Timing issue
#1
Timing issue
More problems. Was running well then just quit. Any attempt to restart and it acted like it was out of time. With cap off, I'll set engine to TDC, the rotor to #1, rotate the engine one turn back to TDC and the rotor is one or two ticks off. Go more revolutions and it's further off still. Sounds to me like something inside let go, but no odd noises. Also, when I look up plug wire position for these engines I find 2 versions. Firing order is the same. One with #1 near the front and one with #1 at the rear. Thanks. 72 350 4bbl.
#5
It's a new distributor so it's fine. If it jumped time, what is involved there? Timing chain? I would think that if the chain jumped a tooth, the dist. would still make a complete revolution with the crank, no?
#8
The distributor turns 2x for every 1x of crank rotation. As stated above, as long as the firing order is wired correctly in the cap and the rotor is pointing to #1 with #1 cylinder at tdc on the compression stroke the engine will run. The difference in the two distributor cap wiring diagrams is one is for points and small cap distributors and the other is for an HEI. Notice that the firing order is the same. It mainly had to do with wire lengths in premade kits, so the distributor can be positioned to where there is no physical interference with the manifold or the firewall during adjustment.
This is for points
This is for HEI, note the 4 screws in the cap vs the 2 above and the extended timing tab.
This is for points
This is for HEI, note the 4 screws in the cap vs the 2 above and the extended timing tab.
#13
If you have never inspected the timing set, or replaced it, it is possible that the OEM nylon covered cam sprocket has worn out and some of the nylon has disintegrated causing the chain to skip.
#14
#15
OK got back on it this morning. Set #1 cyl to TDC on the compression stroke verified by using the comp. tester. Set dist. (HEI by the way and it is new and one of two I have tried) to #1. Checked and rechecked the wires. Cranked engine, spit and sputtered, shot fuel thru the carb, etc. Reset #1 to compression stroke. Removed cap and rotor is pointed to #4. Any ideas? As I mentioned, it was running fairly well when it just quit and when I tried to restart, it was out of time. Thanks.
#17
OK did that. No go. Reset #1 tdc comp. rotor about 45 deg. behind its last position.
Figure it's got to be cam or timing chain. Time to get dirty.
Figure it's got to be cam or timing chain. Time to get dirty.
Last edited by Roger60; March 14th, 2020 at 08:26 AM.
#20
Ok start over, put your thumb over spark plug hole cylinder 1, crank engine until compression pushes your thumb ,immediately stop cranking. Look at the timing mark on the crank, it should be close to zero. Manually move the crank to align mark to zero. Now check where the distributor is pointing, it should be pointing toward number 1 cylinder AND the wire to number 1 cylinder should be aligned directly over it. Next, moving COUNTER clockwise check firing order first is 1 then 8,4,3,6,5,7,2. If all this is done correctly the motor should start as long as you have fuel and spark.
#21
Thanks, but I've done all that repeatedly. The issue that has not been addressed is why did the engine die, then on restart was way out of time? No clunk, no clatter, nothing.
#24
Before tearing it apart, let me ask you this; did you tighten the distributor hold down bolt before trying to start?
if you don’t, sometimes the distributor will move when you crank the engine.
Another thing you can try is to move the distributor either direction while trying to start.
if you don’t, sometimes the distributor will move when you crank the engine.
Another thing you can try is to move the distributor either direction while trying to start.
#26
timing set alighment
In yours, the one to the left on the crank sprocket should be at the 12 o'clock position. The chuck should be about 2 o'clock..
This is where my original (not OEM) set was positioned before I replaced it.
This is the replacement set, before re-installing with chain..
This is where my original (not OEM) set was positioned before I replaced it.
This is the replacement set, before re-installing with chain..
Last edited by BackInTheGame; March 15th, 2020 at 09:15 AM. Reason: additional picture
#28
My guess, after reading through the more knowledgeable responses above: Is there some way the distributor gear drive teeth on the cam shaft have become compromised? Worn, or perhaps broken?
#29
The dist. is new and I got as good a look at the cam gears as I could with a mirror and flashlight and they look ok
Should the cam be replaced at this point if needed?
Can the cam be removed without pulling the lifters?
Should the cam be replaced at this point if needed?
Can the cam be removed without pulling the lifters?
Last edited by Roger60; March 15th, 2020 at 10:22 AM.
#32
[QUOTE=Roger60;1233701]Confused over these timing marks, have not seen this type of crank spocket before. Is the mark at the key or the one over to the left?
The key in the crankshaft should be at the 2 o’clock position not straight up. By pully mark I meant timing mark on crank dampener
The key in the crankshaft should be at the 2 o’clock position not straight up. By pully mark I meant timing mark on crank dampener
#33
i don’t think the cam is your problem, but I suppose it could , inspecting it can’t hurt.
#34
Is this the same engine you were addressing in the 72 350 cooling issue thread?
https://classicoldsmobile.com/forums...-issue-143120/
https://classicoldsmobile.com/forums...-issue-143120/
#37
Just looking at your picture of the timing gear set it looks like its set up wrong. AS stated above the keyway needs to be at the 2:00 position with #1 piston at tdc with your marks lined up at either the 6/12 or 12/12 position, your choice.
#39
3113 (Just a visual example from Summit) >> https://www.summitracing.com/parts/clo-9-3113
#40
Well there's the problem. Have to figure the dist. was not seated properly. Morale: check out the used engines you buy. Other than this, inside looks good, obviously a recent rebuild. Thanks for all your responses.