[D.W]

thanks for the replies guys! ok left out the converter I have a 3500 stall to add to the parts list . Now the intended use of the car is mostely street and some strip . I'm leaning on a hyd for the ease of maintance ,but will not rule out solid or roller just yet as this is a area im open to all suggestions . thanks for the links as I will check them out . Also I had a dyno program I got from a friend but somehow it got erased off the dang puter , so guess i'll break down and buy the program .

I have pretty much the same combination as you do - 3600-3700 lb RR. I'm running 4.88 gears though (want to switch to 4.30's) and 29.5 tall slicks. Here in San Diego I ran in the low 12's before the engine went bye, bye. Now though, new engine and no 1/4 track - 1/8 mile only. I have no idea what I'll run with the new combo; hoping for 12.0's but we will see

If I can getlow 12's with my build I will be veeeeeery happy!!!!!

THANKS TO ALL

[MOPARMANJAMES]

[QUOTE=rumblefish360]Bullshit, No, I'm sorry, I ment to say BULLSHIT!!!!!!!

Wow, I'm not sure why you are calling B.S.
Is it because you don't think a split pattern cam, usually longer duation on the exhaust side, can lose torque over a single pattern cam?
I think the two key elements when it comes to this portion of building cylinder pressure are, 1:When the intake closes, 2: When the exhaust valve opens.
I too am seeking more clarification but rather than just talk to Cam and Head manufacturers Like Harold that used to be at Ultradyne and Ken Brownfield at AFR (formerly Brownfield heads) and Racers and Crewchiefs like Don Garlits and Austin Coil, countless other Stock and Superstock folks, I decided to by the best Engine Dyno simulator that I could get for what I consider to be a reasonable amount, $500.
That's why I bought Engine Analyzer Pro, to save time and money on Dyno time(which Iv'e never had yet) and wondering which parts will make the most torque at a given RPM range.
On your point about the 451, I agree 100%. I was just telling zij576ca about my cheap combo in my car.
One thing I forgot to add, if you are calling B.S. on the amount of lift, as in more is not as good as less, then I agree. More lift is good, but not necessarily at the expense of more duration.

[rumblefish360]

Simple, it's all in the timing events. To have a cam that will lose comp. on an engine .... Come on. Knowing that, would select that cam?
He buddy, I have a cam for you! It'll drop your comp. ratio at least a point so you can loose power and run crap gas.
I do know that some cams are designed this way and even off the shelf comp - crane etc... cams will do this. However, to compare a split durtaion cam to a single pattern cam and come out to say the split will loose comp. when compared to a single pattern cam is just a horses A$$ talking.
Cams are comp dependent. Also application dependent. No one type of cam can be better than another cam. A split duration cam is better in general, but thats not the end all.
Talk about hitting the nail on the head;

I think the two key elements when it comes to this portion of building cylinder pressure are, 1:When the intake closes, 2: When the exhaust valve opens.

Bingo, winner, slam-a-lama, DING DONG!!! Bullseye. Hole in one! ETC....

One thing I forgot to add, if you are calling B.S. on the amount of lift, as in more is not as good as less, then I agree. More lift is good, but not necessarily at the expense of more duration.

More lift the merry to the point of;
1; Loss of power
2; When the head port flow stalls which will bring you right back to #1 above.

When ever someone asks me for a cam, and they really have only a idea range of no clue to somewhat of an idea, I'll explain to them a little about single and dual pattern cams. I won't go into detail about it to them or here. It's just to lengthy to get into theroy and actual practice and why and what nots. The damn subject is like almost never ending. So I result to the KISS method.
Keep It Simple Silly
Split pattern or single pattern cams, which is better and why could take a huge page without getting crazy on details.
No matter what you do, no matter what you get, no matter the maker, theres allways someone on the side with 2 cents more than you can take of there opinion.
The idea of a home computer program is GREAT! A great tool to help you understand the casue and effect. Though, they should allways be taken with a grain of salt, there good enuff to aid in selection. No doubt about it.
Even a cheap version like desk top dyno is very good to help.
Last note on cams;
Bigger the cam, the more pressure it will bleed of at low rpm's non a N/A engine. Tighten up the centerline (ex; 106) for more overlap, more bleeds out. Radical idle appears. Lower vaccum happens. But on the other end, power comes in a tad sooner and theres more power with a tighter centerline cam. Power (HP) also tends to appear as a steeper peak as compared to a exact same cam only ground on a 112. That power line would look less like Mt. Everest.
P.S. MOPARMANJAMES, good luck with your engine. Hope all works out nicely.

