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Update ?? More Cam Theory: Hows about a RDP from OCG?
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Author:  Sprag [ Sat Feb 09, 2013 5:34 am ]
Post subject:  Update ?? More Cam Theory: Hows about a RDP from OCG?
I'm getting close to choosing a cam for my build and before laying out the details I thought to ask if anyone has had OCG custom grind a reverse dual pattern cam or otherwise rolled their own using different IN/EX profiles from existing cams?

Depending on my numbers, I might just go with one of the Erson RDP grinds developed here but thought we could kick the can around first. Any thoughts?
Author:  DusterIdiot [ Sat Feb 09, 2013 9:06 am ]
Post subject:  Yes...
I have not seen them copy a lobe from another cam, but, you can 'mix and match' lobes...I know the 346 cam is a good candidate as an RDP...my last order was for a 4348 but with the lobes reversed (the cam is normally 254/267@ 050, I asked for it to be 267/254 @050 instead...)

You have to let them know:

Intake lobe is Intake or Exhaust from grind ###-list degree and lift from the page...

Exhaust lobe is similar procedure.

-D.Idiot
Author:  Dart270 [ Sat Feb 09, 2013 4:22 pm ]
Post subject:  some cam info...
Here are some cams I just ordered from Oregon. I will be using the XS1 257/248 @0.050" cam in the 64 Dart with 11:1 and the K1/Wiseco setup this spring. Your engine build will really determine what cam you should use. All of these are ground on 102 centerline and I'll install around 100. The first cam on the list (XS4) is for my new turbo motor.

The numbers in order for each cam are:
duration int@0.020", duration exh@0.020", dur int@0.050", dur exh@0.050", lobe separation angle, lift int, lift exh, overlap @ 0.020", overlap @ 0.050", min compression ratio (Lou's eyeballin').

The lobe numbers from the Oregon specs sheets (int then exh) are also shown on the top lines.

Happy building,
Lou

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Madsen - XS4 - lobe 1947i lobe 819e
270, 248, 224, 219, 113, 0.47, 0.437, 33, -4.5, 8.0:1 comp min

Madsen - XS3 - Cam #346 off shelf from Oregoncams.com
262, 252, 234, 228, 106, 0.476, 0.479, 45, 19, 9:1 comp min

Madsen - XS3.2 - lobe 1628i Oregon lobe 1920e
276, 273, 244, 236, 105, 0.483, 0.473, 64.5, 30, 9:51 comp min

Madsen - XS1 - lobe 1080i lobe 549e
288, 284, 257, 248, 105, 0.566, 0.539, 76, 42.5, 10.5:1 comp min

Madsen - XS2 lobe 999i lobe 1271e
303 290 263 258 105 0.542 0.54 86.5 50.5 10.5:1 comp min
Author:  Sprag [ Sat Feb 09, 2013 6:23 pm ]
Post subject: 
Thanks, just was I was hoping to hear and glad you both mention their #346 grind, I'm liking that one but being my first slant, I'm worried it might be a little too big. My basic wag for mild manners in a street car is 225 @ .050" so I'm wondering what the #346 is like? I realize that's an arbitrary figure (225@.050) but I think it helps save me from myself. :lol: This is also my first stick shift car so maybe I should be looking at that differently :?:
The harriest I've run on the street with an automatic was in a RB wedge, 242 @ .050 and loved every minute of it but everything on that one just plain fit, it was a great dual purpose car. I'm lost on the slant though, it seems so different, hence my thoughts on RDP being the way to go here. I'm open to any thoughts or opinions here and hope to have real numbers to go fishing with soon.
Author:  DadTruck [ Sat Feb 09, 2013 6:43 pm ]
Post subject: 
Lou

for the XS-4 cam

did you have a core that had a 113 LSA, or did OCG say they can grind that much in?
Author:  Dart270 [ Sun Feb 10, 2013 4:41 am ]
Post subject: 
Longer duration cams tend to feel a little less wild on the 225 engine, so it sounds like the 346 may work well for you. Make sure you have at least 9.0:1 comp. I would go 9.5-10:1 for pump premium.

They had no problem regrinding to a 113 deg LSA. Maybe if you had a really big/long dur cam that would be a problem? They didn't blink. They even got the 102 centerline grind, although they thought they might.

Lou
Author:  akbmotorsports [ Sun Feb 10, 2013 8:37 am ]
Post subject:  346
hello. not to hijack the thread but i will give my experience so far with the 346 grind. i just built a long rod with the 346 grind and i am having problems getting it to behave under 800 rpm. i installed at 100 icl. even with no load it starts running rough. not just lopey but really rough. no vac leaks, have tried different carb, timing,...the only change i have made that has any effect is valve adjustment. i am installing a vac gauge tomorrow and i am guessing it is going to start bouncing like crazy at low rpm. with a narrow lsa and oversize valves i think i may have reversion issue. maybe needs to be retarded a few degrees. i had 200 psi cranking pressure and changed head gasket to reduce compression (got 160 cold) and did not help.

other than that it runs awesome with tons of torque. if i was running a stick trans it wouldn't bother me and it may not be an issue with a looser torque converter.

i have been considering changing the cam to a erson e470521 intake (242@.050) and the e470302 exhaust (230@.050) or 286/280 advertised with .510 lift intake/ .465 exhaust and 110 lsa.

andy.
Author:  robertob [ Sun Feb 10, 2013 9:14 am ]
Post subject: 
Under 800 rpm??

