Pat Hall

iTrader: (31)

Hey all. I'm sorta torn on which cam I should use in the 355 I've been putting together for way too long now. Here's my dilemna. Right now I've got the 502 cam in the motor(218/224, .495/.502, 112 LSA), but I've also got the 503 cam sitting in the box(224/230, .502/.510, 112 LSA). I initially went with the 502 since I have ported 083 L98 heads on there right now, and I figured those heads would be too restrictive to take advantage of the 503 cam. However, $800 later and I've got a set of AFR 190's on the way here, so there shouldn't be a problem with the heads having enough flow once those are bolted on. With the 083 heads, I was going to run an Accel base and ported SLP runners that I have sitting here. However, I've also got the matching Super Ram plenum/runners that go with the Accel base, and I'm thinking maybe I should use the Super Ram plenum/runners with the AFR's. My goal is basically a street driven car with lots of go, especially in the midrange. Do you guys think the 502 cam would be too little of a cam to use with the AFR 190's and the Super Ram setup? Do you think I'd be better off running the 503? I want a healthy cam, but don't want to end up having most of it on the top end. The lifts are pretty similar between the two, so it's the difference in duration that's got me wondering which would be the better choice. I'm sure someone will inevitably suggest the XFI 268, but I'm done buying cams. The 502 and 503 are already bought and paid for, so I just need to choose which one before I button the motor back up for the final time hopefully. Any advice from guys running similar setups would be greatly appreciated!

Damon

It's not much of a change to begin with- only 6* difference in duration. And with the TPI-style intake I'm not sure if it would help that much anyway. I'd probably stick with what you've got in it right now. If you're going to swap the heads and intake with the engine still in the car I'd definitely leave the cam alone. Even If you're pulling the motor for a complete tear-down I could still go either way with it. The heads will help tremedously, even with your current cam.

Pat Hall

iTrader: (31)

I haven't even ran the motor yet. It's still sitting on an engine stand all nice, pretty, and rebuilt. With that in mind, it's no problem at all to swap cams at the moment. Besides, I'll be tearing off the 083 heads once the AFR's show up on my doorstep, so changing the cam is only tearing it down a couple more steps. I see what you're saying though about 6 degrees not being that big of a difference. That's why I'm wondering if I should even bother going the few extra steps to change the cam. I'm also thinking the 502 might give me a better midrange, but I'm hoping for some more opinions from other guys who've used these cams. The 502 seemed like the perfect choice with the 083's, but with the AFR 190's and a Super Ram, I'm sorta wondering now.

Grim Reaper

Pat, go with the bigger cam, you'll always regret it if you don't. It will give you 15-25 HP (plus what you'll gain from the AFRs) and DEFINTELY upgrade from TPI. Also , you could look at advancing or retarding the cam a few degrees if you would like to emphasis a little more to TQ or HP. Though I am not a fan of the SuperRam (due to the difficulty of installation), it can handle quite large cams.

I was going to suggest using a two piece timing cover to make future changes but once you go through the hassle of installing that Superram, you will probably never want to remove that intake again.

Unless you require emissions testing and need a functioning EGR, you may wish to consider the HSR. I personally think its a better all round intake (and I have a Miniram).

89formula350b2l

iTrader: (11)

im using the 224/230 cam on my 383...it SCREAMS from 2000-6000. I also have AFR 195 heads....so pretty much same head....you wont be disappointed with 503

Pat Hall

iTrader: (31)

I hear ya Grim. When I upgraded the cam on my other car, I was initially worried that I had gone too far, and it actually works really well. In fact, I probably would've regretted going smaller on that one. I also hear ya on the superram. I've read a lot of the posts here about the hassles of installing it, and needless to say, I'm a little apprehensive. However, I figure it'd be doing a disservice to the AFR's and bigger cam if I ran the SLP runners and ported stock plenum vs. using the superram. I am going to use studs for the upper runner to plenum bolts to try and make it a little easier to work with. 89formulab2l, I noticed in your sig a while back that you're running the 503, and I always meant to send you a PM and ask you what your impressions of it were. I'm probably just splitting hairs debating between these two cams since they're so close to each other in specs. I'll probably end up installing the 503 when I swap the heads. I really hate to swap a cam after the motor is installed, so that's why I'm over-thinking this whole thing right now. Lol.