[zij576ca]

Originally Posted by MOPARMANJAMES

the best Engine Dyno simulator that I could get for what I consider to be a reasonable amount, $500.

The best dyno in the world is a strip of asphalt 1/4 mile long.....
with timing system attached, of course.

[bigiron]

I don't mean to step on anyones ideas here but...

I have a split duration and split lift cam in my, as you call them, Ferd 331 stroker. Why??? Because I talked to 3 different cam grinders and for my appication they were basicly all in aggreement.

I believe I will be going to a split duration single lift profile in my HEMI. Why??? Because I talked to 3 different cam grinders and they aggreed that it was best for my application.

I run a single profile in the Dart and the GTX. Why??? Because I talked to 3 different cam grinders and they aggreed that it was the best for my application.

Do you see a pattern here???

These guys love to talk about their wares.. and they seem to know what they are talking about. They go on and on about cylinder pressure and geometry and alot of stuff I know nothing about.... But what is nice is, I don't have to. It's their job... they will explane everything to the point of your understanding and then some.

I learn something new everytime I call.

Alot has changed since I quit building engines back in the early 80s, alot has not... The best way to stay up on all the new stuff is to talk to the people that know this stuff.

Another one, pistons... call JE and Ross... man... you can't get them off the phone... I learned more in 45 minutes than I could with 10 hours of reading... Interesting people...

I'll shut up for now but that's what I do....

[MOPARMANJAMES]

Originally Posted by rumblefish360

"...However, to compare a split durtaion cam to a single pattern cam and come out to say the split will loose comp. when compared to a single pattern cam is just a horses A$$ talking.
Cams are comp dependent. Also application dependent. No one type of cam can be better than another cam. A split duration cam is better in general, but thats not the end all....".

That's the point, in his application which is compression and application dependant, the single pattern cam seemed to work better, given my limited test conditions. I did add 10 degrees duration to the exhaust though, perhaps a little less like 5 or 6 would have been closer to a hughes grind.
I understand that if everyone had their heads flowed then an optimum cam could be custom made. I just want the closest I can get to that for around $50.

Originally Posted by rumblefish360

"Last note on cams;
Bigger the cam, the more pressure it will bleed of at low rpm's non a N/A engine. Tighten up the centerline (ex; 106) for more overlap, more bleeds out. Radical idle appears. Lower vaccum happens. But on the other end, power comes in a tad sooner and theres more power with a tighter centerline cam. Power (HP) also tends to appear as a steeper peak as compared to a exact same cam only ground on a 112. That power line would look less like Mt. Everest."

I agree, this is due to the earlier closing of the intake valve on the tighter lobe separation cam (106). The power comes on quickly and then dissipates
sooner than the flatter (112) torque curve.
Thanks Rumblefish for the well wishes!

[rumblefish360]

MOPARMANJAMES;

That's the point, in his application which is compression and application dependant, the single pattern cam seemed to work better,

I can believe that in a snap. It is true that sometimes a single pattern cam works well. Key here is good exhaust flow to intake balance.
Awhile back, a good fella here was asking why a split pattern cam couldn't have another 5 or 10 degrees added to the exhaust for even more exhaust gas to escape.
I keep saying that a good thing can be pushed to far. Sometimes a split cam in a certain engine is good with a division of 4-6 degrees difference is all you need. He was saying add another 10. If 4 or 6 was good, 14 or 16 would be better.
I couldn't find the words of how to much can be bad. The bigger isn't allways better thing didn't stick.

bigironSide step?!?!? Crap, jump right in. Your self and quietdad give the best and easiest method.
CALL A PRO!
D.W, take note.
Also, I see this from James and say it to alot of people here;

Get a simulation program and start testing, it'll save you money in the longrun.

It's not a end all but it can help a bunch on the next part you intend to change. Unless you like doing things the ol'fashion way. Take a guess and swap out the cam and spend a day at the track testing and tuning.

[D.W]

Notes are taken lol. Thanks for all the posts ! I think I will give a few calls to different manufacturers . I really appreciate all of your thoughts and views.
Guess now I realize I have ALOT to learn on cams !!!!

[Crank]

i think the main problem is scavaging too much duation would pull gas and exhaust out ,and not enough won't draw in to it's full potential.their are to many factors to consider like valve size and type of valve ,ports polished or blended ,intakes single or duel plane .rpm range gear ratio's tire size .how much tork at low rpm's to move all this weight.compresion, it's vary difficult to choose the right cam call around like racer brown or Scotty Brown at straight line performance.