Recipe for 700hp six pack 440 or bigger-

Sorry guys, l've been a SB guy for 30 years and this rb stuff is foreign to me and I have lots of questions so I need some opinions on this.
I just bought a 80's pro street (real) 6bbl cuda that has a mild 906 head, 440 and a 850 with a single plane and want to convert it back to some form of a 6 barrel again with a end goal of around 700-750(streetable) horse and it MUST fit under the factory shaker hood. I'm not really hung up on what head goes on or how big the cam is. stroking it could be on the table but I'm not against a higher revving combination either.My last small block was pretty aggressive and that's OK by me. Pump gas (not e85) is a must here.
My initial thoughts were of going with ported victor or Indy heads, a mod man intake and a efi 6bbl setup but all the posts are quite old and not up to date on people's results. I can't find any info if a mod man six barrel setup will fit under a shaker as I can't find any intake heights.
Carbs are not totally out of the question with the factory intake but what aftermarket head will flow the best and still accommodate a factory 6bbl intake?
I know using a six barrel setup to make bigger numbers isn't ideal but it would be sac religious to not put it back on....but I'm not willing to go slow either.

I don't think it is possible with factory intake / carb set up--that is one lofty goal HP wise and the word streetable close to it
The intake is the governor and choke point
Any 511 style stroker you do will throw up 560-600 HP easy as pie but 750 is a darn long way from 600
This will be interesting

Well congrats on finding a 6BBL CUDA. WOOHOO now the fun begins.
If you remember, Paul Rossi ran a 440 6 pack in a 70 Challenger with the old Weiand 6 pack intake and it fit under the stock TA hood. I had one of those on my car for a while but with a 1050 Dominator intake and with the tall spacer required to make the Dominator work, i doubt it would have worked with the shaker I now have on my car. I have not heard anything good about the mod man intake. My Challenger was dyno'd at 650+ with a stock stroke a big roller cam, the above intake with dominator and a LOT of work on the 906 heads to get big flow numbers out of them. Look up six pack in the search engine. I seem to remember a post a while back about some modifications that were being done by Muscle Motors or someone that was getting really high HP numbers from them.
Good luck with yoru build. Post some pictures of yoru find.

I know the stock intake is a choke point for my goals which is why I thought the mod man might like the big cube or high rpm play field better. I was banking on the efi to resolve the crappy fuel distribution the intake is known to have with carbs.

For your info the Modman is 5.5 inches tall if that helps.
It can be done but not cheap or easy.
Todd

The Weiand six pack intake will not work with the stock shaker hood, too tall. Maybe a sheetmetal short runner tunnel ram with a top for using 3 split Dominators, but that might be something that gets costly.

Thanks for the intake measurement, now I just need to find one for the oem 6 bbl intake.

From member Sasquatch, Carb pad height on the factory sixpack is 5.25 to the pad (edelbrock catalog page 58)
Ask and ye shall receive.
Todd

Thanks! I'm assuming that the mod man intake height was to the carb pad as well?
I'm guessing that the top plates are all pretty close to being the heights- does anybody know if this is correct? Indy doesn't seem to give much tech info on it from what I can see.

Well the six pack intake is a good intake up to a point but I don't think that point includes 700+ hp. If you build a nice RB based 505 with good heads like the Trick Flow 240 and a pump gas compression ratio of 10.5 or so then you might be able to squeeze out 700 hp if you have a really good intake manifold and a big carb and fairly aggressive camshaft.

But as soon as you pull off a really good single plane intake and replace it with a factory six pack intake you are going to lose a bunch of power. I did a dyno test a while back where I tried a ported dual plane intake on a 800 hp race engine. We promptly lost 100 hp and the EGTs went crazy due to fuel mixture issues.

There might be some FAST guys who have figured out how to squeeze 700+ hp out of an RB engine with a six pack intake but I'm guessing that it took a lot of compression, a bunch of porting and a fairly big cam.

I guess I was hoping the mod man with its big plenum and short straight runners would eliminate the intake as being the bottleneck and have the efi sort out the fuel distribution issues that are prevalent with it. I'm ok with a big roller and maybe comp up to 11.0-11.5. I would like to be able to go with the best head that can be made work as if I stick with my ported 906's I'm working around another handicap. Any cubic inch size is fair game as well.
So you think the TFS is a better choice then the Victor or Indy offerings for this?

