OK, so I've been emailing back and forth with Ken Beard at Oregon Cam Grinding, and the guy has been extremely helpful at providing information, however I definitely need more clarification as now I have a lot more options than I know what to do with. Ken suggested I give Dave Mueller a call, but before I bother the man, I wanted to post on here to get advice from all of the gurus (and Dave, if you are seeing this ).

First let me give you some background on who I am: A 32-year-old with no kids, an office job that I love but is slowly crushing my soul (in every interview I ever had I always told them I want to be a race car driver instead of whatever the position was for), a 1972 Plymouth Duster with the original 225ci slant, a broken 220 mph Mercedes, and a daily-driver 1994 Acura NSX running a full race adjustable suspension set to 8 out of 10 (10 is firmest), with extra thick anti-sway bars front and back, and an ACT 3-puck clutch which gets "eased"-in at 3-4K RPM at every light (unless there is a cop there) running a 3" dual exhaust which gets enjoyed by me and the odd dude in a totally modded car on the street who's ear drums have not burst yet, because I have not revved the damn thing to 9K RPMs yet. The NSX was a nitrous build by the prior owner, however the nitrous is now out and I'm running a modest 320hp in a lightened semi-street-legal car.

So, fully understanding that I am a jackass, this is my current conundrum I would really appreciate advice in:

I need to know just how much cam I can run daily, while retaining reliability, and MY sense of daily-driverability... really, as long as the car does not get under 10mpg on 93 octane just sitting idling, does not kill my stereo (not currently in the car), and does not vibrate so hard that the front of the car looks like da Vinci's Aerial Screw trying to get off the ground, or any of these: https://www.youtube.com/watch?v=fw_C_sbfyx8.

The engine the cam is going in has an original 78K-ish miles, and will have the block and head decked 0.050" to have compression increased to 10:1, extensive head work with the 1.7" intake/1.44" standard geometry larger valves, and will have the largest pistons fitted possible... hoping to increase total displacement to 250+ci in addition to a stroke. Everything will be balanced.

The cam kit I currently have (in the box) is a Comp Cams 264 solid tapet with springs, lifters, retainers, and the upgraded timing chain unit.

Separately, I also have some 5/16" "High Energy" Comp Cams pushrods lying around, however Ken suggested going to a 3/8" pushrod for more durability if I intend to go beyond the standard 264 duration cam with .440 lift.

Well, I read that Comp's cams tend to be over-hardened and will eat the poor oil gear, causing a massive engine failure sooner or later... I don't want this. I need a cam that will work reliably for 5+ years of abuse.

I already have headers, full dual 2.25" exhaust all the way back, Offy intake with a 500 cfm carb (running mostly at full to 1/2 choke to not lean-out the motor... running pig rich), a 904 that is in desperate need of a rebuild, and a ton of parts just sitting around the house waiting for the right moment to be installed.

The 904 will have everything upgraded to support 600+ whp, well above the spec of the motor I am building. The stall converter will be 2500 RPM initially with the stock motor and 3.55 8.8" Ford rear end that's going in, but I intend to have it at 3.5K-4.2K RPM stall after the motor is built and installed.

What are the negatives of running a more radical cam?

How extreme can I get with my cam duration and lift before I start running into piston clearance problems?... I am not running the "largest" valves possible, but the Engine Builder-style 1.7/1.44 specifically to retain stock geometry.

Am I able to still stroke the motor if the lift is at .500" or higher?

Right now, my intention is to gather the parts and build the wildest NA Slant I can that can still be driven on the highway (hence no larger than 3.55 gears for the time being).

The car will get a bunch of fiberglass parts to shave some weight after that is done. EFI is coming after to feed it more fuel and air over the 500 CFM Edlebrock which will run out of steam with the built motor, but should be adequate initially.

Long-long-term, I intend to replace the cam, stick a thick copper head gasket on the engine, and run EFI turbo.... but getting the NA build just right for now is equally if not more important.

Besides subpar gas mileage and a cam that sounds like a rambling mad man, are there really any other negatives?

