Here is a block comparison that may be helpful to you http://www.440source.com/blockinfo.htm

The better forgings are better than the factory forgings, and better than all factory castings (400). A 383 forging is pretty stout, depends on your power level.

Downside to low deck:
Smaller case volume makes it more sensitive to pressure changes, blow-by etc. if stroked
Can't get the same rod ratio choices.

I guess you could say I have both I have the Indy Maxx aluminum block,it is a RB with the deck height cut down to 9.965 B block. The crank,dist. and everything else is the 440 RB stuff.
I have been told a 4.25 crank is the biggest you can put in a low deck (B)block. After reading this post I am not so sure about mine,the block should take a 4.50 crank same as any other RB. But what I am not so sure about is finding Rods & Pistons to match.

I too chose the low deck for hood clearance and header fitment with better heads. Right now I have a indy low deck block with 440 mains for better bearing choices. It is a 556, 4.5 bore 4.375 stroke. 440-1 heads and tti headers.

Twin Turbo Mower What's lenght of the rods & what's the compression height on the pistons?Thanks

I prefer a low deck if you want to push the motor past about 630HP on a stock block.

a little less weight when you sum it all up and the bob is usually about 150-200g's lighter. smaller mains coupled with 2.200 rod bearings cut down the reciprocarting mass and total bearing area roughly that of one full rod bearing.

What is a little bit of a drawback to the low deck (I'm surprised noone mentioned any negatives) is that when you run a roller with a Max wedge head/offset intake rocker the (even) shorter pushrod is at a comparatively extreme angle vs that of an rb...that extra 3/4" knocks a few degrees off the angularity and helps with port wall clearance as well.

The individual advantages are small but when you sum them up all else being equal the low deck is worth about 25-30hp for the same cubes. By my estimation and experience a 470 low deck performs in every respect comparable to a 493 RB.

Rods are eagle 6.535 and diamond pistons are 1.258 compression height.

i don't believe the journal overlap amounts to anything when being built in a stock block. any decent crankshaft will be stronger than the block it's being installed in.

the comment about the 470 B being equivilent to the 493 RB is, well, not correct IMO. it always falls back to how you build them and you wouldn't build both of those combo's with the same parts, so how can you even compare them like that?

"usually" the B400 will have stronger main webbing than a RB and that's the only real advantage. bore size isn't really a factor since most factory blocks have so much core shift. i like the RB bearing choices better than the B motor as well as the intake choices. pushrod weight is a total non factor since stronger, heavier pushrods will be used in anything making any real power. the weight on that side of the rocker is almost meaningless anyeway, IMO. the pushrod angles are better with the RB, especially if offet rockers or offset lifters are used.
either engine choice will make enough power to break the block and typically they're within 75-100 horsepower in that regard, but there's no guarantee that either block will safely make X amount of horsepower.

Dan I guess we'll agree to disagree but from my experience (and like you I was building strokers out of 383's, 400's and 440's long before they were mainstream) the combination of the smaller bearing area and lighter bobweight (again from my expereince only) a 470 is more than enough to offset a roughly 5% displacement handicap to the 493 if those motors have the same machine work, compression, heads, cams, induction and exhaust. A bit lower piston speed means less frictional losses at any given RPM as well. Don't get me wrong, nothing at all wrong with a 493 it's just that from my builds the extra "coke can" or so of total displacement only brings it about even...again all else being equal.

I also feel confident backing that up because you can (well, I can) definately feel the difference between a comparable 2.200 journal 511 and a 493, again it's I feel it's the smaller internals. There was a reason Bill Jenkins ran 2.00" rod journals and not the 2.100"s all those years ago. And don't guys still swear a comparable 327 will walk the dog on the same spec 350 chevy? Now NASCAR runs 1.89's, less surface area/rotating friction with still sufficient strength I suppose. It's interesting, in my day job I'm working on a huge 65.5 Megawatt Hydro turbine generator and I'm working with some very clever engineers who I'm learning a lot about the criticality of bearing temperatures and pressures. The stator is roughly 30' in diameter

Lets take a 'real world' example (not an all-out race motor) of a street-strip 10.5:1 E-headed motor with an MP 557 cam, both have a 950HP and an RPM or a street dominator or an M1 (you pick) and 2" x 3 1/2" headers with a 3500 stall 10" t/A and 3.91 gears in a 67 coronet. I'd lay money down that they'ed run virtually a dead heat in the quarter, round after round. if there was a difference it would be that the 470 would peak a few 100 RPM higher, put a 4.10 in the 470 and it would be even quicker. What I've outlined here is the basic bullet-proof reliable 11.70 & high 1-teen street strip combo, I've done it with both motor combos...but with ported iron heads. Of course these days everybody seems to build 511's so I suppose the old school 470's are out of favor...but back inthe day they were the hot "stealth" ticket Heck it's easy to go 11's with just a basic E-head 440 these days.

If you asked "why would you build them the same?", I would have to ask you (respectfully) why couldn't (or for this example relating to heavy street/week-end strip use which is what most people on here build for) wouldn't you build them essentially the same? It's a 'fun' motor either one.

but going back to the original post, I wouldn't EVER feel like I had to defend running an RB and in his case...I'd just smile and say "Because it's the one I had!"

It is worth digging up this over a decade old thread IMO. Lot's of good info and the link from 440source is VERY educational. I learned a lot about big blocks. Only thing I didn't see in the article was any info on RV blocks and whether they are any different so I guess they are not.

Let me guess: rod ratios don't matter?

less journal overlap making it stronger

Backward

Polyspheric,

Can you post some time slips or dyno sheets from testing that you have performed and explain what impact (positive or negative) the rod ratio had?

The best thing I like about my B block stroker, 400/455, is, the chevy & ford boys think its a smallblock. They compare my engines physical size to their 540 cubed big blocks & just see this small rocker covered engine & the fresh meat foolishly think I'm no threat. But I run into the 8's on pumpgas & after the chute gets rolled up & put into the passenger seat, I drive back to my pit as they wait for a tow. My race number is 340 so it's a bit of confussion for them. I rev to 8k & the lite bobweight of my recipricating assembly is very easy on the bearings. I am considering going to RB & make a 572 motor, but for the time being, i like the fact my competition thinking they just got dicked by a smallblock mopar.

How do you think OEM ratios are chosen (if they anything but "what do we have on the shelf)?

Probably chosen with the thought of a long service life in mind and not so much on maximizing horsepower.
So safe to assume you haven't done any first hand testing on rod ratios?

My old 400 block bracket motor is stroke to 4.300 with 6.700 BB Chevy type h beam rods(518 C.I.
The current motor is stroked to 4.250 with 4.360 bore size I race it on E85 and have rana best 8.862 ET at 150.++ MPH in the 1/4 mile.
Best 1/8 mile has been 5.50 ET at 125.++ MPH weighing 2850 Lbs.
No fill in either block ever