Mbchopkins

Hi, I'm new to these message boards, but I've messed with quite a few f-body cars. I just recently purchased my first third gen. Going into the purchase I wanted to change the engine as it already has a pretty good rear end and trans for racing/driving daily. The current motor is a pretty much stock 305 other than a mild cam, some really good hooker headers, and a Holley contender high rise intake with an edelbrock 600. The 305 runs great and pulls really good but I don't like 305's personally so I wanted to swap it. I'm shooting for a good 350-400 horse engine and I know I can get there with a 350 or a 400 small block chevy. I have a solid lead on a good core for both of those and was wondering what would really be the best option. I know my way around 350 small blocks really well but haven't really messed with 400's. I know the 400 would make way more torque but I also want a motor that can spin to around 7,000 rpm's easily. I just wanted to know a good opinion of people more familiar with the third gen platform. Thanks in advance.

Orr89RocZ

iTrader: (20)

I would look for a late model roller style 350 block, preferably 4 bolt main for 7000 rpm. 400 hp is easy with half decent heads. I would do a 383 for some cubes and torque.

Mbchopkins

I've though about that but I don't really want to do a roller motor. I know that it's easier to make power but I prefer older style blocks. I had a 94 z28 with the lt-1 and I made that thing run pretty well. I'd just like to make this more like an old school hot rod/muscle car that would have been modified and driven in the late 80's

Thirdgen89GTA

iTrader: (5)

Why are you limiting yourself? What you want is actually harder to obtain than a generic roller rebuild that uses vortec heads.

Rollers are HUGE improvements over non-roller, and parts are easy peasy.

Vortec 350 long block + compatible intake and carb + headers = 350hp @ crank all day long.

From a difficulty standpoint a Roller 350 is the same as a non-roller 350. The increase in ramp rate speed on the cams is a huge boon, along with additional reliability.

Unless you really want to build something serious, your goals of 350-400hp mean that you don't have to go beyond factory parts at all.

Also, for your HP goals, 7000rpm is completely unnecessary. If you are turning near 7000rpm on a 350, then you need to be shooting for 500hp at the crank if not more. And you are also talking cams that require more gear than you have.

Mbchopkins

I guess I wasn't very clear that this was going to be a kind of serious motor. I don't plan on having any factory parts if I can. I just wanted to use older stuff just because that's what I prefer. It's got a roller 305 in it right now. I just prefer non roller cams and such. Vortec heads are alright for factory but I'm planning on running aluminum heads. I'm leaning towards a 400 small block for the build but I don't know how well the third gen platform will handle the torque the 400 will make once it's all put together

Orr89RocZ

iTrader: (20)

Car will be fine with subframe connectors and a good set of tires and suspension

There is no difference in the latemodel blocks and old style blocks except the roller cam features and rear main seal style. Block accepts all the same parts as old school basically as far as heads and intakes etc.

The thing is, flat tappet cams are outdated old tech. Todays oils are not made for those cams and you are much much better off building a serious motor using roller valvetrain. You'll be at risk of wiping cam lobes. Hydraulic roller like factory 87-92 L98/LB9 tpi cars. Its well worth the cost which isnt all that much more. I would never build a flat tappet moror

Thirdgen89GTA

iTrader: (5)

Serious and 350-400hp aren't really in the same category. Flat Tappet should also be thrown away. The lobe profiles of todays Roller cams DESTROY flat-tappets. The ramp rates give you tons more torque without having to resort to longer durations.

Chassis will be fine with SFCs.

My 350 LT1 probably puts out close to 500hp at the crank. And while yes its an "LT1" there really isn't any technology in it that would preclude a similarly built SBC from attaining the same. LT1 is basically a slightly altered SBC.

midias

Listen to these guys flat tappet is not a good idea when you can go roller. It is number one on my list to swap out when a lobe goes flat. Previous owner installed this cam. 350-400 HP is EZ and does not even require alumn heads not even considered a kinda serious motor.

I swear I want to make it old school translates to I want it to perform worse.

