Hey guys i want to start a thread where we can all input our 2 cents on camshafts; what works for you and what application its intended for..i also would like to know, as i am about to have the machine shop install one for me..

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1970 Dart Swinger Matching Numbers..

I think Ceej as putting together scans of cam sheets for a data page about this.

The problem of posting like this is you are going to get a wide variation of cam grinds and opinions on why they worked better...in some cases some people are choosing their grind for a particular combination of parts and purpose that would not be suitable for anything anybody else would use it for (i.e. top end cam. or turbo only cam, hyperpak only cam).

What may work in one instance may fall flat on it's face if the end user changes something about the build (i.e. torque low end grunt of the hyoer pak motor vs. the shorty Offy being used instead).

Also I have run into a number of machinists that refuse to install a regrind because they feel they are done on old worn out blanks, or have had a bad experience with them in "other brand" engines, in which case the member may need to find another machinist to install the cam they want, or be limited by the assembler's choices...

-D.idiot

thats exactly what im shooting for a thread with various grinds and such so a person like myself can have some refrence and have an idea of what particular cam can work not to exactly copy but to just get some reference. like example i would like a cam with nice valve lift but in the future i would also like to use forced induction will that cam work why or why not? the more variations the better cam specs without examples are very hard to understand for a guy who is just getting into this.. ...

Jose
..Excited,confused slant owner!!! lol

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1970 Dart Swinger Matching Numbers..

The cam cards thread is made up of user submitted profiles. As D.I. mentioned, the cam may be suitable for one application, and totally wrong for another.

Look in the "Engine" main area. You will find a sticky near the top of the list of threads, "Frequently asked questions (FAQ)- Engine."

Looking at numbers can be very misleading. Bigger numbers don't always equate to more power. Some of those big gnarly cams don't make power at useable engine speeds. If it starts making power at 5000 rpm at flow rates a slant six head/intake/exhaust can't support, it's will be completely useless.

There are several threads that start with the word "Cam" in the FAQ. Using the Engine Build Matrix (Linked from the FAQ), you can see where various cams have been used. Most of the builds in the Matrix are for Drag Racing. There are some exceptions, so make sure to look them all over and understand how the car is set up, and for what purpose.

To determine what cam would give you the performance you want, you need to honestly identify what you want to do with the car. The cam needs to match your build, perfectly.

2¢

CJ

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Part of Tyrde-Browne Racing

There is not a one size fits all, forced induction guys are having best success with an almost stock grind because the blow dryer is doing all the work of filling the cylinder. The same cam on an NA car would probably be best matched to a stock 1 barrel car, or a super six car.

There are a number of cam books out there that you can read and get a theorhetical idea of what effects changes can have: narrow vs. tight LSA, more or less duration, advancing the cam vs. retarding it...

It is very tough to specifically know what is going to happen unless you've done a lot of 'building' (for self or others).

A nice lift can mean things to different people...
NA vs. boost are two completely differing disciplines, with boost the hair dryer is increasing the volumetric efficiency of the engine by forcing the fuel air charge into the cylinder. With NA the intake is lazy relying on rpm/atmospheric pressure/intake style/the cam overlap event to help pull the intake charge into the cylinder before the exhaust valve closes, and your exhaust system-headers promote scavenging where as a normal exhaust manifold may not...

If you have to break it down for the noob, NA slant six building has a couple of common paths to follow:
1) Low compression, RV or short duration cam- short overlap event allows cylinder to build pressure sooner, has good idle and you get good lower rpm driveability and torque.
2) High Compression, long duration cam - long overlap event allows both valves to remain open longer to promote scavenging (if using headers), but also are open longer causing cylinder pressure to bleed down allowing the end user to be able to run pump gas...the end result is a car that can be used on the street, but has more performance potential at the higher non-street rpm ranges.


I would recommend a book that Hot Rod put out that combined all the articles they ever had written about cam theory, what happens if we change these variables...although written with the other brand V-8 in mind, the changes to cam characteristics are uniform for all engines, but some engines like certain things than others, so what may work for a Chevy 327 may not be 100% true for the small bore long stroke 6 cylinder.

"High Performance Camshafts" by R.M. Clarke, amazon has used copies at about $10+shipping is worth the $10.

-D.Idiot

sweet.. that's exactly what i was looking for..ill go to amazon and get that book asap!!lol

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1970 Dart Swinger Matching Numbers..

I really like mine, but I'm wishing I had gone a little bit smaller.

If this had been for a light car, I would just LOVE it.



It's from Oregon Cams... Has a slightly larger intake than exhaust.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

Good cam selection is closely linked to DCR numbers.

Start by understanding Dynamic Compression Ratio (DCR) and how it is calculated, then give us the DCR info for your build.
Also give us your intended RPM ranges. (idle, max torque & redline RPMs )
There is way more to cam selection then the "numbers on a page" info. you often get.
DD

What Doc said x 2.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

well i called the guys at Oregon ..super awesome folks..helped me out with my cam selection..im just a bit confused with the part if i get to much of a high lift or duration (radical) when will it be too much that i cant get forced induction? if keeping almost everything stock no head shaving just stock head backcut valves (25degree) and a slight bore out of .040 over

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1970 Dart Swinger Matching Numbers..

You will need to see what others have done and compare their overlap event, forced induction likes a narrow window so you don't blow the air/fuel out the exhaust pipe.

-D.Idiot

with the DCR can i determine that with the bore size and stroke length?

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1970 Dart Swinger Matching Numbers..

No that is Static Compression Ratio SCR.
Dynamic Compression Ratio(DCR) is calculated from the SCR and inlet valve closing point, as well as rod ratio.
Here is a SCR and DCR calculator to play with.
8:1 DCR will allow you to use any fuel ,generally.
http://www.kb-silvolite.com/calc.php?action=comp

Brendan.

PS.
Here are some numbers for a stock slant to save you hunting the info.

Cylinder head volume(varies ) usually between 54-60 cc
Piston head volume ,flat top = 0cc
Gasket thickness .035"- .045"
Gasket bore (my felpro = 3.525')
Cylinder bore (stock )3.4"
Deck clearance varies from about .200" to .100"
Stroke 4.125"
Rod length 6.7" or 7.005" for the 198ci rods

Have fun with that .

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1963 AP5 Valiant 225 PB 904 Stock except extractors & 2 1/4 inch exhaust.


1962 S series valiant 225 PB auto. factory every thing. Full restoration job.
Currently on hold till AP5 is on the road.

By far... the hardest number to get is the Intake Valve closing point. (IC)
There are a few ways to estimate the IC but for me, I always do a trial assembly, using the actual cam, then do a final adjustment of the SCR, to get the target DCR.
DD