Thinking about building my 305 since it already has some aftermarket parts thrown at it from previous owners. (I’m the 9th. And it has 82,000miles)the car is an 87 trans am. And I just want it to be faster and make around 300 hp. Don’t know what motor I want in it eventually but I want a high revving old Chevy v8 or supercharge a 350 sbc. Anyways does anybody have any thoughts?

Plans is to make it street able and be faster and make it look like a scca car

 

It would be faster and easier to achieve your goals by starting with a roller cam 350.

 

fair but I also don’t have the money to start building a 350 and I want to replace it with a crate motor or a brand new block when it comes to it but what block casting should I be looking for if I change my mind and buy a roller 350?

 

Which 305 does it have?

 

Sure you do, pull any old L31 that looks good out of a gmt400 and build that.

 

On the vin it originally had a 4 barrel carb on it from factory. But the intake and carb are aftermarket. I’ll get a picture taken of the engine bay when I get home. The carb is an Edelbrock performer 1406

 

Hoping you find a solution. My investigations from long ago came up with expensive head porting. These guys used to talk about 305 heads on their website, they had some really good flow numbers, but dont see it anymore. https://www.castheads.com/

 

So, the LG4.

Its strongest weakness in stock trim is/was the exhaust. EVERY SINGLE PIECE from the heads to the street HAS TO GO. Get a set of good-quality headers such as Dyno Don's, a stock replacement cat for something like 89 350 TPI, and a good cat-back such as the Hooker.

Then, a decent cam. It would have come with a roller system. With luck, none of the car's POs decided to "throw at it" some old POS flat-tappet. I'd suggest a Comp XR264HR. Use LS6 valve springs with the Comp 787 "adapter" retainers. Those springs give you about .525" of lift capability comfortably, WITHOUT requiring ANY machine work.

All of those things will transfer over to a 350 when you come to your senses and realize that you've wasted your time and money on that 305.

WHATEVER you do, DO NOT touch the short block!!! Because, when you DO figure out that you're at a dead end, EVERY PENNY you spend on that, will go in the trash, where it belongs in the first place. DO NOT buy ANYTHING that is specific to the 305. That means, pistons etc., and ANY machine work to the block, crank, or heads. DO NOT do that, as all of that will go in the trash along with the parts. Money down the drain.

It's a 305. It isn't, never was, and never will be, that. Don't be ridiculous and get greedy. Get what you can out of it and consider yourself lucky. 300 HP at the crank is pretty much about the outer limit of what you can hope for, and that ONLY if you do everything EXACTLY right, without cutting corners; and you probably won't quite get there even then.

 

All of ^that^. An LG4 car w/cam headers/exhaust and an intake is a fun car. It's a mid 14 second car, so not real fast but it'll make the right feels/sounds/experience and be almost twice as good as the stock-parts, 305.

However....IDK your financial situation other than that if you don't think you can afford a 350....I'd seriously question putting any money into that particular car. You'll never get that money back. ka-FLUSSSHHHHH!...glug-glug-glug!

 

It is not hard to make 400+ hp from a mildly built 305. They will rev 6,000+ rpm while making actual power without much difficulty and make power as high as you dare spin the cast crank. It is just easy to build more cubes. To me, why stop at a 350?. Grab a 400 it will amplify anything you do to a similarly built 350.

 

So, I'm putting a stupid question out. Is the lg4 bottom end/block made from lesser quality parts than a 350 of the same year? I'm well aware of the fact that stock bottom ends have a limit and stock parts have a low hp limit. But I've seen plenty of people do some pretty silly stuff on a stock bottom end of a 350. I know it's likely not gonna make a ton of power vs a 350. I guess what I'm getting at is the limiting factor the bottom end or more just the heads/intake/cam and displacement.

to the OP, I agree w comments of the exhaust flow comments. Headers/exhaust make sense. More than that you're gonna open up a can of worms. I pulled the LG4 out of my car in 2000. I'd chill and save money for a 350 swap. A set of headers and exhaust will fit a 305/350. When I pulled my old engine I swapped in zz4 w a standalone EFI system. It was a massive change from the 305. Then in 2019 I put bigger heads/cam w a modern EFI setup. Again it was a massive difference. Swapping to a bigger engine allowed me to build on it more over time. Something to keep in mind is the rest of the drivetrain and brakes. Your car looks to be in good shape and I bet will be a good car to build. Just take your time and plan it out. It will save you money and headaches in the end!

 

I don't know what's in that year of LG4. I doubt it's got the X rods like the L69 did. It certainly has a cast crank and cast pistons if it's still stock. (which judging by the "aftermarket parts thrown at it" deal, who can be sure?) In the end it's not so much a question of the quality of the parts, as the stress you have to put on them to get the equivalent result. HP = RPM x torque AT THAT RPM ÷ 5252.11; to get more HP out of a 305, you have to wind it out to a higher RPM than a 350, all else being equal, since a 305 will produce about 305/350 as much torque at any given RPM, all else being equal; would the parts that live happily at 350 HP at 5500 RPM in a 350, even if they're THE SAME, live equally happily at 350 HP at 6500 or whatever in a 305 to get the same HP? Iunno.

THAT'S WHAT'S WRONG WITH THE 305. Just like when I got into this hobby in the 70s. Back then, 283s and 327s were the "old skool" thing. You could pick em up laying in the gutter driving down the road, they were SO common. Butt then when 350s started becoming plentiful and cheeeeep in the junkyards, I got my A$$ HANDED TO MY 283s and 327s by this "newfangled" contraption. Dollar for dollar, part for part, effort for effort, reliability being equal, the old little motors couldn't compete, PERIOD. Didn't take me losing too many times before I realized that "old skool" is for suckers.

Why of course "they" do. Even I do, on occasion.

OTOH, how silly do you want to spend today, sir? Got a 2nd car to drive while this one is sitting around waiting for some part that broke to show up and be installed? The way hot-rodding works is, each time you strengthen one thing, it exposes the next weak link, endlessly; a hot-rod is NEVER "finished" because of that, especially if it gets put to the test often. Got plenty of money to ride the bus or the train? An endless supply of friends and relatives that'll loan you a car at no cost?

What do you REALISTICALLY - as in, LOOK AT your paycheck from THIS WEEK and your bank account after you paid the rent and insurance and food and ... yeah ... - have available to spend on all this? Balance your goals REALISTICALLY against your resources. Will you have a "silly" car today butt be ALTOGETHER BROKE for the rest of your life because of it? Think wisely. There's more to this long-term than just "I wanna go fast". Or even, "I can go fast when I want to now".

My EXACT advice, in a nutshell; just expressed from the opposite direction of arriving at the same point. If you want BIG power, you're not getting it with a 305, at least not more than once or twice without a shrapnel experience. Best to spend AS LITTLE AS POSSIBLE on that 305, and whatever you DO spend, MAKE DOUBLE DAMN SURE it can be carried over to a better platform; and SAVE YOUR MONEY for what you REALLY want. Every PENNY you put into that POS sets you back ONE PENNY FARTHER from whatever it is you REALLY want.