hey everyone, I have a 1985 z28, with a stock non HO lg4. So my engine is rated at right around 155 hp, and well thats not very much!! I know everyone always says to just replace it with a 350, and i plan on doing that in a few years, but im going to college next year, and my 305 only has 60k original miles, im goin to college outta state and i plan on takin my car with me, so instead of puttin in a 350 now and putting all these miles on it, i want to just use my 305 until i graduate. but my problem is that it isnt very fast, i almost lost to a riceburner, it was not cool. So far i was thinking of maybe converting it from the 4 barrel carb set up to a TPI set up, and adding a new cam, porting the heads, cold air intake, and getting headers, gutting the cat and getting a nice exhaust system, or another plan i was thinkin of doin was upgrading the carb, maybe an edelbrock or a holley street avenger, the dual snorkel intake off a 305ho, or a cold air intake, and then pretty much all the rest of the same stuff i have in the above plan. I was wondering if you guys could give me some input, im hopin to get around 250-300 horse if thats possible, so if you guys know the cheapest or best way to achieve that your input would be greatly apprecieted. Thanks.

 

You'll get very little out of changing to TPI, might even lose some power. That's a very very low HP/$$$$ mod. A huge maze you'll have to run (wiring, a TPI itself, in-tank fuel pump, computer, etc.) with little or no cheese at the end.

Same for swapping out the carb. As long as yours isn't defective, keep it; it isn't what's keeping your car slow. Leave all that alone. It's entirely adequate up to at least 300 HP, probably well beyond that.

The dual-snorkel air cleaner from a HO car is the way to go. It's as superior to the typical open-element ones as those are to what you have.

Headers is a great idea. That's the very first thing to do. Don't gut the cat because the one that's on there is tiny and is still totally inadequate even gutted. Instead, get chassis-specific headers, not generic ones; and NOT FOR LG4. Get the ones for something like a 88 350 TPI car, and a driect-fit cat such as Catco and a cat-back exhaust to match. You'll have to do it all at once as a complete assembly from heads to bumper. Anything you buy that will fit to anything you have, will preserve the bottleneck.

THe next thing you need is a cam. I'd suggest a Comp XE256, with lifters, springs, and retainers to match.

After that, you need gears. Your car probably came with 3.23s. 3.73s work well with a warmed-up but mostly stock motor. You can lessen the limitation from your current ones somewhat with a looser torque converter if your car has auto trans.

I doubt you'll get it much past 250 HP; but still, that's almost 100 more than you have now. A major boost to say the least.

 

what RB said, hes knows what hes sayin. although i think he gets a kickback for recomending Comp Cams....jus' kiddin'. on my 85 lg4, i felt a difference just by adding headers.then when i mildly cammed it, it really woke up.just adding headers, exhaust, and a cam will make it respectable. better heads would be next, thats what im doin in a few months.

 

Yep, everything RB said.

Only possible addition is porting the heads and adding larger intake valves. But, not absolutely necessary. And, up to this point everything you've done will swap over to a 350, so leaving the heads alone is reasonable.

Well, I'd also add ignition upgrades, like aftermarket control module and coil. The factory parts are known weaknesses.

I'd also say the cam upgrade will make you want more converter stall. And, you probably have 3.08 gears - nice on the highway, not so nice at the stoplight (but better than 2.73's... ).

 

go to "400hp 305" and read my post there, it may give you some ideas. I have the dual snorkel ram-air deal on my 305 as well. I did keep the L69 exhaust manifolds, because (if I'm not mistaken) they're bigger than the LG4, plus I'm too old to screw with headers any more. So the headers were a good move on your part. RB83's suggestions sound pretty good to me too. Basically what you're trying to do is make it an L69.

 

would supercharging it do anything, or would that just cause problems?

 

It would cost a fortune

 

Weiand used to make a SMOG legal kit for the 80s SBC. It used a weiand 142 blower. The kit made like 5 psi which is perfect for most low compression 80s applications. You would have to use a cowl hood though. The kit let you keep the EGR and even worked with the LG4s computer. If you could float the $1,800+ dollars it cost. The cool thing is that the blower will bolt to any small block. If you want to build a 350, 383, or 406 later on, no problem just bolt it to it. I think the kit even had a CARB EO #.

In fact an installation of the said blower is even listed in the tech articles on this site. It isn't the smog legal one but it is close to the same thing. The smog legal on only has provisions for the EGR.

https://www.thirdgen.org/newdesign/t...2install.shtml

 

ok i guess supercharging is out then because i am gonna be in college so the things i get done to my engine are gonna be gradual like as i get money, i wont have enough to get a supercharger unless i save up for a long time

 

Note the sig. I've done nothing wonderful, but compared to the stock LG4, my 85's a hotrod.

JamesC

 

Take note of my sig too. This motor is in a 198? G20 Van backed to a 700r4 and 3.42 gears. It runs real well in this application. Makes me wish it was in a 3rd gen. I would be in the low 13s or high 12s with this in a F-body. In the 4,500# van it runs 15.5s all day long @ 88 mph and still gets 18 mpg. I love this little 305. It is still the factory LE9 van shortblock with 265,000 miles. I did the mods in the sig @ 160,000. It is time for rings, probably going to use the gapless total seals (got quite a bit of blowby and starting to burn oil, power and compression haven't dropped much though). I read in car craft total seals were worth 15 hp in a mild 350 not to mention less leakdown equals better mileage. The only thing with total seals are they are expensive. Might just use file fit moly rings. At 160,000 miles the bore showed no wear and still had a crosshatch that looked like new, no taper to the bore. I looked at it throgh a spark plug hole a few thousand miles ago and it still looks the same from what I can see. Probably just going to pull it apart, ridge ream it, break the glaze with a bottle brush hone, put new bearings in it, put new rings in it, reseal it, and drive on. In other words with 60,000 miles I would not be afraid to bolt parts on to it, change cams, port heads, etc.
(Just put this here for reference to a strong, cheap 305)