I got a Comp with .640 gross lift that should be just what you need John.
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| max cam lift with stock valve springs https://slantsix.org/forum/viewtopic.php?t=56922 |
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| Author: | DadTruck [ Tue Jan 13, 2015 7:11 pm ] |
| Post subject: | max cam lift with stock valve springs |
1) what is the max cam + 1.5 rocker lift with stock valve springs at stock installed height? I though that I saw that mentioned on this forum,, have searched for the last 45 minutes,, read a lot of interesting stuff,, some back to 2007,, but not the answer to that question. 2) at what point does one need to trim the tops of the stock valve guides? 3) and I thought I knew how to measure gaps between the coils,, If you want a minimum of .030,, run the valve to full open then if the closest gap is .030, you met the target. asking as I saw a post here where someone said it is acceptable to sum up the gaps to get your target,, for example,, three coil gaps of .010 would equal the .030 is that right? |
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| Author: | sandy in BC [ Tue Jan 13, 2015 7:20 pm ] |
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I have run as close as 12 on a $200 grenade race motor. It worked fine.....I made sure there was lots of oil to the top end and only over revved it when necessary. It won 2nd place in a tight series 2 years in a row........ not recommended |
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| Author: | DusterIdiot [ Tue Jan 13, 2015 7:37 pm ] |
| Post subject: | 2 cents... |
Not sure if I have the correct answers, but the last cam I ran on single only stock springs had a 1.5 at .466 and it was fine.... I went to double/340 springs once I went to the Erson cam at .480, my machinist cut the valve guides a little on that cam...it needed a bit more on anything above .510 lift.... |
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| Author: | Dart270 [ Wed Jan 14, 2015 6:24 am ] |
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0.460" is definitely OK. 0.480" is likely pushing it, and anything more will need some trimming or different springs/retainers/valves. Of course, if worried, I would check everything by slowly rotating the motor with higher valve lash, then close up the lash and check again. I have never had trouble with a 0.460" cam on stock or 340 springs and stock valves. Lou |
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| Author: | nm9stheham [ Wed Jan 14, 2015 7:33 am ] |
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I have understood (for a few decades) that total spring bind clearance is what you are after, not individual coil clearance. .030" total seems pretty tigth; I can recall 40 years ago that .100" total on a 6krpm revving V8 was considered the 'safe' amount to have, to account for some valve float. But if revs are kept down, then closer seems like it would be OK. I think I would not go below .050" total. I recently went through the computations and .430-.440" at the valve with 1.5 rockers was about the limit with .050" spring bind clearance using stock spring dimensions. So tht cam lift would be around .290" and you could go a bit more with the lash adjustment. BTW, I just used some Sealed Power VS510 springs with a .435 valve lift cam (not including lash) and had gobs of spring bind clearance. At <$2 each and about 10 lbs more seat pressure than stock, they seemed like a good deal for stock replacements. OD is slightly larger than stock but they fit under the original retainers quite nicely. (BTW, this is on an early, '62 mechanical valvetrain engine.) I had to buy 16 through NAPA; plenty are left in the KY warehouse as of a month ago. With having a few more lying around, I now have a nice collection of 10 new spare VS510's. Anyone want to build a poh-man's Audi 5 cylinder in their next build? LOL |
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| Author: | DadTruck [ Wed Jan 14, 2015 1:08 pm ] |
| Post subject: | |
Quote: 030" total seems pretty tigth
thanks for the responses,, but no one has really answered..the .030 was just for conversation purposes,, the question was and still is for example,, if .060 clearance coil to coil is desired,, does one need to find .060 clearance minimum at the closest coil,, or if there is .020 clearance at three coils,, does that equal the .060 ? for example this comes from the Lunati site Coil clearance is the distance between the valve spring coils when the valve is it maximum lift (fully open). A minimum of 0.060" must exist between the coils at maximum lift. Coil bind is when the valve spring is compressed fully-to the point that all of the coils are "stacked up" on top of each other. For high RPM applications, .100" is recommended . Coil bind is a catastrophic condition that will result in valve train failure. Disassemble each spring (if multiple springs are employed at each valve). Check all the springs (both inner, and outer springs) If there is not 0.060" - 0.100" minimum of clearance between the coils, the solutions are: the valve retainer, the valve locks, the valve, or the spring must be changed; the spring pocket must be machined. Keep in mind that these modifications will change the valve spring installed height is the .060 a minimum at the closest coil or the sum of all the coils? |
