kylelm

If I bore my base L48 350 .30 over, about how many more horses will I get with no other mods on the engine?

fl_rider

An increase of 5 cubic inches isnt going to give you any appreciable horsepower increase. Certainly nothing you will feel.

Is this a high milage engine that needs a rebuild??

If you are rebuilding it consider putting a better cam into it.

I am making an assumption here but it sounds like you want to keep it pretty much stock.

SanDiegoPaul

Zero. Such an insignificant size increase on the engine will have no effect on power. It's the other things that you do when rebuilding it that will determine power output.

kylelm

NO NO NO! I'm wanting to put up over 400hp and yes the engine will need a rebuild. It was last rebuilt in 86. Any suggestions on where to start?

63mako

Sounds like you need to find a good mechanic you trust and have him drop a crate engine in it for you. Best bang per buck and from your original question it doesn't sound like you have much mechanical experiance. Seal up the original good after its pulled and store it for later. Good luck. Kevin

kylelm

I have no major mechanical experience with a total rebuild and certainly none in building a high HP engine. I do have 3 buddies who are mechanics (one who has a trans-am with over 450hp that he built himself). As far as the crate goes, I would rather build it myself so I am a little more knowledgable when im done! Thanks for the help!

2th farmer

The only way your going to learn is by doing. Get your buddies, pull the engine and get to work. When your done you'll have $3k+ less in your wallet and a great deal of knowledge. (education ain't free) Plus, the feeling of accomplishment that comes with hard work. A crate engine is going to cost the same $ and you've learned NOTHING. Believe me, if I can do it anybody can, Here's my picture from last nights re-install of my BB. Go for it! Ask questions right here, great bunch of guys.[IMG][/IMG]

Sky65

This should get you started.
http://www.ryanscarpage.50megs.com/combos1.html

Yellow73SB

I feel that you get a better quality motor also if you build it your self. You don't get those garbage hypertecnic pistons and stuff like that.

63mako

If your friends want to help and are knowlegable and you want to build it yourself you have come to the right place to learn. The ryanscarpage site will be extremely helpful to come up with a plan, buy books on rebuilding engines, Keep everything spotless, be meticulous, measure everything twice, document everything, take pictures, lots and lots of pictures before and during disassembly. Make sure you have access to the tools you need to do it right. Find a top quality machine shop that will work with you. DON'T CUT CORNERS!!! The weakest link always breaks. Good luck and ask questions here.

kylelm

nice engine 2th farmer. The website is VERY helpful. Thanks a lot. I am new to the tech part of the C3 world and can see this is a great place for help. Thanks for all the advice and hopefully I can post my vette in the future for everyone to see. Thanks again!!!!

Vesa

Do 383

GDaina

If I ever were to purchase an assembled crate, I would tear it appart. Why? To check for cleanliness and the clearances and then assemble. I never trust anyone's assembly and I never assume the assembly is correct.

Way back when during the early 70's, a good friend was racing his 435/427 67 and scattered the bottom end. He purchased an assembled L-88 shortblock over the counter and decided to remove the pistons to check the clearances. What we saw would would make you sick...grit around the rings, the cyl walls. Seems after the finish hone, no one ever cleaned the block.

Anyway, if I were you with no mechanical skills, I would purchase the crate. Your down time will be the amount it takes you to remove and replace the motor, rather that month's while the shop does the labor on your block. You can learn from your friends as they tear down the block, check for cleanliness, clearances, and then assemble. When assembled, then remove and replace.

Jughead

I feel much better now about my engine assembly having read that.

GDaina

I'm sure this was an isolated case, but....it never hurts to double check.

68vertible

Be careful listening to comments such as this too....Hypereutectic pistons are not garbage. In fact, for many engines, they make more sense than forged.

Hyper's are high silicone cast pistons. The added silicone make them more durable than plain cast. They are also much more temperature stable than forged pistons. You can fit Hypers tighter in the bores so they will not 'rattle' in the bore as much as a forged will do until warmed up.

If you're going to go nitrous or forced air (supercharged or turbocharged) then you need forged. If you are going extremely radical in CR in any way, then forged are the way to go. But for most fairly stout street engines, a hypereutectic piston is just fine, are quieter on cold startup, wear the piston bore and skirt less than forged (because of the additional rocking of the cold forged piston in the bore) and cost considerably less.....but it's just not as sexy as telling everyone you've got forged slugs.

But I do agree that you'll be much more satisfied doing your own build, and learn a bit of theory before you start so you'll get to make some of your own decisions about the build....or at least understand why your more knowledgeable friends are sucking money out of your wallet like a hoover on rice crispies!

rcread

Because I'm feeling nit picky today...you mean .030 over?

I agree with those who said you'll never notice the difference based on overbore alone.

Kalway

If it was rebuilt back in '86, then he'd be going to .040 over, wouldn't he? I'd think it was already bored .030 over during the last rebuild.

68sbShark

Cold have only went .010 over for the first rebuild.

~Rich

Kalway

Hmmmm, even my rebuilder went .030 over and I paid less than $1000 to have it rebuilt with slighter higher compression hypereutetic pistons.

I'm actually calling that shop up again to see if I can buy some vortec heads off of them, since they really did a good job on the rebuild.