I just got off the phone with Ken at Delta asking about their cam for the 4.9. He cited the specs for their cam to be 205/480 for both int and exh. with 112 lobe centers. Yet the specs I've seen for stock show 278 and 274 degrees int/exh. What am I missin' here? Did he give me the wrong specs or are what? Can anyone confirm the specs on the Delta cam or the stock cam?

Thanks.

He gave you duration at .050", whereas the other specs are duration at around .004". That Delta cam is very mild.

Well if the specs are even close, the lift is a lot better than stock, but the duration is a bit confusing.

quote Originally posted by Taijiguy: Well if the specs are even close, the lift is a lot better than stock, but the duration is a bit confusing.

The duration figures are a bit confusing to you partly because they involve an apples-to-orange comparison that is not particularly useful.

The 205^o duration figure that Delta Cams quoted you was almost certainly measured at the industry-standard 0.050" lift. That standard was widely adapted to better facilitate more meaningful comparisons between different cams, something that "advertised duration" (usually a much larger duration number) doesn't readily permit.

Accordingly, for a meaningful comparison, you might try asking Delta Cams what the "duration at 0.050" lift" is for the stock 4.9L cam. I gather they regrind stock cams, so I'd think they'd certainly know the answer to that question. If you find out, please post those numbers in your thread here. OK?

The stock intake and exhaust duration figures you quoted, 278^o and 274^o, respectively, are almost certainly those less useful "advertised duration" numbers, because if those actually were durations measured at 0.050" lift, the car would be completely unstreetable with a cam like that, and probably wouldn't even do a good job of accelerating from a stoplight to cross an intersection. That, of course, wouldn't make any sense for an engine that was used to power Cadillacs.

By the way, you stated "the lift is a lot better than stock." Out of curiosity, what is the stock cam's lift?

I have those numbers at my office- I'll check them on Monday and bump this thread then. I'll call Delta then as well and report what they say.

quote Originally posted by project34: The duration figures are a bit confusing to you partly because they involve an apples-to-orange comparison that is not particularly useful. The 205o duration figure that Delta Cams quoted you was almost certainly measured at the industry-standard 0.050" lift. That standard was widely adapted to better facilitate more meaningful comparisons between different cams, something that "advertised duration" (usually a much larger duration number) doesn't readily permit. Accordingly, for a meaningful comparison, you might try asking Delta Cams what the "duration at 0.050" lift" is for the stock 4.9L cam. I gather they regrind stock cams, so I'd think they'd certainly know the answer to that question. If you find out, please post those numbers in your thread here. OK? The stock intake and exhaust duration figures you quoted, 278o and 274o, respectively, are almost certainly those less useful "advertised duration" numbers, because if those actually were durations measured at 0.050" lift, the car would be completely unstreetable with a cam like that, and probably wouldn't even do a good job of accelerating from a stoplight to cross an intersection. That, of course, wouldn't make any sense for an engine that was used to power Cadillacs. By the way, you stated "the lift is a lot better than stock." Out of curiosity, what is the stock cam's lift?

the stock cam is .384 lift.. that delta cam regrind will get you about 20-25HP over stock, but more importantly, the powerband shifts up a bit, so you can generate more power up top. IMO, the best mod you can make is porting and polishing the heads, because the 4.9L heads in stock form are poor breathing heads. if you cam it, P&P the heads too, it makes a big difference.

That Delta cam is still gonna be out of breath by 5000 rpm, even with ported heads. Don't polish the intake ports, especially not the short-turns.

I really dont know much about port and polish or much about building the internals in general. Could you explain why you would not want to polish the intake?

