As you may know, I had wrecked my engine a few months ago. I had it completely rebuild and also had a high performance camshaft installed. I wasn't allowed to get over 3000rpm for the first 1000 miles. What I did notice was that the RPM had dropped a bit. Normally at 100km/u (about 60mph) it did 3000 RPM, and now it did 2800 RPM. I also noticed at idle it was a bit "searching".

Ok, the first 1000 miles passed, and I slowly increased my speed and acceleration a bit.

Yesterday after having put almost 1400 miles on the new engine, I thought it would be time for the a$$-o-meter test. I haven't got my digital dash in my car right now, so I couldn't do a timed 0-60 test.

So at an empty street in the middle of nowhere, I stopped the car, took a deep breath, and floored it. I was expecting to be dazzled by the new found speed, but in fact it felt slower than before the engine rebuild. So I tried it again and this time counted the seconds (no stopwatch or anything, but I'm very good at accurately counting ). It hit 60 mph just under 10 seconds.

Now my understanding of high performance camshafts is that you do gain a little horsepower, but even more torque. Yet the car feels slower than before. The engine was at temperature (just drove it for 50 miles) and the outside temp was about 65F.

So is there anything wrong or am I just expecting too much out of it? Did I waste $300 on a hiperf camshaft (I think it's the Edelbrock, but aren't sure)?

Well, it really depends on the cam. See, a camshaft alters the way that the engine sucks air (and spits exhaust) at a given RPM range.

A torquer cam means that it will suck heap-big air at low RPMs, but start to fall on it's face when it spins up. Kinda like a 4.9!

A High-horse cam will suck ass at low rpms. It might not even begin to pull until 3500+ rpms. You need to find out what kind of cam you got. give us some specs, namely, intake/exhaust lift/duration, and the RPM range it's designed for.

So yeah, it depends

Ya, Mach is right, but also, you can alter the dial-in too...
With advancing or retarding the cam, you can make a cam act different, but you need to know the specs of the cam...
crash...

lol

DO A SEARCH!

Actually, I did.

Anywho, I don't know the specs of the camshaft, I'll have to ask on monday. I did tell them (the garage) what I wanted and that was faster acceleration (don't care much about top-speed). They installed the HiPerf cam and different lifters.

You have an auto, or a stick?

saying that the cruise-RPMs are different puzzles me... at cruise, your drivetrain should be locked. The rpms should NEVER be much different, although they USUALLY go UP, since that means something is slipping...

Get a new clutch? did they fix your auto, so that it locks up on the highway?

As for acceleration, if nothing else, I'd change fuel-filter, air-filter, and plugs/wires/cap/rotor (if not done already.)

Any one of those will result in somewhat lack-lustre performance.

Also, check to see if the ECM is vomitting codes. Assume something is broken, so try and hunt that down, before tearing the engine apart again...

Actually, the other thing to check would be valve-lash... Seems that most manuals describe an improper procedure. too tight, and the valves will never close properly...

So much to check

Since at that speed your convertor is locked.To have an rpm difference there has to be a difference in gear ratios,or there is something making your tachometer read differently.

also you may want to ask them how they degreed the cam. I have learned in the past that it takes more than just lining up the marks to install a new cam. and that the line marks are more of a reference point, than anything else. sure your car will run if you put a new cam in, and line the timeing marks up, but also remember that is for a stock replacement, when you change the stock cam with a perf. cam you have changed a few things, when the engine takes in air, how much air, and when it dumps the exhaust. And in most cases when you change the cam you will need to dial in when everything starts to occure with the changed cam specs. I don't know if he did degree the cam or not, but it is something you should ask. If a cam is not degreed correctly it can cause problems, such as valves opening and closing at the wrong time on your four strokes, and that could also lead to even more serious problems such as pistion and valves hammering each other.

I hesitate to ask this, because I don't want to send you off on any "wild goose chases", but does your car still have its original catalytic converter?
When they clog, the car will have poor acceleration. The exhaust will sound choked up. It won't have the Fiero "rumble" any more, and the temps under the hood will probably be greatly increased. Friend of mine had a Fiero to get so hot that it boiled the fluid in the clutch slave cylinder.
It also may be something as simple as the ignition timing not set correctly. Might need to be advanced.
The manual calls for 8* BTDC, but if you have decent fuel, you can probably run 10-11*. It may not pass an emission test at those settings, though.

