Iron head question

Iron head question - 04/04/10 11:50 PM

looking at some of fast68plymouths articles on the tech board, i was wondering if i could support 500 horse with the heads i have.

links i used for comparison: http://www.moparts.org/Tech/Archive/bb/4.html http://www.moparts.org/Tech/Archive/bb/40.html

my heads: 906 castings, .060 milled off. 2.14/1.81 stainless valves w/ back cut. 3 angel valve job with bowl porting.

from fasts article, and the work done to the heads i have i would assume they are in the 250cfm range @ .550 lift

aluminum is a bit pricey, and these are already done. just wondering if i can get what i want out of them

thanks for any help!

Posted By: blownzoom440

Re: Iron head question - 04/05/10 12:03 AM

i would not assume any flow data.i think you will need some compression to help get the 500HP.

Posted By: CrazyRocker70

Re: Iron head question - 04/05/10 12:21 AM

do you think 10:1 would cut it?

Posted By: blownzoom440

Re: Iron head question - 04/05/10 12:26 AM

i cant say yest to the cr and mean the whole package will work.i think in the tech archives there is a build to match some data.

Posted By: 383man

383man - 04/05/10 12:34 AM

I run a 906 headed 440 that going by my mph and weight I make right about 500 hp at the flywheel and it is a very mild combo by todays standards. A .030 over 440 with the MP .557 cam and 906 I ported myself. It is right at 10.0 comp and has the KB quench pad pistons as it will run fine on 92 pump. Ron

Posted By: CrazyRocker70

Re: 383man - 04/05/10 01:26 AM

thanks ron, i remember talking to you awhile back about that 557 stick and your combo. thats why i was looking at flow around .550

what i have planned: steel crank, stock rods, pistons in the 10:1 range (have to cc the combustion chamber still), the 906's from above, holley sd, 850 speed demon (got a screamn deal on it) 1" open spacer if it will fit, mp elec dist, and either the dough throleys 1 3/4 header or the tti 1 7/8

the car is a 71 runner, 727 3.55's lookn to buid a street car with nuts, it will get a little strip time but not much... dont have the budget for it

Posted By: 67_Satellite

Re: 383man - 04/05/10 01:37 AM

I don't know how old you are or what your time frame reference is,but I recall the old Pro-parts combo from the 80's. It was a 440 with 2.14/1.81 valves, pocket ported 906 heads,street dominator intake,10ish:1 compression 509 purple cam, 850 D.P. It made 511 H.P. and 522 TQ. I think with the .557 cam(or better/newer cam)and some refining it would surely be posible to surpass the results of 25 years ago.

Posted By: Cab_Burge

Re: 383man - 04/05/10 01:40 AM

I have made a bunch(ten or more) of stock stroke pump gas 440 motors that made 500+ HP with more torque than HP. None of them where what I would consider a "quench" motor, all of them had flat top pistons, some with valve reliefs some not. Most of the iron heads had the same size valves as yours but some where stock size with mild porting, the best heads flowed 266 @ .500 on a Super flow 600 bench using 28 inches of water on the intake side. The cams varied from a Comp Cams XE28HL to a solid lifter Reed cam(the most HP ,535 HPat 5900 RPM,and Tque 560 FT lbs at 4200 RPM

)that was ground on a 101 LSA

Take a good hard look at Comps XE-HL sereis hydraulic cams

Most of those motors had either a Eddey Performer RPM intake or a Mopar single plane 4150 with at least a 800 CFM Holley or BG double pumper, three had the Holley 950HP. Your set up and car combination would make me want to use the Comp Cams XE284HL with a set of 1.6 rockers and a good 3000 RPM converter (11 inch )

Posted By: CrazyRocker70

Re: 383man - 04/05/10 02:18 AM

thanks for the info!

67 satellite, i never heard of that build, im 23 so i didnt pick up much from the 80's

Posted By: 383man

383man - 04/05/10 04:13 AM

Quote:

thanks ron, i remember talking to you awhile back about that 557 stick and your combo. thats why i was looking at flow around .550

what i have planned: steel crank, stock rods, pistons in the 10:1 range (have to cc the combustion chamber still), the 906's from above, holley sd, 850 speed demon (got a screamn deal on it) 1" open spacer if it will fit, mp elec dist, and either the dough throleys 1 3/4 header or the tti 1 7/8

the car is a 71 runner, 727 3.55's lookn to buid a street car with nuts, it will get a little strip time but not much... dont have the budget for it

That is real close to my 440 as I use the Street Dominator intake with an 850 DP. I also use Hedman 1-3/4 headers with 3" exh. I use 4.30's but with a 30" tall tire. I drive it 55 to 60 mph all the time taching in the 3000 to 3400 rpm range. In fact I drove it almost 100 miles today (45 miles one way) on a 55 mph road to see my mom and dad. It was just to nice a day here in Md not to drive my 63.

But it sounds like you will have a nice running car in the 500 hp area.

Ron

Posted By: dave571

Re: 383man - 04/05/10 04:29 AM

Quote:

thanks ron, i remember talking to you awhile back about that 557 stick and your combo. thats why i was looking at flow around .550

what i have planned: steel crank, stock rods, pistons in the 10:1 range (have to cc the combustion chamber still), the 906's from above, holley sd, 850 speed demon (got a screamn deal on it) 1" open spacer if it will fit, mp elec dist, and either the dough throleys 1 3/4 header or the tti 1 7/8

the car is a 71 runner, 727 3.55's lookn to buid a street car with nuts, it will get a little strip time but not much... dont have the budget for it

I think you are on track with your build but the 850 speed demon is the wrong carb, no matter how good of a deal you got on it.

Main reason is, that carb is for cams with less than 240 @ 50 duration. ( I think you'll be over 240 to get the 500 horses you want)

It will not tune properly with that much cam. I run a similiar build myself, and use a 750 Mighty demon. It is made for cams with duration of 240 - 260.

You could run an 850 mighty, or a 750 mighty, and either would likely work, but a speed demon is the wrong carb for you. Keep in mind, a 750 demon does NOT flow the same as an 750 it holley. It flows closer to 830 cfm. I replaced my 750 with a 950 hp holley, and saw no performance gain or loss.

Sell the speed demon,a nd put the money into a mighty demon

Posted By: joedust451

Re: 383man - 04/05/10 06:38 AM

You should be able to reach the 500 HP level fairly easy with the 906s, i ported mine but kept the stock size valves, the heads flowed 268/198, & there was alot left to port if i went crazy. Dave is right on that Demon carb, you'll be way better off with the Mighty over the Speed in your combo.

Posted By: CrazyRocker70

Re: 383man - 04/06/10 01:22 AM

wow, thought i lucked out with that carb too

guess its time to go mighty..
any one know where i can find more specifics on holley/ demon carbs? ive heard that the 850 holley dp will flow in the 900 range, the 750 demon in the 830 range.. is there somewhere i could reference information like this?