Polishing the intake ports around the sjhort-turn basically turns it into a ski jump, the air hits the far side of the port rather than making the turn. If you skiied down a real ski jump, but the last few feet had sand, you'd drop right down, which is what we want the air to do. You do want the short turn to have a nice radius, but not be polished. The whole point of porting is to get the air into the cylinders, then back out. Dizzixx, if you ever want to pursue this, PM me, I'm in your valley all the time, and I used to do the porting for RPM machine in Sandy, when they had the new SuperFlow 1020 flowbench. RPM is defunct now.

quote Originally posted by stickpony: the stock cam is .384 lift.. that delta cam regrind will get you about 20-25HP over stock, but more importantly, the powerband shifts up a bit, so you can generate more power up top. IMO, the best mod you can make is porting and polishing the heads, because the 4.9L heads in stock form are poor breathing heads. if you cam it, P&P the heads too, it makes a big difference.

Oh balls. Just when I was starting to think I would just leave it stock for now. I mean, I was going to put an Allante intake on it, and will fabricate headers, but other than that I was just going to leave the innards alone. Dang it. Although, the rockers had already been removed, so I figured I would port the heads anyway. Guess I'll order the cam....

Hear that creaking sound? It's me opening my wallet.....look out for the dust....

quote Originally posted by Taijiguy: ...I was going to put an Allante intake on it, and will fabricate headers, but other than that I was just going to leave the innards alone. Dang it. Although, the rockers had already been removed, so I figured I would port the heads anyway. Guess I'll order the cam....

That sounds like you might have the makings of an interesting build thread titled, "Mild 4.9L Performance Build."


In the meantime, I hope you don't forget to post the durations at 0.050" lift of both the stock and the Delta 4.9L cams, as well as their lifts:

quote Originally posted by Taijiguy: I have those numbers at my office- I'll check them on Monday and bump this thread then. I'll call Delta then as well and report what they say.

Welp, just took the plunge. I actually ordered a cam that's slightly beefier than the first one we had talked about. This cam has .455" lift at the valve, with 215 deg duration @.050". He said this cam will require reprogramming of the PROM which I expected I would do anyway.

quote Originally posted by Isolde: That Delta cam is still gonna be out of breath by 5000 rpm, even with ported heads. Don't polish the intake ports, especially not the short-turns.

Not out of breath but deffinately short on it. Got this cam myself along with porting (not polished, just opened up). With the 4.9 though I don't expect it to rev. It makes power NOW, not once the rpm's get up there. Just the way I like it.

There is quite a bit of material that can be removed during the porting too.

quote Originally posted by Dizzixx: I really dont know much about port and polish or much about building the internals in general. Could you explain why you would not want to polish the intake?

Short answer. Smoother airflow and more of it getting into the cylinders.

[This message has been edited by Fieroseverywhere (edited 06-03-2009).]

That 215 cam should really help the mid-range, yet isn't TOO big for unported heads, it will definitely like good porting.

quote Originally posted by stickpony: the stock cam is .384 lift.

quote Originally posted by Taijiguy: I just got off the phone with Ken at Delta asking about their cam for the 4.9. He cited the specs for their cam to be 205/480 for both int and exh.

quote Originally posted by Taijiguy: I actually ordered a cam that's slightly beefier than the first one we had talked about. This cam has .455" lift at the valve, with 215 deg duration @.050".

Using the numbers cited in the above quotes, I pieced together the table below for your benefit, Taijiguy:

code:

---

                                     Stock Cam    1st Delta Cam    2nd Delta Cam
Int/Exh Duration @ 0.050"               ???            205              215
Lift - Int/Exh                         .384"          .480"            .455"    

---

That table hopefully will make it easier to see that something doesn't look right with those cam specs.


Here's why:

Typically, a cam for a specific engine which has a longer duration also is a cam with a higher lift. If someone knows the stock 4.9 cam's (presumably lesser) actual duration so that I can complete the above table, that probably would be helpful in illustrating this principle.

However, according to the comments quoted above, the 2nd Delta cam, with its 5% greater duration than the 1st Delta cam (215^o at 0.050" instead of 205^o), for some reason supposedly has 5% less lift (.455" versus .480"). That just doesn't seem to make any sense.


