CamaroZ_85

i have an comp xtreme energy cam 218/224 .462/.469 110 lsa and the low end leaves a little to be desired. im sure that's due to my stock converter and 3.08 gears but i wont be able to do anything to my car till the spring/summer to fix that. once i hit about 3500 though it starts to pull like hell. anyway, i wanted to know what the numbers tell you about the rpm range of a cam...

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

RB83L69

There's not a direct correspondence of any sort, that is, like x degrees of duration + y degrees of lose sep = z RPM. Each engine/chassis/induction/exhaust/gear/trans/converter/driver/altitude/gasoline/etc. combo is different, so the best you can hope for is a halfway close estimate.

That is actually a reasonable cam, maybe even a bit mild, for a carbed 350. It should produce peak torque at around 3600-3800, with peak HP at about 5300. The torque should increase linearly from about 2400 to about 3500, level off, and start to fall off fast at about 4500 to 4700.

A converter would make a world of difference by allowing the motor to get up into its power band (2400 RPM) as soon as you hit the gas, instead of being pinned into a range (1600 RPM) where it has no power. Think of it this way: each cylinder firing can produce only so much "push"; beyond a certain point, i.e. 100% fill with clean A/F mixture, you won't get any more "push" out of each firing. Adding more cam reduces from that 100% by allowing some of the pressure to escape, as well as by diluting the intake charge with exhaust because the cam opens so soon that there is still exhaust pressure within the cylinder when it opens which allows some of the exhaust back into the intake. To get more, you have to fire each cylinder more times, which is another way of saying more RPM, which is another way of saying more converter and/or gear.

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"So many Mustangs, so little time..."

mtx28

also, a quick way to get an idea of where your cam is strongest, pull out your summit/jegs magazine real quick and take a look, or just go to the manufact. web site

JakeJr

The cam you've chosen is an excellent profile and should perform exceedingly well.

Did you degree in the cam? If so, where did you set it.

Advancing the cam 4 degrees will really sharpen the bottom end response, improve idle and give you slightly higher idle vaccum. Throttle tip in response will be sharper, too.

I just moved my ZZ9 a couple of days ago and am more than satisfied with the results. I'd originally degreed it in 2 degrees (114) retarded based on Engine Analyzer Pro simulation results and the recommendations from a couple of magazine tech articles.

I moved it six degrees so that it's now 4 degrees advanced, (108) and man what a difference. I'm a happy camper now.

I've lost count on how many camshafts I've installed and re-degreed at a later date trying to get it dialed in to where I like. It involved a little bit of work, but the end result is well worth it.

Take your portable stereo into the garage; tune in your favorite station and have at it.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited November 14, 2000).]

Blade

How do you advance or retard the timing ? You have to have some sort of special cam sproket right ? I just can't see how it's possible with the stock sproket since it only goes in one way. If it does require a special one do they make em for newer 87-up roller cams/blocks ? Thanx

JJ

I installed nearly the same cam, just a little bigger XE 268 (224/230 and 110ls). I just installed it straight up since I'm not sure about degreeing (I hope that's a word) a cam. I've seen the kits in JEG's and such and figured I may mess with it this winter when I have 2.02/1.6 valves put in my vortec heads. The car's bottom end is not what I expected, but it sure does pull from 3000rpm on up (I've only took it up to around 5200 so far), pretty darn rough idle too. Sounds like degreeing the cam may be something I should check into.

CamaroZ_85

i installed mine straight up too...(aligned the dots on the 2 sprockets) although i didnt degree it. I didnt want to advance or retard it any because i dont want to worry about putting the valves into the pistons. i guess i should rip it apart in the spring and advance it a little...i just would like to know how to make sure im not gonna get valve/piston interference...i really dont want to pull the heads and check it with clay, is there another way?

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

md

You would be doing yourself a favor by paying attention to Jake. He's a sharp fella.

To degree a cam is to set the valve event timing in relation to where the piston is in it's stroke. Another term for it is cam "phasing".

By aligning the "dots", you are assuming that the timing set is perfect from the factory. This is rarely the case. I've personally seen them as far as 3* crank rotation out. I ALWAYS degree a cam in anymore.

I'll give you a brief description of the process. By degreeing a cam, you are using a degreed wheel that is attached to the crank, a dial indicator, and a pointer. The cam gear alignment pin hole is drilled out and an "off-set" bushing is used to position the gear where needed. You use the dial indicator to find exact piston TDC. Then you align the pointer (by bending it) to the zero degree position on the wheel. Then you move the indicator to the # one intake lifter and find the cam's base circle. Then rotate the engine until the dial reads .050". Compare the reading on the wheel to your cam card. It will have @ .050" duration on it. It's then a matter of simple addition and subtraction to verify the cam's position. You use the "off-set" bushing to set the cam exactly where it should be. You can also do this with the heads on, just a different method. There are many degreeing kits available. They will come with everything you need and instructions. Well worth the money.

To retard or advance the cam, you are moving the valve events in relation to the piston position. This is again done by using the degree wheel, off-set bushings and/or moving the crank gear (some sets a crank gear with multiple keyways).

Mike

Biochem

I have that same cam and I put it in straight up too. It was right on from the factory also. As well, I don't get moving until about 2300-5500, then it falls flat and I shift around 6000. Maybe too high. I have Edelbrock heads and a 2800 stall convertor, so I really like this cam. The low end power (if you call it that) is real nice for good launches...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock... all the suspension stuff... 9-bolt posi disk is in... K&N filter... 93 octane...

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