------------------
Raydar

I'm not the pheasant plucker.
I'm the pheasant plucker's son.
But I'll pluck pheasants
'Til the pheasant plucker comes.

Hi Cliff,

I suspect you have an automatic transmission. You say you put a high performance camshaft in. A camshaft can be designed to produce a torque peak at low rpm, mid rpm, or high rpm. Generally you cannot have all three unless you have technologies like VETEC. It’s a compromise and when you choose a camshaft you have to take into consideration things like the type of induction system you have, exhaust systems, and the weight of the car. You also have to match the camshaft to the transmission you are running and the final drive ratio. Generally a camshaft that has a lower torque peak will make a car faster to 60 mph with an automatic transmission and a tall final drive ratio like you have. Bigger is not always better!

I suspect what you did was get a camshaft that was designed to make peak torque in the upper rpm range compromising your low-end torque. With a 3.08 final drive ratio and an intake and exhaust system optimized for low rpm torque what you have is a mismatched system and therefore worse performance. Without the needed low-end torque your car takes off the line much slower than it did with the old camshaft and it becomes sluggish like you described.

Does this make any sense?

You may also have an engine management system that does not know what to do with the now lower vacuum signals the computer might be getting as a result of the more aggressive camshaft further hurting the performance of the engine. The lower vacuum signal is picked up by the map sensor as an engine load condition so the computer richens the mixture and causes all kinds of problems like hunting idles, poor gas mileage, black puffs of smoke, and sluggish performance.

The whole engine works as a system and when you change one component without matching it to the others you get chaos.

If you give me a clue as to what camshaft you have I can run figure out which one you have since I have information on every camshaft that was ever made for the 60-degree engine. I can then run it through my engine dyno program and then through my drag program and maybe help you figure this out.

Let me know ASAP. I’ll check back here in an hour.

------------------

[This message has been edited by 88formula (edited 09-15-2002).]

[This message has been edited by 88formula (edited 09-15-2002).]

quote Originally posted by 88formula: Let me know ASAP. I’ll check back here in an hour.

Thanks, but I won't know before tomorrow (monday).

The camshaft was installed by people who really know what they are doing (they are specialized in Fiero's and do engine swaps/rebuilds/repairs all the time).

I'll check with them first tomorrow, and if they don't know what's going on, I'll post some info here.

OK Cliff but you know that when you do get that information it can't hurt to get some insight from another source.

There are allot of things that can make the car slower.

Yes, the cam could be an issue but it may not be the only one.

You could have any number of stupid things screwing it up. Like static timing on the distributor or a fuel pressure problem. Even electrical problems can do it. If something can't get enough power or a good ground, it won't work right.

Also, The new cam may not work 100% right with the distributor set to factory spec. You may have to tweek that one way or the other.

It could be that the cam is wrong for your application or that it is the correct cam but not timed right. Advancing or Retarding the cam itself, even 1 degree, can have a major effect on performance.

Cam timing is done with the timing gears. The usual method is the Keyway is cut in differant places in the cam gear. Each differant keyway advances or retards the cam reletive it's designed base (OE) timing.

It is odd that engine RPM for a given speed has changed. That should NOT happen as it is entirely up to the transmission.

In an automaitc, I'd say you had TC lock problems for the RPM to drop. (Meaning the TC lock is now working when it wasn't before.)

It could simply mean the tach is off.

Would be worth unplugging the tach filter just to make sure it's not a problem. That will kill the tach but you don't need the tach to drive it.

------------------
11-Sept-01, The day the world as we knew it ended.

