Whats it all mean???

[ironman_gq]

I am using a Clevite cam p/n 229-1786
Duration@.050 204 INT 214 EXH
Lobe spread 110 degree
Valve lift .449 INT .296 EXH
SAE Duration 280/289

What RPM range is this cam making the most power on a mild 304 with a 600cfm carb with stock heads/valves/ and compression ratio?

[jeepsr4ever]

Looks like a 3000rpm camshaft

[ironman_gq]

meaning that it peaks at 3000RPM or doesn't start making decent power till 3000RPM. I'm pretty happy with it it seems to pull well from 1500 on up but I'm thinking of building another motor and want to know what would be better for an all around trail rig.

[82Waggy]

You could look for a cam with a 112LSA to widen the torque curve. This along with a shorter SAE duration would give you better off idle response and better bottom end torque.

SAE duration is measured from .006 tappet lift.

A little more lift should help overall power figures as well. Is that 296exh valve lift correct?

[82Waggy]

Here's a cam that should offer an improvement in all aspects over the cam you are currently using.

Camshaft ,Engle 35018-H
Rocker Ratio,1.6
ILCL,109
LSA,112
Int. Duration @ .006,248
Exh. Duration @ .006,260
Int. Duration @ .050,207
Exh. Duration @ .050,216
Intake Valve Lift,466
Exhaust Valve Lift,496
Overlap,30
Hydraulic Intensity,41
Recommended RPM's,Off Idle - 4000

Hydraulic Intensity:

The ideal cam profile would raise the valves to full lift instantly, hold them open for a specified duration and then close them instantly. The laws of physics make it impossible to achieve instantaneous valve opening and closing, but recent advancements in design technology have made it possible to open and close the valves with more area under the lift curve. By so doing, engine efficiency is improved because the valves spend less time at very low lift.

Hydraulic Intensity may be computed by subtracting duration at .050" tappet lift from duration at .006" tappet lift. A lower number translates to more low end power, without any loss of top end power, and solves many complaints of poor idle quality. It also means it may be practical to install a cam with slightly longer duration at .050" cam lift than might otherwise be practical.

In practical terms, if two cams have the same duration at .050" lift, maximum torque and horsepower will be almost identical. However, the cam with the smaller Hydraulic Intensity figure will have a smoother idle, better off-idle response, superior low speed drive-ability, and a broader power curve.

---

If I have done the math right, your Clevite cam has an overlap of 61 degrees and a Hydraulic Intensity figure of 76, which is very high for a stock CR motor. It also has a very late intake closing point that is losing cylinder pressure and torque.

[hotratz]

^^ Now that's some informative stuff right there. =D>

[ironman_gq]

WOW!!! makes me wish I'd done more homework before I picked my cam. That 296 was Exh cam lift. valve lift is .473. where do I find this cam and how much is it? :t: Thanks for the info.

[82Waggy]

www.englecams.com

$134.00

[Goose]

I think I just found my next cam..!! :?
:sa: thanks Waggy

[AMX69PHATTY]

Is that the Clevite CAM 1980_CJ7 used in his 401 build
that hosed the pistons because the builder incorrectly installed
the cam gear on the oil passage instead of the keyway ?
The intake closing angle is early and increases dynamic CR ?

http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+Clevite+Cam+Info.jpg

[ironman_gq]

looks pretty similar but mine has a exh open of BBC 42 not 44. dont know how much difference this makes but the PN is the same.

[ironman_gq]

Do engle cams come as a kit or are lifters seperate. If seperate what lifters would be best? performance for the money wise.

[82Waggy]

Is that the Clevite CAM 1980_CJ7 used in his 401 build
that hosed the pistons because the builder incorrectly installed
the cam gear on the oil passage instead of the keyway ?
The intake closing angle is early and increases dynamic CR ?

At .006 tappet lift and 105 degrees intake lobe centerline:

Engle35018 Intake closes @ 49deg ABDC,

Clevite #1 Intake closes @ 61deg ABDC.

I think 1980_CJ7 was using clevite #2, which has an even later intake closing point.

Yes, the earlier the intake closing point, the higher the dynamic cr.