Send a stock intake to Wilson with your game plan. Have them convert it to EFI after porting and build it over 500 cubic inches.

IMO, you're going about it wrong....... or rather, you're focusing on the parts, and an arbitrary hp number instead of the application.

Figure out the things that are the highest priority for the finished product(like a 6bbl that fits under the stock hood), what gears, converter, etc you'd like to use in the car....... then build the motor around those things that are a "given"......... and it will just make what it makes.

Unless it's a race car that requires a certain amount of power to be competitive in a particular class, or to reach a performance target....... then it's just a number.
For street cars, I find it makes more sense to build the motor so that it works well how it's being used "most" of the time......... and if that means you give up 20, 30, 50hp of peak power...... it's not really a big deal.
Basically, for a given engine size, the TQ won't really change that much even if the top end HP is down 25-50HP........besides.........mostly what you feel in the seat of your pants when driving around on the road, is the TQ.

Yeah... I never considered their services

Yeah, I know this is kind of a ass backwards way of approaching this. I was focusing on the intake as thats what I felt was the biggest bottleneck in this thing making decent power.
Basically it's going to be a streetable strip car, runs a 29x12.5 tire with 4.10s. I have a 2500 stall and a 4500 stall so either is fair game in the car- I can live with either depending on the end combo, Probably will weight 3700 with me in it. Basically I want it to perform as well as my Demon did (low 10's at 130) even though this car will have more motor. I can live with it being a little (a lot) radical. My thoughts were shoot for the moon on power with what can be made fit -simply to overcompensate for a chassis or engine that's probably not always going to be dialled in to the n'th degree. It will never be a class car that I need to worry about rules, won't need to have the worlds best 60' but I do want it to outrun "most" of whats commonly out running around on the street.

Build a reliable, easy 600 HP engine and add a 150 shot of N2O.

I thought of that, the only refill station around here though is my competition who I want to outrun N/A

Rather than put lipstick on a pig by using the factory 6bbl intake why not just space the K-member down for some clearance and use a decent manifold.Dave

I REALLY wanted to run a crossram on my '63 for the "look" more than anything. After seeing how it simply wasn't a good choice for my goals, I ended up going with a single 4 bbl.

The one concession I made was for everything to fit under the stock, flat hood.

I've probably(?) been guilty of the same thing on occasion.

Is the real constraint that it all needs to fit under the factory 'Cuda Shaker hood? Are you're tied to using an RB block?

I have an RB 493 CI 6 pack stroker in my road runner that Nick Wilson built for me about 4 or 5 years ago. The intake had a stage II porting done by Hughes and it made 734HP at 6,950 RPM and around 640 foot pounds torque. THere was a thread from back then where I posted the dyno sheet if your interested.

Paul

I'll keep that intake in mind - thanks!
My only constraint is it has to fit under the shaker really. I forgot about spacing the K, I did that on my Demon to clear the Indy intake and totally forgot about it till now.
It does not have to be a RB Block
If you have the link handy for your 493 build Paul I'd be interested in reading it.

Thanks,
Rick

I figure my 511 six pack is well north of 600. It's been 10.90's at 4000# ( me in the car) running through exhaust and is nothing trick. Even has 50 year old gtx leaf springs. I'm sure more compression, camshaft in a lighter well set up car could really take it up a notch.

I did not think there was enough material for stage II porting on any six pack intakes with out modifying the runners and adding material on the top side of the runners for the larger ports.

I put a low deck (400 block) 6 pack pump gas stroker motor together using a stock unported Eddy low deck six pack intake with stock type 440 carbs, the motor was 517 C.I. (4.375 bore x 4.300 stroke) with 10.29 to 1 compression with a set of Eddy RPM heads CNC ported by MCH, Comp Cams custom ground solid roller cam that was 260@.050 on the intake with .420 lobe lift and 266 @.050 on the exhaust with .409 lobe lift, Harland Sharp 1.65 ratio roller rockers that netted .700 at the retainers with checking springs.
This motor combination ran a bunch of 10.30 at 127.6 MPH through the 3.0 inch exhaust system on with a stock 6 pack air cleaner with dual stacked stock 6 pack Fram air cleaner elements in my 1971 Duster that weighed 3450 lbs. with me in it
IHTHs

Thats respectable. What do you spin that thing too Cab?

