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| rv10 cam - how much advance? https://www.slantsix.org/forum/viewtopic.php?t=43622 |
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| Author: | Doc [ Fri Mar 04, 2011 10:59 am ] |
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You are "good", with the overlap event showing cam advance at lash. Based on your test numbers, the engine will have lots of low and mid range power. DD |
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| Author: | gtdart [ Fri Mar 04, 2011 11:14 am ] |
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Excellent, thank you for all the support Doug! last month, I originally assembled this motor with 8:1 compression and a stock "builder" cam that was too retarded. Car ran great but could not get out of it's own way. I should have this all back together by next weekend. With compression increased to 9.3:1 and a properly indexed RV cam, I'm hopeful I'll find the power I was missing. I'll share my "seat of the pants" experience in the weeks to follow. thanks again everyone. -shane |
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| Author: | Doc [ Fri Mar 04, 2011 11:29 am ] |
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Based on your numbers, this build will have way more "spunk". You will have to listen closely for spark knock, 9.3 static CR with that 'small' cam, has the DCR up in the 8.5 range, that's a bit steep for pump gas. If the enging knocks a lot, tighten-up on the intake lash and recurve the distributer to adjust. DD |
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| Author: | gtdart [ Fri Mar 04, 2011 12:19 pm ] |
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Quote: You will have to listen closely for spark knock, 9.3 static CR with that 'small' cam, has the DCR up in the 8.5 range, that's a bit steep for pump gas.
I was targeting 9:1 compression but when I re-measured the head after machining, I'm well into 9.3:1. I recognize the need to tune-in the distributor curve to support all of the changes but should I also consider a thicker head gasket to get me closer to my original 9:1 target? This car probably won't see the bulk of my driving miles, would 91 octane help support the 8.5 DCR?If the enging knocks a lot, tighten-up on the intake lash and recurve the distributer to adjust. thanks, -shane |
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| Author: | sandy in BC [ Fri Mar 04, 2011 12:27 pm ] |
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You might be a candidate for a larger cam.....if you have the gears for it. Im pretty sure you will need premium fuel. You will need to do a curve. My care with a DCR of 8.3 can run on midgrade but I have a 5 speed and low gears. |
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| Author: | Dart270 [ Fri Mar 04, 2011 1:05 pm ] |
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I would go for either longer duration cam or thicker head gasket. Lou |
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| Author: | gtdart [ Fri Mar 04, 2011 2:11 pm ] |
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Thanks, it sounds like I have options. I'm going to stick with the cam. I'll get it on the road and see if tuning and decent gas will get it done. If in the end I need to lower the compression, than a thicker head gasket seems the easiest. For grins, I searched this site for gasket options. My measurements are based on the standard .040" Fel-Pro gasket. The only options I could find for varying thicknesses are custom copper gaskets. I'm not eager to put a copper gasket on a street driven car. Does anyone make a thicker OEM style gasket? |
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| Author: | sandy in BC [ Fri Mar 04, 2011 2:40 pm ] |
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Cheapest/easiest is a bigger cam.....DCR around 8 |
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| Author: | gtdart [ Fri Mar 04, 2011 2:56 pm ] |
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You might be right. I have to admit, I'm reluctant to buy another cam - just bought this one. I wanted to stay with my single carter, it works well. I considered the RV-15 cam but it is recommended for two barrel carbs. |
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| Author: | Dart270 [ Sat Mar 05, 2011 1:03 am ] |
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Felpro gasket is about 0.034" installed. Permaseal and ACL gaskets, and many others, are around 0.046". Lou |
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| Author: | gtdart [ Sat Mar 05, 2011 8:46 am ] |
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Lou, Thanks for the thick gasket pointers. Considering that my CR is a little high for my cam profile, I decided to scrutinize my CR calculations to insure I knew exactly where I was. Specifically, I started over thinking the deck height measurements and found that there is a measureable (and favorable in my case) difference in how it's measured. I started a new thread focussing on what I'm seeing: http://slantsix.org/forum/viewtopic.php?t=43886 thanks -shane |
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| Author: | gtdart [ Tue Mar 22, 2011 11:10 am ] |
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I've had it running for over a week now. Car is pulling well up my steep hills. While my previous cam was of an unknown grind, I suspect the proper alignment of the new RV-10 cam has more to do with my power gains than the grind itself. I'll never install a cam or timing chain again without degreeing it in - lesson learned. I've only managed to rack up about 100 miles on this rebuild so far. It's been raining pretty steady here in northern CA, not friendly convertible weather. I'm currently running 91 octane, haven't yet looked at my mechanical advance yet but happy to report that I'm not having any detonation issues. I expect to find a little more power when I dial-in the distributor curve. Should be a fun Spring project. thanks again for all the help everyone! -shane |
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| Author: | Dart270 [ Tue Mar 22, 2011 5:29 pm ] |
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Sounds great, Shane. Enjoy the ride... Lou |
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