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| vacuum question https://slantsix.org/forum/viewtopic.php?t=44918 |
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| Author: | 62 alum [ Tue May 10, 2011 3:11 pm ] |
| Post subject: | vacuum question |
I have a 1980 truck engine that I installed a erson rv 15 cam and lifters in along with a older head that had been rebuild with stock valves and .080 removed from it. When this engine was stock it pulled 19 inches of vac. at 600 rpm with 130 to 135 compression. It now has 15 inches at 700 rpm with 150 to 155 c.r. Is this normal or I`m I missing some thing. I have varied the timing with no change in vac. I hope this is enough info. for some input. Thanks |
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| Author: | Reed [ Tue May 10, 2011 3:17 pm ] |
| Post subject: | |
What valve lash are you running? |
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| Author: | polkat [ Tue May 10, 2011 3:58 pm ] |
| Post subject: | |
I see no problem with 15 inches. I've built a few V-8's that only pulled around 12 inches and they ran fine. ________ California Medical Marijuana |
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| Author: | Joshie225 [ Tue May 10, 2011 4:11 pm ] |
| Post subject: | |
When you use a cam with more overlap the vacuum goes down. Perfectly normal. |
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| Author: | 62 alum [ Tue May 10, 2011 4:13 pm ] |
| Post subject: | |
My lash is now set at a loose 012int/022exh. hot. I bit noisey but idles and revs. well. It has a stock one bbl. and exhaust for now but will have a M-1 2 bbl. and dutra dual exh. when I install it in my car. Just would like to get it as close to right before I put it in. |
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| Author: | DusterIdiot [ Tue May 10, 2011 6:19 pm ] |
| Post subject: | Degreed? |
How much advance did you degree into your cam when you installed it? -D.idiot |
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| Author: | 4speed [ Tue May 10, 2011 6:46 pm ] |
| Post subject: | |
Don't most RV cams have better idle vacuum and low end torque? IE its a more mild cam than stock. |
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| Author: | Joshie225 [ Tue May 10, 2011 6:49 pm ] |
| Post subject: | |
The Erson RV15 is more aggressive (higher lift and longer duration) than a stock slant six cam. It's still mild so it has the RV designation. |
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| Author: | Reed [ Tue May 10, 2011 6:51 pm ] |
| Post subject: | |
Your vacuum and lash sounds good to me. |
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| Author: | ceej [ Tue May 10, 2011 7:13 pm ] |
| Post subject: | |
I ended up with looser lash with my RV15M RDP. It will sound a bit like a type writer when you get it right. Not obnoxiously loud, but you'll be able to hear them tapping away. Mine liked being straight up as ground. I ordered Doc's Lobe seperation formula. 2¢ CJ |
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| Author: | 62 alum [ Tue May 10, 2011 7:43 pm ] |
| Post subject: | |
Thanks everyone for your input. I feel better about swapping it in my valiant now. D.idiot This was my first shot at degreeing a cam I ended up with a 102 center line ,I did not use any cam bushing. Ceep You are right on the lash- after it ran for awhile it started to miss I opened up the intakes to 016/exh 026 Seems ok now. |
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| Author: | ceej [ Tue May 10, 2011 7:56 pm ] |
| Post subject: | |
I think that's where I ended up. Not sure about the 102° Intake Lobe center though. I'll have to look the cam card up. Idle vacuum was close to 19" HG. CJ Edit: Yep. 106° Intake Center Line. |
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| Author: | ceej [ Tue May 10, 2011 8:10 pm ] |
| Post subject: | |
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