Here are the specs for the RDP RV-10 / 244 cam:
http://www.dutra.org/pictures/engine/er ... m-212-.jpg

The OC #750 cam looks like the early 70's SL6 factory grind... this is about the best "stock" cam the factory used in Slants.
(I have a good used one, cam and matching lifters, in great condition, that I would sell for $120.00 + shipping)

I also have a couple of different 244 "street" grinds done by Dema Elgin... those cost $175.00
DD

I was going to say that the 750 cam looked like one of the pre 244 camshafts (not the MP 244).........


I've been playing with desktop dyno 2003 to figure out a cam selection.

Desktop dyno is a dumbed down version of dynomation, and from some buried documentation I've found it is most accurate when you use .006 lift AT the valves.

But you'll notice that no cam specs for flat mechanical cams will give you this figure. (usually .050 and .020 or .015)


So by getting various specs here (look in FAQs for various links) and elsewhere;

I've been using excel and the chart graphs to reverse engineer various cam specs for a good guess at the .006 number. (which is why I've asked for OCG cams specs and have been updating the cam card thread).

With my guess of the .006 number, I've been comparing cams.


Anyway here's some of what if think is going on so far:

Oregon Cams 818 cam is a Comp Cams 252
OCG 819 cam is a Comp Cams 264


The RV10 /244 cam comes out at about 255 intake / 255 exhaust at .006 valve lift with 108 lobe separation & 104 centerline
(the MP244 was 108 separation and 106 centerline)

The OCG 818 also comes out at about 255 intake / 255 exhaust at .006 valve lift with 110 lobe separation & 106 centerline


If you have the OCG 818 ground on 108 & 104 like the RV10/244 you should be very close.


Also if you do a 819 intake and 818 exhaust, you can get very close to a RV15/244 cam


If I can get ahold of a OCG 818 cam card, I can fine tune my spreadsheet even more (A 819 cam card has been supplied, I'm basing my 818 guess off the 819 info)


Still working on it, but so far I like the 818 at 107 lobe separation & 105 intake centerline......

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

I asked Elgin about them grinding a MP 244 or a RV10 and this is their response: "We have made a few of those grinds for Doug Dutra and if he does not have any more in stock we can grind your used camshaft to the 244 duration profile."

DD, is this the $175 'street' 244 grind you are referring to? How does it compare to the MP 244, RV10, or OC 750?

emsvitil, it sounds like you know what you're doing... a lot more than I do. But the gist of it seems to be this statement: "If you have the OCG 818 ground on 108 & 104 like the RV10/244 you should be very close." Is that something OC will do?

Can you give me an idea of how these cams compare to each other once installed --- i.e. 'cam A' will have more torque, but 'cam B' will give better mileage, etc. Or does it not work like that? I'm clueless when it comes to cams.

What do you guys recommend?

Disclaimer, I haven't had a cam made yet, so my knowledge is theoretical......


From previous posts here, I believe OCG will do whatever you ask if it's possible to do so.

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

The "marine" cam, the '67-up stock export 2bbl cam, and the '71-'80 stock all-engines cam are all the same. The MP P4120243 (the "MP 244" cam) has more lift and a bit more overlap, and runs noticeably nicer.

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

Lower RPM torque and mileage more often than not go together. Both tend to result from wider centerline angles between intake and exhaust lobes. I recently got one of Doug Dutra's 'street' 244 cams, with the wider lobe separation (112, as I recall) and am pleased with it; my use is street and highway and I wanted torque and driveability. Noticeably more torque that the stock early 60's cam (but probably anything would be better....) Have not driven it enough to give you mileage. I would recommend you spend some time communicating with Doug (Doctor Dodge).

BTW, your biggest mileage improver in the Feather Duster is the OD transmission! And the biggest 'torque improvement' was the light weight body panels.

You got it a bit off...

Mileage will always follow the torque band...except in the extreme ends of it, but as always a flat broad torque band will provide an average mpg at all rpm levels with not much room for improvement.

