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| Valve spring installed height, Comp cam https://www.slantsix.org/forum/viewtopic.php?t=11065 |
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| Author: | slafolle [ Tue Nov 30, 2004 6:11 pm ] |
| Post subject: | Valve spring installed height, Comp cam |
Got an Comp cam 264 and the recommended springs, Comp 970. The installed height says 1.700" on the box, but our stock spring height is 1 5/8 to 1 11/16 (about 1.625-1.670"). I've been told that the cam will go flat unless we get our installed height to 1.700". How can we do this? Someone told me to look for offset (deeper) retainers, but I can't find any that'll fit. Comp suggests machining the head, but I don't have tools to do this. Any thoughts on this issue? My valve and seat grinding has already sunk the valves into the head a bit, would it be reasonable to run the cam with maybe 1.680" installed height instead of 1.7? Thanks Steve |
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| Author: | HyperValiant [ Tue Nov 30, 2004 7:31 pm ] |
| Post subject: | |
What do you mean by"go flat? That the lobes will physically go flat or that the performance will drop off at a certain rpm? I am interested in this topic as I have this cam installed in a 170 cube slant with the stock valve springs and havent noticed any problems yet but have only broken the the cam in and have not run it on the road yet and have only revved it to 3000 rpm. I have noticed that the stock springs seem tight(coils close together)at full compession but I can slide a .020 feeler guage between the coils at full compression. HyperValiant |
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| Author: | slafolle [ Tue Nov 30, 2004 7:57 pm ] |
| Post subject: | |
By "go flat", my auto shop instructor meant that the lobes would physically wear flat due to excessive spring pressure. He is concerned that the Comp springs would be too stiff for the cam unless set at the proper installed height. With your setup I don't think you have to worry about this, since the stock springs are very soft compared to the Comp springs. In fact, I might decide to run the old springs, since I'm on a tight schedule and budget. As you suggest, coil bind might be an issue with the stock springs. However, .020 may be enough clearance. I hope to get more info in the next day or two, I'll keep ya posted. Thanks for the info, Hyper V. Steve |
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| Author: | Greg Ondayko [ Wed Dec 01, 2004 8:44 am ] |
| Post subject: | |
I have used stock340 valve springs on my head with no problems, they are stiffer than stock, but shouldnt cause any other problems - and they are reaidly available. |
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| Author: | slafolle [ Thu Dec 02, 2004 4:54 pm ] |
| Post subject: | |
HyperV, .020 between coils may be too close. For example, http://www.lunaticams.com/technotes/TN8alvesprings.html recommends at least .060. There also might be a valve float problem, but if you've already got it to 3000 rpm, that's not too bad. A friend who's running the 264 cam and 970 springs has ordered special retainers from Summit, about $60. It was about $50 for the springs. I lucked out (for a change) and found some aftermarket springs on a junkyard head that are stiffer than stock (possibly 340 springs?), so I'm going to use those, at least for now. Steve |
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| Author: | HyperValiant [ Thu Dec 02, 2004 7:44 pm ] |
| Post subject: | |
Thanks for the info ,Slafolle. HyperValiant |
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