Watching Engine Master tonight and they had show on lash tuning engine. Long story short they found 14 lbs. tq

In 35 years working on racing engines I have two times where car picked up from valve lash change. One I know was procedure of adjustment The other was combination of adjustment and fuel. Maybe why my experience shows differently. Mostly blown engines and rarely one change when tuning for heads up and controlling power to track thru clutch at same time.

Wondering how many here have found gains from just lash changes?

If you are short on Duration and you close up your lash and find a gain. Then you may have to incorrect cam. We play with lash, timing and jetting quite a bit on the dyno an can find gains. The dyno teaches us, as the engine will tell you what it wants. You have to listen closely. LOL
I do remember looking at a cam card that said suggested lash.

I have been saying that for 30 years. Crew members use to joke when someone walked and observed me starring at engine in thought. Told them I was talking to engine. When asked if it talked back they said" It must because we normally pick up cpl hundreds next run out".

While I agree a gain is again no matter how small. Wondering if anyone found enough to see swing on time slit with just lash change. Agree you can see it on dyno but then 1 hp shows up on dyno and not on track. 15 hp now you might see on et.

Chris, On Rick Santos dyno we found a b u n c h doing timing and lash loops. Every change also changed the fuel curve. Rick, Jeff and Dave are a blast to work with. We have two more toys to play with now! Excited!!!

The answer is yes, absolutely gained at the track.

This message has been edited. Last edited by: BP758,

stk758BP!, I think many people run more timing than they need. Timing and fuel go together. If you are running too much timing then it will burn more fuel.
We are drag racers and tend to think if a little is good a lot will be great but that is not always true. So we throw more N02, Nitro, fuel and timing at it.

As for lash I have not seen much from it so I do not do much there. Fuel and timing is pretty big deal and I think many are leaving a little on the table there. The time spent on the dyno for me was worth every penny. While we do not race dynos we race at the track you can learn things on the dyno you would never learn at the track. Those things help you get most from your motor with a safer tune up and less chance of hurting motor.

Rick Santos is cool, talked to him several times when he was running the small block and kicking tail in top alcohol. Hope he is doing well.

quote:

Originally posted by Curly1:
stk758BP!, I think many people run more timing than they need. Timing and fuel go together. If you are running too much timing then it will burn more fuel.
We are drag racers and tend to think if a little is good a lot will be great but that is not always true. So we throw more N02, Nitro, fuel and timing at it.

As for lash I have not seen much from it so I do not do much there. Fuel and timing is pretty big deal and I think many are leaving a little on the table there. The time spent on the dyno for me was worth every penny. While we do not race dynos we race at the track you can learn things on the dyno you would never learn at the track. Those things help you get most from your motor with a safer tune up and less chance of hurting motor.

Rick Santos is cool, talked to him several times when he was running the small block and kicking tail in top alcohol. Hope he is doing well.

Santos Family is doing well.
On a 287/314/118.5 cam the first loop was 9 hp. I’m pretty sure after we were all said and done the average was 10. I’d have to back in my folders and look. We also did carbs and custom shear plates. That was a huge eye opener.

I have found measurable track advantage running lash loops. I consider it part of tuning the car. Is it going to find you a tenth? Likely not. But we don't spend the money we spend on these cars and engines to leave .03-.04 on the table. If the car picks up, sure it can mean that it needed more or less duration. Part of the tuning process.

Kind of what I was figuring for replies. Like I said about my experience being mostly heads up. Always to many variables and honestly normally to much time between runs. Some what like Bucky said you find small stuff which is what makes big stuff. When running blower deals and making clutch changes, probably jet changes even if just a nozzle or two. Its hard to say which change made difference or heck was track just little better.

I hope to get enough track time this year to get where car is dialed in well enough that I can make little changes like lash and see what I can find. I figure cam is too big too start with and I will find some et in loosing exhaust and intake. Yea right cam now would be better.Its bracket, its few HP yes,its also about 600 bucks for a lets see.

I do agree lot more in timing and fuel. Then I have never been one to leave fuel alone. I may not make total system change,but I am tweaking it some. Given a good test session where I can get 3 or 4 runs I might try a totally news system and if its screwup swap back. If it shows signs of working well then go from there.

Thanks guys.

I too have made big gains playing with lash, I decided one morning to try tightening up lash by a good amount, .010 just to see if it would have any change. It was back in super comp days, picked up 4 mph

quote:

Originally posted by Will Harrison:
I too have made big gains playing with lash, I decided one morning to try tightening up lash by a good amount, .010 just to see if it would have any change. It was back in super comp days, picked up 4 mph

4 MPH is pretty significant.

For decades I had great results adjusting the valves while the engine was still hot, (not running, just hot). BTW Bullet Cams recommended setting the lash while the engine was hot.

Some time ago I decided for the sake of convenience (and the sanity of my neighbors) to adjust them with the engine cool. The process I used (Exhaust opening / intake closing) was to adjust them hot, allow the engine to cool and discover the difference between hot and cold settings. In my case with the engine hot I set the intakes at .022 and the exhausts hot at .026. The cold settings were intakes at .018 and the exhausts at .021.

Last week I decided to go back to the original process and set them (at the track) while the engine was hot. I did them one side at a time. After completing the adjustments on one side I fired the engine to warm it up a second time. I then adjusted the opposite bank. To my surprise there was a significant lash difference, don't know why but the lash settings did vary, some were looser some were tighter. Incidentally these are T&D shaft rocker arms on a BBC and I use a LSM tool.

Once completed I re-started the engine and immediately noticed that the valve train sound was quieter and the engine ran smoother.

One last comment, if you are doing this with a 9 degree head get a drain pan ready, you are in for an overflow mess, the cylinder head drain back feature is not really great.

Bob

Bob,

If you think yours move between hot and cold you need to do a set with billet heads. .012 to .015 is about normal difference. I normally adjust mine cold same E/O I/C procedure, I do loosen all adjuster nuts since I do whole side and not cylinder by cylinder. If you find a you have nut have loose nuts, when you thought you where done your are not paying attention.LOL

I saw .1 in the 1/4 on a single kit 632. Cam was too big. The right cam picked up another couple hun.

I’ve tried tightening and loosening .005 a couple times with different cams and never saw a difference.

I tightened my lash and immediately won a round so I’m going with tighter lash from now on

Tightening your lash tells you that you may want to look into your cam choice. I am not advocating you leave it like that. Lash ramps and lash settings go hand in hand.