a 403 block with a 425 crank(cut down mains of course) should end up being a 472 small block. anybody done this? think a 403 can survive? im not delusional in the fact i can get a solid main web block, probaly will end up with a windowed main. im gonna do it anyway, if i can find anyone who will cut the crank down for less then a rediculous price. of course it'll have big block heads(2.072 valves) and a custom intake, like a cross ram with a dual plane top and 4 2-barrel's. know of anybody in the great northwest that'll take a half inch out of 5 mains for under 1000? i think 600 is possible with a cam and some porting, much better then a 383 chevy huh?
A couple of the Mondello boys are members here. The 403 block should be fine. I have never actually laid eyes on a non windowed block. they make a nice engine girdle. and I have seen a couple with "new" windows so the crank could look outside.
Hey Lux, I think that the 'new window' for crank inspection was also the rev limiter for non-electronic classes. Am i right?
Have you even talked to a crank grinder yet?? Idaho must have more than one along I-84 and if you're up North then you can't be too far from Spokane. Get out the yellow pages. .
Not trying to piss on your parade, but it needs to be asked to educate the unknowledgable like myself- Why would you ever do that when a 030 over 455 is within 10 cubes and doesn't require fancy anything, it's a proven combo with the main external difference being deck height. Nothing at all like the size differences you see in SBC/BBC. I always thought the external similarity of the 350/403/455 was one of the great things about V8 olds Do you have some kind of packaging issue with the vehicle or sanctioning body that requires a 403 block?
Without knowing much about the 425 crank specifically...is it even possible to cut the main diameter by .500 without running into the oil passages? I wonder, also, what this would affect in terms of strength because of the reduced journal overlap on a stock crank, even being forged (if memory serves, all the 425 cranks are forged...but they are all probably 5140 or something similar). It might be possible to weld a 403 cast crank & increase its stroke by .590, though cast cranks generally don't weld well.
I got to agree with Shifty, although its nice to be different you need to also be practical. There are very few combos, very few dreams that haven't been done or at least tried before. There is a reason some things are popular and some not. That being said I have a crank grinder locally that does a lot of odd ball stuff. If you email me I will give you his #, people ship cranks to him all the time and it's not a problem for him. I do not want to pollute the hamb with advertising so email me if you want to talk to him.
well, i already have a 455, and i would do that, or just keep the 455, but its not so much about the cubic inche's but about bore-stroke ratio. the 403 has a 4.351 bore and the 425 has a 3.975 stroke. while the 455 has 4.16 bore and a 4.25 stroke. the longer stroke does give good torque, lots of low end power, but i want to reliable rev my motor over 6 grand, with out spending a ton of money on the bottom end. and well it would be nice to save the extra couple of pounds in the block. and well part of the point is to be unique, i have yet to find anyone who has done this, i foudn a couple people who stroke the diesel block and other small block's. i talked to a couple of machine shops, most dont want to deal with grinding cranks down at all, one of my friends has a 400 chevy crank and they sad they'd do it for like 1500, but you can get a aftermarket forged crank for less, rediculous. btw i dont have any idea were i-84, im about 1 hour north of spokane.
oh and maybe the crank cnat be cut down that much, but i dont know of any bearing that while work between those size's. maybe a 400 chevy's, but then the main journals got to be the same width so....
WAAYYY to complicated/expensive for the return you are trying to achieve. The 403 is inherently weak because of the windowed mains, so the pounding of high rpms you refer to is gonna make scrap iron out of it. Stick with a 425 or 455 as a basis for a build, and put you efforts/money into basic improvements and upgrades to either of them.....OR Spend about 2 tons of cash and build a stroker using a DX (diesel block) and either an aftermarket crank (Moldex, Crower, etc) or a counterweight cut 425. Specialty pistons, aluminum rods, etc, etc, etc. Then make friends with a machinist/engine builder who has knowledge of something other than a small block Chevy. These things are not for the faint of heart, or those on a budget. I'm into mine for over 10K and it's just now ready to assemble. This is a serious piece with a blower and a Hilborn for my gasser. Joe Mondello's guys hang out on here occasionally. Maybe they will chime in.
I agree with Boogeracng you can build a better 455 and save coin by Purchasing a New forged Eagle crank and H-beam rods and still have money left over for Pistons... I know Rocket Racing puts together "Bullet Proof" assemblies for a fraction of the cost of exotic combinations. If you really want to "Spin it Up" Rocket Racing has a "Girdle" available for most Olds engines!
