I have seen talk of different lash settings here lately and I know that the factory cam has .010/.020 and after market cams have somwhat different settings based on lobe design.I have my CompCams 264s set at the lash recomended on the cam card which is .010/.012 and it idles smoothly but I am concerned with the .012 exaust setting for fear of burning valves but also do not want to hurt performance by experimenting to much.
I guess what Im asking is for any of yall who use this cam what is your experience with it and what lash settings have you found to work best?
like I said the car idles very smoothly (170 .030 over/lightly prted head/9.3-1 c.r./cam installed at 105.5/HyperPak intake with 390 Holley/DutraDuals/2.25 exuast)at 900 rpm and other having slightly lower than normal vacumm numbers(14-15 inchs) runs well but I am just paranoid I guess.Any with any experience,your suggestions are greatly appreciated.Thanks
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

I have no experience with comp cams, but my cam grinder told me to set the lash to .08 .08 and I was fearing the same as you're: burnt ex valvles. Guess what: since it never idled decent, I experienced from zero zero to .20 .20 and nothing happened to my valvles. I'm running now .04 .08 and I'm happy. Cam grinder specs are always on the safe side, they're anything but risky. They don't wanna have you jumping on their backs... My vac #s are similar to yours, too. I'm 16-18 depending on the weather idling @ 850 rpm, and 12-15 @ red light brakes on drive.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Juan, are you sure you didn't leave out some 0's?

0.04" (1mm) and 0.08" (2mm) are quadruple the factory lash settings of 0.01" (0.25mm) and 0.02" (0.5mm). Your engine would be making a HUGE amount of noise...that's if the pushrods managed to stay in place rather than falling out.

0.004" (0.1mm) and 0.008" (0.2mm) are WAAAAAAAAAY too small, essentially zero lash, and if you're running your enigne that way, you're giving up a lot of power and will eventually cook valves.

You may wanna recheck your valves and/or your maths

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

You got me--- as always I got math wrong. As far as for lashing is concerned in my car, they're .004 and .008 I tried more open lash settings to find out frustration and power loss. Valvletrain gets noisy as hell and my low end grunt goes to hell. I think it has something to do with my cam lobe profiles. I have to say that I'm not happy with this cam... maybe it's degreed wrong, maybe my cam grinder just was shooting in the dark (I'm more inlcined to the last option) it's a longer duration cam, he said it will rev up smoothly than a higher lift cam, wich it does, but I think that since he had to regrind, maybe he got lazy and just didn't feel like adding material then cut the right lobe on it. I'm trying to advance the cam a few degrees as soon as I can, since there's a rpm range where it works nice. Seems to kick in @ 1800-2200 rpm, so maybe cam is retarded. Maybe my f***ing chain is already stretched, I already have a double roller timing set coming down here (thanks to the good thread posted by greg Ondayko) but if things continues like this I'm gonna throw away this cam and get another.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

The "right" lash setting is designed into the cam lobe profile, that part of the cam lobe is called the "ramp". This is a slow and easy rate of lift off the bas of the cam lobe, before the "flank" of the lobe cuts-in. (the fast lift area)
The lobe designer and the cam grinder will know what the ramp looks like, and they give you a lash setting that gets you into the middle of it. (we hope)

The interesting thing is that all ramps are different, some are "short" and do not not allow for much lash difference before resulting in noise or poor performance. Other ramps are longer and allow for different last settings.
To find the best last setting you either have to have the cam "profiled" (checked outside of the engine) or just try some different lash settings.
I loosen up the lash until you start to hear the "ticking", that tells you that your lash setting is wide enough to miss the ramp and the lifter hits the flank hard, making the "tick" sound. Once you find that point, tighten .002 - .003 and you are in a good spot, where you use most all of the ramp to take-up the lash but the lifter does not hit the flank hard.

You will find that this lash setting will also get you the most engine vacuum.

Another note, hydraulic cam lobe profile have short, fast ramps, made to quickly compress the oil chamber in the lifter, and not take up mechanical clearance. When you put a mechanical lifter onto a hydraulic profile, you end-up with a much tighter lash setting that does not give you much room to adjust in. (short ramp area)
DD

Doc,
Is this something you do on just one cylinder, so you can work it out, and then set them all the same?

Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

wow, even I ain't that lazy

Doc, nice explanation. I think that my ramp is from short to very short. We never had hidraulic cam assy slants so I take that my cam grinder produced that profile on purpose (I hope). The tradeup I have to live with is that when I get nice vac readings I have awful tickling valvletrain noise... like a small 1.5 litre talbot avenger motor I can live with that if it's better for my mill. The larger amount of lash I can dial in before vac gets static again is .008 - .012 I'm .002 .004 now but I can open 'em @ about .005 .008 before it's starts to get noisy. Should I open 'em up just a tad?

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

My question to Doc simply meant, do I determine what the proper lash settings are for intake and exhaust on one cylinder, then set them all the SAME for the rest, or do I go through the entire process for each cylinder individually, potentially having them set at VARYING amounts?

I think you probably know by now, I don't ask questions out of laziness, just ignorance. See my sig below.

Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

I know... I know... sorry, no offense intended. I meant, you'll do better by hooking up a vac gauge (if you ain't already hooked up one) and set your lashes over all valvles, that way, if you're quick and you do it "open heart" you may be able to actually SEE how is behaving (in HG) with your new lash dialing, and if you ain't like what you're seeing you can just get away with one single oily mess.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Now, see there, here's my ignorance showing through, again. I don't have a vacuum gauge or know how (and when) to use one.

That's why I come to this site, to soak up all the experience and intelligence I possibly can. Ocassionally, I actually have something constructive to add, myself. Bear in mind, I'm 47 years old, and this is my first project like this (frame up re-build).

So as to not jack HyperValiant's thread here, I'm taking my next question about vacuum gauges out to a new post. By the way, no offense taken.

Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

Yes, usually I test on one cylinder, then try that setting on another, and then go right down the line, setting them all the same.

The way my luck is, I get to the last valve and find that it's a bit to noisy at my new setting, then I go a little tighter on that one, then go back and readjust them all to the same lash setting.
DD

Argentina,

I think you mean that you have your valves at 0.4 and 0.8 mm (0.016"/0.032"). These would be in the right range.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Hey Lou. Nah, I'm around 0.12 mm (in) and 0.22 mm (ex) that would be about .0045 and .0085 I tried more open lash settings on my custom cam and found out that this cam likes tight lashes (as far as noise is concerned) I think my cam grinder may have screwed it up, maybe I installed he damn thing too retarded or just about right but my timing chain is already stretched... I have to say that when I decided to go with this tight settings my comp #'s dropped big time... like 35 PSI on each cyl. and my vac #'s too. Idling @17-15 HG in neutral (depending on the weather and engine temp) @15-13 in D. The thing is that when I open the lashes I don't actually feel any power improvement, and the noise is horrible. Anyways, my cam grinder told me to set lashes @ .20 mm intake and exhaust... it's a regrinded core.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Who knows what lobe profile the cam grinder used, my guess is that they used a Chebby hydraulic lobe profile and ground that onto you SL6 cam core.
DD

Sounds like a hydraulic lobe to me too. It won't have the gradual ramps to take up the lash.

With the lash that tight (and the 35psi drop), I think you effectively added at least 20 degrees to the duration........

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes