I want to rebuild my Lb9. Before anyone flames me, let me explain. It was a tough, strong SOB.....before the head gaskets blew and the compression took a dive. It was really strong. Just a well put together 5.0 I even thought for awhile and the cars it was taking out it was a 350.

Anyway, I would like to rebuild it. I know for less money and time, I could have a 350 or even an Lt1 in there if I am lucky. But I don't have any money. But I need to do some research and ask some questions.
There was hardly any compression in the cylinders when the tests were done. And yes oil was put in on the 2nd test to see if the heads were the culprit...heads are fine.

With that said:

1) Piston rings are no good right, but could I re-use the stock pistons? I would like to if there is no other reason why they wouldn't be salvageable. How hard would it be to put in new rings........for a novice?

2) Does anything need to be done to the block itself? Like honed and stuff? How much do shops charge? Does that mean I HAVE to buy bigger pistons?

3) Would anything have to be done to the crank?

4) Does the block have to be completely bare? (( For instance, does the cam have to come out in order for #2, or can it stay in there? )) If not, it's staying in there, if so I will put in a new cam.

If anyone has rebuilt a motor in this fashion, what problems came about?

Thanks.

 

1) Reusing the slugs depends on #2

2) The block will have to either be honed (in which case you may be able to reuse the pistons) but most likely will have to be bored out to get everything round again. In which case oversized slugs are needed.

3) most likely not. Unless you have had a bearing go out on you, in which case the crank would need to be turned.

4) Regardless of boring or honing the block should be stripped completely bare when taken to the machinist. With the exception of leaving the main caps on if it is to be align honed also.


Basically as you can see, like most people will say you may as well do a 350. with the time and money it will cost to rebuild the 305, you could have a 350!

But thats completely up to you, but if you can find another block 305 or 350 thats ready to go for cheap i think you would be best to jump on it!

 

Before doing anything I would do a leakdown test to really make sure its the rings. If its just the headgasket then you can do it yourself for under $100 in parts (even cheaper if you get cheap parts). Cross your fingers!

 

if not buy the 350 longblock from GM for $1300 or so and start with a brand new motor, which would probably be the cheapest option, since machine prices are rising around here.

 

sometimes you can mickey mouse it, and just hone the cylinders, new rings, and keep the stock pistons. It'll have more blowby and not last as long, if the cylinder walls were pretty worn, but it can be done.
On the other hand, if the walls are ok, then a re-ring is perfectly acceptable.

You can either strip the motor right down to nothing, and bring it to a machine shop to quote you on it, or you might be able to use a feeler gauge in the bore, at different piston heights, to know for yourself.

But yea, like crazy mentioned, do the easy checks yourself (leakdown), your labor rate is far cheaper then a $$$machine shop$$$

 

If the compression is really so low that the engine won't run, you either have a bad head gasket, or you have some pretty expensive issues to deal with.

If the rings are really the core problem, then the cylinders are going to be so worn that they will need to be bored. New pistons & rings for sure. New main and connecting rod bearings. New wrist pins & bearings. May as well get a new cam, Timing Gear & Chain etc. etc. etc.

By the time you get it back on the road, you're looking at close to a couple of grand, if you can do it on the cheap.

Seems to me like a new GM Crate 350 goes for much less than that.