Chro-Mo pushrods and setting zero gap...

[falcor]

How easily should I be able to spin the pushrod? I put #1 cyl to tdc and the exhaust valve spins easily while the intake valve requires a bit more force for me to spin it about 45 degrees or so....

Is it right to assume that its bettee to be on the loose side rather than the tight side?

[sideshow]

I have all ways done that as loose zero, full rotation.
Are these "new" parts and have not settled/bedded to each other yet?

[falcor]

The engine has been run in for 20 minutes but thats it. I want to set the gaps before installing it into the car for the first time...

[Type 4 Unleashed]

They need to spin freely, and then rock the rockers by hand if you don't hear anything then your good to go.

But they will need to be checked after you run it for a bit, to make sure they don't tighten up.

[falcor]

Thank you Richard!

[Clatter]

After you run it a bit,
Your 'a bit hard to spin with oily hands' works well for intakes,
And free spinning for exhausts..
At least that's what I do.. FWIW.

If running swivel feet, it's easier to spin the foot, BTW.

If you are really nuts for these things,
Check them when hot - Make sure none are tight when hot hot..

[Type 4 Unleashed]

Just for everyone's info, I've ran the valves hot a several times on different motors to verify my findings, after setting them to 0 lash, and they all checked out @ .006"-.1524mm hot. I just needed to know...

[wreck]

Richard have you ever done the same experiment with alloy push rods . I friend builds Formula Vee engines (1600 T1)
and sets his engines with 0 lash with alloy pushrods(well after run in) , his theory is everything expands together and he gets maximum valve lift . It goes against everything I've read and can't check myself because all my engines have hydraulics . his cars are front runners and hold state championships .
My next build will have solid lifters and alloy pushrods so I'll experiment then .

[Piledriver]

FV is limited to a stock or spec cam (which is carefully verified) so that .006" lift may be a big deal in racing FVs...

What you can get away with on a race car and on a daily driver are completely different things...
On a daily, zero lash with aluminum pushrods is an open invitation to burn a valve.

CrMo pushrods are a "safety" against burnt valves as the lash increases rather than decreases as the engine gets hot or overheated.

[wreck]

Hi Pile , yes on a Vee every bit of lift is wanted , I just don't like the valve train noise from Crmo pushrods
and John's engines are always quiet . He did run a bug with a T1 on the street for 500,000km with very little lash , (just making sure you can feel a little lash when spinning the pushrods .)
So just wondering if anyone had first hand experience whether lash stays constant or closes up with Alloy pushrods like most people advise .

[Piledriver]

The exhaust valves stretch over time, and stock valve adjuster tips sometimes wear badly, esp with low zddp oil, but sometimes they are just garbage, they and the valve tips they rub on are most of the valvetrain wear in most situations.
Re-radiused OG is usually fine, new ones seem made from bubblegum.

Stock setup with alloy pushrods goes towards zero lash as it heats up, which means it runs nice and quiet as it burns your valves.

I check mine per the manual every 12K miles, when I change my oil and filter.
Haven't needed to actually adjust them in a couple years. (80-100 miles a day, real 911 adjusters, proper oil)
I can't really hear my valves over my muffler.

EDIT: . Forgot to detail the setup.
I'm running CrMo pushrods and dual springs, solid aluminum spacer kit and 911 adjuster screws.

[Type 4 Unleashed]

Yes, I've checked the lash hot with factory aluminum pushrods, and yes the lash stays the same. Aftermarket aluminum push rods I've never ran. After some one told me they had a backfire thru their carbs and it bent one of their aftermarket aluminum pushrods rods, I think I will stay with the Chromoly ones. On mild performance builds I will use the factory aluminum push rods.

And I use aluminum rocker spacers and 911 adjusters which help quiet the rockers, for some reason the steel rocker spacers seem to make more noise.

[dragvw2180]

On my street car I have been running double taper CM push rods set to a loose zero. I am also running Berg 1.4 rockers and really do not hear excessive valve train noise. My valve adjustment stays pretty consistent but when I do run it hard I will check the lash. Myself I really have not had problems with valve stretch on stainless valves but if I did over rev the valve train I have seen the seats get beaten into the heads ( it will show up as metal coming out between valve seat and head ) and cause the lash to tighten up. When I build a new engine I give the lash a couple thousandths lash and fire it up , after I break in the cam I will shut it down for the day. Next morning I will change the oil , check inside the filter for metal or trash , if everything looks good I will reset the valve lash back to my loose zero . This is the same procedure I used when I raced this engine . Mike McCarthy

[raygreenwood]

I have extensively checked the factory alloy pushrods on my engines hot....as compared to cold.

Because D-jet is overly sensitive when tightly tuned (read that as leaner than stock factory settings in the midrange).....I first set them up to factory. 006" cold. Then drive them for at least 20-30 minutes at highway speed. Then shut down....leave valve covers on and turn engine around to marks I have pre-marked on the fan to get valves into position to check on #1. They need to sit for five minutes to soak up heat. They actually get a little hotter in this period but then work fast.

I use two sets of starrett feeler gauges. I have mic'd both sets to make sure they are equal to each other. I use two feelers of each thickness so that I can cool the one I just used on a damp rag. You only have a second of two to check ad they heat up fast.

What I find with stock aluminum type 4 PRs and 911 adjusters (just for reference)....is that with the stock aluminum PRs...valve gaps consistently close up by about .002" to .0025". So they read .004" to .0035"

On the hottest days in Texas and Oklahoma summer weather when head and oil temps are at their highest...I have seen the occasional. 003" and on one engine I had a valve or two that closed to .0025".
I have also found that after setting cold to .006".....checking hot....multiple times.....that the few valves that consistently had a larger gap....example six of eight valves would run .004" and one or two would run .005".....so adjusting those two to .004"......they would stay that way...and would in fact read .005" when checked cold.

Later on...years later ....when building other engines....I checked several whole valve sets by heating them up in an oven and checking them quick on a micrometer....cooling off between readings and rechecking the mic to a standard......and found that some calves themselves had expansion variability by as much as .002".
This is to be expected in two piece valves. One piece valves do not seem to exhibit the variation.

When setting the valves hot so they are equal in lash and stay that way....with D-jet....makes a subtle difference in idle.
Ray

[wreck]

Thanks for the info on the alloy's ,I'll be running hd ones from ACnet . with genuine 911 adjusters . I service every 5000km so will start at .006 and experiment from there .