Slant Six Forum :: Finding best valve lash setting

Start by setting the lash to where you think it should be, for a factory cam, that is .010 In & .020 Ex

Note how the engine idles and the sound of the valves, turning the idle speed way down helps. (go as low as you can with smooth running.

Now loosen the exhaust valves by .002 (reset to .022)
Does the engine run any smoother? Do you hear any load ticking?
If it runs smooth or smoother without additional noise, leave it looser.
You can use the same process on the intake valves but with intake settings, lashing them a little tighter can help performance. ( Try .008 and see if the idle is still smooth)

Aftermarket cams often have different settings from the .010 & .020
If you have loud ticking and /or rough idle, there is a good chance you are not runing the correct lash for that cam's lobe profile. (lash ramp)
Trying some different settings and finding the clearance that show improvement is how you find the best lash setting for your cam.
DD

Author:	Jopapa [ Thu May 24, 2007 3:18 pm ]
Post subject:	Finding best valve lash setting
A while back, it was mentioned that many stock slants had different lash settings that worked best for them (different from the 0.010 & 0.020 specs). My question concerning that is: how exactly do you know (or find out) which setting is best for your engine? I still have yet to adjust mine (yeah I know, gotta do it ASAP), but I just remembered that and it got me thinking...

Author:	Ron Parker [ Thu May 24, 2007 4:10 pm ]
Post subject:
What camshaft are using. If is stock the 10/20 is right if it a high performance camshaft it should have came with a cam card of reconmended specs. Thanks Ron Parker Jaggers Fabrication Slanted Attitude Dart

Author:	Doc [ Thu May 24, 2007 4:22 pm ]
Post subject:
Start by setting the lash to where you think it should be, for a factory cam, that is .010 In & .020 Ex Note how the engine idles and the sound of the valves, turning the idle speed way down helps. (go as low as you can with smooth running. Now loosen the exhaust valves by .002 (reset to .022) Does the engine run any smoother? Do you hear any loud ticking? If it runs smooth or smoother without additional noise, leave it looser. You can use the same process on the intake valves but with intake settings, lashing them a little tighter can help performance. ( Try .008 and see if the idle is still smooth) Aftermarket cams often have different settings from the .010 & .020 If you have loud ticking and /or rough idle, there is a good chance you are not runing the correct lash for that cam's lobe profile. (lash ramp) Trying some different settings and finding the clearance that show improvement is how you find the best lash setting for your cam. DD

Author:	Jopapa [ Mon Jul 02, 2007 5:54 pm ]
Post subject:
Quote: Start by setting the lash to where you think it should be, for a factory cam, that is .010 In & .020 Ex Note how the engine idles and the sound of the valves, turning the idle speed way down helps. (go as low as you can with smooth running. Now loosen the exhaust valves by .002 (reset to .022) Does the engine run any smoother? Do you hear any load ticking? If it runs smooth or smoother without additional noise, leave it looser. You can use the same process on the intake valves but with intake settings, lashing them a little tighter can help performance. ( Try .008 and see if the idle is still smooth) Aftermarket cams often have different settings from the .010 & .020 If you have loud ticking and /or rough idle, there is a good chance you are not runing the correct lash for that cam's lobe profile. (lash ramp) Trying some different settings and finding the clearance that show improvement is how you find the best lash setting for your cam. DD I've been running the stock setting for a couple weeks now, and it's worlds smoother than what it was beforehand. When I went to adjust the lash, every rocker was more than a full turn too loose. What are the long term effects of having run it a few hundred miles like this? The last owner never put more than maybe 50-100 miles on it himself, and I put a couple hundred on it before adjusting the valves. Next time I have some time to mess around with the engine I'll try the different setting you suggested. One question though; what benefit is there to setting the exhaust valves to a more loose setting? Intake I can understand, as it'll let more air/fuel mixture in, but I'm perplexed as to why to loosen the exhaust

Author:	Sam Powell [ Mon Jul 02, 2007 5:58 pm ]
Post subject:
Too loose is not a problem. Most of those 250K mile slants probably ran most of their life with too loose by .010-.015. Too tight is another thing, because you can burn valves that way. The good news is that too tight usually runs really badly, calling attention to the problem. Sam

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Author:	69a100 [ Tue Jul 03, 2007 5:18 am ]
Post subject:
Not to hi-jack, but as long as were on the subject. "DOC"- why is it that the Erson 218/212 @ 50 cam has the intakes lashed to .15"? That seems awfully fat to me. Explain please. Thanks

Author:	dakight [ Tue Jul 03, 2007 10:52 am ]
Post subject:
Running the valves too loose can mushroom the tips of the valve stems, other than that I'm not aware of any serious mechanical issues with it. The biggest issue is that the engine will not run at optimum efficiency that way.

