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| cam question https://slantsix.org/forum/viewtopic.php?t=24717 |
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| Author: | 82truck [ Fri Aug 31, 2007 8:30 am ] |
| Post subject: | cam question |
still trying to get things figured out with my rebuilt engine. at work there is an 86 van, same year as mine, and it runs fine. i put its carb on my van and my van still runs bad. so i know my carb is not bad. was wondering if the cam i used is too much for a stock motor. adv dur 280, dur @ .050 208, lift .420. lobe sep 110, intake centerline 106? |
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| Author: | AnotherSix [ Fri Aug 31, 2007 9:45 am ] |
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I would look for vacuum leaks first and check basic things like the cap and plug wires, even if they are new. That cam is not too big and is really a low end torque rv type of cam. It should idle fine and while it is always best to degree in the cam, that one is not so large that it would run bad if it is off some. |
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| Author: | AnotherSix [ Fri Aug 31, 2007 9:48 am ] |
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Is there a chance that the lifter pre-load is way off? It often gets to be too much on rebuilds with non-adjustable valve trains. |
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| Author: | 6shotvanner [ Fri Aug 31, 2007 9:54 am ] |
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82truck, What brand and is it hyd or mech cam? I'm running a comp cam 260hyd which is .440 lift,110' sep, 212@ .050". I still think those fellers skeerood ua on that engine.Anyhow,mines a smooth idle cam,not familier with your cam #'s. Doc,Dan,anybody? Good luck Stacey 
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| Author: | SlantSixDan [ Fri Aug 31, 2007 10:46 am ] |
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That 280° (advertised) cam might be too big for the street. The large 72° difference between advertised duration and duration at 0.050" is kind of interesting. Where did you get this cam, and who recommended it? I really think your primary issue is that the guys you hired to do the work are a bunch of incompetent and/or dishonest boobs. 
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| Author: | AnotherSix [ Fri Aug 31, 2007 11:16 am ] |
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Is this not a hydraulic cam? As long as it is those numbers are not at all unusual, and it is not very big. If this is not hydraulic, then that is quite a spread. Even so, unless a cam is actually profiled, the advertised number is not anything to get too exited about. It is the duration at .050" to really look at. You cannot tell what kind of rate a cam has with any certainty by the advertised duration, it's just not that simple. Advertised might be measured at .001" or .005" or who knows what. |
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| Author: | SlantSixDan [ Fri Aug 31, 2007 11:28 am ] |
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Quote: Is this not a hydraulic cam?
Oh yeah...an '81+ engine. Probably is hydraulic, silly me.
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| Author: | slantzilla [ Fri Aug 31, 2007 2:06 pm ] |
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What exactly is it doing? Is it missing or just low on grunt? 
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| Author: | 82truck [ Fri Aug 31, 2007 6:38 pm ] |
| Post subject: | |
it is hydraulic. i told Tom McGibbon at Erson my plans were to keep it stock but wanted a little more power for hills and getting up to speed entering the freeway. i will check the vacuum lines this weekend and make sure they are hooked up correctly. when its running with the top of the air cleaner off and you put a towel on top the carb it runs better. |
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| Author: | greasy 225 [ Fri Aug 31, 2007 9:10 pm ] |
| Post subject: | |
.420" lift, isnt that their 256 cam, unless I missed somethin Erson's 280 is .465" lift? -Jesse |
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| Author: | Doctor Dodge [ Sat Sep 01, 2007 9:25 am ] |
| Post subject: | |
What is the engine's idle vacuum reading? Who set-up the head? Was close attention paid to setting the correct valve stem height in order to give the proper hydro lifter preloads? DD |
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| Author: | 82truck [ Sat Sep 01, 2007 6:20 pm ] |
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Pacific Engine Rebuilders did the engine. i doubt they paid any attention to anything. it still has exhaust leaks or lifter noise because when the rpm's are up they tick so i'll be taking it back to them again to try and fix that. does anyone know what the proper height would be for that so i could tell them. i don't really understand alot of this kind of stuff. |
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| Author: | humdinger [ Sat Sep 01, 2007 9:33 pm ] |
| Post subject: | lifter ticking |
Hi that ticking sound your hearing is probably where the cam you bought from erson isn't letting enough oil to the lifters,The one I bought isn't.I called Tom and he said if I would send it back along with my old cam he would fix the problem.I was pleased with the cams increase in power I just wish I didn't have to send it back(trucks gonna be down a couple weeks or so).I have the same cam you do. |
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| Author: | slantzilla [ Sun Sep 02, 2007 6:33 am ] |
| Post subject: | Re: lifter ticking |
Quote: Hi that ticking sound your hearing is probably where the cam you bought from erson isn't letting enough oil to the lifters,The one I bought isn't.I called Tom and he said if I would send it back along with my old cam he would fix the problem.I was pleased with the cams increase in power I just wish I didn't have to send it back(trucks gonna be down a couple weeks or so).I have the same cam you do.
Instead of sending it back you can grind a little groove all the way around the rear journal. I have an UltrDyne hydraulic cam and that is how it is. The process has been described on here not too long ago. It's not a big deal to do, and is a lot better than just a hole through the cam. 
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| Author: | slantasaurus [ Sun Sep 02, 2007 1:07 pm ] |
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Quote: it is hydraulic. i told Tom McGibbon at Erson my plans were to keep it stock but wanted a little more power for hills and getting up to speed entering the freeway. i will check the vacuum lines this weekend and make sure they are hooked up correctly. when its running with the top of the air cleaner off and you put a towel on top the carb it runs better.
If it runs better with a towel over the carb.  You can bet there are vacuum leaks !!! The towel is restricting air, it has to be getting in somewhere....I know, it's hard to immagine there might be problems with the quality work these guys have done for you. At this point, I think you should work things out yourself, you claim you don't know much, but you DO know more than the guys you have been paying....and you have all of us here to help you along the way.
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