96 9c1 mild project

[91Caprice9c1]

Hey folks,

I've recently purchased a 96 Caprice 9c1 LT1 after running my 91 9c1 L05into a tree (heheh yep..) Anyhow, the car has 52k miles on the drivetrain (refurbished at 100k miles) and I was wondering what kind of stuff i can do to it (safely, tastefully, and without sacrificing too much longevitiy) to bump the power up because excessive is never enough right?

I've read about the lt4 knock module, which seems like a worthwhile mod for the effort and little money involved. I'm a handy mechanic, and im not afraid of more intense jobs. I'm thinking maybe a cam? Will a hotter cam set me up for catastrophe? if not what cam should i look into and will the computer need reprograming? Any other ideas besides cold air intake and exhaust?

The LT1 is all stock right now, stock intake, stock dual exhaust, runs strong, no leaks.

Thanks

Matt

[Blue Bowtie]

Port up the stock iron heads, since they already outflow many aftermarket heads. Install larger valves. The iron heads have induction hardened seats that are usually deep enough to take 2.05/1.60 vlaves, and will easilly take 2.02/1.60 valves. Pull the studs, machine the bosses down about 0.400", and tap the holes for 7/16-14 to accomodate screwed rocker studs. Install guide plates or 0.150 spacers. Machine the spring pockets to 1.32" and install LT4 Hot cam springs or aftermarket springs with 120# of closed seat pressure. Pull the balancer, water pump, Opti, timing cover, and timing chain. Slide the old .420/.430 can out of there and install a Comp Comp 07-304-08 or Comp 07-305-08. Port match the stock iron exhaust manifolds or install Tri-Y headers. Reprogram for a slightly higher injector constant, increase the timign at middle load values between 1600 and 4400 RPM, and drop the upper RPM range timing under high loads. Program about 100 RPM higher for target idle, start it up, and enjoy.

[1986Z28]

chip, cai kit, better exhaust, underdrive pulleys, bigger cam etc.., btw blue bowtie thats sounds like alot more work than he wants to do

[Blue Bowtie]

A few hours of actual work, less than $1,000 in parts and supplies, and an increase from about 260HP factory at the crank to 315 at the wheels (340 crank) make it worthwhile. You can spend well over $1K in sheaves, exhaust, and a reprogram, and not get anywhere near the gains of a cam and head rework. BTW - That $1K in parts includes a new Opti cap and rotor.

I'm a handy mechanic, and im not afraid of more intense jobs.

I took that to mean he didn't mind a little work. Heads and cam are nothing I would call "intense" anyway. That's just a straighhtforward R&R job. Besides, fresh heads and valves couldn't hurt an engine with a few miles on it, even if it's fairly fresh at only 52K.

FWIW, underdrive sheaves on a street vehicle often produce more problems than the 2-3HP at peak are worth. By the time you factor the alternator actually placing more mechanical load at idle due to spinning slower, and the heat generated, it's a real PITA. Everything else is simply an idler as long as the P/S pump is in bypass. That set of sheaves will cost as much as a set of Manley Race-Flo intake valves, and won't do nearly as much good.

Incidentally, you can use the Comp 07-304-08 with no reprogramming, although reprogramming alone is worth something, even without any hardware changes.

[91Caprice9c1]

Originally Posted by Blue Bowtie

Port up the stock iron heads, since they already outflow many aftermarket heads. Install larger valves. The iron heads have induction hardened seats that are usually deep enough to take 2.05/1.60 vlaves, and will easilly take 2.02/1.60 valves. Pull the studs, machine the bosses down about 0.400", and tap the holes for 7/16-14 to accomodate screwed rocker studs. Install guide plates or 0.150 spacers. Machine the spring pockets to 1.32" and install LT4 Hot cam springs or aftermarket springs with 120# of closed seat pressure. Pull the balancer, water pump, Opti, timing cover, and timing chain. Slide the old .420/.430 can out of there and install a Comp Comp 07-304-08 or Comp 07-305-08. Port match the stock iron exhaust manifolds or install Tri-Y headers. Reprogram for a slightly higher injector constant, increase the timign at middle load values between 1600 and 4400 RPM, and drop the upper RPM range timing under high loads. Program about 100 RPM higher for target idle, start it up, and enjoy.

Wow, thank you very much for the thorough reply. I like the idea of all this head/cam work I have only two concerns: Reliabilty/Longevity and California Emissions. When I decide to push some two-foot-rear-winged-body-kit-ricer off the road and wind her out to 6-7k (which may happen fairly often as I am an abusive driver) will all this top end stay together? And when I get a smog inspection do you think this will be a passable set up? (smog isn't as big a deal of course because you can always drop a few hundred bucks to have it bootleged) But I would like to feel safe about traveling in the car.

Now i'll be sending the heads out to have all the machine work done. However, I have no experience reprograming ecu's. Is this something I should attempt myself? Or should I have it dyno tuned somewhere?

[HLandin]

You said it was a 9c1, so you may not have to worry about emissions as much (hopefully). I do know that when departments/municipalities buy police package cars, they only are required to meet federal emissions (even in California). Its been that way since 1983.

[silicon212]

Originally Posted by 91Caprice9c1

Wow, thank you very much for the thorough reply. I like the idea of all this head/cam work I have only two concerns: Reliabilty/Longevity and California Emissions. When I decide to push some two-foot-rear-winged-body-kit-ricer off the road and wind her out to 6-7k (which may happen fairly often as I am an abusive driver) will all this top end stay together? And when I get a smog inspection do you think this will be a passable set up? (smog isn't as big a deal of course because you can always drop a few hundred bucks to have it bootleged) But I would like to feel safe about traveling in the car.

Now i'll be sending the heads out to have all the machine work done. However, I have no experience reprograming ecu's. Is this something I should attempt myself? Or should I have it dyno tuned somewhere?

Send the heads out to a good, reputable shop. Nothing quite as maddening as a machine shop bunging a good set of heads and charging you for it. As for the reliability at high revs, really the #1 issue is the valvetrain, of course. Key is the quality of the valvesprings - you don't have to go insane here, but you will want enough spring to prevent floating the valves into the pistons at that high RPM. COMP has great valvesprings that will withstand those revs, check out their website for information. Good rockers and valvesprings, and those Manley RaceFlo valves (which are single-piece stainless steel - I've got a set in my engine w/ a quarter million on them) are all you need. For rockers I recommend 1.5 ratio COMP Magnum chromemoly rockers - you can go 1.6 if you wish, but check valve lift and clearance first.

I don't have any experience with PCM programming, so I can't help you there.

[Blue Bowtie]

I've got the Comp cam, stock roller lifters, LT4 valvesprings, titanium retainers, Comp 1317 rockers, and Manley valves and often shift 1-2 and 2-3 at about 6,300 RPM. I haven't broken anything in almost 20,000 miles of that, but I'm thinking the 8½" rear end may be the first to eat it.