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| How can I tell if I have a high performance cam shaft or not? (Page 1/1) |
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Cliff Pennock
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SEP 30, 12:54 PM
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About 24 years ago, I had my engine rebuilt. Since they were working on the engine anyway, they told me to install a high performance Edelbrock cam shaft too. That would cost me about $1,000 extra (it was in fact 2,000 guilders, which is comparable to $2,000 today). They said it would give me a 15 HP gain.
I agreed and they installed the Edelbrock 3790. Or so they said.
When I got the car back, I didn't notice any difference in performance whatsoever. I know 15 HP is not much, but I at least should notice some difference, especially in torque. I also noticed they had set the timing to 6 degrees. Which is AFAIK the default for a stock cam shaft. So I asked them why it was set at 6*. They said that any higher would damage the engine. Which is a load of BS because the Edelbrock 3790 on the Fiero requires at least 12*. When I set the timing to 10-12* myself, the engine ran much, much worse.
The next excuse of the garage was that I wouldn't notice any difference with the stock exhaust headers. I would need at least ported headers.
So fast forward 24 years. My car is currently being repaired and one of the things I asked them to do is to install ported headers (which I had laying around for at least 20 years now). I truly don't expect to notice much difference but when there is, that's a bonus.
Anyways, my question is, what should you notice with a high performance cam shaft? With and without the ported headers?
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82-T/A [At Work]
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SEP 30, 02:43 PM
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| quote | Originally posted by Cliff Pennock:
About 24 years ago, I had my engine rebuilt. Since they were working on the engine anyway, they told me to install a high performance Edelbrock cam shaft too. That would cost me about $1,000 extra (it was in fact 2,000 guilders, which is comparable to $2,000 today). They said it would give me a 15 HP gain.
I agreed and they installed the Edelbrock 3790. Or so they said.
When I got the car back, I didn't notice any difference in performance whatsoever. I know 15 HP is not much, but I at least should notice some difference, especially in torque. I also noticed they had set the timing to 6 degrees. Which is AFAIK the default for a stock cam shaft. So I asked them why it was set at 6*. They said that any higher would damage the engine. Which is a load of BS because the Edelbrock 3790 on the Fiero requires at least 12*. When I set the timing to 10-12* myself, the engine ran much, much worse.
The next excuse of the garage was that I wouldn't notice any difference with the stock exhaust headers. I would need at least ported headers.
So fast forward 24 years. My car is currently being repaired and one of the things I asked them to do is to install ported headers (which I had laying around for at least 20 years now). I truly don't expect to notice much difference but when there is, that's a bonus.
Anyways, my question is, what should you notice with a high performance cam shaft? With and without the ported headers? |
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I don't know the specs on that cam, but when you install an aftermarket performance cam, it's usually trying to gain a bit more performance in a specific area. The cam in the Fiero is already considered to be higher performance than many of the other V6/60s had at the time, so that would mean a change in performance for the Fiero would have to either give you more power in the lower rpms, more in the middle, or more in the upper rpms.
The Fiero doesn't respond well to additional lift, etc. in the upper RPMs simply because the stock intake lacks the ability to breath much beyond what's already in there. It becomes a significant bottleneck. In a higher performance cam, you'll often feel much more power in the mid-range RPM, and then suddenly it feels like it "falls off" in the upper rpms because it simply cannot breath.
You definitely should have felt a difference in the way the car performs. And if nothing else, the change in cam would result in the exhaust / idle sounding a bit different too... more or less "lope" if you will.
If you have the hogged out exhaust manifolds (unless you meant performance headers), you'll notice an 8hp difference merely by installing the stock exhaust manifolds that have been hogged out... with nothing else changed. Another thing you can do is port-match the intake components... this makes a difference too. They slopily put them together and there's overlap like this:
I know that's yet "another thing" but worthwhile if you're going to do it.
If you feel like spending the money, the H262 cam is a popular swap... it improves midrange power and increases both lift and duration. You can also go with higher-lift rocker arms. The factory stamped rocker arms are 1.5:1, and Crane Cams sells a 1.6:1 rocker arm set. They just manufactured a new run!
But to answer your question, yeah... you'd notice a difference. It sounds to me like they didn't install a cam. it would be obvious though if lookign at it since the cam would have a stamping on it.
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Patrick
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SEP 30, 03:32 PM
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| quote | Originally posted by Cliff Pennock:
I also noticed they had set the timing to 6 degrees. Which is AFAIK the default for a stock cam shaft. So I asked them why it was set at 6*. They said that any higher would damage the engine. Which is a load of BS because the Edelbrock 3790 on the Fiero requires at least 12*. When I set the timing to 10-12* myself, the engine ran much, much worse.
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Cliff, just to clarify... all "timing" you're referring to is ignition timing and not camshaft timing, correct?
I'd like to hear what others have to say about the ignition timing in regards to different camshafts. I installed 1:6 roller tip rockers (with the factory camshaft) in my Formula, which I believe is the same (or very similar) as running a "performance" camshaft with the factory 1.5 rockers. My engine runs best (acceleration wise) with the ignition timing (set by ear) at about 12° BTDC. It would probably idle smoother with the ignition timing retarded a couple of degrees, but then I'd lose a bit of snap with the acceleration.
| quote | Originally posted by Cliff Pennock:
How can I tell if I have a high performance cam shaft or not?
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Without gaining access to the camshaft itself, I suppose you could remove a valve cover, measure the lift on one or two camshaft lobes, and compare that to the factory camshaft specs.[This message has been edited by Patrick (edited 09-30-2024).]
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Dennis LaGrua
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SEP 30, 06:48 PM
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| quote | Originally posted by Patrick:
Without gaining access to the camshaft itself, I suppose you could remove a valve cover, measure the lift on one or two camshaft lobes, and compare that to the factory camshaft specs.
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You can do this with a dial indicator measuring right at the pushrod. That will give you cam lift. Multiply that number by the rocker lift ratio and that would equal total lift.. Then compare that to the stock cam specs. IMO a high performance cam change will provide a noticable difference in power.------------------
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Cliff Pennock
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OCT 01, 02:20 AM
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| quote | Originally posted by Patrick:
Cliff, just to clarify... all "timing" you're referring to is ignition timing and not camshaft timing, correct?
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Yes.
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WOT-Tech
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OCT 01, 02:23 PM
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Cliff Pennock
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OCT 01, 05:59 PM
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| quote | Originally posted by WOT-Tech:
253/263 adv duration
204/214 .050 duration
.420/.442 lift
107 ICL
112 LSA
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Yes, this was the info I saved back then:
Duration @ .006 lift: Intake 253°, Exhaust 263°
Duration @ .050 lift: Intake 204°, Exhaust 214°
Lift at cam: Intake 0.280", Exhaust 0.295"
Lift at valve: Intake 0.420", Exhaust 0.442"
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La fiera
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OCT 03, 08:56 AM
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For that little displacement that cam should have a noticeable lope to it. On a 5.7L you will hardly notice.
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