Can any one tell me what the ideal combination of bore and stroke, head and piston CC etc is to get the maximum Cubic Inches out of a GM small block is. Is 427 possible and are there any risks, overheating etc? I'm thinking of buying a used 400 4-bolt block and building it up over time.

Many thanks

Anthony Y
Aussie 67 RS/SS
http://www.camaros.net/forum/smile.gif

The largest cid small block I have ever heard of was a 448 CID!!! We're talking about
boring the best bowtie 400 race block you can find to 4.155, adding a 4.125" stroker crank, custom pistons, big, BIG cyl. heads, etc. I bet with the right cam, ignition and coolant system, you could get one to live on pump gas.
I think a better option would be a 434 cid (4.155 bore x 4.0 stroke) sprint car/late model combination. This engine will still set you back more than one pretty penny but there are a lot of guys running these so getting advice on how to build one will be easier.
You may want to check out http://www.speedomotive.com for stroker kits. These guys also have a fairly in-depth article on building hi-po engines.

As for using a stock 400 block, you could probably squeeze the above 434 cid out it.

I once heard a story about a 454cid sbc but don't remember what the bore or stroke was.

good luck.

454 is the limit, not worth the effort. Head flow becomes the determining issue after about 420 c/i. There aren't heads that will support anything over that engine size, and the best ones we have seen are 410/412 c/i. Used slight offset ground crank, .060 overbore.

BTW, if the crank you get for your stroker engine has the letters TH&T on it, the crank is a Chinese crankshaft. Not made here in the U.S. There are two foundaries in China that make crankshafts for vendors here, TH&T, and the other one owned by SCAT Enterprizes, here in Santa Monica, California. Some SCAT Chinese cranks have SCAT embossed on them. China makes both cast iron and forged steel cranks for us.

Scat also makes their own high-dollar cranks here, but not many anymore. More profit from Chinese stuff.

[This message has been edited by IgnitionMan (edited 05-20-2000).]

I've seen a 440 stock block. 4" stroke and .060 overbore, I wouldn't do .060. I got my 410 by .040 over and a 3.76 stroke. I have no problems. Exact is 409.82 CI.

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67 Camaro 410sb 11.63 @117.6
67 Camaro 388 ET-???
website (http://www.geocities.com/lonnie67_1966)

Anthony,
I would just like to add that if you are really serious about a big inch small block, stay away from the 4 bolt 400 block. If you look at the main bearing webbs where the outer row of bolt holes is drilled, you will see that it is very thin and prone to cracking. You would be much better off to use a 2 bolt 400 block and install some good caps with splayed outer bolts. They go into a much stronger area of the block. If you are going to use a stock 400 block and not fill it, I would have it sonic tested and even then limit the bore size to as little an overbore as will clean up the cylinders. I would rather sacrifice a couple of cubes for the thicker cylinder walls.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Bill,

Is there any reason not to "fill" a block used for the street? Is over heating or hot and cold spots an issue? I am going to build a 400 and just gathering as much info as possible.

Joseph

I just saw an article in the new Chevy highperformance mag. Klein Engines in Phoenix built a 461 small block for a streemliner, they hit 344 mph with alcohol and 332 mph with gas. They use a Donovan aluminum block with 4.155 bore and 4.25 stroke. 800 hilborn injected hp. The also have 15:1 comp. and Brodix heads, didn't say which. With todays small block head technology, they are getting flow numbers that put alot of Big Block heads to shame, 350 plus. But I agree, it wouldn't be worth the cost. It would be cool though. By the way, my 400 block is a 4 bolt. When i got it i didn't know they were weaker. This is the second engine i've built with it, no problems so far...

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67 Camaro 410sb 11.63 @117.6
67 Camaro 388 ET-???
website (http://www.geocities.com/lonnie67_1966)

Joseph,

I have two 400 engines in two different cars. The blocks have been filled 2-3 inches in each of them. I bought the parts from Speed-O-Motive and assembled them myself. I do not have over-heating problems with either of them.

One is a roughly 500 horse daily driver set-up with a flow-kooler pump, Spal electric fan, and Be Cool aluminum radiator. The other car has an ATI Pro-charger with 12 lbs. of boost, aluminum radiator, and an ELECTRIC Mezziere water pump (remote mounted, 52 g.p.m.). This car won't go over 185 even at idle for 20 minutes @100+ degrees.

