I was thinking about building a stroked 305 and just wounderd if anybody knew off the top of there head.
I know you can use the 3.75 inch stroke to make a (334), but will a 3.875 inch (345) or a 4.0 inch (356) fit?
Some where along the line you'ed probally hit water or run out of pan rail to grind on.

 

You could probably get a 4" stroke in with a whole lot of work on the block and custom pistons. Stroking a 305 isn't worth the trouble, though.

 

why the heck would you put anything larger than a 3.75" stroke though? i mean, anything larger than that is going to require custom pistons anyhow...i honestly don't know of anyone putting anything larger than a 4" stroke in any factory block though.

 

I don't know why you'd even put anything bigger than a 3.48" stroke in it, except for a handful of cases.

 

I new that I'd have to get custom pistons that's not a problem. I just wanted to know if there was enough room for clearancing the block for a 4 inch stroke.
I can get a used Kroptonite 4" stroke cheep. Just have to pay huge for the pistons.
As for why I just have a sneekie suspision that you would get BUTT loads of torke and good gas milage.
I could be
Just kickin it around.

 

well, i've been reading alot of stuff on the boards lately about how great the little 305 is and how much potential it has and that all the guys bashing it need to be ripped a new one by a 305 blah blah blah. here is the deal guys. unless for some reason you're limited to the 305, build something bigger. 350 cores are a dime a dozen and are cheaper to build and make more power per dollar than the 305 ever will. while i only have $180 in my build to make it a 305, i spent ~$3500 on parts and "labor" (i did all the labor myself, so this is kind of an imaginary figure) to build a 350 that would run 11's, have great streetability and actually have decent fuel economy for having a carb ontop. i think i managed to achieve that, even though the best run was only a 12.16, but i had traction issues and i know had those been corrected, it'd been in the 11.8-11.9 range. then, the block cracked and i didn't have much of a choice on what to do. i bought 1 piston to replace the bad one from the previous 305 build, got a new set of rings, had the block honed and got some .015" shim head gakets and swapped everything over to the small motor. the ONLY reason i've decided to stick it out is cause the "spare motor" i slapped together has gone faster than every other n/a 305 that still has decent street manners that i know of. at this point, i've just got the fast 305 bug. the looks and double takes i get when i say it's "just a little 305" are priceless and quite addicting. once i've gotten to a point where i feel i've maxed the little motor out (or i end up spending more money on 305 specific parts than i feel is necessary) i'll step up the program and go to a bigger cube motor.

 

Not really. The valve shrouding from the small bore would limit the amount of air you could get into it.

 

yep....and gas mileage would be no better than a well thought out 350. i don't imagine that a small chambered head with 2.00/1.55 valves (biggest valves you can stuff in a 305) would flow 356 cubes near as well on a small bore then it would one a large bore 350...

 

I think the 4" stroke would be too much for the bores, the engine would need quite a bit of other changes to keep up.

I'd even be willing to bet there'd be lag if you pressed lightly on the gas pedal, in fact you'd probably have to change the way you drive if you had a manual, and you'd probably need a bigger converter if you had an auto, as the damn thing may just stall if you were running around town feather-footed.

i agree with apeiron about the air flow, although it could be compensated for by "simply" improving/replacing the heads and/or cam and make some considerable fuel changes to compensate for the extra cubes(i mean literally, as in combustion chamber space).

if you made no other changes than to stroke the engine(which i'd also like to mention that most people that do so also bore the engine .03-.04 over, btw) you'd more than likely lose hp, achieve your peak at a lower rpm, and although you might(and i stress might) make more torque, it would peak at a lower rpm and drop off sharply to quite literally nothing thereafter.

as for fuel mileage, when it comes to naturally aspirated engines it comes down to two things: efficency and size.

now, assuming this engine you're building was tuned to perfection(and there's no way in hell that's happening) it's still inherently less efficent DUE to the considerably larger stroke than bore, and on top that, you've increased the actual cubic space in the combustion chamber, requiring more fuel to go, which requires more fuel in general.

you will get worse gas mileage if you build that motor, no matter how you look at it. how much worse is really the question, and that varies greatly depending on how you build it and tuning, although once again, it'll inherently get slightly worse gas mileage than any other engine(of the same size) that has a similar bore to stroke ratio, and also more than likely any engine that has a larger bore than stroke, at least at lower rpms, due to the once again considerably larger stroke than bore, which of course will more than likely force you to stay at lower rpms because anyway, once again, due to the design.


NOW, that all being said, there were several legendary oldsmobile engines(the 400 at 3.87x4.125 and the 455 at 4.126x4.25, to name two) built at varying times in history that had a considerably larger stroke than bore, but they were all much larger engines, and all built with that design in mind.

honestly, I'm out of steam, I'm sorry this was so long. I guess what I'm trying to say is that it may be worth it, but building an engine like that is nothing that you just walk into, there are VERY careful calculations involved in such a process to make it run right, but if done correctly(and incredibly expensively), you can build one hell of an engine.

 

oh ya, and as for whether or not it would fit, I can't say for sure, but I do know that you've gotta shave quite a bit off to fit the 3.75 and that the bores themselves can only be bored .060 over because soon after you hit water passages, so i'd be willing to bet no, you probably can't fit a 4" stroke in there, to answer your question simply.

sorry 'bout that.