Tibo

iTrader: (15)

If you want to spin to 7000 RPM with reliability multiple times you will need a completely balanced all forged rotating assembly.

Thirdgen89GTA

iTrader: (5)

7000hp?

I'm in for that.

Jeremy85

I totally agree with building what you've been craving, but tossing out a strong- running, healthy engine just because it's a 305 makes no sense. A parked car is no fun compared to a driveable car. You want to assemble that other SBC, do it. Once it's ready to fire up and run, then you can consider pulling the 305.
I'm in the roller- lifters camp as well, but the 305 I got, with the Camaro I recently bought is a non-roller, and I could swap in a '96-up L31 Vortec 350 for less than a set of retrofit roller lifters. But that same money will turbo my 305 to 400 HP, and it will pull through 6200 RPM, maybe higher with boost, without taking my Camaro off the road for even a single day.
Then when the turbo pops my 700R-4, I can get to swapping in my 4L80E.
You will be in a similar situation when your 7000-RPM build pops your TH350. Building them to hold 500 HP is no big deal. Building them for 7000 RPM takes a bit more.

sofakingdom

iTrader: (1)

If you don't already have this hypothetical motor, forget "turbo" on the 305 or the old-skool 350, and go get some LSx variant instead. A 5.3 pullout from a truck, straight outta the truck and dropped into your car, will do 350 HP with little more than headers (which you're gonna have to do for whatever you put in regardless) and a cold-air intake; and get 20 mpg in the process. Or you could do the same thing with a 6.0 pullout and get closer to 400 HP, but it'll cost maybe $600 or so more and only get 18 mpg.

MUCH MUCH cheeeeeeeeeper, eeeeeeeeezier, and more reliable than a buncha "turbo". Especially over the long term.

But of course if you want to "turbo" something, you'll get correspondingly more bang for the buck / effort / whatever if you do it to that LSx, than you'll EVER get out of a SBC.

It's 2017. Time to wake up and move on.

Jeremy85

Scrub that, my '99 Suburban K1500 has a stock L31, and my buddy has an LM7 Yukon, mine is heavier, but mine wins from a dead stop, and his can't catch me after that, on up to 85 MPH.
The SBC is cheaper, the car is already set up for it, the LS has no advantages below 800 HP, except maybe emissions, if that matters to you.

sofakingdom

iTrader: (1)

And that's the reason why it's GOOD ADVICE to a n00b (which is a VERY different thing from "I did it myself" or "I like what I've got") to keep a 305 and "turbo" it?

Last few times I've checked, a 5.3 was MUCH cheeeeeeper than a guaranteed-good L31, and FAR more plentiful besides... and the block has 6-bolt mains. As said, a 6.0 will cost a bit more, but will start out with CONSIDERABLY more power than a L31, and again, gas mileage savings over a few thousand miles compared to a L31 (which requires SIGNIFICANT upgrades over its stock form to become a "performance" setup, for example to the intake system) will eeeeeeeeeezily pay the difference.

It's 2017. Time to wake up move on. (yes I've been building SBCs for over 40 yrs now)

Mbchopkins

After thinking a lot I am going to keep the 305 for now just because it's already there. As far as the th350 the one in it is in kinda bad shape but I'm actually picking up a brand new one off of someone I know. I think I'll keep the 305 and save up for a blueprint engine to start with for an actual swap. At the end of the money I'll be taking the car to it's first drag race since I've had it. Hopefully I get at least some decent numbers with the mild 305 and th350

Tibo

iTrader: (15)

On the lines of what sofa said, Anymore, unless you're already invested into the sbc with reusable performance parts (ie good heads/intake/pan/headers/transmission) it doesn't make financial sense to stick with the sbc. If you also factor in the dramatic drop in turbo system prices for the LS world it doesn't even make sense to rebuild anything that's making less than 600 wheel horsepower.

NoEmissions84TA

iTrader: (1)

I'm with you.
I'm making my 84 TA like an 80's musclecar - without the emissions crap.
Because that's what I want.