Here's a strange one. I'm aiming this toward the engine building guys and the ones who've been there-done that.

If I wanted to keep a stock appearance on my '83 5 speed car, yet build up the engine a bit, what would be an optimum combination? with the following requirements

1. Stock type Factory cast exhaust manifolds (L69)
2. Smog compliance (egr, A.I.R., pcv, etc...)
3. Computer Controlled Q-jet (Factory stock for car)
4. Maintain Factory look (NO chrome, headers, holley, etc)
5. Pump gas and very good street manners
6. Dependability. I want it to last "forever"

Things to consider:

1. 350 vs. 305 (Which should I build?)
2. Gear ratio (I think car has 3.23s. Could go to 3.42s or so...)
3. Cam (reasonable idle, low range torque)
4. Compression ratio (see "pump gas" and "dependability" above)
5. Intake manifold (will stock LG4 be fine...can it be tweaked? would it be necessary?)
6. Head work (porting, is it necessary?)
7. Any other suggestions you have along my theme...

How would YOU (the experienced engine builder) build an engine to match with an exhaust manifold (as opposed to tube headers) and complete smog setup and CC Qjet?

I know there will be people wanting to post "why bother", , and that type of thing. I'm not building a car to win races, but I want to get a good baseline (drivetrain wise) to build a weekend driver, autocrosser type car. I want the engine to last virtually forever and get good power and economy. Not to mention...I have no money .

thanks for any insight. Sorry for my typically long post,
Clem

 

TTT

Thanks for any info!

 

Clem,

If you are giving us a choice, go for the larger displacement. The 350 will probably actually be more economical, too. Parts are certainly more widely available than for the 305. The external appearance is the same, but head selection is a lot better and you'll certainly have more potential for power. Fuel economy should be virtually the same. If you really want to get "stealthy", consider a 377 or 383 CID stroked 350. It still looks like the old 305, and can even breath fairly well through factory ram-horm exhaust manifolds of LT1 exhausts that are ported open. Add some larger valves and ports, and a moderate cam profile, and you can easily make 325 HP at the crank with what everyone will see as a "stock 305". And reliability shouldn't be an issue, since those power levels aren't anywhere near the limits of the SBC.

Keep the static compression ratio below 10.8:1 and you should be able to run pump gas if you keep the heads extra cool. Plan on keeping the EGR system to make sure you can use pump gas. A slightly newer Vortec truck engine might be a good starting point, since the PM rods are a little tougher than the older cast iron factory rods. You'll likely at least get a cast nodular iron crank instead of a gray iron casting with the Vortec, too.

Your heads should fit just fine on it, and you'll have the option of several aftermarket iron heads to work with as well, so it will still look very original to the untrained eye. Some nice ProAction or Dart iron heads with 2.05/1.65 valves and huge ports should feed a stroker pretty well, and no one will ever know.

I would plan on dumping the factory intake eventually, since even porting work won't change the runner design enough to make it effective on a heavy breather. The old Rochester will work just fine, however.

The later Vortec case will also be set up with a roller cam and lifters, and that will allow you to go a little more aggressive in your cam selection while still maintaining a respectable idle and good idle vacuum. A Comp XR-276 gives good power and almost no noticable lope at low idle speeds. Regardless of what you end up with for a base engine, try to stick with a roller cam. A roller will afford you more durability, reliability, the wider LSA for better idle quality at a given duration, and more power. You almost can't lose except for the additional one-time cost.

You're as devious as I am, aren't you? If they ask why they are constantly getting their butts handed to them, you can always tell them "It must be the window decals - they're supposed to be good for 20 HP apiece..."

 

Hey, Clem,

I don't have a tire-smokin' beast, but with the mods below, including the L69 exhaust, the old LG4 does pretty darn well--I'm getting 23 mpg with 3.23s. By the way, are all LG4 intake manifolds aluminum?

JamesC

 

Thanks for the info Vader and James,

I think I'm looking for a little more of a budget minded combo though. That said, I've got some more questions for you (vader).

On the 350/305 issue. I have two core 350s in the garage. I think they would be the easiest/cheapest/most versatile to build. So it sounds like the 350 is the best bet.

Stroker motor. Probably not yet. As you'll see, I'm probably going to relegate myself to a motor built cheaply with as many of the existing parts as necessary. I'll probably use cast pistons if that will be ok. (?)

Valves. You mention larger valves. How big should I go? Is there a point where the vavles become too big to see a gain due to the restrictive exhaust?

LT1 manifolds! (?) I don't know anyting about these. You've got me thinking though. I'd prefer the L69s since they came in thirdgens and should be relatively cheap. But I won't likely be able to find any locally, so I'll have to pay shipping on them and the Y pipe and then have the pipe welded up when I get it (cut for shipping I'm sure). Are the LT1 maifolds a good piece? Do they look like a factory thirdgen one? Would the corresponding Y-pipe work from a 4th gen car? You mention porting them. Do they need this to flow good? Are they better than L69s pre-porting? tell me more .

Pump gas. I'll qualify that a little. I'd like it to run on 87 if possible. You can get the ethanol added 89 for the same price here too so that would be ok. I don't really want to have to drive around looking for 91 or 92. I'm at 1000' here in Missouri (I don't think you're much different). Would 9:1 work well with 87 octane here?

Intake. Is the stock one that bad. I've heard varying accounts ranging form "it sucks" to "It's about the same as the edelbrock performer." The performer would be the only real eligible replacement candidate (hood clearance, rpm range, etc).

Roller cam. I probably won't be doing that for the simple fact that I've already got the block. I'd like to stay two piece rear main seal (flywheel compatibility) and the block I have fits the bill. I don't really think I'll see the potential of the roller cam and it's added (one-time) cost. If I ever come across a good deal though...it's possible.

I've got two '83 Z28s. The one I'm talking about now, I'd like to have become a weekend cruiser/autocrosser type car. I'd like to keep it looking like a factory "tuner" car (akin to a ford SVT or whatever). The biggest thing though is cost. I don't really have any budget for this and will do it as I can. Actually, I'll probably do a lot of the things to the 305 first while/before I build the long block.

[edit: reliability/dependability/durability are paramount here. I want it to last and last]

The other car can become a more radical car. Headers, no computer or emissions, 6 speed (or whatever), roll cage, etc. An open track type car...but I digress.

Thanks for all the input, I'd appreciate picking you brain a little more. If you want to shoot me an email...feel free. I'd love to chat sometime.

thanks
Clem

P.S. JamesC...I think the canadian cars had iron manifolds on the LG4s (at least some of them). I like your car (you sent me photos some time back) and would love to have one similar...eventually