Big cube smallblock

Hey Guys I posted this in the forced induction forum figure I would try over here as well.Never can have to much info.Here is my plan to put together a 434 using a F1C procharger.I know I would need a tall deck block guy at gm say they make a tall deck block not a production block it has thicker walls which I would need to run 20 psi +shot of nos.My problem is selecting rod lenth.With a standard deck as explained to me I would not use say 6.00 rods because of ratio.Would that still apply with tall deck?Alot of this will be custom work pistons,cam etc.Any direction would be appreciated

They did a big inch build up on Horsepower TV last season. He's a similar engine: http://www.shafiroff.com/472_675_engine.asp

The rod ratio is not what is holding you back. You can do a 434 on a stock, production 400 block with a 6" rod and a piston with a 1" compression height. This would be fine n/a but I don't think it would live to long with 20psi and n2o. The only way to get a taller piston is to shorten the rod(most likely will not clear a 4" stroke) or raise the deck height. With a tall deck you can use a 6.125 inch rod with a 1.2" CH or a 6inch rod with a 1.325" CH.

You dont need a tall deck block to make a 434, tall deck gets you 472" if you feel like it.

You would likely need an aftermarket 350 block with wide pan rails to make it work easier, I think you can do it on a factory width rail A/M block though. Just pick up either a dart or world 350 main (or honda main) block with 4.125 bores, bore it .030 and a 4.00" crank tada!

Thanks for the replys guys.The block was not really the problem I all ready have a Dart eagle block tall deck.Got it at a super chevy show.Guy had three or four he wanted to get rid of needless to say we took them all.Since I had the block just sitting in the corner wanted to do something with it.I started to do the normal 383 but suddenly change my mind.Think I have that disorder when people change their mind all of a sudden :D My main concern was the rod lenth and wanted to see if anyone tried this setup yet.

Shoot...if you have a talldeck why bother with a 434? Get a 4.25" crank, 6.125 rods and 4.155 pistons and have the biggest SBC you can build?

470 is big yeah but there have been 528 cube SBC's, Mindgame even had a old Sonny Lenoard 504 cube SBC.

Not Cheap!

Bret

470 is big yeah but there have been 528 cube SBC's, Mindgame even had a old Sonny Lenoard 504 cube SBC.

Not Cheap!

Bret

Bret, I was under the impression 472 was the biggest? Maybe its the biggest with OTS parts, or biggest relatively easily built?

As Bret said not cheap.Price has alot to with this project.Even though I can get some things at jobbers price there are many that can get very expensive.Will need custom cam,pistons etc etc.This is going to be a street(not everyday)strip setup just didn't want to get in over my head.Anyone have experiance with a buildup like this?Thanks again

Almost forgot Hey Bret I heard you are a cam wizard when it comes to designing a cam.Maybe when I get all my components together you can design one for me.

Bret, I was under the impression 472 was the biggest? Maybe its the biggest with OTS parts, or biggest relatively easily built?

You're right Jon, although you're kinda thinking in the box.

If you use a custom machined billet crankshaft, you can do all kinds of neat stuff with the counterweights.

Now consider this... if I take my custom 4.437" stroke billet crank, use a tall deck rocket block, move the bores a little, stuff 4.25" slugs in it... what have I got?

Yeah, one big 504 cid small block. :)

Of course there's a little more to it than that, like the moving spark plugs and stuff but that's the mechanics of it.

-Mindgame

You're right Jon, although you're kinda thinking in the box.

If you use a custom machined billet crankshaft, you can do all kinds of neat stuff with the counterweights.

Now consider this... if I take my custom 4.437" stroke billet crank, use a tall deck rocket block, move the bores a little, stuff 4.25" slugs in it... what have I got?


-Mindgame

"Move the bores a little"....this is possible on an existing block, not making one from scratch?

I wouldve thought the major problem with such a huge stroke is the rod bolts cranking the block by the rail and bores, not the counterweights? I guess the counterweights might cause a problem with the bottom of pistons maybe?

Yes, possible although I don't know all the dirty details. Of course, we go back to a custom billet crankshaft making this possible.

The rods clear fine. Notching is about the size of a nickle (maybe a tad bigger) and you'd probably get the nickle about centerline deep in the notch. Lots of meat on the rocket block though.

For the real deep down dirt, you'll have to give Sonny a call. He'll tell you everything for a price. ;)

-Mindgame

lol.....

I kinda wondered about that.....

Any chance that you had some small rod journals in this puppy?

How long ago did you run that thing?

The best part is the move the bores a little, stuff 4.25" slugs in it

Makes me wonder how far you are offsetting the bores....

Bret

I'm still wondering about the offset bores here....

On a standard bore spacing that's not enough material between the cylinders. Now say you offset the bores from the center a 1/16" and sleeve it you now have issues with the lifter bores and combustion chambers..... You gotta give us some details on this... I can't wait till the EM contest in October to ask Sonny abou this.

Bret

Makes me wonder how far you are offsetting the bores....

Me? I didn't offset anything! :D

:lol:
I can tell Bret's gears are grinding away on this one.

The rods, did have a unique profile... they were made to Sonny's specs by GRP. Rod journals were 2.100". As far as that goes, everything inside this engine was made to Sonny's specs. The block came with no lifter bores and SAR machined them where they needed them to be. GM splayed heads get a lot of welding, a little comb. chmbr. move along with repositioning the spark plugs and valve guide centers..... valves were 2.28/1.680 using intersecting seats.

To give you an idea... this was (I believe) late 93'/early 94' so it's been some time. I do still have the block, intake crankshaft and cylinder heads.

