I am getting ready to build a 426 small block for a IMCA modified (circle track). Has anyone every done this? Any problems or areas for concern?

The setup will be:
400 (509 casting) bored .060 over
Pistons are JE forged domes (9cc)
Rods are forged small journal 327 rods
Crank is forged and will be offset ground to 3.870
Heads are some 64 cc fuelies severely ported for now, with plans to switch to bow ties or Brodix later
Engine will have a full roller valvetrain

Calculated compression is 15.2:1 and will be running on alcohol.

I am I smokin' crack or will this work? I am willing to put up the parts and risk them for a bunch of silly power. The only parts I have to buy are the pistons, I have everything else just sitting around collecting dust.

0.60 sounds a bit much for a stock 509 casting 400 block, cylinder walls will be very thin. Is it a 2 bolt or a 4 bolt 509?Olli

Dave, is this class restricted to 23dg stuff?

I run a .060 over 509 casting "2 bolt"....

Yes it is a 2 bolt, but remember it will be really cool to running the alcohol. I have other people I run with that have to cover 3/4 of there radiator and run a thermostat just to hit 180.

We can run any head. I just don't have a ton of cash for killer heads right now. Though they are in the future.

dave, i know someone that wants to sell a set of brodix Track1's complete. $1000.00.

You didn't mention your ignition, but large SBCs on alcohol with very high CRs DO NOT like stock magnetos. If you are running a mag, you need to send it to someone like ZIG and have it 'hotted-up'. Over 14:1 and on alcohol can put so much cylinder pressure in the combustion chamber that the fuel charge won't burn properly, until the cylinder pressure goes down.
I'd run a cam like a Lunati 501C5LUN (291/301 at .020, 261/271 at .050, .645/.645 valve lift, and 106 LSA) or a 501C7LUN (293/297 at .020, 263/267 at .050, .645/.645 valve lift, and 108 LSA) to keep cylinder pressure from getting too high. They will both deliver ample torque and BHP. The 501C5 is our baseline 410 Sprint car cam....

UDHarold

BTW, you obviously need a small base circle cam.....

UDHarold, thanks for the info on the cams. I also sent you a private message asking about another cam for my other car with a little different motor setup on 114 Gas.

Ignition would be a MSD 6AL. Would that be sufficent?

I had a cam (that i can't identify other than "it was out of a sprint car" is what my buddy told me) that clearnce problems. The piston was chasing the intake valve to closely, it was around .06 clerance.

The car I run weights 2570 at the end of a race, starting around 2620 with about 10 gallons of burn off, if not more. We have a minimum of 2550. Would these cams still work with the car being so heavy, in relation to sprint?

We usually run our RPMs from 6200-6600, I use a direct drive (TCI circlematic) powerglide with 6.0 final gears.

Just for info, the piston does not "chase the intake valve", the intake valve is opening not closing & .060 is more than enough clearance on the intake.
The exhaust is another story :D

Couple of things.
First thing is in my opinion you don't need 15.0 compression in a circle track deal especially with a stock type 23 degree head.
If you start making any decent power you absolutely need splayed caps & should have the front & rear strapped at a minimum.
In a 400 you really need a steel rear cap, it will break.
A Bowtie block would be a very good investment.
.060 over is not a good idea in the stock block, you will probably lose more HP than the inches will give you from lack of ring seal.
You are going to be hard pressed to make any power above about 6000 without more head in an engine that big regardless of cam & it gets worse on alcohol. ;)
.

Those heads will be even smaller when filled up with alky.

What are the carb limitations? You would be better served running a 360-370 inch 7000-7500rpm deal with a steep gear if a short track. Dirt or asphalt?

If you have no experience with "alky" motors make sure you hook up with someone who does. We were involved in running an "injected" one in a dragster. The car ran great with a mid-sized BB. 7.48's over 180 MPH. It's much easier to "wash" engines/rings out on alcohol than it is on gas. We never had an issue but I know many people up here who did. Having said that, I'll add this, it's definitley more economical. Just be careful. Thanks, Gary in N.Y.

My machinist told me with a two bolt "studed" 509 400 not to go over 11.5:1 without splaying the mains. I am involved in the "dirt track" thing also and would never bore a 400 .060" and run the stock mains with 15:1 + CR. I think you'll be throwing your $$$$$ down the drain. Those heads are also going to choke that big CUBIC INCH small block. I have heard of people running a .060" 400 on the street with no problems, but not dirt track racing - it will have a short life......

Does the 509 need to go .060" over? If so, I'd look for another block.