It could also be your a$$-o-meter has come out of calibration from lack of use. I rebuilt my motor, spent a good 2 years down (collecting money....slowly working out it) Had daydreams of my screamin new machine, and when it was finally done, was somewhat dissappointed. It actually felt slower. but it was me, not the car. It is faster now, but feels slower?! Maybe its that slight loss of low end from the "bigger" cam. Anyways I think it was the combo of what I was expecting, and not having driven it in a while. Only way to know is to find some kind of speed benchmark from before, and beat that.

hey Cliff

does this place have a website? what kinda swaps do they do? and how much$$$?

not too far from denmark

hans

Alrighty, got the exact partnumber of the cam. It's the Edelbrock 3790.

Spec for that cam taken from my PAW catalog.
int/exh
Dur @50 204*/214*
adv Dur 253*/263*
lift 420"/442"
lobe centerline 112*

I dont know what makes a cam computer friendly or not. so I cant say whats wrong. Thats not too wild of a cam, but Again, I dont know what a computer like for cams.

------------------
Two 88FORMULAS Red & Yellow 86GT 4spd, and 84SE fastback v8 project.
SSFiero@Aol.com

Cliff, What is your ignition timing set at? The Edlebrock requires the base timing to be 12*
It also requires the ignition timing curve to be 34* at 3800 rpm. The stock Fiero is set to 32* @ 3300 rpm. When changing cams, the timing advance curve needs to be set to match what the cam is doing.
The cam I'm using is a custom grind camshaft from Edlebrock but is simular to the 3790. I just increased the lift and duration for my requirements. They offered me that cam at first, but once I talked with them about what I want out of the engine, they recommended the custom cam. (for my 3.4L)
The camshaft your using is a hi perf cam but other things need to change in order to get peak performance. The Crane cams are designed to use the lower advance curve.

------------------

Happiness isn't around the corner...
Happiness IS the corner.

[This message has been edited by Oreif (edited 09-19-2002).]

quote Originally posted by Oreif: Cliff, What is your ignition timing set at? The Edlebrock requires the base timing to be 12* It also requires the ignition timing curve to be 34* at 3800 rpm. The stock Fiero is set to 32* @ 3300 rpm.

Ok, now my lack of knowledge on this is going to be exposed!

Timing was first at the first notch (the notch closest to the front), and today they changed it so it's more the second notch.

I have absolutely no clue what the ignition timing curve is... How can one tell?

HI-Po cam will make LESS power, both HP and tork at lower RPM and same for mid range
and only add HP at the VERY Hi end near the red-line and move the tork peak # up the RPM range too
What RPM do you shift at, is it the same RPM you used before the new cam?? if so yes you are getting less power, try a higher shift point, your new lifters should allso raze the red-line and valve float points

dist curve is the rate of advance that the springs and weights in the dist, add to the idle rate as RPM gets higher CPU may be adding to "curve" tooo.
most HI-PO cams want more advance at higher RPM then stock rates.

did you cutout the ext-manafolds too that will hurt lower end tooo, but add on top power

------------------
Question wonder and be wierd

quote Originally posted by Cliff Pennock: ...Timing was first at the first notch (the notch closest to the front), and today they changed it so it's more the second notch. I have absolutely no clue what the ignition timing curve is... How can one tell?

By "closest to the front" do you mean closest to the front of the car?

The notch closest to the front of the car is 0*, or Top Dead Center (TDC). That's the deepest notch, by the way.
IIRC, the next notch is 4*, the next is 8*, and the very edge of the timing tab is 12*.

The numbers increase as you get nearer the back of the car.

If I understand your post, your timing is now set at 4* advanced.
8* is stock.
Based on Oreif's info, yours should probably be set at 12*. That's the edge of the tab closest to the trunk.
If your engine "spark rattles" after you do this, it's advanced too far. Back it off by a degree or two and try again.

They *are* setting the timing while shorting the diagnostic connector in the console. Right?

quote Originally posted by Cliff Pennock: I have absolutely [b]no clue what the ignition timing curve is... How can one tell?[/B]

The Ignition advance curve on Fiero's is a product of the ECM programming.

Raydar covered setting the timing.
Have them set it at 12* then test drive it.
If it pings, have them set it to 10* which is the point between the 8 and 12 notches.

quote Originally posted by Raydar: By "closest to the front" do you mean closest to the front of the car?

Yes.

quote Based on Oreif's info, yours should probably be set at 12*. That's the edge of the tab closest to the trunk.