Be sure to match up intake lobe centerlines when comparing valve timing.

PS: BTW there is still plenty of flow through the valves at low rpm at less than .050 lift to lower dynamic CR. When considering bottom end performance (torque) I always look at the .006 figure, and use the .050 figure to get a feel for high rpm performance. The less duration at .006 with the most duration at .050 gets you closer to the best of both worlds (Called "Hydraulic Intensity" by Harvey Crane). The abilty to lower this difference is one of the great advantages of the AMC engine with its' large diameter lifters. Unfortunately, many flat tappet cams are just Cheby grinds in AMC clothing.

[82Waggy]

I also want to remind everybody, before I get flammed to death :(: , that when I open my big mouth with a cam recommendation it is based upon what the originator of the question says he has and what he wants to do with it. In this case I think the Engle 35018 will smoke that Clevite all around, but that is not to say that it is necessarily the best choice for every situation. #-o

[1980_Cj7]

Yep, we used the number 2 cam on that Clevite chart, part no. 229-1972. I think we're gonna stick with it and see what it will do when it is timed right. We got the Roll Master timing set this time, so we'll have plenty of adjustability. Gonna put a degree wheel on it this time and make sure it's right.

I sent all our specs to Keith Black, and one of their experts ran the numbers and said we should be OK with pump gas, but would most likely need to run 93 octane. (We're using their KB 354 pistons this time around, for anybody who hasn't been following the saga from hell, ha, ha.)

[AMX69PHATTY]

So like jeepsr4ever said, not making power until 3000 rpm right ?
A little "much" for his 304 motor on the low end ?

[1980_Cj7]

So like jeepsr4ever said, not making power until 3000 rpm right ?


Hard to say. Ours wasn't running long enuff for us to get the bugs worked out and get the carb tuned in and everything set up right. We were having a devil of a time with the ignition timing too as you can imagine what with the screwed up way the cam was installed.

Seemed to be OK on low end though. Tried power braking once and it would drive thru the rear brakes and pick the front end up and slide the front tires...even with the 1 ton brakes and hydroboost.

[82Waggy]

So like jeepsr4ever said, not making power until 3000 rpm right ?
A little "much" for his 304 motor on the low end ?

Well, I would expect the clevite to peak later in the rpm range with a lower overall torque figure. The originator of this thread said he did not feel like it started to pull until 1500 rpm. A cam with a wider LSA may not exhibit much of an actual peak as they tend to make a relatively flat torque curve and hang on longer in the rpm range.

donwags 401 showed only a 28ftlb variation from 2000-4400rpm on the dyno sheet using 256SAE intake duration and a 110 LSA (9:1cr). The curve with a 112LSA would likely be flatter still.

[dwg86]

I had reed cams grind me a cam for my 401. They have been around awhile and have experience with amc cams. I saw an oil article in a hotrod mag where they ground the cam for the build. Anyhow when I talked with them about lift/dur for an amc cam, the guy I talked to said that amc engine like a split lift/duration cam more lika a ford cam. He also stated that the lift on amc cams are higher as compared to a chevy cam. Also with the lifter dia. being big you can get get a little more aggressive with valve opening and closing. My cam specs where int/exh 228/232 dur @.050 lift 512/518 110 deg centerline with 3 degrees advance ground into the cam. www.reedcams.com . Just wanted to give another cam option/supplier. They will grind whatever you want.

[dwg86]

sorry for the typo OLD article

[ironman_gq]

The cam has reasonable low end power but it really doesn't come to life till after 1500RPM I kept thinking it was my carb tuning but after checking everything several times it just doesn't like to run smoothly below 1500 even my idle is pretty rough and I can't get my vacuum over 14in.

[82Waggy]

The cam has reasonable low end power but it really doesn't come to life till after 1500RPM I kept thinking it was my carb tuning but after checking everything several times it just doesn't like to run smoothly below 1500 even my idle is pretty rough and I can't get my vacuum over 14in.

The 35018H should straighten that out for you, but be sure you have no vacuum leaks - especially at the intake gaskets.

[ironman_gq]

pretty sure its not a vacuum leak I checked multiple times