StrokerSVT

Went down to look at the cobra today to find out it has the original 302 cobra engine in it with the 347 stroker kit. My question is, do you think a 302 bored out .40 is to much?

StrokerSVT

My father told me that he thinks bored .40 over is to much. What do you guys think?

USAMuscle

If you have a Mexican block, you should be able to safely bore it up to .060 over. The Mexican blocks are stronger because I guess they have a higher nickel content. Use this article to identify your block. http://www.oldwestracing.com/index.h...es/mexican.htm

I have read about people overboring their 302 engines .060 over, but I really don't know how well they hold up.

Other than that, the only way to be sure whether or not your block will hold up to a larger overbore is to have it sonic tested. All blocks are not created equal. Some small blocks won't do well with anything larger than a .030 overbore, and other blocks can withstand overbores of .060 and larger, provided the cylinder wall thickness is still within reason. Find a shop that will sonic test your block for you, and you'll know if overboring to .040 or .060 over is an option.

StrokerSVT

The cobra im looking at is a 1995. Did they have the mexican blocks in that year?

619socalstang

.040 over is not too much in my op. but im a displacement freak. .030 to .040 is not that much how ever it will promote heat but thats about it, and what is the price of the cobra, if reasonable price go for it. i do not recall a 302 block ever having weak cylinder wall the valley will split before the cylinders have integraity problem.

horatio102

imho .040 would only be a problem in a handful of cases. I'd be more concerned with that 347 stroker kit - how old is it, who did it, etc.

StrokerSVT

The whole engine was redone. The 347 stroker kit was added along with it being bored .040 over. My dad tells me thats bad luck waiting to happen. He says that it could blow at anytime with .040 bored over. He says that 302's should NEVER be bored over .030. My dad knows quiet a bit about mustangs and mustang blocks, so im kinda stuck on what to do.

The car is $10,500.

Its a 1995 Cobra SVT w/ 347 stroker kit. (86,000 miles on it)

619socalstang

dose it come with reciets, for all engine work.

USAMuscle

Your dad may know a lot, but he doesn't know enough to say "NEVER" because that's simply not true. Like I said every engine block is different, and some blocks are fully capable of being bored .040 and .060 over without any problem whatsoever. The only limiting factor to overbore is cylinder wall thickness. It's a very little known fact, and people who know better can save a lot of money on used blocks vs aftermarket blocks like the Dart blocks and such which cost about $2,000. Now I know there are other advantages to aftermarket blocks such as added strength in weak areas (valley) and ability to withstand a lot more power, but if overboring is the only consideration, 2 or 3 blocks out of 10 have very thick cylinder walls and can withstand large overbores, and usually cost less than $100 at any junkyard. Engines like the Chevy 454 is capable of being bored .125 over stock, which makes a HUGE difference, and the cylinder walls are still within tolerance. Again, the only way to be sure is to have the block sonic tested.

619socalstang

stroker i do not think USA is trying to rip your dads knowlage just staten the facts.