Well, I know it's not set to that...

quote They *are* setting the timing while shorting the diagnostic connector in the console. Right?

Yes, they actually use a scan tool hooked up to the ALDL, so I guess they know what they are doing.

quote Originally posted by Oreif: The Ignition advance curve on Fiero's is a product of the ECM programming.

So I need a different prom for the ECM?

quote Originally posted by Cliff Pennock: So I need a different prom for the ECM?

To get the maximum performance, a new PROM would be the way to go. You should at least get a decent amount of gain just by getting the ignition timing set correctly. It sounds like the timing is retarded too far.

Example:
Stock the car had about 140HP
with the cam and timing advanced you should see about 150hp If you spent the money to get a custom PROM made (about $350 U.S.) you might gain 5 more horsepower at the upper end for a total of 155hp.
Before thinking about a PROM, I would first get the timing set correctly and see how it runs for a while. Then you can decide if you want to spend the money for the PROM.

I don't think a custom prom will cost you $350. The HARDWARE to write proms will cost less. And there's a member of the forum that has written some really cool software for it.

OK Cliff here is what I have on that camshaft. Edelbrock states "Matching camshaft for 60° Chevrolet Performer manifolds #3785/3787 and 3785/3789. Use only stock ratio rocker arms. Do not use dual springs. Not for use on computer-controlled vehicles."

Your camshaft specifications are,

Lift intake .420
Lift exhaust .442
Duration intake 253
Duration exhaust 263

I put the numbers into my Dyno program and here is what I got.
Bore 3.530”
Stroke 2.99”
2.8-liters and 172.3 cid
Compression ratio stock 8.6
Manifolds stock TPI (add 3 horsepower for larger TB)
Ported manifolds high flow muffler

RPM Horsepower Torque

2000 64.789154 170.071533
2500 83.913025 176.217346
3000 105.660278 184.905487
3500 124.066765 186.100159
4000 138.030563 181.165115
4500 145.654129 169.929810
5000 146.724564 154.060791
5500 139.406006 133.069366
6000 126.175438 110.403511
6500 109.057541 88.084938

With a fiero GT equipped with the 3.33 final drive automatic your car will go 0-60 in 8.15 seconds and run the quarter mile in 16.173 seconds @ 87.2 mph.

Here is what a stock 2.8 looks like on my dyno program

RPM Horsepower Torque

2000 59.751808 156.848495
2500 77.655495 163.076538
3000 98.767700 172.843475
3500 116.029915 174.044876
4000 128.947357 169.243408
4500 135.045212 157.552750
5000 134.384476 141.103699
5500 124.374107 118.720741
6000 109.110306 95.471512
6500 89.494995 72.284424

With the stock engine your car should go 0-60 in 8.8 seconds and run the quarter mile in 16.699 seconds @ 84.6 seconds.

These dynos assume you have perfect air fuel ratios for power. If I have any of this information incorrect please let me know and I will change it to reflect the correct data.

Hope this helps you Cliff!

Ok, sounds good. I'll drop in my digital dash next week and do some acceleration tests. That should give me a good idea if I have really gained any performance or not. Also makes it a fair bit easier to get the timing right.

Interesting...

I thought those specs sounded a bit familiar.

Just looked up ARI's cam specs.
(ARI is the engine builder that sells the 3.4 stroker motors, built on a 2.8 block.)

As nearly as I can tell, your cam is almost identical to to the Crane 2030, and also very similar to ARI's Phase 2 "house brand" cam.

FWIW, This is the cam that they recommended for my auto-tranny Formula, for increased "street" performance.

All of this was to say that I think your engine builder made a good choice as to what cam to install. If you really needed to hear that.

------------------
Raydar

I'm not the pheasant plucker.
I'm the pheasant plucker's son.
But I'll pluck pheasants
'Til the pheasant plucker comes.

quote Originally posted by 88formula: If I have any of this information incorrect please let me know and I will change it to reflect the correct data.

I just Emailed you the Dyno 2000 Cam file for Cliff's cam. It has all the timing differences. It is from the updated "CamDisk 2" for the Dyno 2000.

