We will get to find out real soon what a nice 3.79/ W9 deal will run. By good local buddy Scottb has exactly that combo built and ready to go for next season.
I dont want to spoil his news, but suffice to say its a mighty stout piece. Big bore, lots of cam and compression, and attention to detail. CNC W9's by Modern

Since you already have the 4" stuff, are the pistons reusable? I don't know if it would be worth it, but I love driving mine on the street with the 4.125 assembly. I have 3.89 gears with a 29.5 tire so it's a pretty mild gear, and I can stab it in any gear at any speed and the response is instant. It made 500+ torque from 4200 to 6400 (540 peak), so it's a fantastic pump gas street motor.

I love it when guys talk budget then mention a roller cam and heads that take special rocker gear, headers and intake manifolds. My engine has a set of twenty year old Crane Gold 1.5 rockers and a 600 lift solid flat tappet cam with stock port windows and geometry. Pretty boring stuff for an engine that's shoved me to 10.39-128 NA and 9.43-139 on a small plate. I know, the numbers aren't very impressive compared to the race cars around here, but it has over 6000 street miles on it so far, drinking 89 pump swill.

Here's a combo off the top of my head based on what I just did with a 4 inch crank, only this one would cost less, using stock valvetrain parts.
Magnum block at 4.030, 4.25 stroke, 6.2 Hbeam sbc rods, 1.350 (?) Co pistons, 12.5 compression with a flat top piston. All this for 434 cubes. Big mutha thumper hydraulic roller, EQ heads with 2.02 intakes, bowl ported , use stock valve train, 850 and an Airgap intake . Should make 540 hp, 560 torque.
Shift at 5800, change plugs and oil for seasonal maintenance.
That is what I see as a good, stock block 4.25 stroke combo. The stock block should live fine, sure, you can say the piston side loading would be higher, but that is balanced by a lower shift point. I can see a lightened A body going 10.00 all day long and the driver is comfortable,

I'd do the 4.125 and not look back for your combo.

That sounds like a bad ass package.

Cool! Can't wait.

By some what budget, I mean no 2000-3000 dollar block. molnar crank and rods ect. sure the heads will cost a bunch, but that's where most of the power is at. Heck, I built my 511 on some what of a budget at about 8000-$8500. Ya just have to shop around. What would a 650-700hp pump gas crate 511 cost? $15000 or more?

The whole bottom end is reusable I am just toying with going bigger since it will be apart for freshening....sorry my top end isn't budget enough for ya, not my fault I got it for quite a good deal. Your combo sounds impressive, but I would be curious to know what your car weighs too 👍

You can offset grind your 4" mopar journal crank to a 4.125" by using the 2.00" '327' chevy journal rod. Bobweight will be lighter too since you also go to a lighter .927 pin.

I like the 4.00 inch stroke SB combo. At 4.125 and 4.250 you start to run into things. Oil pump, windage tray, etc. start to get in the way so the assembly just takes longer and you have to be willing to modify parts and/or buy different parts until you find a combo that works. Using the smaller Chevy rod journals sure helps. For a race engine it might be worth going with the Honda journals or something like that. I think the Hughes Engine kit uses a 4cyl rod bearing to get the size down.

mshred,
I think the 360-2s are perfect for your budget since you already have them!
My heads are 220cc intake runner, and even with the mild flat tappet cam it made peak HP at 6600, so I think your heads could handle more stroke and still be effective.

My car is a real deal street car with big radiator, alternator, two seats, two batteries, 8.50 cert cage, all factory glass and bumpers, 15 gallon cell, then you add in a 300+ driver and it's certainly no lightweight! OK, ok it's 3150 with me and the nitrous bottle on board, those Chrysler engineers really outdid themselves in 1962...

mopar dave,

This is not a personal attack against you, as my own brothers think similarly, I'm just trying to advance the conversation. I'm not trying to invalidate anyone's opinion, just asking that you spell it out in hard numbers.



The typical 4" stroker kits with stock style rods run around 1700$ to 2000$. The 4.125 and 4.25 high quality kits from Bloomer and Molnar are about 500$ more.

W-9's, in another thread it was discussed are 6K by the time they are ready to make serious power.

Any head that requires offset rockers just added another 500 to 1000 over the budget of a standard head.

Then we have to have the conversation about the cost difference between a roller cam and all the associated parts versus a flat tappet. Is it really wise to have a .700 lift roller, with a short valve and a 1.88 installed height?

I've also never understood the love affair with big bores. Granted, I know they make a little more power, but in the conversation of small block mopars, we are dealing with a finite amount of available blocks. My X block was standard bore 4.04 after 15 years of racing, when I ordered the 4.125 stroker kit, I only punched it to 4.070. Why go right to max bore immediately?

For guys more versed in big blocks, remember when 4.15 was the go to stroker kit? Then the 4.25 stuff with the 2.20 journal came out and it was lighter and easier to assemble. Same way with the 4.125 stuff with 2.00 journal over the 4.00 kit.

I have offset ground 4 in cranks to 4.23 (using honda journal rods) and used SBC large journal rods with callies 4.25 dragon slayer cranks (no longer available) and have never had to do any real significant mods that I wasnt already doing for most 4.000 in. builds. I do tend to use lighter rods than many of the beefiest H-beam rods that are on the market.

Windage trays vary but I have used simple spacers and also trimmed some of the tray.

I'm running a 4.125" crank with a 2.00" rod journal and didn't have any Clarence issues.

MoparBilly, please check your pm’s.

What kind of rpm’s is suggested with these big arms ?

What block does the 3.79 crank fit that you have?

Mine peaked at 6750 on the dyno and at the track I usually shift around 7000.

If I remember right the 3.79" stroke was purposely derived to allow a 6.123" rod combo to fit relatively easily within the "new" (at the time) Race blocks shorter 9.2" deck. The 3.79 gives you a 1.18" compression distance with a standard 6.123" rod.

But I think it also can give you pretty close to a near zero deck height when replacing a 3.58" stroke in a 360 while using an off the shelf low compression Smog piston....pretty clever.

This was similar to the reason the 4.15" was settled-on for the big block stroker crank, with only an .022" overbore it allowed you to use an off the shelf 400 piston in a 440 and make a 493.

We've got a 1977 360 block running on the street with the Bloomer 4.125 kit. I like it.

Running a Super Victor single plane, 950 cfm 4150 and using some modified Indy LAX heads and running on 91 octane pump gas it makes 474 LB-FT @ 3,000 rpm, 574 LB-FT @ 5,100 rpm and 629 HP @ 6,400 rpm.

The owner is a little wild and the first time it left the shop it had an ignition box with no rev-limiter. It came back in 6 hours with bent exhaust valves. As it is making over 600 HP @ 5,800 rpm, we installed a MSD 6AL-2 and I set the rev-limiter @ 6,100 (619 HP). So now, damn it, he uses the rev-limiter as a shift light.....you know.....winds it until it hits the limiter and then shifts. If I set the limiter at 7,000 rpm he'd still do the same thing. It's just one of the many small reasons I've decided to not build anymore engines after I finish the ones already here.

La Roy engines, what did you do for a cam?