Sonny is pretty secretive on what it takes to build one of these but he might be willing to throw it all out now that it's been a decade.

-Mindgame

Still turning man....

Never would want to do this, but I do want to know how to do it.

I was figuring that you start with a block without lifter bores and something wild and capable of supporting 500cubes in cylinder heads.

I gotta see that block and the rest of the parts one of these days.

Bret

Bret,

If you ever get the notion to build something like this let me know, Ill volunteer to supply the test car for ya, lol


-john

Just as a side note a production 400 block will handle a 434 ci stroker but it wouldnt live long as you have to grind excessivly into the pan rails to clear the crank/rods. Im in the process of building a 420 ci with a production block and even thats iffy.

Bret,

If you ever get the notion to build something like this let me know, Ill volunteer to supply the test car for ya, lol


-john


lol........ I'd have a lot of volunteers for that one!

you dont need a tall deck block to achieve 434 cubic inches i say give a call to scott shafiroff. he'll build a forced induction small block short block for you as cheap as anybody. but if i was going to subject one to that kind of abuse i might start out with a 427 just for that extra little bit of cyl wall meat. dont get me wrong though it does take an aftermarket block to do it reliably with what you're talking about. i do imagine it takes a small base circle cam unless you go to a dart raised cam tall deck block. which is probably a good idea for you anyway so you can run a piston with any type of ch to it at all. those 434 and 427 cube small blocks have a very short piston in them as you can imagine with a 4" stroke and a 6" rod.

Just as a side note a production 400 block will handle a 434 ci stroker but it wouldnt live long as you have to grind excessivly into the pan rails to clear the crank/rods. Im in the process of building a 420 ci with a production block and even thats iffy.

Yeah, there's a little bit of clearancing but "how much" will depend on the rod design.

Like I've mentioned before... way back when.... there were guys building 427+ ci small blocks for strip duty and they were runnng these engines for the whole season. There are tricks to making one live, but it is easy enough to build a street engine on an old block. Maybe not feasible when you crunch the numbers (machine work) but plenty possible.

-Mindgame

Since were on the subject here, We finished the machining on my 383 LT1 and its ready for assembly but I Have this 400 sb sitting here in my shop and ive been thinking about going down that road instead since the 383 was going to be with a single plane, carb, anyway. so i feel that it would make more sense to go with the 400, converted to 4bolt, and a nice set of 23* Dart Pro 1s, more cubes and more potential.. But what would you guys suggest as far as machining and rotating assembly, I would like to a do a stroker with it 420 maybe 434 but if that would take to much material out of it than ill pass. Or even a simple 406. The car will be mostly set up for the strip but will see occasional street time.


Thanks,
-john

Im building a 420 ci inch stroke 400 with the following parts: 30 over 400 block with Moroso Hard block to bottom of water pump holes, plugged steam holes and restricted deck water passages,moroso 4 bolt splayed main caps, C.A.T lower end cap girdle,and Eagle stroker kit with 14:1 compression ratio JE pistons.Im using a sollid roller specs:Lift .688/.674, duration @.050 is 272/ 285 and im also using the dart pro 1 23 degree heads except im using the cnc ported versions. We hope to make 700-750 n/a hp reliably and 900-950 with a 200 shot of nitrous on top.

Im building a 420 ci inch stroke 400 with the following parts: 30 over 400 block with Moroso Hard block to bottom of water pump holes, plugged steam holes and restricted deck water passages,moroso 4 bolt splayed main caps, C.A.T lower end cap girdle,and Eagle stroker kit with 14:1 compression ratio JE pistons.Im using a sollid roller specs:Lift .688/.674, duration @.050 is 272/ 285 and im also using the dart pro 1 23 degree heads except im using the cnc ported versions. We hope to make 700-750 n/a hp reliably and 900-950 with a 200 shot of nitrous on top.


Its sounding like a pretty solid setup, Im liking the 420... Were gona run eagle crank, H beams, Mahle pistons, I want to use Pro 1s as well, you said your going to run the CNC versions, how well did the flow out of the box??


Thanks,
-john

320 cfm @650 lift out of the box,they are supposed to be THE best flowing 23 degree head out there.

230s correct?


-john

I beleive so,they are sitting in the speed shop right now waiting for me to pick up. As soon as I get them I will be sure to post numbers.

Kind of off topic here but is the bolt pattern on the 400 the same as a LT1 becuase im planning on running a T56 and have been told that they are compatible.

thanks guys,
-john

Since were on the subject here, We finished the machining on my 383 LT1 and its ready for assembly but I Have this 400 sb sitting here in my shop and ive been thinking about going down that road instead since the 383 was going to be with a single plane, carb, anyway. so i feel that it would make more sense to go with the 400, converted to 4bolt, and a nice set of 23* Dart Pro 1s, more cubes and more potential.. But what would you guys suggest as far as machining and rotating assembly, I would like to a do a stroker with it 420 maybe 434 but if that would take to much material out of it than ill pass. Or even a simple 406. The car will be mostly set up for the strip but will see occasional street time.

Don't even think about a 434 on a production block if you're not willing to pay for a lighter rotating assembly. In that I'm saying that this is the place for those 45 lb and lighter crankshafts. Keep the rods and pistons light too... but not to an extreme.

There's a lot of prep work to making a production 400 handle lots of revs (been discussed in this forum before) but some of that can be skipped for a 6500 rpm street build. If you want more revs, why not just build something with a 3.875 stroke and larger bore. May be the best option at that point.

-Mindgame

yah the 434 isnt going to happen but if was able to seing the money on dart block then maybe..

Im looking a max motor of 7000 rpm so a hardcore street build would be ideal as the car will see occassional track time but more street time.


-john