VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Valve Adjustment Before 1st Start Up

All the service manuals say to adjust the valves with the engine warmed up and running, but what about before the first start on a rebuild on 1947 216. Any procedure? It's my first time attempting a valve adjustment, from what I read it can take some experience to be able to get it down with the engine running, so I'm trying to crawl before I walk! Any tips!

No problem. Ignore the "recommendations" for a little bit.

Initially -- just adjust the valves as best you can WITH THE ENGINE COLD. Just turn it over enough to allow you to set each valve. After all, your objective is to START IT!!! ha ha..



Later, after you get it running and know that it will idle properly, you can let it warm up and THEN adjust the valves AGAIN to match the specs.

The book says to adjust when running,but for the inexperiencs I think it would be better for the final adjust to warm up to operating temp. for 15 minutes. then shut off and re-adjust.

I'm getting ready to do this same thing tomorrow (Sunday).

I installed the rocker arms today and added the pushrods.
Cleaned up the side rocker panel.

Tomorrow will "adjust" the values (cold) and then drain out the 11-year old gas. Hopefully trying to start it shortly afterwards.

Fleetboy:

I just went through this on my 48 216. I discovered some bent pushrods, and, some incorrect rocker arms - so I had to take apart the rocker arm assembly and fix things. Here's how I reset my valves,and, did my final adjustment. To set them cold, I removed the spark plugs, and, pulled the engine over with the fan to the #1 cylinder firing position. This allows you to set half the valves. I set them to 2 thousands over the top of the tolerance. Then I pulled the engine over to the #6 firing position, and set the other half the same way. Then, I put the plugs back in and started my engine. I then let her run for about 1/2 hour to thoroughly warm up, and, to make sure her valve gear and oiling system were working ok. There was no problem running her with the valve cover off - she didn't sling oil all over the place. Then I shut her down and pulled the plugs again. Then I pulled her over again with the fan to the number 1 and number 6 firing positions and set all the valves to the correct tolerance. I set mine to the high end of the tolerance because I run the car a fair amount on the interstate at high RPM, and, this lessens the chance of burning valves. Set up loose like this, she'll tap a bit at idle, but, mine runs great now. I came up with this procedure after doing some online research in the Chevy truck tech articles about valve adjustment on the 216. Worked for me - just have to be careful not to burn yourself working on a hot engine while doing the final adjustments. To find the #1 and #6 firing position, note the position of their respective plug wires on your distributor cap, and stick a piece of masking tape at those two positions on the distributor body. Then pull the distributor cap, and pull the engine over. When the rotor button starts to line up with your tape marker, look at the timing hole in the bell housing and you'll see the ball marker on the flywheel appear. Line it up with the timing marker, and, you're ready to set half the valves. Pull the engine over to aligh the rotor with the other piece of tape, and, the ball will appear again, and, you can set the rest of the valves. The truck tech articles will tell you in detail exactly which valves to set at each position.

Regards:
Oldengineer

Wow! Thanks for the great info, I really appreciate it. I'll try it out.

Bill, I'm not so sure just draining your gas is going to solve your tank issues...Up to the level where the old gas resides, the tank will be coated with varnish...Above that, condensation my have left you some brown "patina"...I'd Remove the tank to have a look/see...I've found acetone works good for rinsing off the old varnish. I put a quart in... slosh it around and drain it...Do it about three times...Works surprising well...Kevin

Of course, this means you'll have to remove the tank...!

I set mine cold to the high side of the factory specs then rechecked the lash when hot. Almost no difference.

I usually will set the valve .002 looser than the hot spec calls for. It will get you real close 99% of the time.

Hot and cold valve gap settings are nearly the same. Theoretically the increase in metal dimensions with heat should make the gaps decrease. For some reason, I can't explain, it does not seem to happen.

Chipper, I agree. Never seen meaningful differences between hot and cold settings and prefer to see them loose even with a little more ticky-ticky.
Dan

You got that right, Chipper & DFC...I do it "warmed-up", but heck...Rocket science this ain't...!

no, it isn't rocket science but there are good reasons to follow the manual and adjust the valve lash with the engine running and warmed up. first the method of setting the valves using #1 cylinder to set several of the valves then going to #6 cylinder does not allow you to set the other cylinders on TDC. The setting of valve lash with the engine running and at operating temp is not more accurate but faster and easier once you get the hang of it. You don't drive your old car with both feet up on the dash and the engine off do you?

Actually the most effective way to set the valves is to use a vacuum gauge. Set each to the max reading.

Kevin I love acetone and use it to wipe down everything before I paint it ,It's a great prep cleaner...BUT it dries so fast that I would not use it in a gas tank....It would just stick the flakes it just dissolved to the tank walls again, because you cant reach in there and wipe the residue off while its softened..That's my opinion and I'm sticking to it >>>>..ED

Ed I love acetone and use it to wipe down darn near everything I get my grubby hands on. Heck, I rub the paint on my car with...And it evaporates as quickly as I can rub it on...Keep it in volume, though, and it does not poise such evaporative qualities. Sure, it's going to go away...But not for a day or two...And there's No Scrubbing involved, It just melts the varnish away...I drained it in to a coffee can and it took until the next day to evaporate. There must have been 2 inch's of varnish in the bottom of that can. Friends would ask..."What's that...? And were astonished to hear it was gas tank varnish. Geez Ed, you have a reputation to uphold...Don't let this trip ya up>>>...Kevin

I'd like to try that...Tell us more...!

Put a vacuum gauge on the intake manifold. Run warm engine at slow idle and adjust each valve so vacuum begins to drop, back off until vacuum maximizes and then lock it down. It often takes a few adjustments to get the hang of this method. Works great and gives a nice running quiet engine.

Great...! I can easily find my vacuum gauge...My feeler gauge's, I have to look for them...Thanks, Chipper.

FB,
While the pistons are in proper order, adjust them loose by a couple thousands before start up. Then after warm up (180 degrees at least) and running at slow idle, readjust them to specs. Simple. And this way you can get oil all over the newly painted engine.

There is no need to make this any more difficult than the above. Sometimes I think we study something to death trying to figure out ways around simple, but entirely satisfactory solutions.
Charlie

BTW: Recommendation: If you want to keep your fan blades "true", don't use them to turn the engine. Not always, but sometimes, we may bend then slightly, especially when a tight rebuild in involved. At the harmonic balance use a pry-bar or something else instead of the fan. There's something very satisfying in seeing a fan running "true" in its rotation.

Thanks for all the input it's really helping me move things along