Yes, the hesitation is also a problem. With a too tight lash, the vacuum drops too much. That's bad specially now that I'm running a 1.12 Autolite 4100. The 1.08 was less sensitive to that. After running the engine about a year without touching the rockers, I did some adjusting today, and found 0,60mm as average. I didn't re-adjusted the rockers back to 0,55mm (0.021"), just adjusted the rockers that were looser than 0,60mm (0.023) back to 0.60, and I think I'm keeping it this way. There is no excessive noise, and the car runs great. 



Túlio Lazzaroni "FORD", Florianópolis SC Brasil.

'74 Ford Galaxie 500 292 V8

'82 Ford Galaxie Landau 302 V8

'98 Chevrolet S10 4.3 V6

'01 Ford Focus 1.8 Zetec

While I’ve run up to 0.025” lash on my E4 equipped 272, I seem to have settled in on 0.022” as a compromise between excessive noise and drivability.  Running the lash tight (0.017”) does make for a nice rumble out the pipes but it creates a hesitation at the carb that’s difficult to tune out otherwise.

Here the link to an older thread that goes over several different methods for setting the valve lash.
http://forums.y-blocksforever.com/Topic8614.aspx

Lorena, Texas (South of Waco)

When having worn rocker faces, a false clearance can be a result when using feller gauges.

 I turn the adjuster screws as to take any free play and then out a quarter of a turn.
This gives me .017" clearance every time, .012' of this is the cam lobe ramp and .005" is clearance.   

They still teach us to adjust valve lash with running engines at school, though not the later model cars such as Honda's
which are as of the last few years being left unattended to reduce customer service costs.

Overall, what would be the maximum lash without damaging the lifters/rockers? Don't care about the noise.
On my engine, with a Isky E-4, the idle gets really rough with less than 0,020", and gets nice with 0.021" (0.55mm). Also, the car "pulls" a lot better then. 

Túlio Lazzaroni "FORD", Florianópolis SC Brasil.

'74 Ford Galaxie 500 292 V8

'82 Ford Galaxie Landau 302 V8

'98 Chevrolet S10 4.3 V6

'01 Ford Focus 1.8 Zetec

My Dad used to do them with the engine running in our Lewis clinker speedboat


South Australia

When I was in high school 1965 always took my 57 two door post (312) to the local mechanic yup at the gas station. He set valves with the engine running, he moved very quickly, first finding the noisy lifters, then fine tuning. Gap gauge wrench and screw driver, he was extremely profficient and expensive, probably 3 or 4 bucks but remember that was a tank of gas, so iowa fords I know it was done.

Ted, Redding, CA

I don't think it's a bad idea.  It wears out feeler gauges much more quickly.  I adjusted mine that way when I had the friction adjuster screws in stock rocker arms.  I find it a little easier overall with the engine off.  Use a remote starter switch to turn the engine 90 degrees, follow the firing order and adjust the corresponding valves.



Lawrenceville, GA

Is it a Bad idea to adjust valve lash will engine is running?  I am asking because I have watched my Dad who is 82 do it that way all my life,  now I am thinking I could get better performance if I adjust the valves as described above. 

tom in iowa

54 Merc wagon

54 sunvalley

  The nice thing about solid lifter camshafts is the ability to actually vary the lash which can alter the way the engine runs.  As a general rule, tightening the lash increases the overlap cycle which in turn reduces the manifold vacuum.  Loosening the lash does the opposite in that the overlap period where both valves are open is reduced and in turn, manifold vacuum is increased.  Taken a step further, tightening the intake valve lash allows that valve to close later which is a result of increasing the workable duration on the camshaft.  This in turn lowers the cranking compression which ultimately results in a lower torque number being produced in the lower rpm band.  Loosening the lash does the exact opposite in that the cranking compression goes up which makes for increased torque in the lower rpm band.

What has to be remembered when dealing with camshaft overlap is that when both valves are open, then another cylinder where the piston is going down and is pulling in the intake charge can actually see all the way out to the exhaust on that cylinder that is in the overlap cycle.  That’s where the engine vacuum sees a decrease as this is simply a vacuum leak to the exhaust.  Maintaining a true 180° or dual plane intake design helps to minimize this but if there are any common open areas under the carburetor that will allow one side of the intake manifold to see the other side, then that overlap cycle becomes very important.  This is why open carb spacers tend to reduce the vacuum signal on true dual plane intakes versus the use of a four hole spacer being used instead.

Lorena, Texas (South of Waco)

I won't suggest that I'm in any way better qualified to talk about valve settings than Tim McMaster, but I'm surprised that he would recommend setting them at 0.015". I'll throw the following out there for discussion. When I acquired my 57 Ford & applied for Collector plates, it was required that the car initially pass a basic emissions test. (no I don't know what standard they use) Anyway, the car failed miserably. I had some tuneup done by an authorised shop, but they said it had "internal difficulties" & it failed again even worse. Anyway, to get to the point, with the help of some people on this site, I was refreshed on checking the valve clearances & decided to do that.  I discouvered that some valves were set to tight. Some were as much as about 6 thousands or so under spec. I went thru them twice & used 0.020" cold. The car seemed to idle better after, although when cold there was some that were a bit noisy. Anyway, I had it tested again..and it passed... Any thoughts?      


Paul