They take the bore to 4.250 because Fel Pro now makes a 4.25 gasket to acompany it. So this means you now only have .0150 inch between the bores which isn't much meat. So basicly if you would drop a piston and score the cyinder walls you're pretty much screwed if it needs to be bored.

Here is a good thread on the issue. --> http://forums.corvetteforum.com/zerothread?id=506172

 

If you use an aftermarket block like the Dart Iron Eagle/Rocket Block, you could run a 4.250" bore and still have a minimum of .2675" cylinder thrust wall thickness, which is still thicker than alot of production engines. Some Fords go as thin as .090". Combine that with the tall 9.325" or 9.500" deck block and you could also run a 4.25" stroke crank for 482.3ci engine. You would also be able to run an off the shelf 6.200" connecting rod and still maintain a decent 1.46 rod/stroke ratio.

Only a keen eye would be able to tell it wasn't anything more than a hot 350 depending on how you dress it up.



[Modified by Monty, 10:43 PM 3/7/2003]

 

:iagree:

This guy definitely knows his stroker small blocks!

I do agree with the consensus though. If you already have a big block, it would be simpler and probably cheaper to throw another big block in there.

AC

 

Monty, Chevy High Performance used a Merlin Motown block and only achieved .0150 between the bores after boring to 4.25. Is the Dart really THAT much thicker?


[Modified by Corey 68, 9:05 PM 3/7/2003]

 

There is very little load on the side cylinder walls, the thrust cylinder walls are what matters the most. If the gasket can maintain the cylinder pressure, that's all that really matters, and there are several successful strategies to aid in improving this even with thinner dimensions.

These 454+ci SBC's are obviously maximum effort engines. All of these factors are the main reason why I stuck with the 4.125" bore, leaving me plenty of room for future overbores and block longevity while still retaining adequate cylinder wall and head gasket thickness, even under 20+ psi of boost. I can still safely go as far out as 4.200" bore and still maintain an adequate thickness b/w the siamesed cylinders.

World Products spends more money on advertising and marketing compared to Dart, therefore the magazines typically do articles features the WP blocks. If you're going to do something, inform yourself, don't rely on what a magazine editor decides to showcase in a magazine. Do your own research, make your own decisions, look at what the pro's use, look at what really works well in the real world. That's my motto.

I'll always believe what a micrometer or dial caliper tells me over what an advertising sponsored magazine tells me...


[Modified by Monty, 11:11 PM 3/7/2003]

 

You can always put some block hard in for some increased rigidity.

 

It's really your choice, as the owner. If you've already got a big block Vette, I'd suggest you keep it a big block. Not only would resale value remain high if you just rebuild your original 454, but it's also set up already, suspension wise.

The trick small block is a VERY expensive engine to build, which I suspect is the reason why your engine builder wants to build one. And the rod/stroke ratio of the Chevy small block hasn't really been good since the 327. The 350 is okay, at 1.63, but still not great. And it goes down from there. Stroking the engine to build a trick motor will produce an awful rod/stroke ratio, and what kills me is they stick a cam in it that likes high rpm usage, to build those power numbers. What an expensive mess.

It's so easy to build a powerful 454. Why not just keep it a 454? The handling is not that big of an issue. If you want better handling, you can get that with either a 550#/inch front spring set and glass rear springs, or get the new transverse front spring kit from Vette Brakes. Then use urethane bushings on your suspension pieces.

But I don't think it is necessary to spend an extra 10 grand on a trick small block that'll never make as much power as easily as a big block Chevy. Your dollar per hp ratio will definitely be better with the rat motor.

 

Sheeesh...hope I dont loose points off my 100% but here goes....

I was driving last season amd some kids pulled next to me and yelled
The bigger the block the smaller the Co**!
I never laughed so hard :lolg:

Anyway...a big block sure is cool. If it had it stick with it unless you want to build a nasty small block.
My personal choice woul be to stroke a killer light weight small block.
Keep handling crisp and the weight down while producing monster curves.