What Cam and other questions...512 Stroker RB Block

[Propwash]

Hey guys....

Need some advice with my 512 build. Built plenty of engines with the stock-mild upgrades in the garage, but this 512 i'm stepping up to a new level and I need some help.

Here's the deal. I have a 1974 440 block that just got boiled, checked out good with the Magnaflux and the bore is still pretty much original with no ridge up top.

As far as the somewhat knowns:
Edelbrock RPM Performer heads....84 CC...Looking for a 10:1 (+/- .5) Com ratio. Mild porting to be done
Edelbrock dual quad manifold and carbs (2-600CFM)
1.5 adjustable rockers, pushrods cut/ordered to fit
440 Source Stroker kit (need to figure out a larger bore or longer stroke and dish/flat)
TCI Super Street fighter auto w/3000 stall converter
3.91's in the rear
Distributer (mechanical/Vacuum advance?)
2.5" TTI Headers into 3" to the back
Car is a power brake car
Looking to install a hydraulic flat tappet (low Maint.)
Street/strip with a big majority to street, looking for low to mid torque

So......Don't beat me up too bad on the in depth specifics or to the fact I'm a bit naive to such builds (not too proud to admit it). Also, some parts were bought/some traded/some favors but were compiled mostly to my budget. In this set up I could use some advice on:

1) the cam...it's an automatic and it's a car I would like to use the power brakes without the addition of a vacuum pump. I've been looking at the Comp Xtreme high lift, but the descriptions are pretty vague. Would going with a .564 lift create too loppy of an idle or issues with vacuum? Would a .507 be a better fit and a bit more forgiving or still a bit up there?

2) the bore and stroke....Being the bore is pretty much still at stock with DIA., the door is wide open. With this set up is a longer stroke better or a bigger bore? Also the pistons. thinking I'll use the style for dialing in my comp ratio, but are the other factors to look at as well?

I appreciate any help...Again, most of the builds i've done consisted off the $800 kits you see at summit or from scat/eagle. Tossed is some cams, added-swapped carbs and other mild additions, but this is the furthest outside the box and am looking for some advice from you more experienced gent's on the site, being that the build/internals will be decided by myself and what you have to say, not a builder. So, forgive my ignorance and I really do appreciate the help. I'm excited to learn as well as excited to put fire back in the lungs of my bird.

Thanks,

Will

 

[Meep-Meep]

With 500+ inches you will have plenty of torque so I see it this way. Keep the compression at a level that will work comfortably with 91 gas. You should choose a cam based on the lobe separation, and with 500 cubes you should run something in the 114 deg range. This will give you a nice broad torque range. Also a smooth profile cam that does not require a lot of spring will stay alive longer. In other words, use the cubes to build power rather than pumping up the smaller engine with big cams and high compression to get the similar result.

As far as block prep goes you will not get much from increasing the bore from STD to say .060". But putting in a 4.15" - 4.25" arm will get noticed. Just bore the block enough to make the cylinders round and straight.

A smaller cam will allow a tighter converter and taller gears. It's not uncommon to have a 3.23 geared car go low 12's with the big motor. And you can probably do that with the A/C on eating an ice cream cone. And when I say small cam I mean proportionally small based on the 500 cubes. The big motor will tend to soak up camshaft. I would talk to some cam makers and see what they have to say.

 

[Propwash]

Thanks Meep, I figured you would chime in. I appreciate you putting it in better prospective for me. So basically, I got the cubes..use them before tossing in some thunder cracking cam that will reduce its life and effect the components around it. Go more with the stroke and find a happy medium with the comp ratio that makes the motor gas station happy.

 

[charger360]

i totally agree with meep that is solid common sense advice! as a mostly street engine long life and and a low headache ratio is needed!

 

[RustyRatRod]

Meepamous is goin the right way, as usual. I don't know about a 114 LSA. I do agree keep it wide for good vacuum, but I think you could get by with 112. Also, the lift hasn't narry a thing to do with how one lopes, or pulls vacuum. That's all decided with duration, LSA and valve opening and closing events.

I know you said all that hooha about wanting power brakes and driveability, blah blah blah, but man, you're gonna have 512 kyoobs and aluminum heads. That thing could see 12:1 on pump gas with the right cam and make 600 plus HP easy. You sure you wanna go mild?

If you just gotta wuss out, here's what I would recommend.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1443&sb=2

Ignore the description "rough idle" because you're boastin 512 kyoobs. The added inches will cancel out a lot of the rough idle and also aid in a good vacuum signal. You still might consider a vacuum canister. I run one regardless if I have power brakes. I also think you could bump compression with that cam probably close to 11:1. Lets face it, compression makes power and with aluminum heads and a fairly "large" cam, you can get by with it. Just my 2 cents. That's about all it's worth.