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| Author: | emsvitil [ Wed Jan 14, 2015 2:07 pm ] |
| Post subject: | |
I always thought that the coil bind was additive. If you want .030 and there's 6 gaps, you can .005 between in each gap. Or to directly measure the .030, put a stack of feeler gauges between the rocker arm and valve tip and see how many feeler gauges are needed to bind up the coil. |
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| Author: | Rick Covalt [ Wed Jan 14, 2015 2:25 pm ] |
| Post subject: | |
Not sure about the answer to your coil bind question, but as far as the springs go I can give you a little help. The engine builder springs are $38/ set and are good for .500 lift. I ran them at just a tad over that on my race motor and they worked fine. I did have the guides cut down though. I had enough room at .513 lift until I tried to put a valve seal in between the guide and the retainer. Then I just had them cut down more for a .550 lift cam just in case. Rick |
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| Author: | Rick Covalt [ Wed Jan 14, 2015 2:34 pm ] |
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Quote: If you want .030 and there's 6 gaps, you can .005 between in each gap.
I believe you are probably right. If they want .060-.100 and you had 6 that would put you at .600" on the high end. That doesn't seem right to my pea brain. .100" total seems more likely.Rick |
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| Author: | DadTruck [ Wed Jan 14, 2015 2:40 pm ] |
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Quote: The engine builder springs are $38/ set and are good .500 lift.
that is a good tip,, I phoned the guy that does my machine work,, he confirmed that the .060 is a good number and it is additive. Ed said take the spring that you want to use, compress it soild in a bench vise, measure the distance add .060 and that is max safe lift with that, I took a stock valve spring, got it solid at 1.106, add .060 is 1.166 subtract the installed height of 1.620 .454 would be the max safe valve lift,, the .460 number mentioned is right in line with that,, concerning the valve spring going solid, at moderate RPM's,,, at higher RPM's you may want .100 total between the coils |
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| Author: | sandy in BC [ Wed Jan 14, 2015 4:43 pm ] |
| Post subject: | |
The additive and individual measures have their own advantages. I measure for the smallest individual measure. My thinking is that when the first coils pile up ...the trouble starts. I think Vizzard recommends 10 as a minimum for mechanical lifter individual coils. |
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| Author: | Dart270 [ Wed Jan 14, 2015 5:56 pm ] |
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So, he big question is: What cam ya gonna run? Lou |
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| Author: | DadTruck [ Wed Jan 14, 2015 6:14 pm ] |
| Post subject: | |
Quote: What cam ya gonna run
about the biggest one that will work with stock springs-valvesthis is for the 68 barracuda,, working on it this winter, renewing and upgrading the suspension and brakes,, I did not plan to pull the motor,, but did, since it was out, figured it would be easy to mill the head and up the cam,,putting the OE stock pistons-rings-bearings-valves back in. A better motor will come later, once the car is done and driveable, |
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| Author: | slantzilla [ Thu Jan 15, 2015 3:06 am ] |
| Post subject: | |
I got a Comp with .640 gross lift that should be just what you need John.
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| Author: | nm9stheham [ Thu Jan 15, 2015 7:10 am ] |
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For around $30 you can put in new VS510's or Engine Builder springs mentioned by Emsvitil and run a bit more lift. No machining or anything for the VS510's; just put them in. And with fresh springs, no worries with any weak springs in the bunch. (Well, fewer less worries for such.....) I replaced my 52 Y.O. stock springs for that reason alone. |
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