The Stovebolt Site Forums The Shop Area Engine Shop adjusting timing - how?

hey everyone.
I'm getting ready to check the timing on my 48 3/4 tonne chevy tomorrow, but I have a problem - I dont know how.

I know how to check it, but I don't know how to adjust it if it is not correct. Is there a nut to turn until it all lines up? do I have to remove the timing cover (requiring the removal of the oil pan)?

Sorry for the dumb question, but I've never done this before.

One more question. What kind of spark plugs does this engine need, or prefer?

Thanks a lot folks

Tom

Not sure of your model, but typically the distributor has a screw on a collar around the shaft where it enters the block.

Loosening the screw a bit allows you to rotate the distributor. With the timing light, and the engine running, rotate until the timing is set. Turn off the engine, tighten the screw, and recheck the timing.

One hint, I use a pair of those black chemical gloves that go to the elbow when I time my engine. I got tired of getting zapped!

Ignition timing is checked by either using a strobe light that freezes the motion of the flywheel every time the #1 spark plug fires, or it's checked with the engine stopped by aligning the timing ball on the flywheel with the pointer, and turning the distributor housing until the ignition points break. You don't have to fool with the camshaft timing at all, that stays the same unless gear teeth wear or break.

On your 216 engine there's a hole in the flywheel housing above the starter that allows you to see the flywheel rotate. Connect a timing light to the #1 plug wire, and loosem tne distributor clamp screw enough to be able to turn the distributor. At idle, with the vacuum line disconnected, turn the distributor housing until the ball on the flywheel aligns with the stationary pointer. Tighten the clamp bolt, and you're done!
Jerry

Thanks jgalt_53-235 you've been a great help already!
my truck is a 1948 3/4 tonne 3600 thriftmaster.

I dont know if that changes anything.

to set the vacuum advance i just hook up a vacuum guage to the vacuum advance tube coming from the carb then adjust the set screw on the carb untill it has the most vac. possable right?

thanks a million

Tom

thanks hotrod lincoln

Do i need a strobe light specifically for a 6 volt system or will any of the ones at the auto store work?

Thanks again, and again!

tom

Vacuum advance can't really be adjusted unless of course you've got an adjustable vacuum advance canister. Sounds like your lookin' to set the mixture on your carb. A vacuum gauge definitely helps. You'll want to connect it to a full manifold vacuum port, preferably near the base of your carb. And yeah, shoot for the highest steady vacuum and then back screw in (lean) about an 1/8 to 1/4 turn. The idea is to get as lean a mixture as possible without affecting performance. And you'll want to do this with a warm engine and it's preferable to do this after setting your distributor timing. Also, leave your air cleaner on carb as you make your adjustments to mixture and idle.

You'll probably need to use a separate 12 volt battery to power the timing light. It's been so long since 6 volt systems were used, it's not likely any of the modern lights will work on 6 volts. No problem, just use a separate battery and connect the timing light power leads to it.
Jerry

alright, that shouldnt be a problem
thanks
Tom

Gecko, nice to see a fellow Canuck here, and so close.

1. make sure that before you set the timing that you also set the octane selector to "0" and retighten bolt, then loosen the screw clamp around the distributor. When done move the timing selector back to aprox 6 degrees or 3 marks and retighten.

2. If all's you got is a vac guage you can set the timing. First set the octane selector to "0", then loosen the screw clamp, disconnect the vac from the distributor, plug the carb vac port, then hook up a vac guage to the intake manifold, slowly turn the dist til the highest vac is achieved. Then shut her down and retighten the dist clamp. Reset the idle back and start it up. If it starts good hot you are ok. Finally reset the octane selector to about 3 clicks advanced. Take it out for a ride.

Question for Jerry...

On my bellhousing I have the usual hole with the pointer on the left side and on the right side of the bell housing at roughly the same place as the timng window I have a circular hole in the bell housing.......what is it for??????

I have been told that it maybe used to time the engine if I paint a white line on the flywheel and fabricate a pointer....BUT that it will be set for the firing sequence of a separet cylinder probably no 6....... is that possible???

Thanks for you help.....

Bob C.

...another Canuck living in Hammond, Ontario
..............just a glide East of Ottawa (50km)

The timing ball and pointer above the starter can be used for ignition timing using either #1 or #6 cylinder as the reference point. If you want to use the hole on the driver's side, you would have to pick another cylinder, I suppose, or make a different mark. If you align the ball and the pointer above the starter, then use a home-brewed pointer and a painted line, you could still use #1 as the trigger cylinder. It would just have two different places to check in that situation.

The reason either #1 or #6 work for timing, both pistons come to the top of their stroke at the same time. If you use #6 plug as the trigger, the ball just lines up 360 degrees (1 full turn) away from the #1 firing point.
Jerry

Thanks Jerry

Setting up the engine with no cab will be easy...I have not figured out how the h*** I will ever be able to see the starter side pointer once the cab and engine cover is installed......

....I will install a home made pointer bolted to the timing gear cover and hope to be able to use a white notch on the damper with a timing light.

...or maybe a home made periscope !!!!!!

Thanks again for your advice.

Bob C.

Just a suggestion- - - -
While you've got the pointer and ball aligned, go down to the oil pan rail or timing cover, and fabricate a pointer you can see from underneath, maybe from a creeper. Then paint or scribe a line onto the crankshaft pulley in line with the pointer, and you're in business!
Jerry