The bottom line is filling the lower portion of a 400 block strengthens them quite a bit and as long as you use quality parts for the cooling system you will have no over-heating problems.

Joseph,
We have filled a couple of circle track blocks with no problems, the key is not filling them quite as far as you do on a drag motor. Most of the heat is generated in the cylinder heads and the upper portion of the block, and since the water is still flowing there, cooling does not seem to be a problem.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Like IgnitionMan said, I've seen a 454 in a mag, built by Sonny Leonord. He took a Olds Rocket SBC and bored the cylinders off-center. Had to machine the valve guides off-center also. Anyway, if you want the most cubes possible, the Rocket block is the only way to go. The oil pan rails are spread (requires different oil pan), and the cam is raised. Stef's makes an aluminum pan to fit, and Jesel makes a belt drive. Just depends on how much you want to spend (doesn't everything?)!!

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69 SSRS Frame-off Resto
81 Z-28 377ci Drag Car

Thanks to all for the valuable info, keep it coming.

Regards

Anthony Y
Aussie 67 RS/SS
http://www.camaros.net/forum/smile.gif http://www.camaros.net/forum/smile.gif

We recently did an engine for a customer which is typical for a larger than average small block Chevy. I started with a 2-bolt 400 and installed splayed Summers Brothers main caps(you probably won't have any problem with the 4-bolt block BTW). I used a 3.875 stroke COLA crankshaft, a set of 6-inch Eagle rods, and a set of JE pistons. If you order the correct rods they only require a bit of clearancing on the shoulder to clear the cam. We filled the block to the bottom of the water pump holes, and ground the block to clear the capscrew rod bolts. Driven on the street with a Meziere water pump and dual Flexalite fans it never goes over 190 during the summer here in Southern California. With the nitrous and the progressive controller it went 9.80's so far and we're still trying to finish the suspension setup!

I think it was in Car Craft during the 1970s or 1980s that I saw several buildups of Gen I SBCs over 468-CID (at least one was close to 490 CID).

IIRC, it was claimed a 4.28-inch bore could be made to work in a naturally-aspirated SBC with a stroke up to 4.31 inch (496 CID); however, a more popular size used a 4.25-inch bore and a 4.25-inch stroke for 482 CID.

These engines used both sleeves for the cylinders and spacers between the block and heads, and spacers between the heads and the intake manifold, but there were no apparent reliability problems with them.

With that many cubes, you can hide a pretty radical cam -- and, spacers or no, the guy with the 377 or the 383 is just about never going to believe you've got a 100-inch advantage over him.

Boy, this is an old thread!!!!!!!!!!!!!!

Sonny Leonard's BIG SB was an Olds Rocket blocked 504"er!!!

It was about a 4.25" b x 4.45" s motor....

I have the old mag. article that talk's about how he did it somewhere in my many boxes of old mags.

As for heads, heck, I'd order up a set of either "splayed-valved, mini-BB's" or some SB2.2 jobbers from GM and be done with it.

pdq67

If your gonna go BIG go with an aftermarket block, otherwise you're limited a lot more.

482 max that I know of, but I would never build one. Bill had some great advice. Go 2 bolt block, install splayed caps, minimum bore required to clean up. Some one also added filling the lower portion of the block. I'd probably do that as well. Stroke is also where it starts getting expensive quickly. Best I can tell going beyond the 3.75 stroke is going to probably force you into a small base circle cam and lots of cleare checking and clearancing. You also have to start paying attention to how tight you start stacking the rings on the piston due to reduced compression height pin locations. After 420 it starts to get pretty expensive IMO.

I asked this question myself recently, but got no response. I have a nice set of 6.00 bowtie rods I plan on using in a 377 using a 400 block. I'd consider a 3.75 to 3.85 crank but don't know at what point I start having problems with the oil pan rail, piston and cam clearances. No one else seems to have the answer, but I know someone has had to have tried this with 6.00 rods. Can I go 406, 415 or 420? I would if I knew it could be done with the 6.00 rod without all kinds of rework of the block and running a small base circle cam.

I think the easiest to make is the 4.155" b x 3.875" s = 420.3"er.

