i was tearing down my L03 after spining a rod bearing
and found it had aluminum pistons i was always told 305s had cast iron pistons i also looked on summit and jegs and can only find aftermarket cast iron pistons
anyone elses 305 have aluminum pistons? i tore down an 88 L03 and and a 89 lb9 and both had cast iron pistons
so far my 91 L03 and 90 Lb9 both have aluminum ones
the part number is GM 14093663 3A they are dished with valve relieves and have a # 1 dead center on the top of the piston

also to anyone thinking about keeping the swirl port heads junk them and get something else
the pics they have posted on other threads dont tell half the story when you can compare tpi heads and swirl ports you instantly see why swirlys dont do well at higher rpm the swirl ramp is a major blockage when viewed from the intake port the pics posted of them only shows the view with the valve removed
after looking at both the 081 and 187 heads side by side you see the 081 is a better head

this was my 1st engine tear down about to put in a 90 lb9 engine

also anyone wanting to know the weight of there engine 305 engine
i weighed everything as after i removed it i rounded up on everthing to the nearest pound
tpi intake complete 30 lbs
tbi intake complete 18 lbs
harmonic balancer 10 lbs
valve covers steel 4 lbs
timing cover 1 lb
timing chain/camgear 2 lbs
waterpump iron stock 15 lbs
camshaft peanut 10 lbs
cylinder heads complete 100 lbs both
rods pistons 20 lbs for all 8
roller lifters spider pushrods 7 lbs
flexplate 5 lbs
crankshaft 58 lbs
engine block 145 lbs
every nut and bolt 11 lbs
-----------------------------------
388 lbs for longblock 305
406 lbs for stock tbi 305
418 lbs for stock tpi 305



waterpump alum vette 6 lbs
exhaust manifolds stock pair 22 lbs
Tes headers pair 17 lbs
i did this out of boredom with a bathroom scale lol

the weights really surprised me compared to the fact that most sites say 525lbs for a sbc with aluminum intake

 

Pistons are always aluminum. There hasn't been a cast iron piston put into a production engine in 80 years, probably.

 

Everything I have ever taken apart has cast aluminum pistons. I dont think chevy ever used cast iron pistons in the 305.

 

Actually, the first aluminum pistons for GM were for the new vette back in 1953. No V8 Chevy since then has had iron pistons. If you think I'm wrong, get a magnet and see how it won't stick.

 

Earlier than that even. The original Chevy Straight-4 had aluminum pistons in 1928 until they went back to cast iron for the Stovebolt-6 in 1929.

 

ALL 305s had cast aluminum pistons. Some were fully dished, others were semi dished with 4 valve reliefs, and others were flat-top with 4 valve reliefs.

081s are not necessarily better than the 187s. It depends on what you are trying to do with it. The 081s flow a little better on the intake side, but have a much slower burn and worse exhaust port flow. This allows the 187s to make more torque over a wide RPM band than the 081s. To 4,500 rpm the swirl ports will make more HP/TQ. On a 2.73 geared car with the stock 1,600 rpm torque converter and stock governor in the trans, the engine may never reach a rpm high enough to benifit from the 081s, making your car SLOWER. You will also lose fuel economy with the TPI heads on a TBI.

That 525 number that is often quoted is a dressed engine, WITH fluids in it. You have to remember the 5-6 qts of oil have weight as do the 2-3 gallons of coolant in the block/heads/intake.

It sounds like you do not have the manifolds, starter, flywheel, accessory brackets, alternator, ps pump, a/c pump, etc on it.

Your 305 seems to have a very lightweight casting. The block dressed with 4bolt-caps from my 1983 G20 van was 193 lbs!

 

Aluminum pistons are either cast or forged.

I have lots of stuff if you are looking for something for your set up.
I am in Lakewood


Jeff

 

the reason i figured they where different was the 2 305s sitting in my Friends back yard the pistons are rusted its news to him as well that all pistons are aluminum .

After so many trips to junk yards seeing rusted pistons as well like i said i never tore down an engine this far before ,
and i could have sworn i saw cast iron pistons on summit but apparently they are just type o's as for that i guess you live and you learn

Fast355 what is your deal with tbi parts being the best in the world ?
The heads have a huge wall in the intake port .
People complain about the minor blockage in the tpi plenum but its minor compared to the wall in the intake ports I'm just amazed they flow at all after seeing that major restriction Ive heard before there better below 2000 rpm not 4500 , All i know is when the car was tbi i didn't pull much at all after 3000 and even with tpi it didn't pull well after 4000 . But then again I'm now comparing these to my lt1 wagon daily driver that doesn't stop pulling lol.

From viewing without the valve sure it looks like a good idea till you look into the intake port .
about the only thing redeeming on them is the exhaust port .
ill even say the tbi heads look better manufactured then the tpi heads better casting process .
but that intake port sucks once you get inside
they don't add any economy over tpi heads only thing id see them useful for is starting off with a large load but then even gm got complaints about them and offered a replacement standard port head for trucks and suvs

after taking it all apart comparing tbi parts to tpi parts , its amazing tbis make even the 170 there rated for .
tiny cam , crap heads , even worse exhaust , restrictive intake and tiny throttle bores to boot .
sorry the pics are crappy but they get the point across the tpi heads are a set off the engine with rusted pistons hence why i would assume them to be iron unlike mine that i pulled out

as for the weight i thought the block was kinda light as well i just wanted to see the difference because when they list weight for aluminum block engines its normally the bare engine pan to intake IE in "crate form" the one rating i found for l98 was 600 and that seemed way to heavy and the other weights like i said 525 aluminum intake also seemed heavy .
i also weighed the starter 14 lbs i wouldn't consider coolant in the weight or oil as you don't ship an engine with fluids in it ,
also weighed the flex-plate as i don't have a flywheel i didn't add in the manifolds as i don't consider them to be the engine itself nor is the accessories .
I could never find listed weights for any of the parts online like i said i was bored and had time besides the brackets don't weigh more then 3lbs each there pretty light in serpentine cars at lest .

 

The tops of the pistons you saw in the junkyard weren't rusted. That's carbon deposits from combustion, and if it's in the junkyard, probably from excessive oil consumption.

 

TBI heads pull better up to 4,500 RPM than TPI heads, MULTIPLE dyno tests have exhibited this. Even Dewey 316s larger cammed L03 with a single plane manifold made more power under 4,200 rpm than ported TPI heads did. I don't know where you come off saying the economy of TBI heads is not any better, it most certainly is. Anytime you are able to get more tq from less SA, the engine will take less power to run itself. That means better fuel economy. I put down 176 RWHP/261 RWTQ with only an edelbrock intake and thorley Tri-Y headers on an otherwise stock L03. Stock cam, stock heads, stock TBI. It had torque down low and was fun to drive. 20 mpg highway was not un-common in the fullsize van it was pulling. The stock camshaft and exhaust manifolds/exhaust system is the HP choke.

https://www.thirdgen.org/forums/atta...dyno-sheet.jpg


You don't ship an engine will oil in it, BUT its in there when the engine is installed in the vehicle, which is why the offical GM specs reflect this. The brackets are heavier than you would think, especially when you add in the alternator, A/C compressor, and power steering pump. That is easily 30+ lbs. Once you add everything up a few lbs here and there really adds up. Distributer, coil, throttle cable bracket, etc.