[68Resto-mod]

Hi gang, long time no post.

I had my motor re-built quite a few years ago (2012). It sat till I finished my resto in 2015. Strong running, no leaks, plugs burning clean. I have been getting considerable lifter tap from the left bank and was preparing to do a cold engine overlap adjustment using the standard “engine off” procedure. At 0 TDC, #1 rockers fully relaxed, I noted that I could compress the lifter by hand on #1 intake, #3 exhaust but #5 and #7 intake are fully pumped up.
Is this normal?

68 400, 30 over, Comp cam, stock rockers, forged pistons and rods, balanced, port matched....the works.
Motor not started in about two weeks
I cranked engine (plugs out) for about 10 seconds before pulling valve cover
Only 2600 miles on the motor

Let me know what you think.

Thanks

 

[PontiacJim]

Assuming you are using polylocks and not factory rocker arm nuts which are not used to adjust your lifters to zero-lash - they get torqued down only.

You can use the static (engine off) hydraulic lifter adjustment when you first install a new cam/lifters just to get the adjustments withing running specs. I would not adjust my lifters/valves if the engine was not running. They bleed down over time depending on the position of the cam, so some will be bled down while others will remain pumped up and not a good way to adjust the engine.

I feel that the final and most accurate method of adjusting hydraulic lifters is with the engine running. Get the engine up to operating temperature so all the parts are expanded to the dimension that they will be operating at. Adjusting the valves with the engine running is more accurate than when the engine is stone cold and you hope you don't over tighten something and cause damages. If you over tighten, you could bend a pushrod or a valve may hang slightly open and you'll be trying to figure out why your engine is running so poorly or acting up.

1. Let the engine tell you when there is excess lash by slowly backing the polylock nut off until you can hear it - Tick,Tick,Tick
2. Let the engine tell you when the lifter lash is zero as you slowly tighten the polylock nut - Ticking stops.
3. Wait about 10 seconds for the lifter to bleed down/normalize and listen. If no more ticking, then got to step 4. If ticking returns... slowly tighten up on zero lash again until the ticking stops. Repeat as needed and give it a few seconds to normalize each time until the ticking stops.
4. Once the ticking is completely gone, your lifter is at zero lash. I then tighten the polylock 1/4 turn more and lock the allen screw down. You are now good to go and you can button it up. :thumbsup:

This method will get messy. I use a clip which fits on the rocker arm (stock style) which covers the oil hole so the oil does not spurt all over the engine. Some use an old valve cover and cut open the top to expose the rocker arm nuts, but cover the rocker arm oil hole and keeps the oil from spilling onto your exhaust manifolds. This is probably the best way to go, but I like all the smoke coming off my exhaust manifolds which speeds me up in getting the job done as quickly as possible and praying the oil doesn't catch fire on the hot manifolds - which pumps up my old age adrenaline glands and excitement levels by a factor of five. :cheers

 

[68Resto-mod]

Hi Jim an Happy New Year!

I knew you would chime in eventually. The last time I adjusted the rocker lash (pre-load) was about a year ago. I started with the “cold engine off” procedure as described on the pontiacstreetperformance.com site. I then fired up the engine and the valve train noise was bad. I then proceeded to cut 8 holes in an old valve cover and adjusted with motor running.

After thinking about, I realized the empty lifters that I could compress by hand were the ones that were compressed and over time (2 weeks) has bled down. Nothing left but the lifter return spring pressure.
The really hard part with the engine running method is trying to isolate the ticking sound coming from the rocker you are adjusting from the other ticking lifters and general engine noise. I bought one of those mechanic’s stethoscopes but it was really no help.

I was hoping to isolate the poorly adjusted rocker(s) with the engine-off method first. But in the end, your suggestion to do the final adjustment with a hot running engine is always best.

I will be doing another hot-running adjustment today using your method but will take a bit more time to make sure I get it right. I will update with the result.

Thanks for your help
68 Resto-mod

 

[68Resto-mod]

Update:

Idles like a sowing machine. Took a 50 mile cruise. Ran great.
Thanks Jim

68 Resto-mod