re-torque & valve adjustment

So I've got 17hrs on my freshly rebuilt 158 3 cyl gas 1968 3400.

Should I pull the valve cover and retorque the head and re-adjust the valves? Is there a prescribed time to do this after break-in?

Shop Manual states "see operators manual" which says 150hr oil change, and 600 valve clearance check.

As this is a fresh motor (pistons/rings/valves/bearings/) I would think a more frequent oil/filter change (did it at 1/2 hr after initial break-in) and a re-torque/clearance wouldn't be inappropriate at this time.

Opinions/suggestions?

You must run the engine at least long enough to thoroughly Saturate the entire engine and all it's parts at FULL Operating temperature..

This settles the parts in place and sets the Head Gasket, etc reach full compressed dimensions..

At that time and while the engine is still at full operating temp, remove the valve cover and Rockers ( if necessary) and Re-Torque in the Manufacturer's detailed Order.
After Re-Torquing, re-assemble the valve parts ( if removed) and Set the Valve Clearances while the engine is STII HOT...

This is usually done after a few full "Heat-Cycles" which could be several operation..

It is actually a good idea to NOT put the engine under a FULL Load until after the final Re-Torque, to avoid the risk of causing a Head Gasket Leak..

I prefer to use Lubricated Threads and a "Running (Moving)" Torque reading...I mean, the reading is reached as the Head-Bolt Nut is in motion..

The Torque reading on the Torque wrench is meant to be a measure of the Stretch of each Head Bolt.

Dry threads and not obtaining a "Moving Torque Reading" will give a false indication..

Thanks Papa, I'd never heard of doing a hot retorque. I knew these motors did spec a hot valve lash.

I find it funny that when the factory built these engines they recommended readjusting the valves every 600 hours but made no mention of ever retorquing the head.
When one rebuilds one of these engines people are telling them to retorque the head and adjust the valves after a couple of heat cycles and before they load it.
Dealers would rebuild a engine and give it thirty minutes at high idle then hook the tractor to a dyno and start loading it, 1/2 load, 3/4 load, full load with cool downs and checks for leaks or other issues between loads with all this being done in a few hours time, after the last cool down if all looked good they let the customer have their tractor back telling them to follow the maintenance schedule in the owners manual.

I've rebuilt dozens of tractor engines and have never retorqued the head, I did have a head gasket failure on a IH engine I rebuilt a couple years ago, farther checking showed my torque wrench needed recaliberating as it was off about 20 lbs, I pulled the engine back off and rechecked all torques with another wrench. When I got it back together the customer asked what he owed, I told him I didn't charge for my mistakes, now when they have equipment problems they call me first.

I like to do first oil change after 50 hrs then every 200 hrs.

(quoted from post at 09:42:36 11/09/16) Thanks Papa, I'd never heard of doing a hot retorque. I knew these motors did spec a hot valve lash.

Click to expand...

If you set the lash on the max clearance .019 E - .016 I cold , 99% of the time they will be with in the min spec .017 E - .014 I when checked hot.
If you want to play safe set them at .020 E - .017 I cold and you wont have any valve problems.

I am not a professional mechanic and haven't rebuilt a lot of engines. One of the things that soured me on this subject was a 1964 Rambler
American that I purchased new with the old 6 cylinder, 3 main bearing designed engine (1965 being the year they introduced the new 7 main
bearing engine).

I don't remember the time line, but not too long after purchasing I had to take it back to the dealer (warranty requirement), we're talking about a
brand new, squeaky clean, shiny, freshly painted new car, FOR A VALVE AND HEAD TORQUE ADJUSTMENT!!!!!!

What I said about that, after having it done in not printable on this site.

As a result, none of the engines I rebuilt after purchasing in their worn out state, were touched after I built them up and got them painted nice
and pretty. Only have one in the corral at this time, my 3000 Diesel upon which I did an inframe OH some 15-20 years ago. Hasn't had a
wrench on it. Earlier Fords I did are not here any longer so I don't know their current condition , but on my watch there was no follow up. One
thing that may have helped was my insistence on using a coating on the head gaskets and I always used K&W Copper Coat head gasket sealer
on both sides of the head gasket......yeah I know the manual says install it dry and the same manual tells you to come back and fool with it.

Thanks for the reply. All the motorcycle and automotive engines I've done I have never retorqued. My 9N though was starting to run warm and make strange gurgling sounds. Re-torque showed several center studs had lost their clamping force and needed a full turn or two to bring iit back to spec. That was with CopperCoat sprayed on both sides of the metal gasket.

If every valve train component is placed back in their original position, the first valve lash adjustment should be okay until the next interval. I never trust the initial valve adjustment though, and recheck them after running them anywhere from 5 to 30 minutes, just in case some grit got in between mating surfaces.

If valve train components were NOT put back in their original locations or if some where replaced, or the head was redone, it's possible that there are high spots that will break in sooner than what is afforded in normal intervals, so I often recheck valve lash sooner than recommended.

Although I usually re-torque a head after the first warm up and cool down, I never retorque them after that. I think those retorque recommendations were due to the lower quality of head gasket materials made back in those days.

Thanks for the input Montana. I decided to wait for the recc service interval.