Or sonic check the cylinder walls to see if it won't bore .060" over to make a 426.4" motor......................

OR!!

Young Luke, come to the Dark Side where the Force is STRONG!!

He, He!!

pdq67 and his about 9.8 CR., 550hp at 5,500 rpm "tow truck" 496" motor!!!!

But Master the force is also EXPENSIVE!

Pdq don't think I haven't been tempted to go back home to the BBC family. I was pricing it out again even tonight. "Problem" is I've got a great 1182 forged 10/10 350 crank, 6.00 bow tie rods with HD 7/16 cap screws, a good set of Dart 215 heads, Moroso pan, tray, studs, oil pump, drive, chain & gear, thrust button, ect. The "siren song" of a high winding SBC is calling me again!

If I'm going to do it I might as well really unshroud the valves with a 4.155 bore. Mahle makes some forged 377 pistons for the 6.00 rod in the 64cc chamber size I have at 11:1 or 12.4:1. I'm thinking of a set of aluminum 200 angle plug heads and that'll allow me a point higher than the iron head. A -140 cam or similar grind (I know it's an old grind, but so was the G/K cam I took out and it really woke up like no other 350 I've driven under WOT) will bleed off quite a bit of static compression and run it with 1.6 rockers. Top it with a SY1 and an 830 annular Holley and I'll be back on the road! I know I can run the 11:1 without any problems. The 12.4 I don't think so. Having just destroyed a 12.5:1 sbc I'm willing to back down a point or so on the compression. I'd really like something in between, I could run the 11:1 and run it with 58 cc chambers, that'll bump it up to around 11.8. Decisions!

Gotcha guy!!

Please carry-on..

pdq67

i saw an ad from some performance engine shop in a national dragster recently for a 499ci small block. it was only $26000.00! i think we should all have one in our cars & a couple on standby for backups! i just fired & drove my new 434 sbc last month for the first time. no overheating problems at all. it never has been over 195 degrees even in stop & go traffic. mine is based on a dart block with eagle & je internals (11-1 cr.), pro topline alum heads, solid roller w/jesel rockers. alum. radiator w/ a black magic electric fan. i plan on driving the hell out of it when the weather permits. good luck! bill.

The old Super Comp engine in my race car was a 420 inch. Used a 2 bolt block, with splayed caps, filled to the bottom of the water pump holes. 4.155 bore X 3.875 stroke cola crank, Carrilo 6" Stroker rods, Venoila 15.1 pistons, 477 grams with pin ). Had to do a ton of grinding on the bottom of the cylinders as well as the pan rail some, especially around # 7 cylinder. Used a std. Crane R288/4714-2S-8 camshaft ( although the lobe base circle did look small), clearance to cam lobes was very marginal .045 to .050 on the bad cylinders ( 2 & 6). 20 year Old Brodix -10 heads ported in my garage, 25 year old ported and welded and heavily modified Edelbrock Pro Ram/660 Holleys, Crane 7/16 stud roller rockers. Moroso wet sump comp eliminator pan, jesel belt drive. This combo made 735 HP on the dyno, it ran 8.98 at 3,600 feet.
My new comination is 447". Olds Rocket tall deck dry sump block. 5 stage dry sump. GRP 6 &1/8" rods, JE pistons 16 to 1, 470 gms + pin, Cola 4.125 knife edged crank, ( still needed heavy metal), Brodix Canted Valve heads 330cc intake runner, 410cfm intake flow., Jesel valve train and belt drive and front dist. drive, Comp roller- intake-.810 X .288@050 & exhaust -.748 X .300 @ .050.
Sheet metal intake, 2-1050 Dominators. Made 985 HP on the dyno.
This combination was VERY EXPENSIVE and very time consuming to build. Lots of grinding and clearance issues, even with the Rocket block ( probably due to the aluminum rods). Lots of Custom Fabricated parts, lots of clearance issues with all parts, as well as other misc. problems. Almost nothing fit with out some form of modification, including the Moroso pan /valve covers etc. etc. Plumbing has been quite tricky with the 5 stage dry sump, also the Canted valve heads have 4 external water lines on each head. This has taken 5 years + to complete. Probably would not ever build this big a small block again, it is with out a doubt the worse race engine i have ever put together, and i have built some 638" to 707" Donovan Pro Mod stuff for a friend.
I still have not ran the car yet, it is all done and it will be run this spring.
I personally agree that big inch small blocks are hard to build, i would probably just stick to a 406 and use Nitrous, and call it a day.
Hope this helps. Mike.

