350 borded 60 thousandth?

Question

im thinking about boarding my engine. but does anyone know what kind of gas millage ill get and can i still drive the car long distances.

Answer 1

.060 overbore is a sure way of overheating that engine, the cylinder walls can handle .030 but you're taking it to the max. Don't do it unless you have the block sonic tested and know the wall thickness is sufficent for the overbore.

Answer 2

I own a shop, and build engines. I just got one thing to say here. We have a wrecker with a .060 over 350 in it, and we have ran the he!! out of it for over 20 years now without a problem. You need to talk to the local engine builder at the machine shop for advice. They can tell you the truth. By the way, we also have 12.0:1 pistons in this wrecker. Sonic testing a block is a good idea, and so is magnafluxing it for cracks before boring it out. I have built probably several thousand small blocks over the years, and many of them were .060 over. The only problem is you will have to go with a larger radiator to keep it cool. At least a 3 row, and if you have AC you will need a 4 row.
Out of my years of experience I have no idea what a piston would climb a cylinder wall for.
Ok, this is copied straight out of this book I'm looking at, and the name of it is: "Chevrolet Power", The Official Factory Performance Guide, book #24502488. I bought this book from the Chevrolet Dealer Parts Depatrment for $19.95 a few years ago. Quote: The 350 Chevrolet production block is bored to 4.00 inches. A production block's comparatively thin cylinder walls limit how far the cylinders can be overbored--an especially important consideration when preparing a used block. In most instances, production blocks can be safely overbored .060-inch for street and moderate competition uses if the block does not have significant core shift. Boring a production block more than .060-inch oversize is not recommended.. quote/unquote. A siamesed "Bow Tie" cylinder bore block can be bored to 4.150-inch overbore, but the standard production type block can go to only 4.060-inch overbore safely.
Now, unless General Motors was telling a lie in this book, I've got to believe what it says.
As far as your gas mileage goes; its going to depend on the vehicle (weight) its installed into, the gearing behind it, the induction system, the ignition system, and the exhaust system, and many other parameters that come into play. I have seen a 350 get 10 mpg, and another get 30 mpg. If its installed into a vehicle that doesn't weight too much, geared properly, and the right induction system on the engine, you should see some pretty good numbers. There is no way in the world you shouldn't be able to drive this engine all day long without a hitch.
Glad to add my 2 cents worth!!!

Answer 3

Experience speakin here, I did this one w/ a 73 Nova SS and the main issue I experienced was the stock starter couldn't handle the extra compression. Not to mention the pistons climbin the cylinder walls w/ the wall being thinner. But yes, I would made sure the radiator is large enough to handle the coolin. Btw, this short block was professionally rebuilt and had a set of camel hump heads(w/ a 4speed rock crasher tranny) on it.

Havin said this, you will not be able to race or hot rod a 350 bored .060 over due to the piston climbin the cylinder walls. But if, you don't plan to hot rod it. It should be fine as a daily driver and get decent gas mileage.

I drove the Nova(gently, for the most part) w/ this set-up for 4-5 yrs. Before I sold it to some teenager. Who blew it up w/i a month after buying it.

Good luck!

Answer 4

I'm sure some of these guys have experienced this in the past. A .030 over bore is actually better in the long run unless you have the bores ultrasonically for core shift. What happens is this in a nut-shell. As the motor runs and gets over 5,000 miles the cylinder bores may become mis-shapen because of un-even cooling. Your new piston rings may experience an uneven seal as the pistons travel up and down in the cylinders.

If you consult the 2007 GM performance parts manual available at your Chevrolet dealer for a cool $5.00 there are race small blocks that can be safely bored to 4.180. These blocks are cast differently and made of select cast iron, nickle, zinc and antimony to make them much harder than the run of the mill cast iron.

Diamond, Mahle and JE make great forged pistons. Remember that flat top pistons are the hot set-up these days because of the great flame travel in the combustion chambers. Slightly larger pistons will raise your compression ratio also slightly.

Answer 5

The gas mileage will depend on how you drive. The car can still be driven long distances. Dont forget, if you have the cylinders bored out .060", you will have to replace the pistons and rings.

Answer 6

Your fuel millage will be affected by 2.4% assuming your current bore is 4.00 and your fuel/exhaust system can afford to apply another 2.4%.
You can drive the vehicle long distances. Your cooling maybe affected depending on your current systems ability to handle and increase in demand in cooling needs.
If you think your going to have an increase in performance, please learn more about performance engines and ppl's preconceived notions about engine myths. And/or ask more specific question.

Answer 7

Is your engine using a lot of oil, poor power, etc? Refresh rebore is usually .030. unless you are going for maximum cubic inch displacement and performance. What is your goal with your engine?