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| Cam Choice for Backup Motor https://slantsix.org/forum/viewtopic.php?t=62924 |
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| Author: | SpaceFrank [ Sun Oct 14, 2018 10:23 pm ] |
| Post subject: | Cam Choice for Backup Motor |
Well, it turns out I won't have time before the next Lemons race to put together the long-rod engine I'd been planning. Not enough weekends left, too many other things to do, and I want to take my time with the oiling mods on this one. My backup option is a stock '73 long block with the head from my old race engine (1.70/1.44 valves, ~48cc chambers, mild porting). I haven't measured the deck height yet, but I assume this engine will end up around 8.8 SCR with stock pistons. My question is which camshaft I should use in this engine. Using a Holley 350 on a 2-bbl aluminum intake and Dual Dutra Duals with 2" primaries into a 2.5" pipe. It'll be raced on a road course primarily between 3000-4500 RPM in a ~3100 lb. car with a stock A904 converter and 3.55 gears. Options: 1. Stock 1973 225 camshaft that's already in it 2. Isky camshaft from the old race motor (single-pattern .448 lift, 264 advertised duration, 109 LSA) 3. OCG 346 regrind that I ordered for the slightly higher-compression long-rod build (not ideal, as I'd either have to pull it out later or order another) I'm leaning toward snagging the used Isky out of my old engine, but I'm also looking for suggestions on how to degree it. I previously had it slapped in dot-to-dot, but I'm not in that much of a hurry this time around. |
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| Author: | Greg Ondayko [ Mon Oct 15, 2018 8:10 am ] |
| Post subject: | Re: Cam Choice for Backup Motor |
I will let Lou or others will chime in on this one. I don't have words of wisdom in regard to cams - however take into consideration the oil pump gear shredding factor. If you are endurance racing I might use a known good pump gear / cam gear combo unless you are going to an external pump. Greg |
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| Author: | SpaceFrank [ Mon Oct 15, 2018 10:40 am ] |
| Post subject: | Re: Cam Choice for Backup Motor |
Good point about the pump gears. The '73 block still has a factory aluminum oil pump, so it's probably fine with its existing cam, but I'd have to eyeball the gear and check the rotor clearances at least. The Isky has been running for years with a cast iron Melling oil pump that I know still makes good pressure, so I'll swap it over if I use that cam. |
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| Author: | Dart270 [ Tue Oct 16, 2018 5:12 am ] |
| Post subject: | Re: Cam Choice for Backup Motor |
For that RPM range, use the Isky for sure. Degree it at 100-102. You would make more power overall with the OCG, but at higher RPMs. Lou |
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