Loosing lash on number 2...

I was doing between round maintenance on my BAE Fuel head hemi Saturday and noticed that number 2 intake had closed up. It seemed to be right at zero lash. I though hmmm, that aint good. So it re-lashed it and made another run. Back to zero lash. So I will be pulling the heads tonite. What am I looking for? What are the typical causes of this and what are the solutions? Is this a common thing?

Thanks.

-Brian

 

3 things
1 timing
2 valve stem pulling
3 look at the seat

but 1 would be the least of the problem here,,Dave

take a good look at the stem of the valve and retainer sounds like it is pulling out

 

anytime lash changes I always look at stem streach

 

your a lucky man to have that happen then run it again and still have a complete engine,
when we check our lash the bigger part of what were checking for is closing lash clearences,
its a sure sigh of problems and imminent falier,
id expect the valve is pulling through the lock so when the valve is closed the height of the retainer/lock/lash cap is increased by the amount the valve has pulled decreasing your clearences, use the best locks/retainers you can and check them carefully and regulary

 

loss of lash

Its either the valve is sucking in or the seat is sinking.Put a straightedge on the face it usually happens when the vales are cut to thin--thin margin

 

OK. I am still at work, but thought I'd add this. Remember this is a fuel-head deal. We had a little better air Saturday (8400' density), so I knew it would be running a little leaner, but the plugs still show about half the base ring being shiny new, and the other half being dull gray. I am certainly no expert, but I think that's OK. On the top end I was running 34 degrees. All the electrodes look fine, and are dull gray. I'm spinning my Mert 14 HH at 33%, and the recorder shows 25lbs boost. I don't think any of that would cause a problem, but correct me if I'm wrong. Also, this is just a play car, so I shift at 7000 and burn out at 6800.

Tonight I'll pull the heads and see what it shows me. I'll test the spring tomorrow, and check the installed height, when I originally installed it was around 400lbs on the seat. I'll check the retainer for fit, measure the stem, and put a straight edge across everything and then post the results.

Thanks for your help.

-Brian

 

if you do need valves give me a call before you buy..Dave

 

Check the overall length of the valve. On a fuel head, it's usually 5.015 or 5.020.

Old fuel valves will stretch on occasion.

If you need valves, I have them in stock in Inconel or titanium.

 

Good news. It looks like I'll get out of this with just a valve and a keeper. The keeper actually looks fine, but after what it's been through I'm gonna replace it. Retainer is fine.

The tip of the valve is bunged up pretty good. I tapped it with a hammer, and tried different angles with the compressor to no avail. I finally just had to put some pressure on the spring compressor to get it to pop loose. I still haven't found the other half of the keeper, but I can see the mark where it hit the wall on the other side of the shop. Probably should have thrown a rag over it. Lesson learned. I have to file the valve stem a little bit before it will come through he guide, then I will measure and all that. I don't know what may have caused it to do this, but it is obvious to me there was some play in there somewhere, and over time it just kept hammering itself into new and creative shapes. I'm gonna call an expert tomorrow and get some first-hand advice.

Thank you gentlemen, for your help. I will update this post as I move toward a solution just in case it may help somebody else later on.

Oh yeah, before I forget, there was plenty of margin on the valve, looks straight, and appears to sit the same as the others in the seat. I think the problem is all in the other end. (Knock on wood)

-Brian