Narrow LSA (104-108) typically provide higher torque over the power band and the more narrow the LSA idle will get choppy (one of the reasons the stock cam is a 108 LSA for torque but has good idle characteristics)...Wider LSA (110-116) typically have very smooth idle and give up torque for top end (the short overlap even makes things very ideal for TPI and Boost).

Feather Duster package is a combination of 'opportunities' that work with each other...the Aluminum hood, trunk lid, bumper inserts, intake manifold, and gas tank fill spout limiter only reduce the stock Feather about 150- 200lbs, reducing it to the stock weight of the 1970-1972 Dusters (but not as light as the 1963-1966 and 1967-1969 cars).

The OD transmission is some of the concoction, specially calibrated Holley 1945 to work in the RPM band that would normally be considered in the idle circuit and with the 2.94 rear in OD the car at 55pm is on the edge of 'lugging'...Some of the secret of the mpg is the distributor curve that allows loads of timing most of time (heavy vacuum advance allowing 22 degrees of advance at all vacc readings except heavy throttle...12 degrees BTDC initial...and a lot more at cruise...), and to cure the engine being on the ragged edge of detonation, it has a rather large EGR valve that will knock back most of the ping except at true lugging or heavy but not "full" throttle.

Just to put things in perspective...if you put it all back together with the "stock" cam, a true 8.4:1 Static compression ratio and everything is functional, you will get great gas mileage, but as these car were stock, it almost can't get out of it's way trying to merge in traffic...but my beater FD got a top of 28 mpg on a very tired engine...

I upgraded mine by going to the Comp Cam 252...252/252/110/.435... the MP244 should be fairly similar...going to 9.2:1 SCR and the carter BBD... it still got 26 mpg and was much better driving...it went to 24 mpg when I installed 3.55's but it had no problem merging or passing...

I eventually caught the slant sickness and went to a much hotter build, but was able to keep it in the 24-26 mpg range depending on 4 barrel carb I was using...

So there is a fair amount of room for how much mpg you want to offset to have fun or get up and go...(but there is some limitation if you have to smog the vehicle)...

-D.Idiot

DI, I drove a stone stock Dart Lite for about 10 years, and getting out of its way in traffic was definitely NOT an issue at all! It was quicker that my prior 73 /6 with the floor shifted 3 speed in all situations. It would go 85 mph up in 3rd gear, Christainsbug Mtn no problem (an old, steep, straight road here). The lighter weight made all the difference in the performance, despite the lean carb. We must have had different expectations......?? Interesting on your mods and the results But changing the cam and rear gear as you did and the lower mileage results should come as no surprise.

Since good mileage normally comes along with lower RPM's in general (reduced pumping losses, using OD, etc) , the point of the wider LSA is to get that lower RPM torque band and give up the higher end torque for the sake of better low RPM operation. Nothing new there... wider LSA was one of the common factors in 'torque and mileage' cams that came out in the70's gas crisis, along with higher lift/lower duration.

I own 2 1/2 Feather Dusters for the last 17 years and my parents bought one new, and I drove it to school when I turned 16...but...compared to my mom's 3 on the tree 1968 Valiant...the feather would loose the heads up race at the light against it, and Dad's stock Feather tended to need much more room to merge into busy in-town traffic on a good day...it got great mileage and we took it to the Cascades and back almost yearly (lots of altitude gain, not so straight roads..Dad typically got 32 on the flats, 24 uphill at 40 mph in 2nd on the steep grade, and 36 running MOD on the return trip down the pass), and the poor thing would get lapped on all but the down hill run unless it was a VW bug... ...so I've been around and driving this platform for a quite a spell, stock or other wise...not trying to preach to the choir but having autopsied a stock car I know all the ins and outs of the build and what the intent was when the engineers pulled their last tricks out of the book ...during the final days of the A-body, not all Feathers and Lites got all their special parts out of the factory...the early cars can be 100% (the very early Feathers around August/Sept 1975 build dates...were drum brakes with a 3 speed floor shift cars...oddly enough), panels were all the rave on weight savings...not too long ago I went through my stash of fill necks because all 1967-1976 A-body gas tanks have the same shape and dimensions...the question arose on why a '67 had a fill capacity of 18 gallons, the 70's had a 16 gallon capacity and the Feather had a 14 gallon fill...the answer lies in the tongue position in the fill tube...a neat trick that save the Feather/Lite 2 gallons weight by limiting the fill early...(I put the 1974 fill neck in my Feather and I can get 16 gallons into it now...), so they didn't hang their hat on one big change to cure it all, it's all about a little bit here and there to make it all work out.

