captjim

http://72.22.90.30/phpBB2/viewtopic....er=asc&start=0

"I dont really care about the horsepower i want to get as close to 500 ft/lbs of torque s possible. torque wins races."

That statement changes things considerably. I don't think you would hit 500 hp while only spinning it to 5500, but you certainly can have a mid 12 second car that is a blast to drive while doing so. It sounds like you have a pretty well thought out plan, except for the 500 HP. You might want a 780 vac secondary carb if you plan on doing a lot of street driving.

dman0712

if i was going to switch to a 455 would my 403 stuff such as my roller lifters switch over?

captjim

Yep. Distributor, timing chain and gears, water pump, oil pump, fuel pump, valve covers, valve train, oil pan are the same. Rods, pistons, crank, intake are different. But, not sure of this but have heard that there are hood clearance issues with the shaker. You have the 403, you have the parts, it will be fine for what you want to do, have a fun car top blast around in. But no 500 HP and no 11.0 ETs.

dman0712

well im real tempted now to switch to a 455 because if im keeping the 403 the only option i would consider would be the full block girdle but thats $700. I have the .24 kb pistons in my 403 that i would want to usein the 455. I want to use the nodular crank. what year engines were they in. whats would be the best crank to use? So basically i would want to switch everything over including my pistons but i know i would have to use a different crank and rods. My main concern is the pistons. Will the roller lifters switch over aslo? I have rpm intake so thats not a big deal. that will go on the 455

J-(Chicago)

Your 403 is almost complete, and your rods, pistons and crank won't swap into a 455.
I'd put it together as it is. It sounds like it will be a decent motor.
It won't be 500 horse though. Probably closer to 350hp.
If you can live with that, than by all means, carry on.

If you're dead set on 500hp, start all over with a big block. Or a DX/stroked build.

captjim

x2. You are not seriously racing this, right? Forget the girdle, keep the Rs down, drive it, have fun. It will be plenty fast and perky enough, IMO.

joe_padavano

Time for a reality check. If $700 for the block girdle is a problem, you can't afford a 500 HP motor.

MI455

the max safe overbore on a 455 is in my opinion is .060 or 4.185 the 403 pistons will not work

captjim

IIRC, John from RR bored his out to 4.250" x 4.250". But you are certainly correct, no way a 403 piston will work, wrong p/h, too.

cutlassefi

I'd be careful going that big on the bore. My 455 was sonic tested to have an average of only .150 to .160 wall thickness at STD bore. Not alot of room there.

MI455

What year block was it? My 70 455 had way more metal on a .030 overbore.

cutlassefi

Mid 70's.

captjim

I am certainly not advocating a .125 over bore, just saying it can be done. I know several guys with 4.155 350s (.098 over) and 2 guys at 4.185 (.128 over) but I would not recommend that, either.

cutlassefi

I respectfully disagree. On the last 350 I did, bored it to 4.125, still had about .200 left.

Bottom line? You gotta check it.

Boldsmobile

Status of the 403?

507OLDS

Just use a 350 gas block,with solid main webs,if you want to build a nice SBO.You can make as much power with one of those as a 403,& you won't throw the junk out of the bottom.Yes,the 403's have a larger bore,but now you have more piston weight,& you don't have enough cylinder head to accomodate that bore anyway.
Take that steel 330 crank,offset grind it with more stroke,put a long SBC rod in it,with a short piston,& you will be on your way to making more than what you were expecting with the 403.