If anybody has a magic cam, piston, rod, pushrod, etc. formula they can share for a 250+ci NA slant with 250+ hp, I would love to hear it... I would love a PM if you don't want to share it publicly.

I do want to bracket race a little bit, but mostly it will be the fun car to get me to work and back (with tires smoking the entire way) so that I don't lose my mind working with Excel all day long.... if it gets to be too much, the next car will probably be a Tesla Model 3 or something. ... the NSX is getting kept until the day I die, so that's always an option, too.

Thoughts?

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1972 Plymouth Duster:
- 225ci
- Offy 4-Barrel Intake
- Weber 38/38 DGES
- Clifford headers
- Split 2.25" dual exhaust
- Pertronix digital ignition conversion
- Black-out custom digital gauges
- Front disc brake conversion
- Viper Blue

I don't have a cam opinion for you but some of your plan will probably need to be revised AFTER you actually decide on a cam. Such as how much you will mill off the head and block and the target CR. Also the stall speed of the future torque converter. Both of these should be chosen to match your choice of cam and not the other way around. Also, if you are going to turbo it later you will need to undo some mods or start over with a different motor or head.

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--> Check out my FI Turbo build <--
--> And the race truck build project <--
--> The Diesel Corvette <--

A 225 (and+) is a torque motor, not hp......

Think of how to maximize your TQ.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I'll take you at your word, bro.
No, if you take 0.50" off the head you won't wind up with 10:1 compression; who told you you would? But seriously, let's assume you meant to say 0.050", who told you that will result in 10:1 compression? And even if that number were valid, why 10:1? How did you arrive at that number? Where's all this coming from?
Just what is it you're trying to accomplish here, aside from throwing money around? What are your concrete, specific goals in terms of what you want the car to do (or not-do, or do differently than it does now)? What's your budget for the whole project, including the highly necessary upgrades to the car's brakes, cooling system, suspension and steering systems, wheels and tires, etc?
That's an imaginative description of the problems with Comp's cams.
Yeah? How's that workin' out for ya?
Oh. Sorry I asked.

LOL
So far I'm seeing a pretty solid wall-to-wall, floor-to-ceiling coverage of negatives in your plans.
Oh, the negatives on just the cam? An engine that runs poorly and guzzles gas, and a car with poor driveability.
You're doing it wrong, dude. Parts selection and purchase is the second-to-last step in the process, right before build. Y'don't say "I WANT THE BIGGEST CAMSHAFT NUMBERS BECAUSE BIGGEST IS OBVIOUSLY BESTEST!!!!!!111!!!!!" and expect to wind up with anything but…yup, exactly the same expensive, undriveable mess bren67cuda904 built himself. It was his own fault, too; he spent a long time asking questions that sounded a lot like yours, then pissing all over the people who tried to warn him he was doin' it wrong. Scoffed at us, told us we were full of it, assured us all his car was gonna be faster than a 440 on account of all the BIGGEST AND BESTEST parts he was putting in his motor. Nobody had to say "Toldjya so" in the end, because it was so obvious it managed to seep through even his thick skull, but he tried to save face by saying something like "Obviously the Slant-6 is a piece of junk and you all don't know what the hell you're talking about" or something like that. You're a step ahead of him, though; he never acknowledged what a jackass he was.
Sure! Why the hell not! Just get someone else to hold yer beer while you do it.
Oh, fer sher.
Donno what kind of pipe you've got there, Jack, but it sure must be a big one to hold so many vivid dreams. Remember to light the right end.
Uh-huh.
...it's also a tad chilly atop Mt Everest, and water is said to be somewhat damp…
No, it's gonna be just every bit as magical as you imagine. You go build your biggest and bestest and wildest et cetera. Do it up extra-big and extra-loud so everyone can see how much money you threw at it (which as far as I can tell is your primary main objective). Don't be swayed by pesky things like realism, or by silly notions of using the right tool for the job, or by the fact you already have one and a half cars that'll do a better job of going fast and quickly than this one ever will.

LOLROFL!
Me, I stopped being (and wanting to be) a 9th-grader some years back, but suit yerself. I bet you're single.

You, uh, may want to check into traffic laws; you might come to discover the public roads aren't your personal playground, and there are other people using them, too, who didn't sign on to get dragged into the eventual consequences of your childish driving.