 

[Propwash]

Thanks 360 and thanks RustyRatRod for drilling down a bit deeper on it. Big thing is I don't want to over cam...Nice tickety-toc cam with good low end-mid torque, but not something that idles like a old misfiring Evinrude and sounds like a Detroit with bad injectors. I was wondering about what most of the cam MFG's were referring to as far as "Rough idle" so your depiction of that puts my mind at ease a bit. Don't get me wrong, with a 512 I want the rumble that comes along with that, but I don't want to build something with no street manners either.

Thanks again guys for your time, learning a lot here...

 

[67Satty]

If I had to do it all over again, I would put a solid lifter cam in my car from the get go. I too, thought a hydraulic would be good because of the decreased maintainence but I'm going to make a case for using a solid lifter cam. I will be changing out my cam to a solid lifter as soon as I can. Here goes:

1) The maintainence arguement in favor of hydraulic cams. It's not very hard or time-consuming to adjust valves. If you run adjustable rockers with a hydraulic cam (which you will probably have to anyway), you will have to do it at least once already. Besides for or a street/strip toy, it's not going to have enough miles piled on it to where you are going to be constantly adjusting valves with your solid lifter cam.

2) If you take two cams with the same specs, the solid lifter cam will make more power throughout the rev range and also rev a little higher on top before the power falls off. Like maybe 30-40 hp. People with more time and resources than me have proven it with back to back cam swaps and dyno pulls. Do you want to leave 40 hp on the table just for ease of maintainence?

3) Solid lifters themselves. They are as simple a part as you could ask for, a solid chunk of metal. The part you leave off is the part that won't break or give you trouble is my motto and the simpler the better in my book. Also, hydraulic lifter quality is all over the map depending on supplier, intended use.

On another note, the cam's valve lift will have nothing to do with the drivability. It's the duration you want to look at but as others have said with that many cubes, you can soak up lots of duration. Just my two cents.

 

[RustyRatRod]

The biggest reason I prefer solid lifters is they are more accurate than hydrauilc lifters. Hydraulic lifters have a plunger range of around .250". That's a mile when talking about valvetrain adjustment. How do you know just how much the hydraulic lifters plungers are moving? How do you know they are all the same or even close? I wonder how much valve timing 1/4" of plunger movement equates to?

With solid lifters, all of that concern is thrown in the garbage. You set the solid valve lash and there is where it stays, with the exception of minute changes in temperature and wear, the solid lifter lash does not change. This one reason is enough for me not to run a hydraulic unless I am building a stock or very close to stock engine.

 

[benno440]

to make 512 you need 4.25 stroke and .60 bore
i made my 505 using the 512 kit but only bored .30

and look for a cam around the 240-250" lift at .50.
you want to make around 10.1 you will easily make that with your kit.

 

[splicer]

Hey Propwash: I have a similiar build to the one you're proposing.......505 Eagle stroker, Eddy 88cc heads, 10.5 CR......was running a flat tappet hydraulic(.490 lift, 280 duration) and am now running a mechanical roller(Comp Cams 23-701 with .570 lift and 280/286 duration)
My car is a 64 Polara with power disc brakes and is a street/strip ride....Both of the above cams are just fine for vacuum and street driving....as has been said, big inches can take more cam....
I'm also running the super street fighter tranny....85 runs on it and 2000 miles...no problems...
If you want more detail on my build to help out, let me know

Splicer

 

[Meep-Meep]

On another note, the cam's valve lift will have nothing to do with the drivability. It's the duration you want to look at but as others have said with that many cubes, you can soak up lots of duration. Just my two cents.

It's not only duration. It's lobe separation, or overlap and the intake closing point vs. the compression ratio.

I have no issues running a solid cam either and my next build will have one for sure.

 

[67 B-body]

I run a solid lifter MP .590" lift camshaft AND 1.6:1 ratio rockers..... Less Cubes, "standard stroke 440 + .030 bore" than your stroker build would generate,,,,,, 72cc Aluminum heads "Victor", and it doesn't have toooo much of a radical sound or lopey idle,,, just a quick crisp chop sound..... It has LOADS of torque and doesn't stop pulling like a mule up through the RPM range!