The carb isn't lean they come stock with a 612 jet..and is plenty fine considering that the 1974 stock Holley 1945's came with a #58 and those are lean (once the end user ups it to a #60 or #61, the 1974 suddenly stops being a slug...LOL). Most of the lack of "performance" is the EGR doing it's job at part throttle after warm up and lowering the volume in the cylinders with inert/unburnable gasses, which also cools them and lowers Nox emissions and supressed ping....so you might have a "200" if everything is working properly.

Dart Lites aren't that light as the added Dart sheet metal makes them a little heavier than the comparable duster...If I added an average 8th grader to the passenger seat in a feather duster the weights would be even between the brands, but they did fine and are actually rarer than the Feather since they only made 1/2 as many.


Lower mileage was no suprise on the mods, but doubling the HP and adding 30% to the already generous torque curve and still hauling down better mileage than most standard stock 225 equipped cars...the point was to illustrate for the original poster what he can expect with his build if he steps up to various levels of street so he can make an informed decision based on real life experience and put together a balanced package that will do what he desires.

All dyno data across the board and the engineers know that advancing the cam adds low to mid range torque , retarding the cam loses that torque but makes the build work better at top rpms... Narrow LSA (low numbers) increases maximum torque, moves best torque to a lower rpm band....Widening the LSA(high numbers) raises peak torque to a higher rpm, reduces max torque, broadens the power band (which in a smog regulation laden car, is needed so it functions well from off idle to passing rpm), and improves low rpm vacuum readings and improves idle quality... (in the 'good old 70's days', Ford actually set the cam in the 460's retarded 10 degrees to keep it on the street in both the trucks and cars... hoping that the band-aid would allow the end user to pass smog, and hoping the end user would not notice the decrease in seat of the pants 'umph'). When posting it's always good to cover a fair amount of scenarios so there is much food for thought, I am just lucky to have worked through a fair amount to my duster and a few other A-bodies for typical street use and some for a lot more performance.

There are a fair amount of very good articles on cam basics, dynamics and theory which all mirror the same characteristics and data in their end results...some have distilled all the results down to a good table and make for good reading for up and coming engine builders... as always there is a compromise...when you put your foot down on one end of the scale or the other in configuration, advance, etc....something will be a give or take...more power for a little less mileage...less low end grunt for better idle and even power over a wider range of rpm...

Back to the original post: What Feather_Duster wants out of the end result will be determined by staying with the 1 barrel or upgrading to a 2...and if he wants to retain the stock mileage or sacrifice a bit of that 28-30 something mpg for mid-20's and some nice low end gump..


'nuff said, let's get back to helping our member figure out what he expects or desires out of the build...



-D.Idiot

Good info. After looking around, some more info on the effects of changing LSA and timing can be found here: http://www.compcams.com/technical/FAQ/LSAproperties.asp

I am willing to sacrifice a little mileage for better drivability. My feather duster was a slug; although I'm sure part of was because the head gasket looks like it leaked between 3 cylinders . Overdrive was practically not usable - car would chug too much, even on the interstate. I have a 3.23 rear end in it. I would like to keep at least 25 mpg. I am interested in low rpm torque and mileage.

I understand the basic concepts, but the problem I have with cams is how interconnected everything is. I feel like you really need to have a deep understanding to correctly choose a cam.

My engine is currently:
Bored 0.030" over
stock style pistons
0.060" off the block
0.030 off the head
valve grind, balanced forged crank, etc

Being a feather duster, it has the larger (2.25" ?) exhaust
I will likely keep a one barrel carb, but I'm not sure which one.

