[rreruption]

A friend of mines has a vortec 350 in his Yukon.Its fuel injected.And he wants to know If I can do a performance rebuild.(More Compression,More cam,Better exaust,etc.)I just wanna know If I can rebuild it?Or do I have to take it to the shop?Or can you make any Changes at all?
I was thinking of,
A low end roller cam(more than stock maybe a comp)
A 383 stroker kit(Around 9.5:1)
Maybe a gear drive(he likes the sound)Or a good timing chain
underdriven pulleys
Edelbrock intake
Magnum roller rockers 1.6 ratio
Upgraded springs,and screw in studs
Headers,X-pipe,and he already has a pair of original 40 series flows.(He will still run cats
Is all/any of this possible?Will the computer be able to run?Im only really experianced in older stuff.But Id like to figure out if any of this is possible.Thanks.

 

[DoubleVision]

A gear drive is out, the noise will be picked up by the knock sensor and will retard the timing. More cubes you can do, but the computer will have to be remapped. Vortecs came with 9.3:1 compression ratios which is close to the max for pump gas. Headers, X pipe, intake, rockers, you can all do without issue, I don`t know of any company`s that make a cam for a vortec, but I`m sure there is, I`d advise calling them and asking what they would recommend that wouldn`t require the computer to be remapped and would be street friendly. If the lift isn`t over .500, you don`t need screw in studs. Make sure the rockers are self guided.

 

[curtis73]

Every cam company I know of makes vortec cams. They're just roller SBC cams, nothing special. I like Crane's line of Compucam sticks. Make sure you know which distributor gear you want on it because their default is cast iron.

Anyway, 112-114 LSA and a mild intake duration around 203-210 should do really well on a 383. Torque monster You can bump compression a tiny bit if you want, but 9.3:1 is on the ragged edge with 87 octane. Once you exceed the realm of what the knock sensor can compensate for, you're into 94 octane territory. 9.3 is PLENTY fine. Bumping it will only add a few hp and you'll be into custom-programming a new timing curve. Not worth it in my opinion.

I shy away from underdrive pulleys. They advertise big numbers, but the ones I tried only added about 3hp. They also slow down the waterpump and alternator which frustrate me. Again, not worth the potential overheating in my opinion. You'll be adding a substantial amount of power so you need all the cooling you can get.

I also shy away from gear drives. Like DoubleVision said, it will play games with the knock sensors. They also are VERY hard on valvetrains. They're great for race where you tear the engine down all the time, but I don't like them for a reliable street build. The crank is singing with harmonics as if it is getting hit with a 10-lb sledge hammer 2000 times per minute at IDLE. With a gear drive, all of those harmonics are directly transferred to the cam, cam bearings, lifters, pushrods, rockers, distributor... not good. A good true double roller chain is just perfect. 150,000-mile reliabilty, dampens those vibes, and stays accurate just as well as a gear drive.

The rest sounds great. Really your only big cork on that engine is the factory cam. Its not the greatest. The heads are already fantastic as-is. The compression is fine. I'm not sure what the factory intakes are capable of flowing, but it might be worth investigating. Cam and 383 should make an easy power bump.

 

[rreruption]

Sounds good.Is there any worry about changing the programming?Can I do This work myself without a shop?Or Should I build the short block.Then have the shop do the rest?

 

[rreruption]

So would a 9.5:1 383 mess with the computer?9.5:1 is only a little more than 9.3:1

 

[curtis73]

I don't think 9.5 would mess too much with it, but they are designed with very little buffer. A tiny bit more compression or a tiny bit crappier fuel seems to default them to full retard and then you're either looking at swapping to 93+ octane or putting up with the loss in power.

I put a more aggressive timing and fuel curve on my 96 Impala SS and it took my octane requirement from 87 to 93. The best I can get here is 91 and I get some audible ping when the A/C is on or its really hot.... and thats on factory compression even with lowering the stat temp to 160. The nice thing about vortec heads is you can drop total timing to 32* and not lose any power... those heads are very efficient and that's part of the reason why you can run 87 octane with 9.3:1.

Hacking an OBD2 GM computer isn't easy and the sofware/hardware required to do it can cost well over $2000. I'd suggest talking with Bryan Herter at pcmforless.com . He has the equipment and the knowledge and he might be able to help. He's also not big business so he doesn't charge an arm and a leg. Make sure to tell him that Curtis Mittong sent you. He may or may not remember me, but I think he keeps track of referrals and I'm saving up for a big one

 

[Vortech 4.3]

96-97 vortec trucks obdii computers are fully adjustable. i have the software to do it. but, you better know what you are doing. otherwise you are waisting your time, at best. a mailorder is probably the best for you. unless you are always modding the truck, like i do.

 

[ChevelleSS_LS6]

if he likes gear drive whine, go for a blower :evil:

cam and good rebuild aside, gapless rings and quality headers... crank scraper (easy to home build one, keeps oil from getting splashed around the crank when it would be better used getting pumped around the engine)