You mean it has a rough idle?

Maybe your carb needs some tuning work - like more throttle valve bypass or something?

Have you done lash loops on it?


I really like the 346 on paper although I wish it had more lift. I was planning on installing one just like you have it, at 100 deg icl.
Author:  akbmotorsports [ Sun Feb 10, 2013 10:11 am ]
Post subject:  346
hello. when i say rough, it sputters and coughs back through the carb. sort of like dieseling or run-on. it smooths out some with more valve lash.

i am not sure what you mean by lash loops, but have tried various settings.

freshly rebuilt eddy 500, and also tried a new holley 2300. no change.

i like the way the engine runs and i am probably making a mountain out of a molehill here. this is a smallish cam and i thought i could get away with running stock 904 until i do the trans swap but it doesn't like the stock stall at idle. as it is now when i come to a stop i have to give a little throttle to keep it from bucking or have idle speed set really high.

at this point i think i will put cam at 104 icl and reinstall new permaseal head gasket, according to kb/silvolite calculator that will give me 9.79 scr and 8.08 dcr which should lower cranking pressure a bit with intake closing at 60, put in the new trans with higher stall and then just run it.

andy.
Author:  Sprag [ Sun Feb 10, 2013 12:22 pm ]
Post subject:  Re: 346
Quote:
.......i like the way the engine runs and i am probably making a mountain out of a molehill here......

andy.
Obviously I'm no expert here, I asked the question after all, but I'd be elated to have a good idle down at 800. I wouldn't think twice about it unless it somehow made it impossible to hold the car in gear, but I'd probably be thinking about a converter upgrade by then anyhow. I'd love to be wrong about this though :lol:
Author:  Sprag [ Sun Feb 10, 2013 12:28 pm ]
Post subject: 
Quote:
Longer duration cams tend to feel a little less wild on the 225 engine, so it sounds like the 346 may work well for you. Make sure you have at least 9.0:1 comp. I would go 9.5-10:1 for pump premium.

They had no problem regrinding to a 113 deg LSA. Maybe if you had a really big/long dur cam that would be a problem? They didn't blink. They even got the 102 centerline grind, although they thought they might.

Lou
I'm hoping for 9.5 - 10:1 with premium so this one is looking good. The next question is what valve spring? Is it a must to run the 340 spring with this one?
Author:  robertob [ Mon Feb 11, 2013 7:28 am ]
Post subject: 
Quote:

I'm hoping for 9.5 - 10:1 with premium so this one is looking good. The next question is what valve spring? Is it a must to run the 340 spring with this one?


I don't know what the stock springs are good for but I used the Engnbldr springs from ebay and they are good to .500 lift.
Author:  Dart270 [ Mon Feb 11, 2013 8:00 am ]
Post subject: 
Stock springs probably won't be enough. 340 springs are cheap and will work. We are about to run this cam in the new LeMons motor, so will have more data in the summer.

Lou
Author:  Sprag [ Mon Feb 11, 2013 9:13 am ]
Post subject: 
Thanks for the info this gives me a solid game plan for now. I'll go through the motions once I get my numbers from the machine shop and probably ask for a check on my SCR/DCR calculations. For now, my early drool tube head looks to need nothing other than a clean up so I'm shooting for 9.5 to 1 and the proper valve springs that I'll swap over to the better head later. With both the car and engine apart now, I hate to - but I have to do this in two steps in order to focus time/money on a proper cyl head build later.
Author:  Sprag [ Tue Feb 12, 2013 7:15 pm ]
Post subject: 
OK, thinking about the 346's 106 lsa, I forgot to bring that up before. Maybe I'm a being a girly-man, but this seems pretty hairy, even with the other somewhat mild figures for this cam, I'd be expecting a pretty rough idle @ 106 lsa, maybe too rough for my better half? She like's a car that gets out of it's own way, but not sure if she'd be too keen on this if it were too 'choppy'.
Am I over-thinking this because the /6 doesn't exactly related to other engines? If nothing else, can someone please validate my concern with this lsa thing, I'm thinking 108 is a tad aggressive for a true stop-n-go street car with an automatic?

EDIT: Again, using an arbitrary number with the lsa, I know there's more too it than just that, but just like with the .050" figure I referenced earlier, I use them as a gauge or 'flag' to remind me that I'm not looking at grinds for nana's grocery getter anymore :D
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