i noticed on my last build that it was loosing a large amount of power possibly due to a tight valve lash. i ran 006 and 007 int and exh with stage1 cams and vtec did not pull at all. was the valve lash too tight for my application or should i have run it tighter/looser for more power

thanks

 

From what I understand (correct me if im wrong) running a tighter lash causes your cam lobes to be on the rocker arms for a little longer, so it kind of advances the timing a little bit to a certain degree. I'm pretty sure running a tigher lash is better than running the valve lash on the looser side. The lash you said you ran is also within honda specs so it should be fine.

 

ttt im looking for some experience on this. anybody have any personal experience on it

 

Running tighter valve lash wil only increase the lift of the cam. Has nothing to do with duration or timing.

I would think running the lash @ only .006 or .007 would help power slightly versus the typical .008.

If valve lash is too tight or your springs are close to coil bind as it is this could cause a valve to stick open too long and that can be detrimental to power becasue you lose charge before it is combusted.

 

u sure?

i believe the opening and closing of the valve is directly effected becasue of the rocker sitting closer to the cam which will make it open earlier and close later, right?

also there will be an increased amount of lift, but form what ive seen this isint always a GOOD thing. i need to know how people with more experience have found the #'s they use, and what would work out.
its a gsr motor with 13.3:1 comp

 

I have my valve lash set at .007"IN and .009EX and works out well.

I check the lash often to make sure it hasn't changed.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Big Teggie &raquo;</TD></TR><TR><TD CLASS="quote">I have my valve lash set at .007"IN and .009EX and works out well.

I check the lash often to make sure it hasn't changed.</TD></TR></TABLE>

That sounds a little on the loose side to me, but then i guess if it works and you haven't had problems its ok. The tighter the lash, the longer the lobe will be on the rocker arm, therefore the duration will be increased. I'm not talking huge amounts, but it will be increased slightly. I'm not sure how it will affect the lift.

 

A tighter valve lash is also going to create more drag and friction, so its not clear cut that tighter means more power.

 

It's probably best to stay within honda specs, unless the cams require otherwise.

 

I use .007intake and .009ex as well. THis is on a built all motor set up- since your looking for experience.

PM Rocket, he likes this lash as well and I know he has a reason for it.

 

Lash the valves tight = More top end
Lash the valves loose= More bottom end

Anywhere from .006 to .008 on the intakes and anywhere from .007 to .010 on the exhasts i use 6 and 8 with the engine absoutly COLD

Seth

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 550whp &raquo;</TD></TR><TR><TD CLASS="quote">Lash the valves tight = More top end
Lash the valves loose= More bottom end

Anywhere from .006 to .008 on the intakes and anywhere from .007 to .010 on the exhasts i use 6 and 8 with the engine absoutly COLD

Seth</TD></TR></TABLE>

not that cut and dry. Sure if you are ONLY looking at the effect on how much the valves are opened, that could be a result.. but there are other factors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StyleTEG &raquo;</TD></TR><TR><TD CLASS="quote">

not that cut and dry. Sure if you are ONLY looking at the effect on how much the valves are opened, that could be a result.. but there are other factors.</TD></TR></TABLE>

Ive always tried to keep them tight. It just seemed better to run them tight so that the valve opens quicker to allow more air faster. But like you said theres more factors here. What do you set your valve lash at???

 

I run crower cams, and they don't have a range. So I just set it to what they recommend.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asubennett &raquo;</TD></TR><TR><TD CLASS="quote">Running tighter valve lash wil only increase the lift of the cam. Has nothing to do with duration or timing.

I would think running the lash @ only .006 or .007 would help power slightly versus the typical .008.

If valve lash is too tight or your springs are close to coil bind as it is this could cause a valve to stick open too long and that can be detrimental to power becasue you lose charge before it is combusted.

</TD></TR></TABLE>

Hence, duration has been increased by a tighter lash.

 

Tightening valve lash does indeed increase duration somewhat. Here's the best way to think about it (on a B-series motor, that is). As the cam lobe comes closer to the follower, the distance from the cam lobe to the follower decreases until the cam lobe makes contact with the follower. The valve is then opened and closed. After the valve fully closes, the cam moves further from the follower until the part of the cam above the follower is simply the base circle of the cam. If you adjust the valves tighter, you basically move the rocker arm up closer to the cam. So the cam lobe will make contact with the follower SOONER and leave the follower LATER than it would if the valve was adjusted tighter.

On SOHC engines, the process is much the same. But in this case, the slack is probably taken up between the tappet and valve rather than between the cam and follower. Regardless, the idea is the same - tighter lash means slightly more duration.