Hey: I have a job that peeves me off, too. It even involves Microsoft Office, just like yours, more Word than Excel, but they're both badly-written bloatware that causes endless aggravation. I do my job anyhow, and I sure as hell don't take out my aggravation in ways that endanger other people. I'm not a hunnerd percent fer sher, but I think this all might have something to do with being a grownup.
Roof don't leak when there ain't no rain.
Aw, you broke your toy? Gosh, now how'd that happen?
Naw, I don't have an opinion on any of this.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

First thing that stands out to me, why keep the 904, it IMO effects a lot of your other goals/expectations.

And going turbo/efi right out of the gate would reduce a lot of wasted effort/time/money, etc. IMO.

Enormous Tq on the street, with any light car is not very useful, unless you are towing your non running 220mph Merc

To be a mopar guy,you have to be at the extreme end of the car guy world. To be a slant six guy, you have to be at the extreme end of the mopar world.

I think, judging from your post, that you will be very disappointed with a slant build.

My advice to you would be to buy a stroker small block crate motor and enjoy. Don't forget to upgrade the suspension, steering, brakes and cooling systems as SS Dan advised.

P.S. I know some Plano cops and they don't play around.

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1976 Feather Duster /6 4sp
1984 W100 318 727 np241
1972 'Cuda 340 4sp
1985 D250 360 46RH

Dear Dusty,

Sounds like a fun project. You sound like my kind of jackass.

I have had big cammed NA Slants that make 250+ HP and are streetable in the way you describe (not the weeny version of "streetable"). Also, I have gotten 20-25 MPG with these setups. The responses you have gotten here do not appear to be helpful to your project, as far as I can tell. If you want to talk, please PM me. I like talking about cams and wild buildups. I also have a turbo+EFI 225.

As mentioned above, if you want 10:1, then you will need more than 0.050" off the head and 0.050" off the block. You or your machine shop will have to measure your parts before building it to know how much to mill, but more like 0.140" total is about right.

As an initial try, if you are shooting for 10:1 static comp, then here is a good grind from Oregon.

Lobe 34 intake, Lobe 1628 exhaust.
deg int deg exh LSA to use lift int lift exh
250 243 105 0.494 0.48

You can go higher comp if you run a bigger cam, to keep things matched, and still run pump premium. I ran a cam like this with 10:1, carb, and modified distributor for several years in the late 90s.

Slant on,

Lou

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Home of Slant6-powered fun machines since 1988

(Sorry, Lou and I were typing at the same time)

If you want a big bore motor go with the K1/Molnar rods and .100 over piston combo that many of the racers use. That will put you at 238 CI. The pistons have deep piston reliefs and my .566 lift cam still had .200 clearance.

You can run a cam with over .500 lift on the street and get decent mileage if you have a good combination and have an OD transmission. 3.55's may be tougher. Lou Madsen has a Dart that gets over 25 MPG and handles well and runs 13's on the Dragstrip. Plus he drives it all across the country. It can be done and be reliable. It may not meet all your criteria, but it would be a good combo.Lou runs bigger cams than most on the street and gets very good results. You would do well to pick his brain.

My son's Dart has a .510/284 cam on a basic stock bottom end and had no clearance issues and I believe it has a head that was cut .090. The key is to check clearances. It ran mid 14's(3300#) and got 22+ mpg with a 4 speed OD. It was driven 50,000+ miles, drag raced hard, and towed a trailer to the races in Kentucky from PA.

Good luck

PS. 200-225 HP out of a Slant 6 car feels really good

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

From your description of what you want, a big cam is the wrong direction. You need a turbo setup.

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Official Cookie and Mater Tormentor.

Ummmm, ?????????????? uhhhhhh, ????????????????, Yeah, what Dan said!

Step one, pick your intended use.

Step two, measure your current deck height in relation to your piston.

Step three, measure the volume of the combustion chambers in your head.

Step four, keeping your intended use in mind, select the appropriate transmission and rear axle type and gearing.

Step five, use the gearing in the transmission and rear axle combined with the intended use of the vehicle to calculate the RPM range in which the motor will most often operate.

