Okay so my stock 305 engine has about 120k miles on it, and i feel like its about time to get it rebuilt. I know just about nothing about rebuilds. I have read that its not worth it to get a 305 rebuilt when you can buy a 350. Im looking for opinions on that as well as an explanation of what an engine rebuild actually consists of. (Sorry im new to all of this) Also im looking for estimated price for parts/labor. Is it something my dad and i could do as a project or is it something that needs to go to a shop? I have a few more questions but ill start out with these.

Thanks, Chris.

 

Basically you take everything apart, taking careful notes because some parts need to go back in the exact same spots facing the same directions. Look for anything unusual. Scratches, looseness, bad bearings. Bring the block to a machine shop. Have them measure your crank. Maybe its fine, maybe it needs to be resized. Same with your cylinders. Maybe the wear in them is slight and you can get away with just a hone and new rings. If not, then you'd need it rebored to a standard oversize. Couple hundred dollars plus new pistons. THAT's when its no longer worth keeping the 305. If its okay, do the honing, have the block cleaned, cam bearings changed, new water plugs. New seals and gaskets, new crank bearings, new piston rings, new rod bearings, new oil pump, maybe new cam and lifters, lap valves, new timing chain. Put it all back together.

Chances are its not worth doing yet at 120k.

http://www.amazon.com/Rebuild-Small-.../dp/188408995X Great book. Helped me through my first rebuild.

 

First- of course you can rebuild a 305. Your choice is not rebuild your 305 or buy a junker 350 and just drop it in. if you rebuild your 305 and don't have a 350, then the equivalent 350 would run you at least $2,000, maybe more. Rememeber the comparison must be a rebuilt 305 to a purchased/rebuilt/ reman'd 350

You can't assume that a $500 or $1000 used engine is any good despite the insitence of the seller. Unless there is documentation then the asumption must be it's junk and needs to be rebuilt. Any other thought process is a roll of the dice, in other words, a gamble.

If you want performance then go buy a 350 long block.

If you just want to get it back on the road and you're ok with the 305, then find a shop to do it.

What's involved? well, it's more than just removing parts and slapping in some new ones

disassemble
hot tank block or bake and shot blast block
hot tank or bake/shot blast cylinder heads
bore/hone cylinders
deck block
clean all bolt holes
install new cam bearings
new "freeze" plugs
new main and rod bearings
resize rods, replace if needed
new pistons/rings
new lifters
grind or replace cam
inspect/replace push rods
new timing set
new valve guides
3 angle valve job
test/replace springs
inspect/clean/replace valves
machine heads
grind crank
new oil pump
new gasket set

basically, it's more than just slapping in some parts.

 

First off thanks for the replies! it seems like quite a bit of work but my dad has rebuilt engines before so i think we should be fine. What did you mean when you said chances are it isnt worth rebuilding at 120k miles? Just that we could wait a while longer before doing the rebuild? Are there any rebuild kits out there that anybody would suggest to me? Im not looking to build a racecar, but a little more power would be nice Another thing ive been thinking about is searching around for a used 350 so that i can still use my car as a daily driver while rebuilding the 350.

Thanks!

 

ahhhhhhhh

now that is the correct question

perform a compression test. If things look ok, then leave it be unless you are burning a ton of oil

then, do not, and I repeat do not even try to use 87 octane

sea foam the car.

After a few days, replace the spark plugs

flush the cooling system, not simply drain the radiator but flush the cooling system. You have about 4 gallons in the block and elsewhere so perform a real good flush and then refill.

replace your fuel filter


and back to the rebuild, please do not discount it and make it sound like something that anyone can do. Even though dad may have rebuilt an engine before it doesn't mean that dad can perform work that a machine shop should do.

My son has experienced 2 rebuilds with me so far. The first time he thought it was simply tossing in parts. I asked does he want to replace parts or rebuild it correctly. The 2nd time he asked which machine shop were we going to use. He learned.

he has a friend who tried a junker engine, a junker tranny (junker= used but not rebuilt before installation) and the vehicle is down more than it works. My son's 4th gen LT1(rebuilt correctly) fires up every day and could be driven cross-country with no issues.

 

Why do you want to rebuild it? Is it running badly? Generally smallblock chevy's will last 200k miles unless abused without maintenance. Especially low-power stockish engines like a thirdgen 305.

 

We are wanting to get it rebuilt because it seems to be running sluggish, and has been using alot of fuel and oil lately. In no way am i saying its going to be an easy task. I was saying that ill have good guidance but yes, we are going to be using a machine shop for things as well. I also have a friend like your sons who does similar things and ive learned from his mistakes. Im not planning to just throw parts in it and call it good. Still looking for rebuild kit suggestions!

 

Running sluggish could be solved by a tuneup. Get some fresh plugs and a fresh oxygen sensor. If you're gonna rebuild it you will be smart to get those while you're at it anyway.

Is it blowing out blue oil smoke when you drive it? Does it smell like oil when it runs? Or is it just leaking from some place? I just find it hard to believe a 305 needs a rebuild that early. I had one that hit 190k miles and burned less than a quart of oil every 3k miles AND it had a small oil leak. It would have hit 300k miles if I didnt replace it with something faster.

Either way dont be concerned about a "rebuild kit".

You'll need to strip the engine down. You've got a flat tappet cam, so you'll want to replace the cam, the lifters, and the valve springs with new replacements. Your call as to whether or not you wanna go with a higher performance setup. The farther you deviate from stock the more the stock fuel injection wont like it. But you have a MAF sensor - it self corrects to a certain extent.

You'll need to take the block to a machine shop and they'll check how out of round the cylinders are. They bore them over .010, .020, .030, .040, and .060 over. I'd suggest avoiding using a .060 over block for various reasons. Most commonly they need to go .030 overbore. That means you need new pistons.

Then you buy pistons and rings to fit the newly overbored block.

They'll then check the crankshaft. Turn it down if necessary then polish it. Then they can refurb your rods, or you can provide new ones. I'd suggest replacing rod bolts at least. The cost of refurbing them and replacing rod bolts isnt much less than new rods with good ARP bolts included. It's your call on that one.

From there they can choose to align hone the mains if necessary, deck the block if necessary, and then hone the cylinders out, install new cam bearings and clean it up and get it back to you unless you have them build it, in which case they'll build it, then get it back to you.

Then you'll want them to go over the cylinder heads. Unless you just want the basics done, you'll want a valve job and valve seals and then just cleaning it up. They can refurb the valves for you.

Likely you'll need the following new parts:

Connecting rods/rod bolts
Camshaft and lifters
valve springs
pistons
gaskets
bearings

The cost involved with even factory replacement parts isnt much less than mild performance parts, which is why a lot of people dont like rebuilding 305's. 305's and 350s cost the same to rebuild, and a 350 core is cheap and common. The more you deviate from OEM the more expensive it will be, and the more trouble you'll have to go through to make it work in the car. If you go all out and build a performance 305 or 350, you'll need to get the TPI re-tuned or switch to a carburetor or other fuel induction method.