Slant Six Forum :: Fun with Valve Lash

I thought I'd share this info, for what it's worth...

I have a fairly built up Slant. It has a cam that DD designed. I do not know the specs - but I am guessing it's around 260 - 264 duration, and about 460 lift.

When the engine was built, DD set the lash at 11/21. But he said it was OK for me to change it to 9/19, if I wanted a little more top end power.

Well, I didn't think it would make that much difference, so I didn't try it. Then one day I decided to see what would happen.

I went to .009 intake and .019 exhaust.

I instantly gained about 50 RPM at idle and the idle actually got smoother! I also seem to have picked up about 200 RPMs at the top - so now I get power up to 5000 RPM instead of 4800 like I used to.

I also got more low end, and in fact had to change to a different "hole" on my accelerator pump linkages (i.e., needs bigger squirts now).

Just thought I'd pass this along.

The caveat would be that my experience with Slants is that the lash tends to DECREASE over time as the valves wear "into" the head - so this means that I have to be careful to make sure I always have enough lash.

Author:	63Dart [ Fri Dec 30, 2005 5:49 pm ]
Post subject:	Fun with Valve Lash
I thought I'd share this info, for what it's worth... I have a fairly built up Slant. It has a cam that DD designed. I do not know the specs - but I am guessing it's around 260 - 264 duration, and about 460 lift. When the engine was built, DD set the lash at 11/21. But he said it was OK for me to change it to 9/19, if I wanted a little more top end power. Well, I didn't think it would make that much difference, so I didn't try it. Then one day I decided to see what would happen. I went to .009 intake and .019 exhaust. I instantly gained about 50 RPM at idle and the idle actually got smoother! I also seem to have picked up about 200 RPMs at the top - so now I get power up to 5000 RPM instead of 4800 like I used to. I also got more low end, and in fact had to change to a different "hole" on my accelerator pump linkages (i.e., needs bigger squirts now). Just thought I'd pass this along. The caveat would be that my experience with Slants is that the lash tends to DECREASE over time as the valves wear "into" the head - so this means that I have to be careful to make sure I always have enough lash.

Author:	SpaceFrank [ Fri Dec 30, 2005 7:44 pm ]
Post subject:
I have a fairly stock, recently rebuilt 170. The only non-stock item is a slightly hopped-up Isky camshaft. I set the valve lash to .010/.020, but the engine still chatters a bit. Is that normal? If not, how much can I safely tighten it up?

Author:	SlantSixDan [ Fri Dec 30, 2005 9:05 pm ]
Post subject:
Did you use something similar to This procedure?

Author:	SpaceFrank [ Sat Dec 31, 2005 6:30 pm ]
Post subject:
No, I did it cold. After reading that, I guess I'll try it while running. I didn't even know you could do that. Still, is a little bit of chatter normal?

Author:	mcnoople [ Sat Dec 31, 2005 6:32 pm ]
Post subject:
Slants are allowed to rattle and chatter some. They do have solid lifters they will never be silent.

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Author:	Mark [ Sat Dec 31, 2005 7:32 pm ]
Post subject:
To me a little valve chatter is prefered over none on a solid lifter motor such as a slant. A little chatter means the valves might be a little loose or even just right but none means they are too tight and that can lead to burnt valves.

Author:	63Dart [ Sat Dec 31, 2005 7:47 pm ]
Post subject:
SSD - yes - did it while running. Best trick I ever learned!

Author:	emsvitil [ Sat Dec 31, 2005 7:47 pm ]
Post subject:
My Harley with hydraulic lifters clatters more than my slant with mechanical................

Author:	SlantSixDan [ Sat Dec 31, 2005 8:14 pm ]
Post subject:
Quote: No, I did it cold. After reading that, I guess I'll try it while running. I didn't even know you could do that. Still, is a little bit of chatter normal? It's really tough/impossible to get an accurate final adjustment with the engine cold. Usually cold adjustment leads to insufficient (too tight) clearance when hot, but there are other errors possible (forgetting that the port order changes in the middle of the engine, etc.) that could lead to loud operation on startup. With proper clearance, the amount of noise is a function of the camshaft's lobe profile. Some run noisier than others. With any of the stock or near-stock Chrysler cams, near-silent valvetrain operation is possible to attain without endangering the valves or causing running problems.