Author:	Aggressive Ted [ Fri Jul 06, 2007 11:57 am ]
Post subject:
Jopapa, Let us know what worked the best. The .022 and .008 Doc mentioned sounds interesting. I am running the stock .010 and .020 settings for now, but it would be interesting to compare.

Author:	Doc [ Fri Jul 06, 2007 12:14 pm ]
Post subject:
Quote: Not to hi-jack, but as long as were on the subject. "DOC"- why is it that the Erson 218/212 @ 50 cam has the intakes lashed to .15"? That seems awfully fat to me. Explain please. Thanks Erson has many cam lobe "masters" which they use to grind any cam you want. Most cam grinders don't remember where they got there masters, they just know the basic lift and duration numbers. The special Erson grinds I worked with them on used some of Erson's masters for the intake and we copied the Moper 244 cam's exhaust lobe for the exhaust side. The bottomline, that Erson lobes have a taller lash ramp that needs a little more clearance. Always start by using the lash that is suggested by the grinder but also try some different settings to see if you like more / less lash. I found that the special "dual pattern" cams I am using seem to work better / run smoother with .016 - .018 of lash on the intakes. DD

Author:	Aggressive Ted [ Fri Jul 06, 2007 1:27 pm ]
Post subject:	Schnider Cams
Doc, How do the Schnider cams, like the 132F, 137F and 142F compare to your dual pattern cams in terms of lash settings, gut wrenching torque and over all driveability? Are the lash settings that much different? I am not concerned with a perfect idle, just low end torque between 1500 and 2000 tops 2500. Which would you pick as an upgrade from my 254 .435 lift? One of your dual pattern cams or one of the Schnider cams?

Author:	Doc [ Fri Jul 06, 2007 1:43 pm ]
Post subject:
I don't have any info. on the Schnider profiles you listed, I would have to see the actual plots on the lobe shapes to really address your question. I already did this review with Erson's profiles so I would think that the dual pattern 254 / 244 Erson grind would have better low RPM power. (a later "blow down" event) For better mid-range, the 260 / 244 is the next step up. For the group buy price of $128.00, I bought one of each. DD

Author:	Jopapa [ Mon Aug 06, 2007 7:21 pm ]
Post subject:
Quote: Jopapa, Let us know what worked the best. The .022 and .008 Doc mentioned sounds interesting. I am running the stock .010 and .020 settings for now, but it would be interesting to compare. I still haven't tried the different settings yet. What's interesting though, is that since I adjusted my valves, my last two tanks of gas were only 13 MPG! I haven't gone through a full tank since doing the HEI so I don't know if that made any difference in mileage yet, but does anyone think it kind of weird that my mileage would drop so drastically after adjusting the valves to the correct, stock setting?

Author:	Aggressive Ted [ Tue Aug 07, 2007 1:00 pm ]
Post subject:
Jopapa, What was your mileage before you set the valves? and what were they set at before you changed them? I was getting 18 mpg at .008 and .016. After switching to .010 and .020, it went way up! So thats double weird!

Author:	Dart270 [ Tue Aug 07, 2007 1:44 pm ]
Post subject:
Too tight lash means the valves are open a little all the time, thus mileage suffers. I've seen this happen, esp on motors that are breaking in, or are really old (recessed seats). Lou

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Author:	Jopapa [ Tue Aug 07, 2007 4:59 pm ]
Post subject:
Quote: Too tight lash means the valves are open a little all the time, thus mileage suffers. I've seen this happen, esp on motors that are breaking in, or are really old (recessed seats). Lou That makes sense, but I would figure that as long as there's a gap between the rocker and the stem, the valve is still closing fully, or is this not necessarily the case? Ted, my mileage beforehand was 17 MPG on average. I never did check the actual gap before setting the lash, but they were all at least double the stock setting (and very loud when running).