Choosing Cam for budget 383, and some other advice

[Yonash70c20]

Please keep in mind here, I am not looking for extreme power, just something to wake up my tired old truck. Something maybe in the area of 300hp or so, with in the area of 350-400tq. I am not going overboard on the internals as I plan to rebuild the motor later on for a different purpose and will beef it up then. The engine is going in my '70 C20 that my brother and I are converting to 4x4 and will be used primarily for towing duty. I plan to build a completely different motor for the truck down the road when funding has freed up a bit (or maybe a diesel swap), and this motor will be reconfigured then and most likely put in my '91 Camaro.

I am building a 383 out of a Vortec 350 shortblock I acquired from a friend pretty cheap. I will be using the stock rods and pistons (still in good shape, motor spun a main bearing) and a rebuild kit and new rings (would like a suggestion here please), a set of World Products Sportsman II heads (http://www.summitracing.com/parts/WRL-01150/ IIRC) with 1.6 aluminum roller rockers, an Eagle Cast Steel stroker crank, and currently an Edelbrock Performer intake with Edelbrock 650cfm carb, but am working on collecting the rest of what I need to run a TPI setup I have in the garage.

The two cams I have been considering are the Lunati Truck Avenger 90350LK and the Crane PowerMax 113902, both can be found on Summit for pretty good prices. I am perfectly okay with sacrificing some horsepower for the sake of torque. These cams are both listed as .427/.454 204/216 @ .050" 112 LSA. Lunati's website shows as suggesting this spring/lock/retainer kit for the previous Lunati cam (http://www.summitracing.com/parts/LUN-73943K1LUN/).

Do these cams sound like a good choice for the parts I already have (short block, heads, rockers, intake and carb)? Or should I reconsider anything that seems crucial and just a plain bad choice? I have a full list set up on Summit ready for me to click "Submit" to get the parts on the way, but thought I should ask more experienced people for some opinions before firing off all my money. I do have the finances to fudge a bit over what I am looking at now, but what I have seems (at least to me) to be a decent combo good for fair power and reliability without breaking the bank. Have I missed or just overlooked anything vital?

[POPO1984]

the summit brand LT4 hot cam would do pretty good i think. Nice torque for the heavy truck and good hp too.

[Schralper]

those cams are WAY small for a 383
you need @ least 185cc, preferably 195cc heads.
a solid flat tappet will give you better power but ya gotta deal w/ adjusting valves.
for hyd flat look at something w/ about 220ish @ .050 and .5xx lift. and 110LSA
try rockers 1.6 on intake & 1.5 on exhaust
4x4? what kinda gears? what's your desired rpm range? what kinda trans? stall?
650 cfm is WAY to small a carb, 750 vac or DP.
think more like performer RPM than reg. performer.
seriously anybody that expects idle - 5K power is smoking some bad shiz
4x4 w/ transfer case in 4Lo and you'll be spinning you're engine.
towing? well gears & compression will help there.
if ya wanna tow more than a jet ski @ 2K rpm well.....
better get a big block or diesel.
most of my towing (uphill) is @ 3K rpm w/ comp cam XE276HR (roller) in my Burban.

[Sinister]

Comp makes one I Desktop Dyno'd for a 383 with RHS heads and only 8.5 CR. About 330 HP, 416ft/lbs. Lot's of torque down low. The grind is XR258HR, .480/.487, 206, 212 at .050, 110 LSA.

[Ticker]

There are a number of factors here that limit our choices.

The factory spider/dogbones/lifters, which I'm assuming you're reusing, are limited to around .525 lift with 1.6 rockers. The GMPP HOTCAM was designed with this limit in mind, being the largest cam that could reasonably be used with the stock configuration. Note that it was also designed for higher RPM power, and not for low-end torque. There are other GMPP choices that are good here if you'd prefer to stay with a GM cam.

The Sportsman II heads are slightly upgraded stock heads - they're an "S/R" type head (Stock/Replacement) with just a touch of porting. The intake runner size on these heads is absolutely fine for a 383 (200 cc) with a focus on low-end torque at 245 intake/165 exhaust @ .600 lift per World Products. Make sure you look closely at the port size - they come in both 64cc and 72cc.

Although the exhaust port on SBC heads is always weak, there's no reason to run mixed ratio rockers - and as an aside never a reason to run a smaller rocker on the exhaust.

http://www.worldcastings.com/product...ron-heads.html

So if we net all this out we're looking for a relatively short-duration cam to provide off-idle to midrange RPM torque at around .525 lift with 1.6 rockers.

I would be looking at the CompCams Xtreme 4x4 P/N 12-411-810 (Grind #X4260HR) with 260/264advertised duration and .474/.474 lift (.505 with 1.6 rockers). This is getting most of what's available in the head, provides power in the range you want it and is well within the capabilities of the stock lifter setup. You could look at the XR252HR with 252/258 and .472/.480 if you'd prefer a smoother idle and don't mind a lower power peak. The XR258HR Sinister mentioned is a good pick as well.

Note that you won't be using the stock pistons if you're going to a 383 as the compression height is different, so it's simply not possible.

The existing springs on the heads are fine for this level of lift.

I would strongly recommend a Scat crank over an Eagle crank, as Eagle in my experience has real issues with holding a tolerance.

If you've already got the carb and intake they'll work, but the RPM is a better intake overall since we don't have hood clearance issues, and the carb is right on the edge for a mild 383 like yours and definitely short if we take the power up any further.