Consider also the cam advice offered in the link Fieroseverywhere posted in regard to how the magnitrude of a cam's increased valve lift can result in "several other required modifications" with a 4.9L. Given that caveat, it might well behoove you to be certain of the duration and lift specs for the Delta cam you mentioned that you purchased, especially since, with one cam's longer duration but reportedly shorter lift, those Delta cams' specs which you were given just appear to be suspect.


You're better off knowing the correct duration and lift figures, and those don't appear to be it.

Anyway, I hope this helps you out with your 4.9L cam project, Taijiguy.

quote Originally posted by Fieroseverywhere: A must read for a bigger cam... http://www.fieroaddiction.com/caddy49h.html

the only thing that confuses me with Jon Lagler's info on his fiero addiction page about the cam, is the fact tha he states: "The stock valve springs will coil bind at 1.3125", or .4175" cam lift. The spring retainers will also contact the valve seals at about .435" lift",

This makes no sense at all, since Delta sells a camshaft with .480 lift and it will fit the 4.9L with no mods...

can anybody explain to me why this would be? perhaps i just dont understand cam dynamics

To be honest, I decided to buy the cam Ken suggested rather impulsively. I told him my intentions, which were to have the heads shaved about .050", as well as have the prom reprogrammed. I also intend to fabricate a set of headers and run the Allante intake. After telling him all that he suggested the second cam would probably be a better choice as it will require the reprogramming, where the the first grind will run with the stock programming. The price was the same so there wasn't really incentive for him to lie to me about it, and Delta seems to have a pretty good reputation, so I pretty much just went with his recommendation. Aside from a custom grind, there isn't a lot of options for this motor. Also, I'm not exactly going "all out", but rather just looking to beef up the specs a bit and squeeze a bit more power from it while keeping it streetable, Given those two things, I didn't see a need to be too picky.

quote Originally posted by stickpony: the only thing that confuses me with Jon Lagler's info on his fiero addiction page about the cam, is the fact tha he states: "The stock valve springs will coil bind at 1.3125", or .4175" cam lift. The spring retainers will also contact the valve seals at about .435" lift", This makes no sense at all, since Delta sells a camshaft with .480 lift and it will fit the 4.9L with no mods... can anybody explain to me why this would be? perhaps i just dont understand cam dynamics

I don't understand the reason for that apparent discrepancy either, and your question certainly seems a straightforward one to me.

However, if the only source for your information is Delta Cams, that could concern me because of the odd Delta cam specs Taijiguy apparently was quoted by them: As shown in the table I'd created in my previous post, of two 4.9L Delta cams, the one with the longer duration supposedly had the shorter lift. That doesn't make much sense.


I don't see any particular reason why a cam manufacturer theoretically couldn't purposefully design two cams that way, but it would be odd.

The more typical pattern is that in any particular "family" of cams designed by a cam manufacturer for a specific engine, the ratio of a cam's lift to its duration is roughly constant. Said differently, if within a family of cams for a specific engine, when duration is increased by X%, lift typically also is increased by roughly that same X%. Thus, if either Delta Cams (or Taijiguy) inadvertently had transposed the lift specs of the two Delta cams, correcting that error then would yield virtually identical lift-to-duration ratios of 2.22 and 2.23 (versus the current, somewhat questionable lift-to-duration ratios which, if derived from the cam specs quoted in the above table, would be noticeably more disparate, 2.34 and 2.12, respectively).

Between that apparent discrepancy in the Delta cams' specs, and the one you just mentioned, stickpony, this 4.9L cam project seems to be getting more and more confusing, so hopefully we'll get to the bottom of this soon.

As I said before, I'll post the specs as cited on the grind sheet once my cam arrives. I don't put it beyond my ability to screw up and might have either misunderstood him or jotted it down wrong. Frankly, we were both pretty busy at the time, and had already mostly decided I was just going to take his advice on the cam anyway.

