Valve lash questions??

[dave blackburn]

Ok. So I have my engine out and decided to take one head off and check some things out. Everything looked great!
While the one head was off I checked valve lash on the opposite side. It was about .014". When I put the other head back on and the valve train back together it went back to around .006".
I adjusted all the valves to the .006" @ TDC, but noticed the valve lash will become larger (up to .009") when I check it at different spots through out the cam rotation.
It seems to be related to the load from the valve springs on the opposite side of the cam from where I am measuring.

Is this normal? Is this because of worn cam bearings? Something else?

Any thoughts would be great.

Thanks, Dave

[AaronM]

.006 is tight for the exaust valves, should be .008 at TDC IIRC. I'm pretty sure that the clearance changes with cam rotation, which is why it's important to adjust it at TDC.

Aaron

[dimmer]

I believe for the 1.8 it is .006 for both exhaust and intake valves. check out the tech articles on how you adjust your valves, it makes it very easy

[Dave at Pelican Parts]

Yes, 1.8s have the same clearance as 1.7s, according to the factory workshop manual. (Some 1.8 owners think differently, and use 0.008" for their exhausts. Right, Clay? )

I have observed the same effect with growing clearances at different cam rotation points. I have seen this on several different engines, and have not come up with all that satisfactory an explanation of why so far. This is the main reason I am reluctant to trust the "opposite valve rocking" method of valve adjustment, and prefer the TDC method.

--DD

[dave blackburn]

Thanks Guys.
I am trying to track down a loud tapping noise from my engine. A few people have this noise - Noisy after warmup

Any ideas???
I have never heard any other type 4 engine run except for mine so it might be normal. The engine runs flawlesly otherwise.
If I stand about 20-30' away from the car @ idle, the main noise I hear is a hard tapping or knocking.
If I stick my head in the engine compartment I can hear the noise from both sides (kinda like a knock or hard tap alternating left then right).
Any Ideas??
Thanks, Dave

[evill]

Well I don't know what it is either, but I have the same exact sound with the same exact conditions. I have 911 adjusters, web 73 cam and lifters with a web gear. It has about 2k miles on it, and it made that sound from day1. I have adjusted the valves at least a dozen times, they are always right on spec. I just tried setting them a little tighter, .005, as an experiment, and the noise have not changed at all. I have listened to the push rod tubes, valve vovers, heads and intake runners with a stethescope and cannot hear the tapping in these areas. It is most noticeable from the top of the engine, with the engine lid open, or when standing alongside the car.

There is no metal inthe oil or sump, it runs and idles very smoothly and screams to 6k rpm when asked to.

I'm calling the noise a "nature of the beast" type of thing, especially after seeing several other listers with the same sound.

Ed

[Dave at Pelican Parts]

Could it be piston slap?

--DD

[dave blackburn]

Dave,
I have thought about it being piston slap, but I don't think it would be that loud at idle. I had my engine apart within the last 100 miles and everything is good. The pistons and cylinders were right on spec.
The engine has only 80,000 original miles.
Thanks, Dave

[M. Hendrix]

I never came up with a solution either. My sound is similar, I still think it is something with the fan-part-contraption thing.




M

[Peter_Hinkle]

Originally posted by dave blackburn
Thanks Guys.
I am trying to track down a loud tapping noise from my engine. A few people have this noise - Noisy after warmup

Any ideas???
I have never heard any other type 4 engine run except for mine so it might be normal. The engine runs flawlesly otherwise.
If I stand about 20-30' away from the car @ idle, the main noise I hear is a hard tapping or knocking.
If I stick my head in the engine compartment I can hear the noise from both sides (kinda like a knock or hard tap alternating left then right).
Any Ideas??
Thanks, Dave

You don't have hyd lifters do ya? I had read an article awhile back about how type fours with hyd. lifters can sometimes get a dry lifter after sitting awhile and cause an awful noise for the first few minutes of run time. I have personally experienced this problem so i do know it exists. I really wish that someone on the list that knows more about this could/would discuss it in greater detail...peter

[dave blackburn]

Nope, no hyd lifters.
I replaced the rings within the last 100 miles and I am wondering if it could be the new rings hitting the ridge at the top of the piston travel from the old rings??