The Stovebolt Site Forums The Shop Area Engine Shop timing on my 350

I am having a problem with the timing on the engine in my '53. It’s a ’86 350. It runs good if I time it by ear. If I put the timing light on it, it is so far advanced the mark is out of sight. If I retard it to bring the mark back, it runs really bad. At first I thought it might be off a tooth on the distributor, but shouldn’t that adjust out when I turn it? The engine is a rebuilt/crate engine that I purchased from Advanced about 10 -15 years ago and has been sitting waiting for completion. Any thoughts???

I'd suggest an adjustable timing light. On my 350 I plug the vacuum advance, set the timing light on 35 degrees, rev to 1500-2000rpm, turn distributor to the TDC mark.

You can only trust the factory timing marks if you have verified that they are in the right place.
Lots of room for error here.
1) many times the rim of the dampener, which has the mark on it, has moved in relation to the hub because the rubber between the two is not bonded anymore.
2) several different timing covers have been used over the years with timing tabs/marks in different locations requiring the matching dampener.
3)you don't know how the builder selected these related parts.

The most accurate way to verify that the marks show top center is with a piston stop which you will have to fabricate and we can talk about that and the way to use it---but if you use care you can remove the plugs to allow easy rotation BY HAND and feel with a wire or small screwdriver for the end of piston travel through #1 OR #6 spark holes.this should be close enough to determine if the TC mark is close to right.
Also can pull a valve cover and watch #1 or #6 valve movement during overlap position, knowing that when inlet and exhaust are open equal amounts ( the exhaust is closing, the inlet is opening)this SHOULD BE TDC for that cylinder therefore the marks should be lined up.Observation of this overlap should show TDC within 4 or 5 degrees.
If the dampener rim has moved you could make your own mark but many times it is only a little way from flying off altogether many times leaving some things in the vicinity with some battle scars.

You can try to use a vacuum gauge, use manifod pressure,an outlet below the carb and turn it up till you reach max pressure and then back it off an inch of pressure and try it. This takes the marks out of play if something moved!

I believe enginenut has it right....it sounds as though the harmonic balancer has slipped !!!???

I believe engine nut is talking about a 6 and the question was about a 350.

He's correct either way. #1 and #6 are companion cylinders on either 6 or 8 cylinder engines. The timing tab can be at the 12:00 position on some 350's, and about 2:00 on others, so the damper and timing cover MUST match. Pull either valve cover, and bump the starter over until you see the first cylinder's valves on the driver's side or the 3rd. one back on the passenger's side move in opposite directions, exhaust closing and intake opening. The mark on the vibration damper should be in the TDC position, or very close to it when the valves are "rocking". If the line on the damper is anywhere other than 12:00 or 2:00, you've got a slipped damper ring. 2nd.-generation inline engines, 194, 230, 250 or 292 will work the same way with #1 or #6 rocking. The timing mark should line up with TDC on the timing cover. 216, 235, and 261 engines have the timing marks on the flywheel.
Jerry

I had the same problem on a crate 350. The damper I was for an 12:00 timing mark instead of 2:00. I set the timing mark at 12:00 TDC on #1cylinder on compression, then made a new mark on the damper that aligns with the marks at 2:00. This seems to work untill I get the correct damper and change it out.
Be careful moving the timing too far, mine kicked back and took several teeth off the flex plate. Many cuss words along wiith tranny removal I fixed
both problems.
The damper may have slipped , but yor ear is telling you that the marks are not aligned for the damper you have.
Good luck
Hank

Good point, Hank. If a little timing advance is good, a lot is definitely NOT better. On several dyno runs, I've observed that once the best power is reached by adjusting ignition timing, the power loss caused by one degree of over-advance is approximately equal to retarding the timing 5 degrees below the max-power point. Always err on the low side when making timing adjustments "by ear".
Jerry

Belated thanks on all the advice. Turns out it was a mismatched HB to the timing chain cover marks. I ordered the 2 different HB from advanced. Placed one on top of the other and aligned the key ways. Then put a piece of masking tape on the bottom one. Trimmed it at the timing mark and then using a square marked the tape where the other mark was and trimmed it there. Then I took the tape and aligned it with the mark on my HB and gave it a shot of black paint. Once dried I covered the black with tape and shot it with white so I had a distinct white/black line. Once the white was dried I used the line to time it to 6 deg advanced and it now can smoke the tires.