To answer Project34, while I'm not saying anything you typed is flat wrong, I am saying I've seen the exceptions to the "rules" and have pursued the whys and wherefores. A lobe with 205 duration and .480" lift is obviously more aggressive, with a greater rate-of lift, or intensity, than a lobe with 215 duration and .455" lift, assuming none of those numbers are typo's, either from the OP or Delta. However, more intense lobes are your enemy for high rpm with hydraulic lifters, even though this 4.9 won't be seeing high rpm. And with the elevated compression of milled heads, I too would increase the duration.

Oh, I agree with that increased duration recommendation.

Also, there are always exceptions, just like there are some cams for turbocharged engines which have more duration on the intake than on the exhaust, unlike the typical cam for a normally aspirated engine. That is why I'm curious to learn the actual specs for Taijiguy's new Delta cam, and hopefully, the duration at 0.050" lift of the stock 4.9L cam as well.

My guess is that whatever the correct duration and lift numbers for Taijiguy's new Delta cam turn out to be, they'll probably represent healthy, welcome increases over the duration and lift of his stock 4.9L cam.

Something that I didn't think of...this cam is supposed to be a simple drop-in cam. I believe the intent is to provide better performance without having to do extensive work to the valve train or the heads. Plus, with additional lift you *are* in effect increasing the duration in a way. But what occured to me is that being this is supposed to be a drop-in cam, that by increasing lift and duration, you run the risk of the valves hitting the pistonsI don't know what the clearance is on this motor, but this point was made in this post from another member who built a 4.9 : https://www.fiero.nl/forum/F...L/061613-3.html#p102

I don't know this as a fact, but it certainly would explain the discrepancy and why the duration would be shorter on a cam with greater lift. There's a lot of information on these cams in that thread, it's just sort of spread out some. Still waiting on the cam to arrive...will post the specs when it does.

Bear in mind that top dead center is not when the valves get closest to the pistons. But those specs are still so mild that clearance shouldn't be an issue with un-shaved heads. The greater likelihood is a possible need to cut down the valve guides to maintain adequate retainer to seal clearance. Stock rocker arms should have long enough slots. I'd choose valvesprings with around 75 pounds on the seat. You just don't need much more.

quote Originally posted by Isolde: I'd choose valvesprings with around 75 pounds on the seat. You just don't need much more.

Unfortunately with the 4.9 "choosing" another set of springs is not an easy task. I have yet to find anything appropriate that will fit without modification to the spring seat. There are choices out there if you can do (or have done) a bit of work on the heads.

Wasn't the OP gonna have them milled 0.050"? The shop that does that can do the spring seats.

I was/am having them shaved. Don't know if the springs will need to be addressed or not. The guy at Delta said the stock springs should be OK. We all know how that goes though...

quote Originally posted by project34: Oh, I agree with that increased duration recommendation. Also, there are always exceptions, just like there are some cams for turbocharged engines which have more duration on the intake than on the exhaust, unlike the typical cam for a normally aspirated engine.

Many also have greatly reduced overlap - some almost to zero when measured at .050", the point being to avoid just sending the charge right back out the exhaust pipe, which does not much for power and even less for emissions. It is a mistake (often made) when people choose a cam profile for a turbo application based on non-turbo grinds.

Be aware that there is only so much you can do with nothing but a cam change. These engines are almost as stifled by head design as our V6s are, and without serious modification, you aren't going to make 6000 RPM zingers out of them. But then with the torque they produce, you don't really need to. Think of them as a bigger and much torquier Iron Puke except that it won't spread it's guts across the roadway of you ask it to work hard. ;-)

My 4.9 has the largest cam he was able to grind.
Advertised duration: 282 intake/282 exhaust
Duration at .050 in. cam lift: 220 intake/220 exhaust
Gross valve lift: .498 in. intake/.498 exhaust
Lobe separation: 110 degrees
Peak horsepower rpm: 5,500
Peak torque rpm: 2,500

I am running heads shaved .050 with some port cleanup and matching, and have never had a problem with piston valve contact. I have run it up to 6200rpm, but there is no need to go that high, as there is no power to be had there.