Note that this isn't a "max power" cam - the heads really don't support that

As an aside, you need to be very careful to check ALL the valvetrain clearances and geometry when we get to this lift and 1.6 rockers.

[Captainfab]

Just a little FYI....you can not use your stock 350 pistons when building a 383. You will need to get new pistons that have the pin location to accomodate the 3.750 stroke.

It sounds to me that what you're trying to build is a copy of GM's HT383 crate engine. It produces 340hp and 435ftlbs torque. The cam that you posted specs on is real close to the cam used in the HT383. In fact if it were me, I'd keep the Vortec heads (they're used on the HT383), and look for the same roller cam used in the HT383. They can often be found on ebay as 'new' take outs for a good price. Assemble this with the appropriate 383 parts, and you'll have a good low to mid range torquey engine.....perfect for offroading and towing. There's my .02

edit: looks like Ticker beat me to it on the pistons.....

[Ticker]

regarding keeping the stock Vortecs, which can probably be reused with little or no work.

The cam is also a good pick and a good match to the stock Vortecs...but too much for 1.6 rockers, which aren't really needed for this build anyway.

I wasn't thinking very holistically, but I've kinda been beat up for providing information beyond what's asked for a few times so I'm getting gunshy

[Yonash70c20]

I appreciate the suggestions everyone. I won't be using stock Vortec heads, as I only have the block and rotating assembly. Besides, I already have the World heads, though they are nearly bare. I got them from the same friend as the roller rockers and Vortec, and he had gotten rid of the springs and such, so it's the valves and bare head, and he advised I worry about what springs once I decide on a cam. As for the rockers, Ticker, I got them for cheap and that is why I plan to run them, plus they could be utilized better once I repurpose the engine later on. I also didn't realize about the pistons, so I guess i need to get to looking at those. Any suggestions that will work well for the intended build? I was reading a thread on here recently about hyper pistons, and may just go with cast after reading that thread.

As for other questions asked, I currently have a TH350, but am saving up for a 700R4, and am unsure what stall converter I will need, so some guidance there as well would be helpful. I am not sure of the gearing in the axles, but the chassis my brother and I are working on is a 1971 K20 with I believe a D44 front and Eaton HO52 rear.

And for the intake setup, I already have them, they are in the truck right now, and would only be used temporarily to get the truck on the road, and wouldn't be used for towing purposes, only to roam the city a bit as a backup for when my wife has the DD. As I said, I am working on getting all the parts together for a TPI setup and that will be going on before any real towing is done, as i realize the intake and carb are just not enough to really get decent performance out of my planned build. Unless someone has a suggestion for similar economy, power, and drivability, this is what I plan to run.

[Ticker]

I would sure have the heads checked over by the machine shop before making any decisions.

On the rockers, sometimes cheap parts can end up being pretty expensive when they're junk - but your call.

For piston choice, I need the chamber size on the heads. Are you planning to buy a complete rotating assembly? That's definitely the best way to do this - ideally an internally-balanced one.

I don't know what the thread was regarding hypereutectic pistons, but there is no reason in the universe to run a cast piston unless you're trying to save every buck possible in a cheapo rebuild.

[Captainfab]

If you plan on changing to TPI, or any other EFI in the future, you will need to choose a cam that is compatable with EFI. Generally you will want to be conservative with the duration and a LSA of 112 or greater.

[Yonash70c20]

Well, I have been rethinking some things lately for this buildup, and I wasn't originally planning on buying a complete rotating assembly, but am now thinking I probably should. Will probably save me money in the long run, I just won't have the engine up and running as soon as I had hoped, I will have to save a bit longer for some of the other parts. as far as a towing motor goes, what cam specs should I be looking for? And what ranges would be best compatible with EFI? Could anyone perhaps suggest a good cam to look at for an EFI build, since I've already gotten some good examples for carb cams? As for the size of the head's chambers, I can post that up tomorrow, I gotta check with my friend I bought them from. I believe they are still unused heads, so I shouldn't need to check into them too much for straightness. And the rockers weren't cheap because they are off-brand or anything like that, they are good rockers, just my friend has 7/16" studs, and the rockers are 3/8". He was originally going to use the World heads on his project, and got these rockers for it, but has changed heads, hence now I have them, but his new heads have the larger stud, so he has no use for these ones. I can find out the rest of the info you guys are asking for tomorrow, as I will be going over there.

[Yonash70c20]

Okay so after talking to my buddy, I have a few options. I did find out my World heads are indeed the 64cc chambers. Depending on the type of pistons I should be using for this build, I have found a couple Scat stroker rotating assemblies on Summit for the area of $800-$1000, one or two even with forged pistons. These certainly look like good options for me, and hopefully won't take me too long to save up enough for it.

I apparently misunderstood what exactly I purchased from my friend, and it actually worked out in my favor (I have zero space in my garage right now, so i have yet to pick it up from him, and he has some room to hang onto it for me for a while). My $250 scored me a complete Vortec long block, not just a short block. So I would be willing to consider running the Vortec heads, but I'll need to look into the differences between them and my World heads, see which ones better fit my goals.

Anyone have any suggestions for a cam in a mild 350 with the previously mentioned Performer intake and Edelbrock 650cfm carb and some Hedman long tube headers? I'd like a little pep for the time being while I build the Vortec, which will also be used for mock up purposes on the chassis, no extra building, no extra work, just a warmed over 350 to keep me happy while I build a decent Vortec 383 haha.