I shifted at or above 7000 RPM after testing a bunch different shift RPM
I dyno tested that motor several different times on several different engine dynos, two different DTS and s Studka dyno, that motor made peak HP at 5500 and 5600 RPM with the six pack and it made peak torque at 4500 and 4600 RPM, depending on which dyno
I tried shifting it at 5500 RPM and then 6000 RPM, it ran faster at 6000 RPM so I then tried 6500, then 7000 and then 7500 RPM, it ran quicker and faster the higher I shifted that stupid motor I got scared of it above 7500 RPM so I decided 7000 to 7300 RPM was good enough for me It would repeat ET real well at those RPMs
That was a good car, lots of fun, especially on the street

Single carbs are too passé
Build it BIG!

Rick, I barely know how to log in, don't know how to do a link but the post was from 06/07/10 in this forum.

Paul

I just pulled out the invoice from Hughes and it says Stage II porting. From the outside there was definitely no welding or material added.

Paul

Best et 6.27 at 3600+ pounds
Around 720hp. Just a smidge to tall for a shaker. Drove this car everywhere

OP, this is the first tunnel ram six pack intake I've ever seen
Mechanical carbs also
Not a Weiand two piece SS or stock Eddy dual plane OEM intake

Ray better add some more pics of that intake before Cab's head implodes from curiosity.

https://board.moparts.org/ubbthreads/ubbt...html#Post715629

Thanks Paul!
Ray- what was the test of your combo that it made 720?

did you ever put any passes on this combo?

Unfortunately no, I would have had to drive to Norwalk and could never make it happen with friends, schedules, etc. Now I'm happy just going for rides around town.

How bad does it knock the tires loose on the street

493. EZ heads MW port. Roller cam .630 265. 12-1. 185 cyl pressure. 9" converter. 3.55s with 28 or 4.10s with 30 tires.
I had 3 500 cfm carbs. Center carb was 4412 i modded

Thanks Ray, looks like a nice combo.
So...this may sound retarded and I know there will be a myriad of answers but why did you guys choose the heads you chose? I look at the combos that are scattered around the internet and some guys use a Indy EZ, others a SR others a ??? What I mean is why stop there- why not say a 440-1 or larger? Is it that the ports are too large to be a efficient head for this power lever, pure overkill, a big price jump, or that other required parts to go with them becomes a little exotic or ???
I'm just sitting back looking at my original plan and saying why not go 440-1's or big easy with a modman that will fit them with EFI, on something like 570" 11.5-1, and a stick around .700 274-282. What are my plans biggest flaws?

Reused standard rockers when i went to EZs. Also no header issues. -1s have a raised exhaust port. Plus EZ heads are pretty cheap

Ray, were you able to open up that Weiand TR to MW size without building up the outside?

No problems with that plan.

It's an 800hp motor with a 700hp induction on it....... should work fine.

Fast, it needs to be welded. I bought it from a member here welded up

Two good reasons, that's the kind of info I am after- thanks.

Rick:

You should find this righteous piece of machinery up your alley:

'70 Cuda, Black Series


The car belongs to John, jbc426 on here.

Thanks Grizz, John's got a great car there and pretty much what I'm going to do with mine (the previous owner had already started down that path in 82) The guy interviewing/hosting though....that's another story...

World block 4,32 bore
Ohio crank 3,76 stroke
Molnar rods
CP 10,5 pistons.
BIG I mean BIG roller cam
T&D 1.65-1.7 rocker arms
Jesel belt
Max ported Mopar stage V heads with 79,5cc chambers with stock size intake and exhaust runners. 2.08-1.74 valves
Custom sheet metal intake
Revers cooling
"Stock" sixpack carbs

738hp 652lbs tourqe

Thank You!

I've heard that above 650-700 HP, RB blocks go boom! For the power level you're trying to attain, you may need an aftermarket block, or at least some help to stabilize the bottom end (Girdle). Good luck with your build.

They go boom only if you use them........crank likes going on vacation through the pan.

I don't know of any crank girdle that reinforced the main webbing
It is the main webbing between the bottom of the cylinder walls and the main bearing bores that fails on the RB,440, blocks, not the oil pan rails or main webbing ribs from the oil pan rails
The girdles can't fix that, new better race block do that well

Would you be willing to put an Indy block in this project? Many advantages, if you will. Weight off the front is a huge advantage for starters. On top of that, 35 less HP should mile an hour as fast.

