Valve lash, With WEBCAM #494 Options

[jeffdon]

Ran the 2056 on the stand for a last time to get the oil warm, and do the initial change, and get her ready for installation. Did another valve check. Which got me to thinking.

I am setting it to the spec that came with the cam, .006 for both exhaust and intake. Lift (.465) and duration (280 deg.) are the same for both valves.

Question is, if exhaust valves expand more due to heat than intake, why does webcam recommend .006 for both? Why not .006 and .008 as is standard?

It SEEMS to be running pretty well, but I know i have a good deal of fooling around with jets and such once its on the road and i can test her under load. At one point at about 3500 rpm it started firing back through No 4., but that was right about the time i was running out of gas in my temp. tank. I shut it off, and got a big pop and some flame out the tail pipe.

I would really like address/double check anything now, as its way easier accesing things on the stands.

[Jake Raby]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

[jeffdon]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

I did a dry assembly and did a quick and dirty visual check of the adjuster/pushrod relation, and it looked pretty well aligned throughout its cycle. Then again, i only looked at one cylinder and just assumed that it would be the same for all others. Probably hosed myself on that one, but at this point, I dont think i want to pull her apart again.

[VaccaRabite]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

I did a dry assembly and did a quick and dirty visual check of the adjuster/pushrod relation, and it looked pretty well aligned throughout its cycle. Then again, i only looked at one cylinder and just assumed that it would be the same for all others. Probably hosed myself on that one, but at this point, I dont think i want to pull her apart again.

It could be the difference between a 5,000 mile engine and a 100,000 mile engine. It would take a weekend to make sure its right.

If you did not measure the valve lift, you are leaving power on the table, and might end up with a very difficult to tune motor that runs too hot. If you did not make sure that the valve stem and and valve foot were on the same plane at exactly 1/2 lift, you are going to have excessive wear to your valve guides and seats.

And it would only take a weekend to check it, if the engine is not in your car yet.

Even if you don't have a dial indicator, a 1 inch indicator with a vise-grip flex mount is only ~$30 from harbor freight.

Learn from my mistakes. I cut corners on the first motor that I built. I had to rebuild it 6 months later (with only about 10 miles on the motor). its better to only do it once and have it done right.

Once you get the procedure down for the first pushrod, making the next 7 is EASY! But the first one will take ~2 hours to make.

Zach