Author:	69a100 [ Sat Dec 31, 2005 9:39 pm ]
Post subject:	Valve Lash
I mostly play with the big Mopars, and Im sure that this same rule applies to the beloved slant. Mopars like high lift with not alot of duration to help get the air in and out. I know that porting helps on my 383 as Im now running a 272/276 dur @ .507/.512" lift aas compared to the 262* dur @ a lame .435" lift and the car flys now. Just got to get the head built for the /.

Author:	Eric W [ Sat Dec 31, 2005 9:56 pm ]
Post subject:
I adjusted the valves on my stock slant to .009" intake and .019" exhaust. Seemed like a happier engine from idle up to 80.

Author:	Mr. D-150 [ Mon Jan 02, 2006 8:33 am ]
Post subject:	Re: Fun with Valve Lash
Quote: I thought I'd share this info, for what it's worth... I have a fairly built up Slant. It has a cam that DD designed. I do not know the specs - but I am guessing it's around 260 - 264 duration, and about 460 lift. When the engine was built, DD set the lash at 11/21. But he said it was OK for me to change it to 9/19, if I wanted a little more top end power. Well, I didn't think it would make that much difference, so I didn't try it. Then one day I decided to see what would happen. I went to .009 intake and .019 exhaust. I instantly gained about 50 RPM at idle and the idle actually got smoother! I also seem to have picked up about 200 RPMs at the top - so now I get power up to 5000 RPM instead of 4800 like I used to. I also got more low end, and in fact had to change to a different "hole" on my accelerator pump linkages (i.e., needs bigger squirts now). Just thought I'd pass this along. The caveat would be that my experience with Slants is that the lash tends to DECREASE over time as the valves wear "into" the head - so this means that I have to be careful to make sure I always have enough lash. You've learned something that makes the Leaning Tower of Power so great. It loves duration . . .to a point. With the long stroke/ small bore, I've found it helps a lot on a STOCK cam to go to 0.008" (IN) and 0.010" (EX), so I'm not surprised at your gains on a hotter cam. I once tried 0.006" and 0.008" but the idle quality and throttle response dropped severely. My last /6 was a 65 225 and I never ran into the valve recession you mention. Commonly, at the tight clearances, I had to tighten the clearances, but I was also using a small, home-brew water vapor injection system and a recurved distributor (all in at 1200 rpm) on 89 octane unleaded. Budd (the one with the double D's)

Author:	SlantSixDan [ Mon Jan 02, 2006 11:02 am ]
Post subject:	Re: Fun with Valve Lash
Quote: With the long stroke/ small bore, I've found it helps a lot on a STOCK cam to go to 0.008" (IN) and 0.010" (EX) Urf. None for me, thanks, I'm drivin'. IME those clearances on a stock cam are a good recipe for Valves FlambÃ© (recipe serves 12).

Author:	Mr. D-150 [ Mon Jan 02, 2006 11:57 am ]
Post subject:	Re: Fun with Valve Lash
Quote: Quote: With the long stroke/ small bore, I've found it helps a lot on a STOCK cam to go to 0.008" (IN) and 0.010" (EX) Urf. None for me, thanks, I'm drivin'. IME those clearances on a stock cam are a good recipe for Valves FlambÃ© (recipe serves 12). I'm sorry, but I did say I was using a stock lift cam and I failed to mention an uncut head, so, there was plenty of room. There were no problems or noises from those clearance settings at all, It just ran like a striped ape. Now the 0.006 and 0.008 settings didn't make any noise either, the engine just didn't run as well. Admittedly, it ran poor enough in the drive that I did not take it out on the road. As the old acronym goes, BTDT and the engine ran another 100,000 miles afterwards (350,000 miles on it at time of replacement with a "new low mileage", 120,000 mile, engine). Budd

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Author:	SlantSixDan [ Mon Jan 02, 2006 1:40 pm ]
Post subject:	Re: Fun with Valve Lash
Quote: I'm sorry, but I did say I was using a stock lift cam and I failed to mention an uncut head, so, there was plenty of room. Mmkay, if you say so. I don't feel like arguing.