This is NOT a drop in cam. It required machining of the valve seats and guides. I am using a late model chevy V-8 valve spring and retainers. I am not sure what they are, as I have misplaced my notes, though I am sure my cyl head guy will remember. I am running much more seat and open spring pressure, and I am using the Allante/Export steel rocker bridges to avoid pulling the rocker pivot bolts out of the aluminum. There is no valve float with this setup ( there was some with the stock engine and a higher rev limit). With this cam, you will need some longer pushrods, even with the heads shaved. I also elongated the slots on the rockers to prevent them binding on the pivots at full lift.

If that cam is one of their standard grinds, then it's the same one I'm getting. It makes sense that my numbers above would be off, as I think he was giving me lift at 1.5:1 rather than 1.6:1 And yes I've ordered the steel supports just because I don't want to mess with the aluminum ones...I've just seen too much bad news around them.

Elongating the slots on the rockers is really planning ahead.

quote Originally posted by Taijiguy: Something that I didn't think of...this cam is supposed to be a simple drop-in cam. I believe the intent is to provide better performance without having to do extensive work to the valve train or the heads. Plus, with additional lift you *are* in effect increasing the duration in a way. But what occured to me is that being this is supposed to be a drop-in cam, that by increasing lift and duration, you run the risk of the valves hitting the pistonsI don't know what the clearance is on this motor, but this point was made in this post from another member who built a 4.9 : https://www.fiero.nl/forum/F...L/061613-3.html#p102 I don't know this as a fact, but it certainly would explain the discrepancy and why the duration would be shorter on a cam with greater lift. There's a lot of information on these cams in that thread, it's just sort of spread out some. Still waiting on the cam to arrive...will post the specs when it does.

There is a lot of information on 4.9L cams in that thread whose link you posted. Thanks.

By the way, regarding an issue that scrabblegod briefly mentioned, although I don't know if you saw them in that somewhat lengthy, multi-page thread, there also are a couple of caveats there re pushrod length (of all things):

quote Originally posted by GT: I actually have more valvetrain noise in my engine than I feel comfortable with. I called Bud, and in his usual laid back manner he gently reminded me that he had asked me last year if I had used longer pushrods. I had told him no several times because Delta insists that my cam is a drop in. Bud laughed at me (in a nice way) and gave me a Competition Cams part number for pushrods that are .060" longer and won't flex (7823-16) and told me to give them a try. So I ordered a set. They're less than $50.00 from Summit. So then I called Delta and asked if the "drop-in" cam ever needs longer pushrods. Now he says,"yeah on some engines you'll need longer pushrods depending on different factors. Usually about .060" longer." And I asked him if they knew about this. He said they knew it, but that not all 4.9's require longer pushrods. Sheesh... ....I'll let you guys know what happens when I put in my new pushrods.

quote Originally posted by GT: Just an update on the pushrods. I installed the new pushrods last Saturday and it definitely made the valvetrain much quieter. I'd recommend them to anyone whose doing the cam swap. Bud said he puts them on all the 4.9's that he modifies the valvetrain on.

I'm sure the 4.9L still is the easiest V8 swap there is, but the cam and pushrod length issues associated with this swap suggest it may not be quite as easy and straightforward a "drop-in" as I'd once thought.

In any event, although I think your ride will be great fun when you're done with it, I wanted to ensure you're quite aware of this "longer pushrods" issue, Taijiguy.

Yup, I am.

i have the part number written down with all my other documentation and research..of which there is a LOT!

quote Originally posted by scrabblegod: My 4.9 has the largest cam he was able to grind. Advertised duration: 282 intake/282 exhaust Duration at .050 in. cam lift: 220 intake/220 exhaust Gross valve lift: .498 in. intake/.498 exhaust Lobe separation: 110 degrees Peak horsepower rpm: 5,500 Peak torque rpm: 2,500 I am running heads shaved .050 with some port cleanup and matching, and have never had a problem with piston valve contact. I have run it up to 6200rpm, but there is no need to go that high, as there is no power to be had there. This is NOT a drop in cam. It required machining of the valve seats and guides. I am using a late model chevy V-8 valve spring and retainers. I am not sure what they are, as I have misplaced my notes, though I am sure my cyl head guy will remember. I am running much more seat and open spring pressure, and I am using the Allante/Export steel rocker bridges to avoid pulling the rocker pivot bolts out of the aluminum. There is no valve float with this setup ( there was some with the stock engine and a higher rev limit). With this cam, you will need some longer pushrods, even with the heads shaved. I also elongated the slots on the rockers to prevent them binding on the pivots at full lift.