Could you run it and see if you get any differences?

BTW ~ The cam is designed to use the Edlebrock intake manifold and a carb. It's part of their "Performer Series System" You buy the intake, carb, and Cam as one designed package. That is probably why they say not for computer controlled engines.

[This message has been edited by Oreif (edited 09-19-2002).]

I had the same problem with my first V6 rebuild. It turned out to be valve adjustment. The crane 2030 kicked ass w/ forged pistons & ported/polished heads SSI valves etc. I found the stat sheet that came w/ the cam & it has almost same stats as yours:
Lift INT/EXH@cam 282 (both)
Lift INT/EXH@valve 423 (both)
Dur INT 264
Dur EXH 274
Let the shop know whats up- maybe they can fix or give you some $$$ back-
OUT>

[This message has been edited by G-Nasty (edited 09-20-2002).]

One thing I just noticed that nobody's mentioned...

A big healthy cam requires more compression to work properly. Did they do anything to up it a bit? Better pistons, shaved heads, etc, etc?

You might even find that things 'perk up' a bit after time when things get seated a bit better.

The other thing is - is it stock ignition? With all that fuel in there, you might not be getting a complete burn and it's just going down the pipe. That'll also lead to a plugged up cat after a while.

Ok, I asked them about timing and they said it's now set to 4°. I told them somebody recommended 12° and go back from there if the engine pings. They said that would work but that there was also a very big chance that would ruin the engine in no time (burn a hole in the cylinder). They said to run it relatively safely at 12°, I needed to get rid of the ECM and maybe even install the complete Edelbrock package (headers and stuff).

Like I said earlier, I trust these guys because they do a lot of engine work on the Fiero.

(edited for spelling)

[This message has been edited by Cliff Pennock (edited 09-20-2002).]

I disagree I think that you should be able to run more timing because the engine is getting more fuel not less. why cant the engine have the stock timing? This is probably screwing up youre computer because it is still using the 8* as its base timing not 4*. This will deffinately affect youre power and milage. I would have it set to factory specs and drive it for a week and then think of changing it. 4* is not enough you will not feel anything and will find the car is slower. It can also ruin the cat because you will not be using all the fuel and be running rich. Just my thoughts cliff.

------------------
Stock 85 GT Bracket Racer
My record so far is 1W 1L
Fastest time 16.54

Cliff I know you trust those guys in all but 4-degrees is just not enough timing for that engine.

It really should have more than that. Running your timing retarded like that may save your pistons if the engine is running lean but it makes the exhaust valves run hotter risking burning your valves. The fuel mixture could still be burning as the exhaust valve is opening wasting power and putting more of your exhaust valves in contact with the flame for a longer period of time.

If you adjust the timing like the above poster said until the engine just starts to ping and then back off the timing even three degrees you would be so much better off for power, drivability, and gas mileage. You are not likely to burn a piston either unless your engine is running very lean.

Another reason why they will retard the timing is to help stabilize the idle speed. It helps stabilize idle speeds masking minor air fuel ratio issues so that you won't think anything is wrong but man does it kill your power.

Honestly what good is modifying the engine for more power if you are going to run the engine with less than ideal timing for it?

Ok, keep talking, you guys are starting to convince me.

Ok Cliff it seems you you just have to bite the bullet and call Archie I think
Seriously though I can relate to why you want to mod the 2.8. I want to turbo mine and play around with it a little. Having a second engine is a bonus now.
Keep the cam talk coming. I am wondering which will work well on a turboed engine.

------------------

Fiero Shop - International | The Classic Fiero Owners Group - International

Aus,
Here is a list of most cams and links to their websites. http://www.60degreev6.com/Performance/Pushrod/2831/cams.html

Yeah keep us posted cliff!

quote Originally posted by Oreif: Aus, Here is a list of most cams and links to their websites. http://www.60degreev6.com/Performance/Pushrod/2831/cams.html

That is a good site Oreif. I saved most of the interesting bits of that site to a text document a fair while back. Been using it as my rebuild bible.
Here is another cam link I found. http://users.spec.net/home/emxjc/cam_shaft_power.html