Grim Reaper

Pat, a LOT of the rational for recommending smaller cams (in the past) was to avoid having to get a new eprom for your ECM. By your signature, I will assume it's the 1989 MAF ($6E calibration) and that is probably the most advanced MAF system used on the 3rd Gens.

It is true that the MAF system can tolerate a lot of modifications without HAVING to re-program the eprom. But, in all honesty, even a bone stock MAF (or SD or TBI) car can benefit from tuning the eprom (as well as increasing the car's gas mileage as well).

Today, with the knowledge we have on tuning the eproms on the DIY Prom Board, you can install cams that in the past, people would call you NUTS for installing on an EFI car.

I have helped tune a few people's cars with a cam similar to yours (with a variety of intakes). A 383 with AFRs will breath very well. And expect it to max the MAF around 4,500-5,000 rpm.

In the past, you would be forced to look at a different system, but there is now a "work around" that is very effective in tuning your car once it "maxes the MAF". Basically, we just add more fuel at the higher RPMS via the P/E Fueling Table (P/E is ECM terminology that means WOT).

The cost of getting all the necessary equipment to tune your own eproms is quite inexpensive (and for some thing free). When you compare it to buying a custom eprom, it isn't that much more expensive and possibly cheaper if you go with some of the "freeware" instead of purchasing some of the software. A lot of guys even start out with the "freeware" and once they realize that burning their own eprom is not that hard (and actually fun), they later buy some of the fancier software that makes tuning even easier.

Lastly, when you factor in the money you can save by invoking "Highway Mode" (something GM developed but was stopped because it increased NOx emissions but only when you are operating on the highway...but saved on fuel), it can actually save you money in the long run.

And, if you are subject to emissions, it is possible to do certain modifications if it was failed just a little, to make the car pass. It won't work on something that is GROSSLY polluting, but will on a car that "just missed it". And, it is possilbe to do it so your testing station has no means to detect it unless they actually take out your eprom and compare the actual programming to a 'known stock' bin. I use to be subject to emission testing and they NEVER did that (in fact, they didn't even look at my ECM and probalby don't even know where it is located).

But do come to DIY Prom (if you haven't already) , check out some of our "stickies" on tuning (as well as doing a search on "$6E" on DIY Prom for more info) and consider burning your own eprom for your new engine. It is difficult to predict how much more HP that will add, as it dependent on how badly out-of-tune you are initially. But 25-35 HP gains would not be unrealistic based on engines I have helped tune.

Pat Hall

iTrader: (31)

Oh yeah, I've been to the DIY prom board quite a few times, and read until my eyes bled. Lol. I read some of the posts there about hitting the 255 gms/sec limit on the MAF's, and how you can tweak the PE or AE tables to compensate for it. It all seems to make sense in theory, but probably the only way to really grasp and understand it, is when you actually do get the equipment to start burning your own. I am, in fact running the 89 MAF system. I've even got the Micro-Tech MAF, so I don't have to worry about the burn-off circuit and the delicate, thin wire on the Bosch ones. As far as emissions testing goes, we do have that where I'm at. But the places I take my car for testing really aren't picky at all when it comes to the visual inspection. As long as it passes the sniffer, that's all they really care about. In other words, I know the right people for getting through the emissions easily. So running a HSR wouldn't be a problem if I decided to go that route. Heck, with the superram, even if you did have a functional EGR valve on it, good luck trying to actually see it underneath that ridiculously huge plenum. Thanks to how silly the laws are here, I still have to get my 69 Camaro to pass emissions each year, and the cam in that car won't pass no matter how you tune it. It was pretty ingenious the way my buddy got it to pass this year. He told the machine it was a DIS (distributorless) ignition system. This cuts the rpms in half when it's hooked up to a car with a regular distributor, and as most of us know, racing cams usually fail miserably at idle. He was able to run the motor at 1600 rpms for the idle test, and the machine only registered 800 rpms. I was amazed when it passed with flying colors. Lol. Every year before that, they've always used another car in the shop to get it to pass. For the high speed test, he had to punch it up to about 4K for the machine to read 2K. I was sorta cringing, but damn it sounded good.