So I got a 83 z28 with a 305 in it. Its in running condition, but a lot of work needs to go in to get the power up in it. Since the 305 was never intended to be a high performance engine Im thinking swapping it out for a 350 will produce better results in the future.
Is it worth doing the swap? or should i keep the original engine?

 

Yes, no

 

Well this was helpful

 

Yes you should do the swap no don't keep the original engine. Answered in order exactly what you needed to know.

 

It basically is up to you in the long run I would say yes unless it's a super low mileage all original car but hey that's my .....

 

Headers, free-flowing exhaust, and a cam swap will do wonders to how the 305 will run.

Doing headers, free-flowing exhaust, and the same cam in a 350 would about double the improvement (not the power, the improvement over the stock 305).

Doing a 350 swap in place of a 305 without doing headers and free-flowing exhaust won't yield much better results than the 305 with headers, free-flowing exhaust, and cam swap.

Do you see a common theme here?

Pretty much all of the factory 350s were dogs as well. The ones that weren't won't be on eBay or craigslist. Meaning more details need to be addressed than "350".

 

If you are wanting performance out of your car and plan to mod the engine, then yes the 350 swap is what you need.. It's a better base to work with, bigger bore, not limited like the 305.

The 305 is the small block with asthma.. It can't breath good.

Like five7kid said though, stock 350's for the most part are dogs too.. Unless you get a 70/71 LT1 350 or a 96-00 vortec 350, but all 350's will respond better to mods than a 305 will.

Keeping your stock engine, well if you have the room to do so and if you think you may sell the car 10, 15, 20 years from now it would be worth while maybe, but storing an engine for 20 years in hopes that it will help the resell vaule of a car with quite a lot of miles on it is not very practical

 

At the tail end of my swap that I started last year.

Bought a L98 350 that came from a 89 IROC ... It's a roller block..good thing
Had it rebuilt. Bored .030 over. Custom cam. Vortec heads off a 99 blazer.
dyno don headers. Magnaflow exhaust. Estimating around 400hp at the crank.

 

Did you see the PowerBlock tv series they did on using a Summit block and other parts to make a nice 383 combo? This was about a year ago, I think. Much better low end torque and about double the hp. It seems like the lowest cost way to get my 87 Formula 305 back on the road unless Overhaulin' wants to use my car for an episode...

 

The "SEARCH" function works wonders....

 

I'll throw in here because I've been looking at the same thing. Do the swap. All the performance stuff the threads talk about for the 305 don't seem to exist anymore. 350 parts are plentiful and cheaper.

 

Every part that will bolt onto a 350 can be used on a 305, save for the pistons. There is still "performance stuff".

Not trying to say dumping the 305 is a bad move, I'm doing it myself, just saying you can work with them if you want to.

 

The heads won't, 58cc chamber (305) vs 64cc (305). The heads are the trouble I'm having, don't want to modify 350 heads to work. I'm keeping my 305 for now, only 60 thousand miles on it, but most of the stuff you find with the search function is 14 years old and a lot is not available. I'm getting a crash course in engine building by cross referencing specs from the old threads with what is available now.

 

Heads will fit just fine. Corvette L98s used a 58cc head IIRC. Compression might be too high if you don't use the proper piston though.

 

Swap complete. A few updates for those tracking:
1- new blueprint 350 crate. I didnt go 383 as i felt the 390hp/420# would be plenty. Had a shop do the work, (lucky to find a shop that would, most wouldn't touch it). There was a lot more labor and custom work installing the motor than i understood.
2-added headers, 3 inch exhaust
3-with the 305, the exhaust note was no louder than a civic. With the crate motor and headers, the same muffler is over the top loud, putting a magnaflow on it with some baffling to make it drivable
4-went 350 thinking the current cooling system and rearend etc would be good. Well... it overheats on a hot day now, so adding a four core radiator, dual fans.
5-with taller tires (car is sitting on lowering springs with riddlers now), and the 5 speed, the car just feels like its geared too high. Gears are long. Going to swap rearend gears to 3.73 this winter.

Its a fantastic car now, but we are deep in the rabbit hole, and by admission I'm not a mechanic.

 

ARE you the OP?

NICE to hear an update! So many Threads die without conclusion or updates.

 

OP? original poster? yes, i'll put some pictures up when i get it back with the final work done.

 

I've got an 84 Camaro Berlinetta (305/Q-jet) that I'm considering doing the 383 swap to. Did you go with EFI, or keep the 4BBL carb? And which headers worked with the swap, since the 305 exhaust manifolds are too restrictive. Let me know if you can help, ok? Jim email:sales@scumbackspeakers.com

Thanks in advance!

