how often should you be adjusting valve lash?

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how often should you be adjusting valve lash?

Post  racinghabbit on May 30th 2012, 10:36 pm

how often should you be adjusting valve lash?

if you make 4 runs on a motor of 200 ft at wide open .... at each show how often do you need to adjust the valve lash???
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Re: how often should you be adjusting valve lash?

Post  cool40 on May 30th 2012, 10:38 pm

i check mine often but dont adjust it much. Very Happy
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Re: how often should you be adjusting valve lash?

Post  Race Ready Fabrications on May 30th 2012, 10:57 pm

On my new motor I check after every race. Anywhere from 3-10 1/8th mile passes. Better safe than sorry.....
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Re: how often should you be adjusting valve lash?

Post  dfree383 on May 30th 2012, 11:01 pm

Like said above check it often, hope to not adjust ever.

It's a good idea to keep ay eye on everything often it can save a motor.

You notice something loosening up, it could indicate problems.
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Re: how often should you be adjusting valve lash?

Post  69F100 on May 30th 2012, 11:19 pm

I check mine everytime I get ready to go to the track like was said I check mine but have not had to adjust them any so far.It ezs my mine plus it gives me a chance to check under the covers to make sure rocker arms are not wearing on the tips are anything.I never pull the valve covers at the track or had a reason to so far
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Re: how often should you be adjusting valve lash?

Post  LETHAL_DOSE on May 31st 2012, 11:11 am

One of my pet peeves is for a racer to bring his cylinder heads in here that are all beat up and hurt,,,,,,,,because he was too lazy to perform preventive maintence.

Now then, broken valve springs are not that uncommon. It happens all the time. But when you break one, you should catch it, by that I mean you should realize that you have broken one. Own a valve spring tester and USE IT every weekend! The silliest excuse I have ever heard is that it is too much trouble to remove the stud girdle. Don't be so damn lazy! On C-460 heads you don't use a stud girdle because they are shaft mounted rockers. So to use your valve spring tester, all you have to do is remove the valve covers, but some guys act like even that is too much trouble.

I have seen heads come in here with two valve springs broken on the same head, and not only that, but they ran long enough to be broken in two different places, meaning both at the top and at the bottom. It gets worse! Futhermore they were run long enough to totally chew up the top edge of the spring seat cups and break off all that metal from around the perimeter! Where do you think it goes???

Another sign of going too long without a valve job is when you start sinking the edge of the titanium valves and the seat surface becomes cupped instead of flat. Once this starts happening the titanium valve starts wearing out quicker than a normal wear pace. The tool that you should be using is a feeler gauge. Constantly check your valve lash and when it starts closing up a bunch, that is a pretty good indicator that you are sinking the valve.

Steep seat angles such as 50, 52, and 55° are used by a lot of cylinder head gurus in order to increase the flow numbers at high lift and be able to win the bragging rights about how much their heads flow. However, they do NOT wear as long as a conventional 45° seat! If you are going to run steep seat angles, then have a full time crew chief and/or mechanic/engine builder that will tear the engine down very often. If you want to run a full season and make 300 passes a year, you better be running a 45° seat!

Spark plugs. They are the eyes that let you see straight into the heart of your engine!!! Learn how to read your spark plugs, they have a story to tell. In general, the better that you get you air/fuel atomized, or broken up into finer droplets and a more homogenous mixture in the chamber/cylinder, then the less jet you should have to run, and you should be able to pull timing out of it and make more power.

I can tell when a guy is running too much timing by the amount of detonation I see in the chamber. If the chamber has little pinholes that look like porosity holes, thats a sign of detonation. On the alum. heads with two valve seats, there are two areas where the alum. in the chamber comes to a point. When this point or tit of alum. starts to erode, that's a sign of detonation. (As a note of explaination, the current Roush heads have a one piece figure 8 seat. I'm sure that the other top NASCAR teams have one piece seats also).

Alcohol guys pay attention. After every race, R&R the spark plugs and spray light oil into the cylinders! Then reinstall a set of warm-up plugs. Gasoline guys don't have to do this after every race, but you should do it if the engine is not going to be run for 2/3 weeks or more. Likewise you should do it if you are close to the seaboard and have saltwater air or in high humidity situations. The bottom line is, you would be surprised at how bad and rusty the rings get. The second ring even more than the top ring. You can't have good ring seal, if the rings have to spend a 5 minute "warm-up" just scraping rust off of the cylinder walls.