Now I just need to figure out which cam. I am loosely following Ted's build, and I believe he recommended a RV10 RDP, but these seem to be difficult to get.

Not to ask the obvious, but have you replaced or removed the cat convertor?...if it's original, you may not be getting all your flow out the tailpipe...
Assuming that you started with the same chamber and deck heights my 1976 Forged Crank 225's started with, that will bring you up to about 9.5:1 or 9.6:1 SCR...so the 1 barrel went out the window....and so did some of the RV/short cams.... (using the MP244 cam would put your DCR at 8.58:1/ ...so you would be stuck with plus/super depending on your distributor curve (the Feather Duster curve won't be to happy with all it's advance on them numbers...), Comp Cam 252/OCG818 and delta 254 weigh in at 8.4:1 DCR with the slightly kinder 8.4:1 DCR so you may be able to run 87 with some judicious tuning (and probably be fine if you went to a 3.55 rear gear with the OD tranny...but you will sacrifice some mpg as previously posted, and the head could use oversize valves to get more flow)

using the same numbers and an Erson 270 cam, the DCr number goes down to 7.79...so regular is no problem, but the cam is bleeding down some of your cylinder pressure and will want some rpm to be in the power band....(here again, 3.55 rear gearing would work out for this cam, but you will sacrifice some MPG, and it will want a 2 barrel minimum and oversize valves)...

If the machine work is already done, then we are stuck with what we get and making things work together....I would not have put the money into balancing a crank as more "gains" are to be had in the head and bumping compression....(slant six cranks are zero balanced).

Ah, well, it is what it is. Yeah, the machine work was done almost a year ago, so I'm stuck with what I have. Looking at Ted's info, it looks like he runs the Delta E254, but also has water/alcohol injection... maybe that is an option? (Don't know much about it)

I would prefer if no more machine work is required - Does the head need to be ported to benefit from oversized valves? Any other work required? I'm kind of just blindly quoting Ted's build again, but I believe he went with a one-barrel as well as stock sized valves. Do you think mine is better off with a two-barrel?

As a side note,
emsvitil - I got a hold of an OC 818 card - do your magic

Yes it is...but...this is a band aid to combat knock when running more timing or compression (high cylinder pressure)...it is easier to build a balanced engine before pushing it to this limit....but it looks like you don't have much choice...

This is a kit that introduces water into the intake manfold to do te same thing that an EGR does (the water turns into steam and takes heat of the combustion chamber to combat knock and takes up room with an unburnable vapor...)

I also do not think Ted used an OD transmission either, so he had a fairly limited RPM band to work with in 3rd...and your highway cruise RPM will be much lower...(what tire size are you using? I can run your gearing RPM chart to see where you need to make your fattest torque band)

Cleaning up the ports is a good thing to do with the stock valves....if you go oversize valves you are wanting to port the head to get the best flow to support the larger carb and exhaust to maximize the power you are after....I had to redo one of my heads in my early builds because the machinist opened up the bowl before installing the new seats....the sudden widening killed the port flow and the engine was doggy at lower RPM....I used a different head without that mod and things worked great...I then ported the crap out of the other head and went to hi-compression and now use that head strictly for racing and it works great.

Oops. Yeah, I might not have much choice. Since I obviously don't know what I'm doing, hopefully I can lean on you guys to help salvage my build.

I'm pretty sure my tire size is 205/60r15 (can't verify right now). Rear end is 3.23

DI (or anyone), would mind giving me two hypotheticals here:
1) Let's say I build it the way it is (single barrel/stock valves/etc), but give it a new distributor (curved) and possibly alcohol/water injection. What cam would you recommend - sounds like the 818/delta254 (is there much difference?)

2) If I were to modify some things maybe two barrel and/or larger valves, etc. What mods would you recommend and what cam? Keep in mind I'm looking for mpg and torque.

How would these two builds compare? I'll be honest, currently I'm biased toward the first option unless you guys say it's a terrible idea or the second one is WAY better. Is 25-26mpg still obtainable?