This is a short video of how it idles:
http://youtu.be/BVGNBiHfhLA

https://www.youtube.com/watch?v=BVGNBiHfhLA&feature=plcp

- - - Updated - - -

To the OP.... I think that a nice Zero deck flat top piston is about as good as you can get in that stroker build,,,,,,, but You'll likely need to bleed off a bit of the cyl pressure to control detonation, and the EVEN squish of the flat top piston along with the resulting even flame front will provide gains in torque and HP! The expanding gas will exert its ENTIRE force across the flat surface of your 0 deck flat piston straight down VS the dome piston required in a non stroker build like mine to get the same compression.... Imagine the % of expanding gasses placing effort in directions other than straight down on a domed piston.... This does nothing for power..... Your long stroke pushes more volume into the same combustion space, so your cyl pressures go up.... Camshaft overlap will help bleed this excess pressure off, and also create a faster intake charge as the gasses exiting the exhaust stroke actually "scavenge" pulls the fresh intake charge into the cyl.
I went standard stroke high RPM as an Old School build more than anything,,, so I chose a dome piston, but the dome itself has a large flat top on it.... Your flat top would be more efficient.....

 

[Meep-Meep]

Actually, overlap does not bleed off cylinder pressure. What it does, at low engine speeds, is dilute the intake charge with exhaust gas and that is what causes the lopey idle. As the engine reaches max speed the overlap period creates a scavenging effect and that increases maximum torque, but at a relatively high RPM. The intake valve closing point is what bleeds off cylinder pressure and the later it closes the less pressure. The latter scenario is typical of putting a big cam in an 8:1 motor.

What you need to do is build the engine with a compression ratio FOR THE FUEL USED. Do not rely on band-aid-ing a high compression engine with a late intake closing cam to blow off pressure. Just design it right to begin with. Also, don't band-aid with timing. Run the full advance based on fuel octane, compression ratio and mixture strength.

 

[67Satty]

It's not only duration. It's lobe separation, or overlap and the intake closing point vs. the compression ratio.

I have no issues running a solid cam either and my next build will have one for sure.

Good point, I forgot about lobe separation.

 

[Propwash]

I can't thank you guys enough....Learning a ton and formulating a path moving forward. 1st off, ditching the hydraulic flat tappet idea and going mechanical. I'll have adjustable rockers anyways so why trash extra HP across the board with the wide envelope in a hydraulic lifter.

Couple more questions coming out of your guys posts. Sounds like a flat top piston has (for better words) a better dispersion than a dish/dome? If I went the flat top route, from the rotating assembly spec's, looks like I would need to jump up to an 88CC chamber to get my comp ratio down to just a tad under 11:1. Is that pump gas territory?
They also show a distance below deck at -.010", would that mean I need to run a zero deck or gain some space if I was up at a .550+ lift? Any other way to dump the comp ratio a bit or am I straying way off base here, or reading Chinese but speaking Japanese?

67B-Body....Nice sounding car man!
Good to hear you're having good luck with the TCI Splicer...you're build sounds pretty similar

 

[RustyRatRod]

Yes, 11:1 is pump gas friendly with aluminum heads and a camshaft to match the compression ratio.....probably 250-270 @ .050. Now, if you're going solid roller, you'll need to get what's called a "street roller". Their lobes are such that they are easier on valve train compenents. Not as aggressive as a race roller.

Also too, to make sure you get all the HP potential I would get on the phone with Dave at Hughes Engines. They will set you up with real Mopar lobes designed for the .904 lifter diameter, instead of lobes for the smaller chebbie lifter nearly everybody else uses industry wide. It's just my opinion since you're spending the money to get into big stroker territory, you'll want to use everything to your advantage and get the most out of your build. Normally, I suggest away from Hughes, just to try to be easy on peoples pocketbooks. But I think in your situation, you would really benefit from their expertise and their lobe designs.

I think with a big stroker like you're building, you want to take advantage of all the latest technology. You've already spent a load on good aluminum heads, the reciprocating assembly and so on and so forth, so I don't think there's any need to use something off the shelf regarding the camshaft. I would go somewhere in the .650 lift range with 268 @ .050 on a 112 LSA. But you need to make sure your heads are ready for that both physically in terms of valve length and spring and in terms of flow. I am sure building a 512, you've had the heads ported. Right?

I went back and read. You say "mild porting". Go ahead and do it all the way. You'll pay the same price and you'll have regrets if you do not. Aluminum is easy to port. The engine will only use the flow it demands. At your level of engine, it will gladly accept max ported cylinder heads. 700 HP here you come.