Step six, pick a camshaft that will optimize engine efficiency in that RPM range.

Step seven, once you know your cam profile, calculate the dynamic compression rtatio of the engine using the centerline, combustion chamber volume, and negative deck height numbers you obtained previously.

Step eight, using the dynamic compression ratio you just calculated, determine how much needs to be removed from the head and/or the block to get you to the compression ratio you can live with on 93 octane pump gas. Note that if you change pistons you will need to redo the calculation of the negative deck height because new pistons may or may not sit higher or lower in the cylinder bore.

Step nine, get the machine work done, including porting the head and possibly installing oversize valves (it sounds like you probably will want oversize valves).

Step ten, choose your induction system accordingly. Correct size, carb or efi, NA or forced induction, etc...

Step eleven, choose and size your exhaust system appropriately.

Actually, I forgot step 0.1 (get a fat bank account) and 0.2 (upgrade the braking and suspension systems).

Seriously, Dan has much wise advice mixed in with his comments. I second the recommendation that you sound like you will be happier skipping straight to a small-block stroker with a supercharger or turbo setup. Just don't forget to upgrade your brakes and suspension.

Today history was made.







(I've peered into my crystal ball and I see a glimpse of the OP's car out for a drive.)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I like you!

I ran an OCG 34 for quite a while with a bit of compression more than your target. With 2500 stall, it wasn't up to the task. Dropped out of the power on the 2-3 shift. 1-2 was fine. With more converter, you should be fine. Depends on what you go with. If it's not quality and slippy, then even a 2500 will make it, with something solid, you definitely want 3500+.
It did make a nice sound, but I use a single out. Dual may make a better sound.

I run a 250" slant, done primarily with stroke. I can't recommend that, as it will limit your engine speed. Big numbers on the HP graph need a 6000rpm motor. Mine sounds like it's ready to scrape the stuffing out over 5k. I have 4.475" stroke, and 4.445" bore. Go for the 4.440 stoke, and punch it 0.060 for the best of both worlds. It'll unmask your valves too.

As far as doing clearance, once you stroke there is nothing that beats knowing where things came out. Gotta measure to figure out where things will get close. I'd still measure after the machinist gets done, and run a play-dough clearance turn to see where you end up. Sometimes the guy with the micrometer makes errors. When I check, I leave the head gasket off, bolt it down and clay it. Turn it with your hand, if it doesn;t want to turn, pull it apart and find out why. If you don't have 0.100" then you don't have enough. Add your gasket crush to the equation afterward, and you have a solid street engine. If you decide to run at the strip only, then get more involved with it.

Getting an inline to sound rumpity takes a bit more than a v or a four cylinder. an inline six likes to run pretty smooth and civilized even with a bunch of cam. Taking some wieght out of the reciprocating assembly will help to give it the mad lope, but that tends toward the less reliable end of the spectrum. Been meaning to see what I can get away with for a forged crank. Got plenty of them, and lot's of blocks to play with!

Have fun!

CJ

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Part of Tyrde-Browne Racing

Forgot to touch on the carburetor thing. Double check your Eddy. If somebody messed around with it, you could run into problems. The AVS spring must be set to base or the secondary will not work right. Alternatively the AFB can be messed up if somebody has played with the secondary air valve weight. If this wasn't an out of the box Eddy, then get it back to as close as you can to the OATB condition as you can. There are some builds that need more than the 500 AFB can handle. Those are pretty stellar, and tend toward completely useless on the street. If you need more than a 500cfm, it's a race car.

If you have excess weight cut out of the air valve, buy a new air valve, or epoxy some pennies to the air valve weight.


CJ

PS: At 60 MPH with an Erson 280, 4.10 gears and 10.7:1 I was getting 20 mpg with a mechanical only distributor, premium pump gas and a shot of 110. Have no idea what it gets on the 10.0:1 head change, ignition 30° all in.

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Part of Tyrde-Browne Racing

You left him guessing at the last variable... what was the tire size for this exercise, also assume this was an A904, not any kind of OD to knock the 4.10 back to a nice highway 3.xx....