Trying to figure out the validity of wat the previous owner told me about the engine, without tearing it apart. He said it has a 284H cam from comp cams. Its supposed to e 284 duration. One hell of a big cam. The car has lots of power, so it might be true, but it sure as hell doesnt sound like such an agressive grind. Sounds very nice, each power stroke sounds good and constant. Not choppy like a mean cam.

If your running this cam, plz post some of you car's behaviour, along with your location, or height to sea level.

Trying to figure out vacuum readings, idle setting, idle rpms, stuff like that. A sound clip would be perfect! thanks in advance, any help appreciated.

 

if you had that cam you would know

 

yea thats real helpful, anyone else? i dint build the engine.

 

okay, well i will tell you what everyone else will tell you... the only way to KNOW is to take it out and have a look besides that if you want to believe you have that cam then you do...

 

Alright guys, seriously, if you have nothing constructive to say, save the board some bandwidth and dont post.

If you ARE running this cam, id appreciate it if you can tell me how your car behaves.

 

I don't have this cam, but many other factors can change it's effect.
Low flowing smogger heads, high swirl heads, good flow heads, big/small valves, etc. That can drastically change how it'd run.

Off the top of my head, i'd guess you'd barely be getting 12" vacuum at idle in park. It should be pretty lazy below 2000RPM. But should just snap at over 3000RPM.

I can get 14" at 4000' altitude with my 268, but Fast355 got like 15" with an xe274 in a 305 - So that's really hard to compare.

 

Ok sonix, that the kind of info i was lookin for. I doubt its that cam then. I dont think anything has been done to the heads, i can get the numbers next time im in the garage. I get 17-19" of vacuum at idle (1200rpm) and im in ottawa. Its about a 1000ft above sea level i think. Its definately powerful after 3k rpm, but it seems to have a stall around 1800-2200 range, so i cant judge its low end power. I know it doesnt take much for it to spin the wheels, coasting at 1800 rpms, if i tap it up to 2500, ill break the tires loose.

Its also, stock exhaust manifolds, stock cat, and dynomax muffles, around 2ish inches.


EDIT:

Also sonix, what kind of influence are we talking if the components are mismatched? Maybe a couple of inches in vacuum? Not as high as i have probably.

 

Not exactly that cam or your application. But, I'm running the XS282 in the 396. A 284, which I would assume is a Magnum grind (might not be, but we don't know all that much about it, right?), in a 350-ish engine, wouldn't have any guts below 3000 RPMs. and would wind to 6500+ RPMs with ease, assuming the rest of the engine was equipped to handle it. Which, as SpitotRs305 said, you would know.

Actually, he said it all. From your description of the way it runs, it ain't like that at all.

What intake manifold does it have? Carb? Exhaust?

 

the only 284H cam i seen is the crane energizer..
description goes: strong mid range torque, street and mild bracket. Rough idle. RPM 2800-6200. 9.5-11.0:1 compression ratio

i dont think you have that.. you would know a rough idle when you hear one.. you probably have something like a comp 268H..

 

Exhaust like mentioned above, is all stock, manifolds up to cats, but has a new dynomax muffler on it. Its runnin a stock iron intake with q-jet. Timing, it has double roller timing chain, HEI ignition, with upgraded super accel coil and thick/low resistance spark plug wires. And its also bored 30 over, with TRW 11:1 compression. That last part is probably where it gets its power.

Also, it revs up REAL EASY. Not knowing it would do this, i gave it a quick snap to about 3/4 - 4/5 throttle, and once the tires broke loose, it must have revved up to about 6500-7000 rpms. The factory tach only goes up to 5k but it went enough past that by eyeing it, looked to be in the ball park of 6.5-7k rpms.

 

I have the Comp XE284H-10 in my 406.
Can't help ya with the idle vacuum cause its in storage.
Has a rough-choppy but steady idle. idles at 850RPM in gear.
about 950 in neutral I can set it lower but.... I run the distributor "Locked out"
Meaning there is no mechanical timing advance curve.
Its 36deg at idle and 36deg at hi-rpm. It's something like 5 or 6 "manifold vacuum while idleing in gear. Power brakes just have enough vacuum to work right. You can exhaust the vacuum while in gear by applying the brakes too many times in a row. (reduced idle vacuum.)
you could measure the cam lift off the pushrod end of the rocker arm with a dial indicator. .338" intake .340" ex.

 

More info on the measurement plz. Not sure where you wantme to measure.

 

set up a dial indicator that has half an inch of travel. Set it up on your rocker arm, right where the pushrod touches it, not on the valve side.
If it shows .338" total travel (ish), then you may have a 284. But I think we can all conclude that you most likely don't.

 

5678TA has a point. I checked out the crane 284H as well. The 284 is an advertised duration. The duration at 0.050 tappet is only 228, which would make it a very tame idle. My brother's 305 78 camaro had a cam at about 227 for 0.050 tappet lift, and it sounded very similar. The ignition upgrades and proper carb tuning probably make up for the rest. Ill see if i can post a sound clip of my car, maybe you guys can judge it better than me.

The reason this is so confusing, is the engine definately has the power, but i didnt think it would idle so nice. Crane also says it has "fair" idle.

 

i believe comp cams sells one cam with an advertised duration of 284 intake that has a LSA of 112 other then that they are all 110-106 lsa and like i said you would know a 110 lsa when you heard one...but F-bird is running the XE284H-10 in a 406 which he believes has a rough idle. do to your smaller displacement 350 the effects of the 110 lsa would be much more noticable i mean like old people diving off the sidewalk when you go by

 

Ok guys, heres a video i made, decided to fire it up to break off the winter slumber, brought it up to temperature, and here it is. The plugs are a little fouled because i wasnt getting a spark, so it needs a slight tuneup. Not audible, but you can see it through the vacuum gauge. Two vids.

1) Me inside the car, you can notice how the idle isnt the smoothest, because im shaking, and it translates a bit through the camera, also i got a shot of the sound at the mufflers. Smoothest idle ive HEARD for a carbed car. Also, i apologize the lighting isnt the best, it was fine when i was recording, but it didnt turn out. You'll notice the vacuum INCREASES as the idle increases? Whats that about? Hard to see, but i go up to about 2500-2700 rpms before the vacuums starts falling. So peak vacuum is around that rpm. At idle (1200 today), but usually 1000, its at 17-19 in.

2nd vid) Again the lighting isnt the greatest, if someone knows how to make it brighter, im all ears. But i was filming the underhood vacuum gauge. I revved it to about 4-5k. This video is just to give you a better idea of the sound.

NOTE: The exhaust is all stock exhaust, except for dynomax mufflers. Cat is still there.

1)

2)

 

Now that you have indicated it is a carb set up I can say might be. That duration on a cam with a modified lob sep angle could run like that.

If it was TPI you could pull the ECM and check the memcal. It definitely would not be stock if it were TPI.

 

It's totally normal for your vacuum to raise as your bring up the RPM.
That sounds like a stock cam, or barely above it.

A 110 LSA is pretty tame and normal. A 108 or 106 LSA is "noticeable", assuming it's a long duration cam.

That's exactly right. My 224 is a bit more aggressive sounding at idle then yours, with stock mufflers. I'd say you're below that size. But it's hard to say, if you have access to a magnetic base and dial indicator i'd want you to try that. It'd get you in the ballpark.

 

ok cool, sorry i didnt record the idling very long, so its hard to judge. Im still trying to find a dial indicator, ill ask and see if i can borrow one at the university, as i dont own one. Will post those results when i find them out.