Oil weight question. I'm in the '500 mile break-in' phase of my bone stock 1965 Pontiac 326 engine. Im using Driven BR30 break-in oil for the 500 mile break-in. I have a hydraulic flat tappet cam which I did correctly break in, drained the oil & changed filter afterwards. When the engine is cold, and until warmup, the engine is nice and quiet, but I've noticed that when it's hot, theres a little bit of audible ticking from the rocker arms. Not audible in the car, but audible in the engine compartment. My question is could this be caused by the 30 weight here in warm California and if so, which weight is recommended to add after 500 miles? Thanks
On this 1965 Pontiac 326. There in no adjustment whatsoever. The nuts are not self locking. You just run all of the nuts down and torque to 20+ pounds.
Lifter pre-load is set by the machinist doing the valve job setting the installed ( stem) height correctly . unfortunately , most machinists who knew this have long since hung it up !
I have zero Pontiac experience but is it possible to swap adjustable rockers from a different year? For example, my 340 Duster had shaft rockers that were not adjustable but earlier 273's could be had with adjustable shaft rockers that I could have swapped on if deemed necessary.
If the valve sinks into the head (valve job), wouldn't that tighten the lash/preload not loosen it? An interesting read: https://pontiacstreetperformance.com/psp/rockers.html
There are several of ways to increase the lifter preload on a Pontiac. The easy way is to add a hardened machine washer under the nut but hardened washers with both faces machined flat and parallel can be hard to find. The second way is to order longer push rods. They used to be available with an extra .015" length but may not be available with out custom ordering now. The rocker or ball could also be worn out. You may just need a new one.
Unless the machine shop took a lot of material off the tips of the valve stems dressing them the preload should be should be more rather than less as the valves will be slightly deeper in the seats. The average automotive machine shop isn't going to be setting those heights on a regular valve job on a set of daily driver heads though.
Could it be rocker noise ,,,,,kind of like a ticking sound . Sometimes there will be slight noise from the rocker face and valve tips not being perfectly new and smooth . Just an idea . Tommy
30 is good for ~95°F max ambient. 40 is good for ~105°F max ambient. 50 is good for ~120°F max ambient. I run 40 weight in just about everything unless it is the cooler months and then I'll switch to 30 weight. 50 is too thick for anything outside of Arizona heat or race events. Ideally you would have an oil temp sensor and see what that shows. Use an oil appropriate for those temps.
No not with the the style rocker stud he has. You just tighten the rocker nut untill it hits the stop on the stud. I have put shims above the pivot ball or longer push rods if needed
I had assumed that there *wasn't enough lifter preload, hence the ticking, but it appears my assumption might be 180° off. I checked the preload and it appears that with my studs (which dont have adjustable nuts - just torque to 20#) that each nut seems to turn about 1 3/4 turns after zero lash. I've read that a half turn should be enough. Could this be the reason for the ticking?
This may sound stupid but I have encountered the same thing on my 40 coupe with a small block Chevy. I listened and listened and when cold the engine was quiet and as it reached operating temperature at highway speeds it began to tick. After much frustration with the noise I finally chased it down to a slight exhaust leak when the engine was at operating temp. Got out a wrench and went over the exhaust manifold and header connection and the tick seems to have went away.
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