The advice you got to avoid this combo is spot on.Running an Olds motor thats a proven combination is unique enough.Spinning past 6000, Olds motor,and reliable are not words usualy put together, and using a 403 block puts you over the edge.Be ready to spend alot.I cross the line with my 455 at 7200 but this takes alum rods,lite pistons and pins,a main girdle,block filler,oiling mods,etc. Hey Chuckie,is that DX block motor going to run soon? Gregg
Hi Greggie....hadn't heard from you for a while, thought you had gone over to the dark side (Chevy). Ever heard the phrase "one step forward and two back".......I'm close. Heads and valve train components have been the biggest/latest headache. Still working towards late spring/early summer.
well my original plan was to make the main bigger, but.. yea the 403 isnt a terifically strong block to begin with. maybe if i find a solid web 403... not likely. yea you would think someone would've done it before, but im sure its easier just to mod a 455, im pretty sure i can pull 500 or 600 out of my 455 with out to much work, but thats not gonna stop me from doing it, and well people telling me not to is just gonna make it happen. it probally gonna take while and probally a few blocks to get it right, but hell. noones done it yet as far as i can tell, and most people avoid the 403 for the reasons people avoid the chevy 400, it has overheating problems(siamesed cylinders) and thin cylinder walls. I've done enough research, i could do a deisel block, but it will cost more then stroking a 403, and i dont want to deal with all the bs that comes with dealing with a deisel block, all the holes you have to plug, and the oiling system mods, i read about, considered and decided to go with a 403, more cubes and all anyway. It may be difficult, might take a while and a few motors to get it right, but at least im doing and i wont give up on it
So, if you are bound and determined to do this thing, and apparently, money is not an issue, nor is the time and efforts to do it, why did you start this thread, seeking input/advice/comment? Sounds like you had your mind made up ahead of time, and to hell with what the hands on builders have offered as advice. An old saying comes to mind about leading a horse to water.........
like already said, NOT W/403 block...this normally done with the dx block and is nothing new to olds preformance crowd, thought about it myself, but havent convince myself that it is cost effective.... the solid main web 403 is a myth....they're all window....
another option to improve ratio: use 7" rods in your 455 (stock 425 or bb chevy)...either one will require custom pistons...and some crank grinding if you choose bbc rods... if you serious about 600hp...get you wallet out and dont look back...
Only one thing to add I suppose. Unless you're Ritchie Rich, going fast AND being different requires a brilliant plan with a combo that's got an inherent advantage over the competition. Otherwise all you are is a guy talking about his awesomely fast, awesomely expensive, and constantly broken car. One the rare occasions that guy strings it together, the cars put on impressive displays before breakage, but never live up to their potential.......because the car isn't reliable enough to get sorted out, the exotic motor sucks all the cash, and you can't chassis tune with the engine on a stand. In your case, the exotic motor doesn't even look exotic, doesn't make significantly more power than a cheaper 455, doesn't offer a racing class rule advantage........yet offers high risk of expensive unreliability. You might ask yourself why a couple more times. Third time it throws a couple paychecks out the oil pan you might look back and realize you've spend hundreds of hours and 15K on something that coulda been done in 2 weekends for $3500 and still run hard. Those kind of moments are when people decide old cars aren't worth the hassle. Because they deliberately overchallenged themselves without a proper payoff for the success. not every mountain needs climbed daniel-san
403 blocks are weak, if you must use a small block it would be wise to use a DX block. the crank - 425s are forged, its going to be hard to find a forged 455 crank. If you're spinning that fast, you should consider a forged crank even though 425 cranks have a shorter stroke. DX blocks have big block size mains... save money on grinding a crank! the heads - big block heads have big valves but have large 80cc chambers... unless you have some H/O or w-30 heads, a good compresssion ratio will be tough to get. and your worry about engine weight, i know i read somewhere that a big block olds weights 60 lbs more than a small block... it was some article about the new 1964 olds engine lines. Think about it, it makes sense. the rod and piston combo i have no idea about, you'll have to look that up. I am no expert, but I have done my reading on these Olds blocks. All this came from spending time at http://www.442.com/oldsfaq/oldsfaq.htm and http://www.realoldspower.com/phpBB2/index.php Go to those places, all the answers are there. sometime there are reasons no one has done something best of luck -PaX
doesn't someone offer a crank and rod kit to stroke a 425 to some outrageous number like 517? (Mabey it strokes the 455 to that, but either way...) That sure seems a helluva lot easier. And the power numbers You are looking for...I am making that with my 455, and it's nothing terribly exciting inside...little crank work, pistions, and a set of unported edelbrock heads cut for big valves. (2.125, 1.95 exhaust). solid roller cam, decent non exotic valvetrain...childs play. I think You're going from Dallas to Houston Via Omaha.
there is no shortage of olds performance parts (mild to wild) and suppliers and i know a couple of you guys are aware of them.... btr performance rocket racing dick miller racing olds performance products fcr performance mj performance just to mention a few.....
There is an article floating around the web somewhere (Hotrod magazine or something) about Dick Miller's 600hp 403 that he built for about $13K. You can build a strong reliable and sturdy 403 for much, much, less. With stud girdle and oiling system work I think you could easily build a killer engine with a 403. My experience with one was great and I plan on rebuilding the block in the future (the car it was in was stolen and I would not run the engine without rebuilding after I got it back, who knows what the thieves did to it in the mean time...). However I now have a '66 Toronado 425 just fresh from the machine shop. They are factroy rated at about 385hp, 480ftlbs torque have forged crank and rods, good flowing heads and 10.5:1 compression. If you want big cubes, I say start with a big block.
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