Mark may scold me but .001 isn't going to make that much difference. Pull a valve cover and check the lash COLD. I bet it still had a little temp in it.

 

I bet it still had a little temp in it.

X2 :yes:

 

I do not have the answer but I have a question or two?

If it calls for 20 and you set it at 11 or 12 cold would that not be 10 or 11 hot .
If so that means you are half of what the setting should be.
So what are the benifits of doing this??

Still learning so I am asking from a leaning point.

 

With aluminum heads the lash generally opens up around .006 when hot.

 

Sinister, not trying to steal your post,but I have a dumb question about lash, if clearances only grow a few thou than why do we need to run more than that? I ask because my new roller calls for 26thou and sounds like a thrashing machine. Do solid rollers really need that much lash?
Thanks Brian

 

Dude, don't worry about it. Mike Lewis/Chris Straub or a few others will answer that for you. All I know is I remember them saying you could play with the lash for performance. I may get this wrong so take it with a grain of salt. If I remember correctly it was mentioned if you tightened the lash a little you could move your power band towards the higher rpms. If you loosened it you could bring it down so you would get more tq. I already blow my tires off so I chose to slightly tighten mine so they would be .018 hot. I am not really sure if it is any quieter or not. I think it sounds like it is but for some reason I remember UDHarold mentioning that it wouldn't make the valve train any quieter.

A solid roller is a whole lot more noisy than a solid flat tappet. I will tell you that. Its just valve train noisy. As long as it isn't ticking, I wouldn't worry. Loud is just part of it.

My .02 cents but again, I too am only repeating what I have searched and heard on here.

 

Read this.

http://www.harveycrane.com/lashloop.htm

 

Garrett, that is great. I am bookmarking it! Thanks for posting it. Answers a lot of questions and seems simple enough.

 

1. Set the lash COLD at the specs furnished with the cam. Test and record ALL the number

If I am reading this correctly. He recommends do the following. Please clarify if I am wrong. My card calls for .020 for both. According to the above statement, he actually says to set it at .020 cold and therefore it would actually be .026 hot. Is this correct?

If this is the case then I am pretty tight right now.

 

I didnt read the article but if you are setting the lash cold, you better have checked it HOT and then entirely cold to get the delta for your engine. Dont assume its six thou. I'll check it hot, leave the cover loose and come back and check it dead cold on the same valve next day to see what the delta ( change ) is.

 

I have that part. I have set cold, checked hot, and then rechecked cold. I only did it once but I checked all the valves and they were anywhere from .006-.007 difference. I'm not sweating it. I don't have an exact "feel" with the guages after one time so I think I am good.

I am wanting to clarify the article. Thanks though.

 

Del have you thought about asking your engine builder? You don't say whether your cam card says .20 cold or hot? JMO but set it to spec (the way it was built) and leave it alone, you're not going to pick up any performance moving the lash a couple of thousands up or down, you still don't know what your performance is yet. Playing with lash is a very fine adjustment tool, you're not close to that point with this motor and car setup.

Master the 817+ hp you have and then if you think you need more look at it then....

 

The card doesn't say cold or hot. Mark set the lash based off the card.

 

We adjusted the valve lash on my 496 several times on the dyno. After we had the timing set for most power then we tightened the intakes down 0.005" at a time (from 0.025" to 0.010) making a pull at each adjustment til we found what adjustment made the best power (0.015"), then did the same for the exhausts (also bested at 0.015"). It made for a long afternoon and alot of dyno pulls but we picked up nearly 16hp tightening the lash up from the cam card spec of 0.025" to 0.015".

Bowedup

 

817 hp is alot dyno hp is not what always gives best ET. Your playing with lash do you suspect cam is to big ?

 

Del,
You might even talk to Mark about softening it a little. Not just try to move the power up, but soften it so it will hook. Hell, unhook the secondary's once and see what it does. You'll get your 5's by leaving hard. That's what my car does. My mph is low for the et and I know my hp is lower than it looks. It just leaves hard.
There's nothing better than dead hooking especially in the 1/8. If it spins right at the hit, it's not going to lift the front end and transfer weight and it'll never hook.
More JMO... Dal

 

Another thought Del, and I'm not being sarcastic or a smart as-. This might be a way to sneak up on it. Start at 2/3 wide open..
Moroso 65042 - Moroso Positive Throttle Stop

 

I know your not. but I could just adjust my throttle cable so it doesn't fully engage. Couldn't I?

Tried starting the car today. Started up but still felt very tight and not responsive. Let it warm up and got better but I didn't like it. Going to set the valve lash back to what it was in the morning. It definitely should be "cold" by then. :yes:

 

Del, if the cam card says .020. That's probably hot. I'd get it warmed up and set them at .020 hot. See where they are after sitting 12 hours. Then see how it runs. Most cam cards are hot lash. Not saying all, but you might be getting too tight for the profile when it's cold. Did Chris do the cam? Call him.

The throttle stop is a more solid way to set the throttle. I'm thinking about getting one just so I'm not pulling on the butterfly shafts so hard when it's wide open. Your foot and leg can put a lot of pressure on everything. And I know I probably bend the floorboard when I'm wide open....

Bottom line here Del is that you have a super fast car and it's going to take time to get it under control. I think going slower first will end up faster down the road. But I'm old and :wacko:

 

No your not old....but you are funny. I am just going to set it back at .020 hot like it was. I will set it .014 cold like I did last time, warm it up and check a valve, then wait until the next day and check the same valve and see if it is .014 cold again.

Thanks for the input though. I will get it. I'm not going to do anything stupid with it. I definitely think it is a little tight right now.

 

set it .014 cold like I did last time, warm it up and check a valve, then wait until the next day and check the same valve and see if it is .014 cold again.

Delbert,

Playing with lash is either adding or removing duration. More lash, make the cam smaller. Less lash, making it bigger.

If you pick up mph from -
Tightening lash - current cam is too big
Loosening lash - current cam is too small

You always need to check with the cam maker, to see how much lash you can lose, or tighten up. The lash ramp dictates that.

And yes, tightening up lash will make it quieter, if your cam's lash ramp will allow it.

 

Davey and Dal have it well covered here. Go back to base settings. Concentrate on the details. You'll get there. One small change at a time. I started @ 10.50's and chased a 9sec pass for 2 seasons. It will come together. Get the lash set and then just check it periodically, it shouldn't be changing unless something is wearing.
You don't have enough consistant baselines to even see the effect of valve lash tuning right now.
Hang in there :beers:

 

Thanks for the replies. Got up early, early this morning before the heat. Engine had ran in almost 36 hrs so I know it was cold. I went through the entire valve train and reset lash intake .014 and .016 exhaust. I warmed it up, checked lash hot....and that is the last time I do that. Burnt the sh!t out of my hands. I only checked one intake and one exhaust. Intake was .020 and exhaust was .021. Close enough. Took it out and after about 10 minutes of driving around, I romped on it from a dead stop. The bog is gone, no hesitation an feels normal again. Must of had it too tight.

Parked it and in the morning I am going to check those same two valves and see where they are cold. I assume I won't need to touch these for the rest of the season....correct?