A 4.125" stroke crank in a 9.325" tall deck Dart Iron Eagle block (spread pan rails and raised cam) is a snap. A little clearancing on the bottom of the bores is all that was required. TONS of cam clearance. I used 6.125" Lunati Pro Billet rods, which still allowed for a 1.125" compression height on the pistons.

The biggest issue is fitting the pan and headers in the chassis.

More info here:

http://members.aol.com/jgchevelle/engine.html

Due to the heads power is down from where it should be, but that will be fixed once the chassis and rest of the drivetrain is ironed out. ;)

Best ET with a broken converter and poor 60' time is (@~3650 lbs):

1.64 - 60'
4.40 - 330'
6.69 - 1/8th
107.4 - 1/8th MPH

Drag Racer, Checked out your pictures, nice job. Steel rods are a bunch easier for clearance issues. For my application with the RPM involved and Lenco ( clutch= sudden shock load ) aluminum rods are more desirable for my application.
The Tall deck Rocket block also has the spread pan rails and the raised cam. I had no problems with cam lobe to rod clearance also. My compression hite was 1.137 by the way. I did not have to grind the pan rail, but had to extensively notch the bottom of the bores on both side because of the bulkier aluminum rod big end. Let me tell you this Rocket block was hard, it has a lot of nickel, carbide burrs just sort of shine it (compared to normal cast iron 400 blocks) until you really lean on the grinder, and use the coarse flute aluminum grinding burrs.
Stock 400 blocks are very limited IMO as to how big a stroke you can use because of the clearance issues.
My advice is -If you want to go big get a aftermarket block like the Dart etc.

Yes, I figure that it is a real chore to put a 4.00" crank in a block that originally came with a 3.00" crank..

pdq67

AMEN!!! What ever happened to just building a small inch and buzzing the living S__t out of it. LMAO. Good Memorys.

rszmjt,

I agree, for what you are doing aluminum rods are a must. I cheated on clearancing the block (the only way to do it IMO) and had my machininst do it with mill. All I had to do was make sure he took enough in the right places and there was adequate clearance.

IMO, when using the common aftermarket H-beam steel rods in a stock block 3.875" is as big as I would go.

Drage Racer nice looking peice you have there as I can see you did once the right way as we have worked with customers the think the 400 blocks are the way to go but we have had a few of those guys come back for a good Dart or Bowtie block and do it right just with the better ring seal you get with a the better blocks is good horse power gain.

And we can check blocks for blue print locations cylinders, cam tunnel locations, lifter bore locations and deck heights ETC. and I can tell you this there not even close to a good Dart or Bowtie block.

And filling a 400 block does not make the webbing of the 400 block any stronger as it only helps keep the WEAK CYLINDERS a little rounder as I tell people that ask me about filling blocks if you have to fill your block your not using the right block.

At least the weapon you built is much more dependable then a guy using an old 400 block.

Again good job there

I personally agree that big inch small blocks are hard to build, i would probably just stick to a 406 and use Nitrous, and call it a day.

OMG, was that you that said that out loud Mike? Why that would make you a Greaser! (LOL)

All kidding aside, I'll have to post a couple pictures of that new motor as it sure is a work of art, and I can't wait to see the new time slips. Congrats on completing it bud.

Quote:
Originally posted by mister copo-

"OMG, was that you that said that out loud Mike? Why that would make you a Greaser! (LOL)"

Figures, coming from a guy who likes blowers hanging out of a hood. LMAO. JK.

How is it??

One atmosphere pressure increase, almost double the power, two atmosphere's and three time's the power and so on!!

And think about the pressures that the little Miller 91 Indy motor took for it's size and how much power the little bugger made!! (If I have my stories right??).....

I want to say 45 psi boost?? But I may be wrong here???

But you have to remember they didn't have headgaskets b/c the head and the cylinders were cast in one piece, plus they were burning alky!!

pdq67

http://www.jegs.com/webapp/wcs/stores/servlet/category_10001_10002_28673_-1_10763

They also make a short block that does 415, 427, or 454. :D

Matt