Hello all.
I have a '79 with an L-48 engine.
It has quite the engine problem. It eats oil like people drink water. I have to put in 1 quart every 250-400 miles. It smokes quite a bit on start up. It fouls 3 plugs on the right side of the block (I forget the cylinder numbers). The worst fouling occurs in the cylinder closest to the firewall on the passenger side.
Anyway, I'm betting on blown piston or cylinder rings, so I'm going to pull the engine apart and have the heads & block machined.

Can anyone offer advice on how best to attack this project?
Thanks!

 

Never do a stock rebuild. Read a few books and figure out what direction you want to go. Some people find it very convienient to just by crate motors with a warranty.

 

What are the cons with rebuilding a stock engine?

 

Tell us what you $ budget is and I'm sure that you will get some sound advice.

 

If your Vette is #'s matching, park the engine in the garage and go with a crate motor. You get a waranty and a brand new motor. If it is matching #, you'll lose the numbers when you have the deck milled. A crate motor will run about the same as a rebuild. Now, you might think about something hotter :D :D :D

 

You don't have to get the deck milled. A machine shop (which will become your friend during the process) will tell you if it needs to be done. But if they know it's a corvette engine, they know the importance of leaving the numbers.

Rebuilding your engine can be a rewarding experience if you like working on things. I'd highly recommend a book on 350 rebuilding, but I can't remember the exact name. It had lots of pictures (I like pictures) and detailed step by step instructions.

Expect to spend at a minimum $1500-2000 for a rebuild.

 

It really all depends on what you are looking for. If performance is not the biggest factor for you (heaven forbid ) then there is nothing wrong with a rebuild to factory specs, and it can be done fairly inexpensively provided a minimum of machining is required.

I've done inexpensive rebuilds for around $500 (not on my motors though - only for others)

You are probably experiencing a combination of items including leaky valve seals or worn guides and perhaps the oil control rings on those three pistons are worn.

A classic re-ring job which would be new bearings and rings (get new cast pistons - they are way too cheap not to be bought) and add to that a valve job - would bring you motor back to the life it once had, for very little money.

The real grabber is for very little more money you can bump your CR for a little more power - upgrade to more durable pistons, get a set of aftermarket iron heads (very inexpensive - on a par with a high quality valve job) a new intake, carb and ignition system and your L-48 will be able to run very strong.

All of that could be done for as little as $1500 depending on how much machine work is required on the block.

It is extremely rewarding to build your own motor, and if you can do your own labor , quite economical. Engine building is NOT difficult, once youve done one, you will be amazed at how simple it really is. Attention to detail, patience and research is all that is required. Obviously, you will need to find a reliable machine shop to do the machine work, there are hacks out there.

The forum is by far the best resource for information on what parts work, how to put them in, who to buy them from etc...

Things you will most likely not need.
-block decking (I've built over 6 motors - 4 bangers, V6 - V8 - Big blocks, and only had to do this once)
-Line bore or hone
-new crank or rods
-regrind crank (sometimes this is required)

Things you really want to do
- always replace main and rod bolts (My opinion only BTW)
- resize rods when having new pistons installed
- have block completely stripped of all plugs and cleaned
- chase all threads
- new OEM pressure pump w/ all steel driveshaft (no plastic collars)
- new timing chain (no nylon gears)

Do not be intimidated by doing your own rebuild and dont be afraid to do a simple factory rebuild, you may not have a 13 second car but you will be very happy driving around in a car whose motor you built yourself.

 

My L48 is not nearly in the shape that your's is but is numbers matching and 26 years old without a rebuild. The valve seals are dying and I debated on whether to have it rebuilt and reinstalled. The biggest problem was that this engine, by leaps and bounds, is the LAMEST motor I have ever owned in a C3.
After looking at cost, time and so on I have definitely decided that I will replace it with a ZZ4, freshen the original motor up and bag and tag it in the garage as I definitely want to keep the original motor "as is". The ZZ4 will give this Shark the bite it deserves. Fortunately, in my case, I don't have the wife factor to deal with :cheers: You can find the ex tooling about in her Z06 in Houston :lol:

 

Hello, I really like your comments in this post. I kike to get a liitle feedback about my situation. So, here we go. I recently acquired a 75 model and although it's not one of the fastest vettes. I believe it will be great to just have one. This particular car has no oil leaks or any other leaks that I can tell. I have not been able to get it on the road yet, being that the brakes are shot. So i will start there by replacing every item in the braking process except the steel lines. It starts up... no problem. It runs... no problem. A little smokey from one tailpipe though. The mileage approx. 95k and not sure if this is the original mileage. The motor compartment looks as if it is still all factory. The only definite change that I can see is that it was Bright Green originally, but has been painted Black and will need a paint job much later in the process. My question is simply... Should I look into replacing this engine with what you guys call a "crate"
or keep as is. I have not necessarily decided to keep it numbers matching.
But I would like to get it into a sound condition so that it will not give me trouble very frequently. All the components and name brands that are used in this forum make no sense to me. I guess you have to start learning somewhere and a CORVETTE has got to be at the top of the list of cars to start with. Thanks in advance for any advice from anyone about where to start with this engine. :confused: :cheers: :seeya

 

I am currently replacing the L-48 in my '79 with the bottom o' the line GM Crate 350. I'm using a HOlley Street Dominator Dual-PLane Aluminum Intake, Dynomax Ceramacoated Headers, a Comp Cams XE268H, and 2 1/4" True Duals (No Cats). According to Chevy High Performance Magazine that combo should put out over 300 hp and about 350-375 lb-ft of torque. Check ou
http://personal.clt.bellsouth.net/clt/m/g/mgervin/chp/gm350.htm
for the whole story. I'm only going to have about $1,800 in my new setup... Thats about $6/hp. That's a pretty good deal IMHO. Just my $0.02

Good Luck,

 

Gerry,
My 427 is currently at the machine shop being thoroughly reworked. Bubba had rebuilt it previously and put in the higher compression pistons which ended up blowing the head gaskets. On further inspection, the main bearings were shot.

In my opinion, you should only do things once, and do them right. I took the whole engine apart to see what was wrong. I took the block, crank, rods, and heads to a shop that was recommended (don't just pluck a name out of the yellow pages). I am having the block fully reconditioned, including shot peaning and magnafluxing. The same goes for the crank and rods. The heads are having hardened valve seats installed as well as new seals, springs, valves, and retainers. The crank had to be ground also.

I am rebuilding the engine basically stock except for three pieces that can't be seen, the rockers, pushrods, and cam. My goal was to keep the value of my car as high as possible, but add a little performance (the car is not slow). To keep the value high, I had to have the block restamped ($300). The guy doing the restamp has original GM style numbers (this is the only area I'm worried about).

I am replacing just about every piece of the engine, because based on what Bubba did, I can't trust anything. Total cost is about $2000 so far. I'm still not decided on how much assembly I'm going to do. This is with name brand parts, roller rockers, and every bit of machine work besides line boring the mains.

I know this is long, but rebuilding an engine shouldn't be a quick job. The work just to pull the engine and replace is enough to make you sure you don't want to do it again. Finally, I agree that if you want to build a monster engine, don't do it with the numbers matching.

Ken