One of the most important tools you can have in your toolbox is a leakdown tester. Use it! Use it while the engine is still warm. Record the data in a log book and continue to use it. If and when the recorded data ever starts changing, that will be a clue, that "Houston, we have a problem"! A leakdown tester also helps pinpoint the problem.
1. Air out the exhaust header indicates a warped or bent exhaust valve.
2. Air out the manifold/carb indicates a warped or bent intake valve.
3. Air through the radiator cap indicates a blown head gasket.
4. Air into the oil pan/crankcase indicates poor ring seal.

Oil filter cutter. Own one and use it whenever you change filters. Cut the old filter open and look at it. Run a magnet through it. Some particles may be magnetic and some may not, such as bronze or babbit. These engines will tell us something, we just have to learn how to read the tea leaves.

On the 850 Hp racing engines and higher, let's plan on replacing parts as often as needed. Develop a good preventive maintence program. You guys that were mechanics in the military know what I'm talking about. Check things often and replace them before they break. It's always more costly after they break. On the bigger Hp engines, valve springs and roller lifters are consumable replacement items, the same as spark plugs. Plan on replacing them at the end of each season, when you do that freshen-up over the winter.

I have leased engines in the past, and the tools that I furnish with a lease engine, if they don't already have them are;

1. Valve spring tester
2. "On engine" valve spring compressor
3. Leakdown tester
4. Feeler gauge/lash adjuster
5. oil filter cutter.

I feel that every serious racer should have at least these five tools with him at all times and he should use them often, in the name of preventive maintence.

Hope this helps,
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Here is a what Charlie posted about maintenance. I normally pull the valve covers after each night of pulling. It is a good practice to get into. You can tell alot about what is going on by taking a peek under the valve covers.

Mike
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Re: how often should you be adjusting valve lash?

Post  racinghabbit on May 31st 2012, 1:10 pm

that helps.

my only question is how does a 200ft pass in the mud compare to an 1/4 mile pass or a truck pull down the track???

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Re: how often should you be adjusting valve lash?

Post  kjett on May 31st 2012, 1:29 pm

racinghabbit wrote:that helps.

my only question is how does a 200ft pass in the mud compare to an 1/4 mile pass or a truck pull down the track???


It's at lot shorter diatance Very Happy


Seriously though, I check mine after every race event. I usually make 3-4 200' passes per event. It's a peace of mind thing that I am prepared to do to keep my motor together and running right.
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Re: how often should you be adjusting valve lash?

Post  LETHAL_DOSE on May 31st 2012, 1:35 pm

Don't know exactly, but we normally come to the line, wait for a green flag. When the green flag appears we start bringing the engine up on RPM's to about 6-6500 rpm & slide the clutch out. As the clutch comes up, the throttle goes down, and we are normally at full throttle by the time the clutch is released and the rpm goes to about 85-8700, and stays there until the end of the run. Then it normally pulls down some to around 78-8200(depends on track sometimes it never pulls down) and spins out. From coming off the line to spin out normally takes 12-17 seconds depending on track, sled, how far and fast they let us run. Normal track length is 300', but have went as far as 370'. Changing are set-up a little this year. Going from Alky carbs to fuel injection. I put on a enderle bird, with both nozzles in the intake runners and down nozzles directly in the head. First pull is coming up June 9th, be interesting to see if there are any differences.

Mike
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Re: how often should you be adjusting valve lash?

Post  racinghabbit on May 31st 2012, 5:41 pm

my motor will never go over 6500 rpm.
and my passes are off of idle and last about 4 to 8 sec. usually make 2 at a show.. at most 4.
Fyi i'm running iron heads with ford racing valves.
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Re: how often should you be adjusting valve lash?

Post  LETHAL_DOSE on June 1st 2012, 10:38 am

Even back in the day before I built this engine and turned it as hard as I do, I got in the practice of checking things over under the valve covers. It doesn't take much time to do, and you can find/fix a problem before a catastrophe. I have found broken valve springs, I found one of the valve locks that started to shear the square groove off (about half gone), bad rockers, etc. I also look at the oil that lays up in the heads between the springs and in the corners. I normally run my finger through it to make sure that there is not any debris in it. To me it did not matter whether I was running a mild engine or a radical one, you can save a lot of headaches by peeking under the valve covers on a regular basis. Even if we pull 2 days in a row, the valve covers come off before pulling the 2nd night. I also run cleanable filters on the oil and fuel system. Anything you can do to keep an eye on what is going on inside you engine is a plus.
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Re: how often should you be adjusting valve lash?

Post  Barney on June 1st 2012, 11:14 am

As with many I check my valves every race. I rarely have to reset them, but always check them.
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