Yeah, It certainly seems like I would be pushing the blocks longevity and that a mega block would be strongly advised. I would like to ultimately go that route, it will just mean that I'll have to wait longer to do this buildup- I'd rather only have do it once though.

The girdle will keep the main caps from moving around which I would think would put less stress on the webbing ribs. Tying everything together, pan rail, main caps plus a half fill on the block should stiffen things up. But, your still working with a 50 year old block.

I was thinking a max-wedge port, not sure what a stage 2 port is, is that just gasket matched and cleaned up?

I was wondering about that as well as the website does not say anything about a stage 2 port.

IMHO a megablock in cast iron will put a lot of weight on the front, making it very hard to hook. The traction difference for unpreped surfaces is huge!! Go aluminum, or at worst a low deck with a lowdeck sixpack, my opinion on this. If you are also going to have a less than optimal suspension, the situation snoballs some more.

Why a lowdeck Greg? What is the advantage?

If you go to the Hughes website on the tab "Instructions & Tech Articles", then "Intake Manifold Articles" and then link #4 you will see a bunch of manifolds they flow tested and give the flow numbers for stock, Stage I and Stage II porting.

Paul

Some interesting reading for sure ported intake

Thanks- that answers that.

You can push a low deck block a lot further than a tall deck. Most say 650 hp is about it with an rb, 800+ with a low deck. On top of that there is some weight savings, both from the block and rotating assembly. I don't know how well the low deck 6 pak flows, so that needs to be looked at.

The Indy EZ's will raise the intake slightly higher than the stock heads due to their design. The Shaker still works on my '70 E-Body though. It is snug though.

Those old sixpack intakes surprise a lot of people with how well they can be made to work. The 493" motor I was running dynoed at 684hp below 5500 RPM. There's a write up on it on Hughes website. It's all about the combination. That was with a hydraulic roller. I dropped the compression 2 points and am converting to a slightly larger solid roller cam. The motor won't get on an engine dyno, but I'll eventually run it on a chassis dyno one of these days.

I've since learned that even ported sixpack intakes do significantly hinder the flow of my ported Indy EZ's, which flow around 345cfm at .600 lift. I had Hughes port my intake to the limit of their current knowledge, but they are digging deeper into them to find more flow as of this writing. This could get interesting real soon.

I'm going to installing a set of 3 modified 2300 series mechanical secondary carbs (the old Direct Connection Mechanical secondary Race carbs) that flow more than they did stock. Just how much more I won't know for a few weeks. The center 350cfm carb is being replaced with a 500CFM outboard mechanical carb, which didn't have idle circuits in them stock. This is being addressed so it can be used as a center carb. The boosters and barrels are being removed and the carbs are being converted to aerosol booster style by C&S Specialties. They build a lot of race two barrels for the roundy round guys.

Thanks John- nice car car you have there!
I'd be curious to see how the car responds with those different carbs and the solid roller.

The six pack engine in my GTX is 708 horse on pump gas. I used a 73 block, installed cross bolted main caps, put bushings in the lifter bores, bored .030 over, 4.5 lightened stroker crank and assembly from 440 source. Solid comp roller cam, 633 lift I think, 1.6 crane rockers, ported Edelbrock RPM heads. Head flow 327 on the intake side. Port matched the intake, installed 1/2 spacers on top of the intake. Do not mess around with the top side of the manifold. Leave it as cast. Now I sent my carbs out to Gary Williams and had him work them over. I wasn't happy with the throttle response so I got a set of mechanical carbs. Sent then out, very happy. Now the stock air cleaner with a paper filter will cost you 40 horse. A K&N filter robs 22 horse. My 535 is all done by 6000 rpm. When we dynod my engine, we tried 7 different manifolds. A single 4 barrel ported made 15 horse more. A tunnel ram made the same, just pulled more rpm's. Tried a crossram, that castrated the engine.

When you say you went to mechanical carbs are you talking about the ones that have accelerator pumps on the secondaries or just straight mechanical linkage?
Thats quite a power loss from the air filters- more then I would have initially guessed. Maybe I shouldn't be surprised the element doesn't look very tall so maybe not a lot of area to it overall...