scrabblegod, that looks identical to the E303 mustang cam profile. Is there any significant lope at idle with that cam's duration? which computer are you running with it and did you get it tuned? i assume you are using the stock rockers since you slotted the fulcrum? i have an allante engine that has been sitting in my garage, and i was thinking about doing the same mods to it, but with the addition of larger intake valves and a port and polish. it has somewhat of a unique valvetrain too, even for an allante engine. Bud Aldeman said it was one of a very limited addition valvetrains sold with '91 allante engines. here's pics for everyone to analyze:

[This message has been edited by stickpony (edited 06-10-2009).]

The E303 cam does not make peak torque at 2500 rpm in any application, and in a 5.0 with AFR heads, the torque peaks up around 4500 rpm. But the torque is plenty driveable from 1000 rpm up in first gear with a manual trans, and the E303 likes to cruise at 1900+ rpm, which is fine for most Fiero gearing choices. If you try to run the E303 below 1900 rpm in top gear, it tends to give a sensation called "surge" It's not a cam I regret having tried, nor do I have any complaints, but there are better grinds available. For an E303 with 1.6:1 rockers, a 90# spring is adequate for 5500 rpm.

quote Originally posted by Isolde: The E303 cam does not make peak torque at 2500 rpm in any application, and in a 5.0 with AFR heads, the torque peaks up around 4500 rpm. But the torque is plenty driveable from 1000 rpm up in first gear with a manual trans, and the E303 likes to cruise at 1900+ rpm, which is fine for most Fiero gearing choices. If you try to run the E303 below 1900 rpm in top gear, it tends to give a sensation called "surge" It's not a cam I regret having tried, nor do I have any complaints, but there are better grinds available. For an E303 with 1.6:1 rockers, a 90# spring is adequate for 5500 rpm.

strange... that information is also on jon lagler's site.. looks liek he used the same cam.

assuming we can solve the breathing problems of the 4.9L heads, or most of them, with a P&P and larger intake valves, allante intake, etc.., what cam profile would you recommend, Isolde, with a 6000-6200 rpm redline in mind?

[This message has been edited by stickpony (edited 06-10-2009).]

I've been doing some research into the possible shorter duration of the cam I ordered (which arrives today so I can verify it's actual specs) but it seems higher lift and shorter duration is a pretty common practice in cams recently. http://www.chevyhiperforman...nstalled_height.html

It would seem that lift is more important than duration, and given this is a roller cam, it can handle some serious ramp, so the shorter duration may not be that big of a deal. I *am* anxious to get this thing so i can finally figure out what I'm getting!

You're gonna be out of breath by 6000 rpm due to the heads, even if you go full-race on everything. The heads just don't have that much potential. If you want to be pulling that kind of rpm, the 4.9 isn't it. The E303 grind is as big as you would want in a true daily driver. Go ahead and finish it as you are, then drive it. If you then want more, then you can either add boost, or swap to a SBC V*, or a N*, or an LS4. You can be fast without high rpm, and rpm, not HP, is what kills most older engine designs. The 4.9 qualifies. You're well on course to make the most of your 4.9 within what's practical. You're already this far, with parts and research, so keep going.

I'd still like to know what the chamber volume is. I can't find that data ANYWHERE.

I don't have it, but the shop that cuts them .050" should be able to cc them afterward. You should go up at least half a ratio in compression no more than one whole ratio, so if it had 9.0:1, you should end up somewhere between 9.5:1-10.0:1. Getting them cc'd afterwards will help if you want to know your final compression.