Since I'll be down over the summer due to the new arrival (XY) in early June, I was considering building something that has a little more umph over the summer .... OK a lot more umph. I'm considering a Nitrous Engine that I can still bracket race Normally Aspirated.

I have two good seasoned RB blocks ('66 and '68) and a set of Manley H Beams OEM (2.375/1.094) on each end. I'd like to survive 725-750HP NA with a 150-300HP shot w/ annual teardowns between seasons.

1. Aluminum Caps, Billet Caps or 4 Bolt Conversion?

2. Fill the RB block to where? Bottom of the freeze plugs or higher?

will it be driven on the street?
?

Seldom. I like to take it 15 miles to a local car show once a year and a few family cruise-abouts a year. Maybe 200-500 miles. Everything else is on or in the trailer.

I'd lean towards steel, 2 bolt main caps. I'd really prefer a 400 block, though. I fill my 400 blocks to 2 1/2" below the deck. All of my B-1 engines are done this way.

Thanks Ken - I'd really like to stay Raised Block, but I understand the inherent risks. Although, IF I went B Block for some Big power, I'd be looking aftermarket since most original blocks I've looked at are no bargin with the work that they'd need.

B Block Post

i would do a 1/2 fill, run the steel main caps, run your rods, & good set of rings w/ the end gaps set for the nitrous, watch the cam selection w/ the added cylinder pressures you'll run, have a good ignition system/ rpm limiters, if you don't already, an rb block will work fine, for added strenghth in the bottom you could add the girdle from gears & rears ( member name i forgot)

if you are going to the expense of the dvorak girdle wait and get a megablock ..

I was looking to get something to tide me over and add a margin of safety w/o alot of effort. I need to be back in business Mid August - Early Sept for shakedown to get ready for some FALL racing and some cooler weather

Anyone using the Girdle from Gears and Rears? Looks simple, even for me.

Be careful when buying a girdle. I bought one last year and about all it's good for is an expensive paper weight.The #5 main cap nuts are right in the way of the oil pan rail. Be prepared to modify the oil pan for this.If anyone wants it, it's for sale.

725-750 HP may or may not last with either block. dvoraks girdle would help the most out of what i've seen though.
i have my own idea's on what i would build, but sorry to say it probably wouldn't include the manley rods you already have. i hope you have some real good cylinder heads too.

Harpo, I ran a 446 with aluminum caps on a stock block with B1/BS heads 2years ago. I ran the motor for two seasons. I don't remember how many runs. It was making around 700HP with a tunnel ram. I had picked up 4.15 crank and was going up to 493cu.in. When I tore down the motor for the change I discovered one of the aluminum mains broke! After considering the cost of changing over to 4 bolt program steel caps and line boring the block, I bit the bullitt and bought a Mega block. I know there are no quarantee's with race stuff, but I felt it was money better spent. especially, if I want to make more power. Fast68Plymouth helped me put together a 528 that made 750HP with 720TQ. The bigger motor made all it's grunt down low. I switched from 4.56's to 4.10's. I shift @ 6000 and go out the back @ 6800. I feel like I am not even beating on this thing. Just my 2 cents!

Harpo, it was brought to my attention that what i posted earlier could be misinterpreted. i want to clear up the statement about the rods.
the reason i wouldn't use those particular rods is because of the big and small end size, for starters. to make the HP you want to make, i would be looking to slow down the bearing speed with a 2.200" journal instead of the 2.375". naturally i would want to lighten everything up and that would include going to a .990 pin. i didn't mean to imply that because the rods were manley's that i owuldn't use them. sorry if there was any confusion. Dan

Harpo,
As you know from other posts I've answered, I really think the RB block is more than capable of what you're asking from it..I went the Aluminum rod/ Aluminum Cap route with mine, also with 2.375/1.094 ends. and rocked the block all the way to the bottom waterpump hole. While I doubt that I'm making as much power as you motor for motor...I have successfully smacked mine with 425 HP of spray 10-20 times, and have 310 passes on the engine now without any problems.
I have purchased a set of 4 bolt pro-gram caps (the three center ones) but have yet to install them on a block.
I have seen a few broken stock and aluminum caps..usually the cracked caps are found before any major damage ensues...not that thats any consolation!!

I will probably open another can of worms even worse than questioning the weight of Montessa's Charger...but I've filled 3 blocks so far...after machining, with no adverse affects. My machinst does my work for free, (what were you saying about free stuff having a cost, Harpo?)and flat out refused to rock them first.
The water temp is actually easier to control ith a filled block, but I guess oil temp can be a problem in an application that sees extended run time.

Hmmmm .... fill the block, add the girdle .... is it too good to be true to keep me safe for 300-400 passes w/ teardown at 150-200?

I like the 4.30 stroke idea, if you're gonna spray it I'd go with the 7.100" rod, It gives you a ~1.46CH piston, @514 cubes and the rod angularity will be a little easier on the thrust sides of the block on a spray combo. I'd probably forgo the girdle, go with steel caps and a fill to the freeze plugs. Depends what you plan for heads but I wouldn't mess too much with the tree side of the track, you've got solid, consistent and quick and at that weight that's a tough thing to nail. My idea would be keep the consistency while easing down the ET's in the first 1/8th with a little added torque/CR and hp. Spray it with a 250 shot on a 1-2/10th sec time delay relay triggered right after you're in high gear, (I like a microswitch right of the shifter detent to the TDR in series with a WOT switch), that'll be easier on both the motor and the trans and you'll be on the spray down the whole big end of the track with consistency and not tearing anything up too bad. Going sub 6.50 in the 1/8th can be snuck up on, that's ~10.20 without the spray, let the bottle pick up the big end load. Heavy cars usually break motor parts right off the line, this way you've got kind of like a "Hemi in a bottle" with the big end charge. Like they say if you can hear a hemi at half track...he's got you!!

Also, if he or you red light or are comatose on the light, you save the juice. Besides you'll still be within the stress levels of the block on every launch, should last a good long while.

This way, I think you could go high 9's without either tearing things up or having to re-science your whole set-up.

in an application like yours the 2.375/1.094 rod combo doesnt bother me a bit(thats whats in the 528 BTW).

my .02 .....tall fill in the block, install the 3 middle steel caps, hope for the best and run with it.