I am trying to put together a 520 tall deck BBC(4.350 bore x 4.375 stroke) for my mud buggy (4,100lb) ( not a pit cruiser but an all day wheeler) and need help picking a set of heads. I want to run a set of oval ports so i dont loose bottom end torque. I am gonna redline it at about 6,500-7,000 RPM and have about 13:1 comp, race gas. I am looking for about 650-700HP. Are aluminum heads problematic with getting them hot and dipping them in water/mud? Are cast heads more reliable? What set of aftermarket heads do you guys think will best suite my needs?

I am trying to put together a 520 tall deck BBC(4.350 bore x 4.375 stroke) for my mud buggy (4,100lb) ( not a pit cruiser but an all day wheeler) and need help picking a set of heads. I want to run a set of oval ports so i dont loose bottom end torque. I am gonna redline it at about 6,500-7,000 RPM and have about 13:1 comp, race gas. I am looking for about 650-700HP. Are aluminum heads problematic with getting them hot and dipping them in water/mud? Are cast heads more reliable? What set of aftermarket heads do you guys think will best suite my needs?

not asking much, are you?

are you putting this in a short deck (9.8") block? If so, you will find that you have to grind the wee outta the block to make that big ol stroker fit in there. You would be able to fit a 4.25 incher in there much easier. and you will run less risk of holing the block. It can be done, i guess. Its your money.

as for oval ports, dont bother. get the rect ports to put on it. with 13:1 compression, you need em. It will make enough low end torque to do whatever you want to do. AFR makes a NICE set of heads that will provide you with plenty of torque. They are aluminum.

cast iron heads dont expand as fast as aluminum and they retain more heat in the combustion chamber. this is the selling point. They are heavy. they weigh a lot too.

aluminum heads are lighter, repairable, more conducive to modification, dont weigh as much as cast iron, and a whole bunch of other things.

Im building a reasonable bbc right now myself. 475 inches, 4 inch stroke x4.350 bore, Grumpy Jenkins heads with 2.30/1.88 valves, Eagle crank, rods, Manley 12.5:1 pistons, solid roller cam with 260/270 at .050, .680intake / .720 exhaust lift. Im estimating 685-730 with the right tuning on a 1050 dominator.

I think you will find yourself having a challenge finding 650 or more horsepower and having it trail capable.

This is, of course, just my humble opinion.

with big inches you need big heads

x 2 on that, oval port heads are better suited for low end torque building and I doubt that you would get very good flow past 6000 rpm with them.

13:1... 700hp ...all day wheeler... they contradict themselves.

I've been around a couple heavy hitters in the hp department but nothing like 700-plus ponies, a rig that makes those numbers reliably all day long will cost big coin.


Ever consider building a milder BBC with a blue bottle in the bed..:smokin:?

I personally think he could do it.

with a 700 inch motor.

using that combo is asking a hell of a lot to make that power level.

The block is from a 1970 C60, It is a tall deck 427 truck block. The guy building my motor just had dyno sheets on a 496 that made 615 HP, about the same bottom end (a lil less stroke,same comp ratio, roller motor), and a set of ported rec chevy cast heads. I heard that rec port heads start to really work above 6,500RPM but i don't want to spin the motor much faster than that. What combos have you guys put together with what results? Don't just bash me, instead help me out. This is my first built motor that i am gonna run and would like it done right.

These are my engine dyno sheets, hope you can see the print.

I put this engine together for low end torque but with the ability to make it a screamer later if I wanted. With the roller cam it should be very drivable and still roll up to 6000 rpm when I want. don't see a need for more with a BB. It makes 627 tq and 552 hp. The torque off idle is around 400 with 345cc as cast AFR heads.

Scott

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I think you could easily make your hp goals with a set of 290 cc AFR CnC OVALS. I made 575 out of a 427 short deck motor with 12.0 to 1 and a set of ported cast oval ports with big valves. I would put stock in those heads for your app. no problem.

I think at that Hp rect. port heads are the way to go.The small amount of torque loss will be small.Also 13 to 1 comp.will = race fuel only.The best way to get the numbers you want would be roller valvtrain,aluminum heads and supercharged so you have a chance to run pump gas.The cost involved to supercharge would be saved quickly by the fuel cost savings.

there wont be any cost savings in fuel if its supercharged.. unless you dont count having to buy 6 dollar a gallon race fuel.

13:1 on a trail rig is stupidly high.

go down to 9.6:1, buy the right parts, and build a 600 hp engine. It WILL cost you much less, and will live a LOT longer. and still have 600 HP.

scott do you have a build sheet of the parts you used in that motor?

Having owned very high compression BBC's - I cannot express to you enough how I think you are going about this the wrong way.

A 520 tall deck is a fantastic short block start. But there is no way in hell I would build anything that takes exotic fuel for wheeling - unless it's a comp only buggy. You roll and lose your fuel - get a fuel leak in a line and run the tank out before you realize it - you.. well, you make the rest of the scenarios. You going to sit there with your rig while your buddies go into town and find out that all the speed shops are closed till Monday and you can't get any fuel? You can say that you'll always have a drum in your garage or whatever, but it just doesn't happen man. I got so sick of driving cross town to buy C16 I scrapped a beautiful (and extremely expensive) 440" BBC to go about things another way. I know everyone has an opinion - so take it with a grain of salt. If it were me...

I'd shoot for 10:1. Go with a smaller rectangle port head - all the hype about ovals making so much more torque is .. well .. hype. Especially with a 520 - you think you'll really get yourself in a position where you'll be like.. damn, if only I had 20 more foot pounds of torque, I coulda made that waterfall! Unless you are going with some expensive aftermarket ovals - I really think your going to choke your motor - especially at the RPM's you were looking to turn.

For a trail wheeler - I'd make it as reliable as possible - if that means only 550-600hp - well - you can always put a little bit of nitrous on it for the dunes and mud holes -

I think you'd be happier in the end with a slightly more mellow engine than you first described :D

Good luck :)

Edit: Oh, and I would definitely go aluminum on the heads. Much easier to repair - and the weight savings alone on a BBC will make up for some of that *lost* horsepower you'll have with a more mellow setup :D I had to get a set of extremely ported iron Merlins repaired once and there are very very very few places that I'd trust - I ended up taking it to a diesel head repair place in downtown Phoenix that came highly recommended from my machine shop. If that same head were aluminum, I coulda fixed it in my garage with the TIG and then had my machine shop guy throw it on the Sunnen and I woulda been back in business. Cast iron repairs are a bit... creepy. You really can't go wrong with most of the aftermarket heads out there now - but I think something in the 325cc range would be super for you - might wanna look into those Edelbrock Vic Jr's - it's basically just a cnc'd RPM head - but I've seen them make some good HP - and Edelbrock is usually pretty good about standing behind their shit. But I've been happy with World Products, Brodix and AFR as well -

run 8:1 compression and a GT42BB turbo. fast spool, pump gas friendly, can run a "normal" cam with some low end grunt and still have potential for 800hp when you want it. That's the only way to make it an all day wheeler ...