 

After research and thinking about budget, we went with the 670 cfm Carburetor, part of the crate motor set up. This simplified the entire build. You just need to deal with the fuel lines and fuel pump. Finding the right header for this set up was key too. Doug's headers. They are excellent quality. I kept my original cooling system, as i was hoping to match the driveline, cooling, brakes, etc., without rebuilding entire car. Truth, it worked, but shortly after did a massive upgrade on cooling system as well to keep temps down.

 

I've got the 700R4 speed auto transmission. Is that what you had, or the manual tranny? Thanks for your reply, too!
Jim

 

Mine was a RS, with the 305/5 speed. Which is the perfect sleeper. I did upsize the tires / wheels and lowered it (not quite a sleeper, but clean as can be). Next move is a lower rearend, i'm geared too high.

 

 

This is my 84, with a Z28 front end. The paint is something I came up with years ago. Like to have this car go as good as it looks...for once. LOL
I gave it to my nephew in 2013, but he's been unable to upgrade it in CO since they adopted the CARB regulations. He already bought a complete
Hotchkiss suspension kit, etc for it, too.

84 Berlinetta w/Z28 front end, custom paint.

 

Yes swap please.
I Have a question for some options..... First off I have a 1987. 2.8 MPFI V6 sport coupe with t-tops, got it cheap. Did a top end myself. She runs great and the body would blue paint. Original looks sexy. However, I also bought an 83 berlinetta sport coupe with t-tops, stock 305 700r4, I bought a running 350 out of an 86 Silverado, just to learn I'm doing the complete swap using that trans. In the process of disassembling the 350. Doing the rebuild and putting it in the berlinetta, everything is the body on the berlinetta is not that great, t-tops interior wheels, brakes seats – everything is nowhere near as nice as the blue Camaro. Does anybody think I should use all my parts from the blue car and detail out the berlinetta or just say f*** it and drop the 350 into the blue car using all the parts from the berlinetta? Also the 305 block only is for sale if anybody needs one.

 

Did you convert to a true dual exhaust system, or still the single Y pipe setup?

 

How much torque is the T5-WC rated for? The trans is why I kept the 305 L69, I can't afford a Tremec.

 

Can't say. Don't think "rated" matters very much.

I WILL tell you though, the first 4 or 5 I tore up, were with my OE 305. (83 L69)

 

LOL. Thanks for the encouragement SofaK!

 

I've even heard of people that have tore em up with 6-cyls, but that's just hearsay, I have no experience whatsoever with 6-cyls. (and intend to keep it that way) Just, tearing up T-5s. Which is REEEEEEEEL EEEEEZZZZY.

 

I have read it is about 280 no idea if that's true but mine has been holding up just fine for 7 years behind my 350 but I don't drive it very nice at all

 

I had a regular t5 behind a zz4 for years. I did lots of burnouts, and beat it pretty well but was careful. I'd call it "cautiously abusive". It held up till I removed it and swapped a t56. I think it's doable to keep one alive behind a 350. How long and how much it will handle is certainly a question and your results may vary!

 

Looking to go with a 383 410hp 87 octane BluePrint engine long block to swap in and take my 305 V8 out. Does anyone know if the 305 harmonic balancer and pulleys work on a 383 block? Trying to minimize the whole swap out of the AC, PS, ALT, etc accessories for the new motor. This is what I'm hoping to put in.

https://blueprintengines.com/collect...-for-87-octane

Thanks in advance!

Jim

 

The pulleys will all be the same. The balancer will depend on the crank used I think

 

Time to contact Blueprint on what's compatible, I guess. The HB they offer is not used with this particular engine, so maybe it will swap directly. Thanks for your reply!

 

After more research, it turns out the 383/400 cranks use a different harmonic balancer than the 305/350 setup. So I'll need to buy a new HB for the 383 stroker. Does anyone have experience with the flex plate & flywheel compatibility between the the 305 and a 383/400 block?

 

It's not a balancer. It's a dampener...

 

Actually it is a harmonic balancer on the BluePrint site. Other sites refer to it as a harmonic dampener, so you're 1/2 right.

 

I'm 100% right. It doesn't balance anything. Its job is to dampen torsional vibrations from the crankshaft...

 

And yet BluePrint has it listed as a harmonic balancer, not a harmonic dampener. I suppose Blue Print is wrong, too?

 

You're both right. It's a damper. It's a balencer....in some applications and is called a "balancer" by name not only by BluePrint, but also by GM...much to my chagrin.

On neutral balanced engines, such as the 305, 350, and every other SBC (besides the 400), it balances nothing and is strictly a harmonic damper and pulley flange.

On externally balanced engines, such as a 383, 400, Ford, AMC and other V8's, it also serves as a balancer, as well as a harmonic damper and pulley flange. So what to call it?

IDK. Either? Both?
I call 'em Dampers, on 265, 283's, 302's, 305's, 307's, 327's, and 350's. I call them Balancers, on 334's, 383's and 400's....and "the other guys" engines.

 

Thanks Tom...