I have quite a few "standard" 509's and 511's. They're not cheap though.....

GOOD LUCK!!!

Wolfplace you right it was exhaust, my bad. THe only reason I am using them heads is they will be free, I will switch them at the begining of next year. I was thinking about the splayed caps, we are not allowed to use aftermarket blocks, just stock blocks.

At the local we can run any 4 barrel, though we need a restictor plate with 4 1" holes or a holley 4412 (500 CFM) unrestricted. At the other tracks (big shows) run what you brung. This is asphalt, the normal track is a 1/4 high banked and high speed, the others are 1/4 and 3/8 mile.

My machinst is familiar with akly build ups.

Yeah the block is pitted some still (took it to .040) and it needs to be opened to .060.

The only thing I need to buy for this are the pistons and main caps, rings and bearings. Everything else is free, so I might be out $1000-1200. My plan was to run it for a few races, then pull it back out check all clearences and then change the heads.

I absolutely understand that I could loose this whole motor becasue .060 over is pretty thin and the high compression. Maybe I will look at another block I have laying around.

Should I use flat top pistons, which would put my compression at 12:1?

Thanks for all the input.

Dave, you might want to explore spending your money building a smaller motor that works more efficiently. On these big cube SBCs unless you have some super crazy 18* heads that flow 350/280+ you're going to be suffocating the motor with those fuelie heads, and most any other 200cc head like the brodix that you put on it. I was going to build a 434 years ago and went to S&S and talked with Rick Santos' dad and he broke it down for me on why not to build a big inch Small Block. You could probably build a 383 or something around 400 inches and make more power witht he heads you want to use. I would suggest talking to somoene who specializes in these types of motors. S&S had the worlds fastest small block, and definately know what they're doing so might be worth a drive to San Leandro to pick their brain.

Dave, you might want to explore spending your money building a smaller motor that works more efficiently. On these big cube SBCs unless you have some super crazy 18* heads that flow 350/280+ you're going to be suffocating the motor with those fuelie heads, and most any other 200cc head like the brodix that you put on it. I was going to build a 434 years ago and went to S&S and talked with Rick Santos' dad and he broke it down for me on why not to build a big inch Small Block. You could probably build a 383 or something around 400 inches and make more power witht he heads you want to use. I would suggest talking to somoene who specializes in these types of motors. S&S had the worlds fastest small block, and definately know what they're doing so might be worth a drive to San Leandro to pick their brain.
=
You will not get much better information on a small block than from George or Rick.

I drove their Blown Alcohol dragster for about 10 years before Rick started driving & George has probably forgotten more about small blocks than most will ever know,,,
Plus they are very cool people :)

And yes, the flat top engine will make more power than the hi compression one
On the heads, it has very little to do with flow numbers, deal is they are just too small in cross-sectional area & will "choke" the engine somewhere around 5500 at a guess on an engine that big on alcohol & the torque curve will head straight south,,, damn near like hitting a rev limiter :D
The other deal is alcohol with a carb needs more head than a gas engine because the alcohol takes up space in the runners
You are running with an AFR of about 6 to 1 vs 12 to 1 with gas,,,,,

PS: J70,, tell the Santos gang I said Hi :waving:

If I ever get back down to their shop I will do so... I had them do alot of machine work for me when I built my first motor back in 95 or so. I now use Rex Hutchison in Sac for all my work now. Should be dropping my motor off to them this weekend if it works out to have some things done.

Thanks for all your input.

I will consider dropping the CR and give that a try. This is just a temp motor, until I build a my real piece. The future plan was for a 377, this one was so I could talk smack to my buddy that has a 406 SB.

I do plan on taking this to Rex to have the Dyno tune it.

I was trying to experiment, because I have an old block I really don't plan to use (the .060 canidate) and a free forged crank and rods. The machinst wants to do the work for free, I just need the simple stuff and pistons. I guess I will step back and look at all my options, maybe I can trade some parts to make a smaller setup.

Dave,
I just finished a 406 with 6" rods and Wiseco Pro-Tru forged pistons (weighed 432 grams each ;) ) and the CR ended up being 11.3 to 1 with 64cc 041 GM heads... These were flat tops. The rods were the Scat I beams with 3/8" cap screws - the rods weighed 598 grams.

On a side note - I installed a 4/7 swap cam (Howard's small base custom grind) also to experiment a little. We may or may not notice a difference.... I should know in a few weeks :)

dave, i know someone that wants to sell a set of brodix Track1's complete. $1000.00.


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