Quote:
rumor is Erson wont answer the phone anymore
Not good. Maybe they didn't pay the phone bill. 
Rick
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| Cam question - I know it's been beat to the ground, but. https://slantsix.org/forum/viewtopic.php?t=42785 |
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| Author: | 65CrewCabPW [ Sat Dec 04, 2010 11:30 pm ] |
| Post subject: | Cam question - I know it's been beat to the ground, but. |
I've got an 81 W150 w/slant six, and the engine's been replaced with an older one, meaning I've got solid lifters, etc. I believe it's a mid 70's engine, but don't know how to date it for sure. Years ago, I had a 78 D150 w/225, Carter AFB, Offenhauser 4 bbl manifold and an Isky cam... It loped at idle, and even after re-degreeing the cam 6 or 8 advanced, it was still quite the buzzer, and liked to turn rpm's. However, mid-range, it was one strong puller. With 3.55 gears and 31-10.50-15's on the back, it didn't pull good on the highway until you hit about 55 or so. About 65 it would get right out and move until about 85-90, where the wind resistance kinda sorta hit a brick wall. We used it a lot for towing and hauling, and third gear @40-50 that six really had a good roar - pulled well, too. I walked away from guys with smaller loads and 302's and 305's. Now, I have a 4x4, and I need the low end grunt, good idle, but I'd sure like some better torque after about 1500 and up to 3500. I want to use it for trail running, field crossing, mountain climbing, etc. I have, I believe, 3.55 gears. This engine currently has a some 1bbl I don't recognize (doesn't look like either Carter or Holley to me), which is cold blooded and gets horrible mileage (15). So, I'm going to replace the intake with a super six and adapt on a GM TBI and use a Megasquirt. So, no loping idle, but I do need a little more breathing power. So, no need for ultimate horsepower, and anything with a loping idle is definitely out. Since a stock cam is 244 dur and .410 lift (or so it seems), I'm thinking about something in the 250 to 255 degree duration, 108 to 110 LSA and .440 or so lift. I've no intention, at least for a while, of changing valve sizes or raising the compression - though I might consider shaving the head .030 or so, for a smidgeon more. So, now that I've given a rough idea of what I'm looking for, could someone who's in the know direct me to where I might find something at least in the ballpark? Much appreciated. |
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| Author: | Charrlie_S [ Sun Dec 05, 2010 2:42 am ] |
| Post subject: | |
In my opioion, you would gain more of what you are looking for, by milling the head, to get about 9-9.2 to 1 compression, then you would get from a cam change. But doing both would be better, yet. As for the cam itself, I will defer to the truck people. |
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| Author: | 66aCUDA [ Sun Dec 05, 2010 5:57 am ] |
| Post subject: | |
Doc's RV15 Dual Pattern would be great for a truck. He designed it thru Erson but rumor is Erson wont answer the phone anymore. Ask Doc to give you the specs and have your cam reground by Oregon Cams. JMHO Frank |
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| Author: | Rick Covalt [ Sun Dec 05, 2010 6:29 am ] |
| Post subject: | ?? |
Quote: rumor is Erson wont answer the phone anymore
Not good. Maybe they didn't pay the phone bill. Rick |
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| Author: | Charrlie_S [ Sun Dec 05, 2010 6:40 am ] |
| Post subject: | Re: ?? |
Quote: Quote: rumor is Erson wont answer the phone anymore
Not good. Maybe they didn't pay the phone bill. Rick |
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| Author: | 66aCUDA [ Sun Dec 05, 2010 6:43 am ] |
| Post subject: | |
Thanks Charrlie that would be GREAT. I have some cams to get made and like my Ersons. Frank |
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| Author: | 65CrewCabPW [ Mon Dec 06, 2010 2:48 am ] |
| Post subject: | |
Quote: In my opioion, you would gain more of what you are looking for, by milling the head, to get about 9-9.2 to 1 compression, then you would get from a cam change. But doing both would be better, yet. As for the cam itself, I will defer to the truck people.
That's an interesting response... Is pinging not an issue? How much has to be scraped off the head to raise compression that far? Would I run into valve adjustment issues? I'm curious about your thinking here, could you tell me a little more about the rationale of why you'd do this, rather than change cams? Much appreciated. Mark |
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| Author: | sandy in BC [ Mon Dec 06, 2010 5:30 am ] |
| Post subject: | |
Quote: the rationale of why you'd do this
Its all about Dynamic Compression Ratio. Changing to a larger cam without raising the static compression ratio will lower your DCR. Raising the static compression ratio without the cam change will still raise your DCR. |
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| Author: | Charrlie_S [ Mon Dec 06, 2010 5:53 am ] |
| Post subject: | |
Pinging should not be an issue at around 9-1 compression ratio. If you do get ping, a little modification to the timing curve should cure it. The reason I suggest a CR increase, is it will give a power/torque increase across the complete rpm range. In general slant six engines had a little less the 8-1 CR from the factory (regardless of what the books say). A cam change will (in general) have more effect in a particular narrower rpm range, and with a low compression engine, actually hurt torque, in the range where you want it. The best way would be to raise the compression, and then match the cam to your requirements. Then play with ignition curve to really optimize everything. PS: I hope you are running electronic ignition (but not the "lean burn"). |
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| Author: | 66aCUDA [ Mon Dec 06, 2010 6:03 am ] |
| Post subject: | |
Im with Charrlie on this. Plus use HEI for an ignition. You wont have any valves issues. Frank |
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| Author: | Doc [ Mon Dec 06, 2010 8:39 am ] |
| Post subject: | |
Here are a couple of links to cam profile sheets. The key to these RDP cams is the exhaust lobe, it is the old MP 244 cam's exhaust lobe and has a nice lash ramp. lashes at .020 like other factory cams) DD http://www.dutra.org/dutraorg/pictures/ ... am60bd.jpg http://www.dutra.org/dutraorg/pictures/ ... m-212-.jpg |
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| Author: | MotoGrey [ Mon Dec 06, 2010 2:21 pm ] |
| Post subject: | Hydraulic |
Hey Doc what changes would you make to thes recipes if it were hydraulic? Thx, Ray |
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| Author: | Doc [ Mon Dec 06, 2010 3:29 pm ] |
| Post subject: | |
You would need to find some suitable hydraulic lobe profiles, something that adds 10 to 20 degrees to the RDP numbers shown. (Hydraulic cams are "slower" at lifting the valves so you have to adjust by giving the the lobes a bit more duration) DD |
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| Author: | MotoGrey [ Mon Dec 06, 2010 5:23 pm ] |
| Post subject: | |
Thx doug, it sounds like it would be better to go solid. Response is welcomed, ray |
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| Author: | Joshie225 [ Mon Dec 06, 2010 6:56 pm ] |
| Post subject: | |
Quote: You would need to find some suitable hydraulic lobe profiles, something that adds 10 to 20 degrees to the RDP numbers shown.
From all the camshaft information I've read a mechanical cam needs to have more advertised duration to achieve the same valve opening and closing events as a hydraulic cam because of the duration needed to take up the lash. Also, lifter diameter is generally what limits the valve opening and closing rates. Is there some technical reason other than the lifter compressing for a hydraulic cam opening the valve slower?
(Hydraulic cams are "slower" at lifting the valves so you have to adjust by giving the the lobes a bit more duration) DD |
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