 

[67Satty]

Couple more questions coming out of your guys posts. Sounds like a flat top piston has (for better words) a better dispersion than a dish/dome? If I went the flat top route, from the rotating assembly spec's, looks like I would need to jump up to an 88CC chamber to get my comp ratio down to just a tad under 11:1. Is that pump gas territory?
They also show a distance below deck at -.010", would that mean I need to run a zero deck or gain some space if I was up at a .550+ lift? Any other way to dump the comp ratio a bit or am I straying way off base here, or reading Chinese but speaking Japanese?

Usually people say with the aluminum heads' dumping off more heat, you can run one point more static compression than you would with an iron head. But the other thing that is more important is the dynamic compression, your actual compression ratio taking into account the cam's timing. Once you pick out your cam and know all the rest of the specifics of your build, you can go online and find a dynamic compression ratio calculator. I believe a ballpark is a dynamic compression ratio of 8:1 is considered safe for pump gas.

Lots of builds go with a flattop piston at zero deck (or very close to it) with an aluminum closed-chamber head (most of the ones available are going to be less than 84cc) to get you a quench motor, a motor where the piston to head clearance is going to be between .035 to .055 at the very most. The tight piston to head clearance is going to create a near-collison between the piston and the head that is going to help combustion. If you pick the 88cc Edelbrock RPM head, you are picking an open-chambered head and you will lose the quench advantage.

It doesn't mean you can't go fast with open-chambered heads, lots of people do. But again, you will leave a little on the table if you go that route.

You'll have to pick some parts and crunch some numbers but a couple common builds are 440 with pistons at zero deck and 440Source Stealth heads (80cc) I think gets you about 10.5:1 static compression and same engine with Edelbrock RPM heads with 84cc chambers gets you about 10.2:1 static compression. Either one would have the closed-chambered heads that would let you build a quench engine.

 

[Meep-Meep]

Prop, with a stroker crank you will have more compression because you have more swept volume crammed into the same unswept volume. A flat top zero deck piston with a 3.75" stroke can be in the 10.5:1 range, but the same deck with more stroke may put you over the top compression wise, which is why stroker pistons often have a dish in the piston. The location of the dish is usually well thought out and is right under the big part of the chamber thus preserving quench.

I'm not sure about 11:1 for pump gas, and being in CA I don't think I want to go there - even with aluminum heads. You may also want to consider fuel availability in other places away from home. I wouldn't build it at the hairy edge of compression but design in some margin. See who is doing what in CA, FL, where you are, etc.. The one thing you can't easily change is the piston so get it right to begin with. And as a side note, check out what people are doing with 500 inch Cads. 4.3" bore and a 4.3" stroke. Those things are pump gas beasts!

Regarding the solid cam, if you use quality components and not insane valve spring pressures, you shouldn't have to adjust the valves all the time. I have often heard from people that you have to adjust solid cams all the time. This is only true if SOMETHING IS MOVING, i.e. wearing out or? Many cars come with solid cams and are just fine. Again, design it right and you won't have a problem. On the other hand I wouldn't poo-poo the hydraulic cam. Plenty of successful hyd builds out there. But for both my HEMI's I consider it an insult to put a hydraulic cam in them!

 

[RustyRatRod]

IQ52 (Jim Leroy) would be a good one to ask about the pump gas issue. I think he has gon very close or slightly over 12:1 on pump gas. He's made some really impressive numbers for sure.

- - - Updated - - -

There's also a guy over on The HAMB who has an early iron headed Hemi with a blueprinted 13.5:1 and runs on pump premium with zero spark knock. He's pretty well known over there. Course that's an early Hemi too. They are extremely efficient. So that's kinda comparin apples to oranges. Still impressive though.

 

[coloradodave]

"Hydraulic lifters have a plunger range of around .250". That's a mile when talking about valvetrain adjustment. How do you know just how much the hydraulic lifters plungers are moving? How do you know they are all the same or even close? I wonder how much valve timing 1/4" of plunger movement equates to? "

Rusty,
The most 'travel' I've ever measured in a 'quality' hydraulic lifter was right at .100". If you take the time to correctly adjust the preload I don't think you'll have any more variation in lift at the valve than with a correctly adjusted solid lifter. The main difference is in profiles you can use and RPM capabilities. Most of the advise given (by all the posters above) is good, but geared more toward a race motor, where parameters are much different. Personally, I would give up some top end horsepower for ease of maintenance and a forgiving valve train. Instead of money being spent for all the little horsepower tricks, I would rather see it spent on chassis improvement so that the torque from a 500" big block could actually be used for 'motivating' the car instead of 'frying' tires. Or for building the transmission, driveshaft, u-joints, rearend, axles, brakes or a miriad of other things that tend to break when hit with all that new power.
Different strokes for different folks and another perspective for your consideration.