I've got a 4 speed backing up my 535, a dana with 4:10. I run 275/60 R15 tires. At 60mph I get 11 mpg. If I go 65 mph, I get a whooping 4 mph, lol. Great combination. Have to run a duel disc clutch.

Sounds like a great car Copchaser

I've tested a single 6 pack Fram paper air cleaner versus two of them stack on top of each other together and then a single K&N and then two K&N and finally a six pack air cleaner base with no air cleaner and it made 5 HP more with no air cleaners, 7 HP more with two paper elements compared to one, same results with the K&N elements
My motor was much smaller, 511 C.I. with a 4.250 stroke and 4.375 bore with 9.25 to 1 comp ratio, it made the best HP, 612, at 5500 RPM and the best torque of 644 Ft. lbs. at 4500 RPM.
I flogged the heck out of that motor testing three different sets of carbs., ignition timing, valve lash and air cleaners that day
Once the motor was broken in and leveled out I saw 12 HP gain from worst to best parts tests

The carbs I'm running are the old direct connection mechanical carbs, the ones with a accelerator pump on each carb. The GTX runs in the lower 10's. Stop by, I'll take you for a ride.

What's the general consensus on max cubic inches vs horsepower for a stock six pack intake and carbs? How about with the DC aftermarket carbs?I know cylinder heads will be a variable here.
RT

Why would I want to go slower, my pump gas 3450 Lb. duster ran high nines at 134.6 MPH with the full exhaust and air cleaner on
My current bracket car runs 9.0 at 147.+ MPH Quicker and faster this year, hopefully
BTW, my old six pak motor did make the most HP and torque with a set of the mechanical carbs. jetted stock The stock 1971 replacement 440 carbs made 7 HP less

Hey glad i found this post
Stock appearing motor right ?
Lol .
I think i recently posted one like this ..
there was lots of feedback
But only 5-6 hund horse

It's not a requirement by any means but if there is things I can hide or disguise I will be trying. The size of shaker scoop will certainly help me out There. This isn't nessesarily a stock appearing deal so my only big limitations are the block and induction choices to fit under the shaker. My power number isn't carved in stone either, it's just to where I think I'll be happy with its performance, anything less it would be a under-achiever. My last pump gas street driven small block made 1.59 hp/cube and was "good enough" I expect no less from thing and it will likely have another 60 cubes minimum on my small block.

You'll be better off with a low deck for fitting something under the shaker. My origional a12 base didn't really fit under the hood on the rb with raised port sr heads. Works great on the 400 block though.

There certainly appears to be some advantages going that route- and that one right there is a biggie.

All the 400 blocks have way better main webbing than any of the 440 blocks, build it big C.I. wise

Ok, how about this thought. With 440-1 heads the exhaust port is raised but the low deck is "shorter" we'll say- do you think there is a chance of using a regular header with that combo. If I didn't have to buy headers that's money that can be spent elsewhere.

Nice. What kind of mph?

Better keep a set of stock carbs on hand in case that experiment doesn't work out.

No way would I be firing up my fresh new build with some unknown carbs.

There would be an m1 with an 850 on it for me.

After the thing had some miles on it, rings properly seated, etc......then the aerosol carbs can get installed and tried.

I do have a second stock set that was dialed in nicely on the motor before we did the mods I will use to get it broken in. Thanks, Dwayne.

440cu .055 over FT piston 80cc chambers Edelbrock NHRA heads 201cc runners 2.08x1,74 valves, custome billet sheet metal intake ( fit under Cuda shaker hood) stock vaccum six pack carbs and roller cam,,,,,,750hp plus horsepower...

Impressive. How fast is the car, and what does it weigh?

At what rpm are you turning it to get that power and what
does that custom intake look like.

Most guys are spinning them 7500 + in Super Stock. Here is a pic of Chuck Stubecks' manifold - CFE looks very similar. Picture credit to Wes Allison.

That manifold looks nice....
I'll throw this question out there again- in case a used set of 440-1's crosses my path- With 440-1 heads the exhaust port is raised but the low deck is ..."shorter" we'll say- do you think there is a chance of using a regular header with that combo. If I didn't have to buy headers that's money that can be spent elsewhere.

I believe a low deck with raised ports should fall into the same spot as an rb with standard port. Although I have never made the swap to confirm.

Runs 9,20 sek weight 3200...