Jumped timing bent valves??

[Moparboss]

I have a 1960 348. It was running wonderful very smooth. I opened the good while the motor was idling. Then I slammed it shut while the motor was running. Suddenly the idle slowed and the motor starting running wonky. So I took my timing light and the timing mark on the balancer is no longer there. It is not even close to where it was two days ago. My question is do stock 348’s bend valves if the timing Jumps? I was going to do a timing set but if they bend valves I don’t want to waste my time.
many information would be highly appreciated. Thanks in advance.

 

[64ss409]

Could your distributor have slipped? If so that won't bend a valve.

 

[Moparboss]

Do you mean rotated? I checked the clamp and tried to rotate the distributor and it would not budge. I also loosened the distributor and regarded it some so see if it helped. If did not. I am really worried. Hopefully it didn’t bend the valves.

 

[wristpin]

Valves dont bend from distributor timing being off.

 

[Don Jacks]

You've got issues but bent valves isn't one of them unless the timing chain failed.In that case very likely.

 

[1958 delivery]

and timing doesn't "jump"(as in timing chain) from slamming the hood closed. It wouldn't be running if the chain /sprocket gave way

 

[64ss409]

Years ago I worked on one where the distributor cap was not seated correctly on the distributor. The rotor made contact inside the cap and broke it. You might check that.

 

[Don Jacks]

Right,I'd get that dist.cap off and look at the points and rotor.

 

[Moparboss]

and timing doesn't "jump"(as in timing chain) from slamming the hood closed. It wouldn't be running if the chain /sprocket gave way

I understand timing would not jump by closing the hood. At first I thought maybe it was a tired old wire somewhere shook loose and was making contact somewhere causing the misfire. But after putting the timing light to it is when I realized it must have jumped timing when I could no longer find the mark on the balancer. It still starts and runs but poorly. I was just hoping that motor doesn’t bend valves when timing jumps. Thanks for the help. I appreciate it.

 

[Moparboss]

Right,I'd get that dist.cap off and look at the points and rotor.

I pulled the distributor cap. Everything looks fine as far as I can see. Thanks

 

[Moparboss]

You've got issues but bent valves isn't one of them unless the timing chain failed.In that case very likely.

What do you mean by failed? Broke completely or fell off? The motor still runs. I started it for a minute to check timing with timing light. Ran poorly. So if it jumped timing does that bend valves in this particular motor?

 

[Don Jacks]

Only if the cam timing [timing chain and or gears] failed would the valves get bent.An ignition failure will not cause bent valves.Go over the ignition including checking the color of the spark.Check voltage at the coil while you're there.Recheck the ign.timing,if it's way low and that dist.hasn't moved then I'd look at thec chain.Do a compression test.If it's normal[150-160 on a stocker],then the cam timing and therefore the valves are good.If it's really low [120 or less]then you've got bigger issue.Was he engine running when you slamned the hood and it went to crap?

 

[64ss409]

The only ones I have seen that actually jumped a tooth was years ago when the plastic teeth on the cam gear wore out and broke off. I don't think there are any of those gears out there anymore.

 

[La Hot Rods]

If you suspect the timing chain has slipped pull the distributor cap then get on the crank pully and rotate it back and forth watching the rotor for movement, you shouldn't have more than 10* of movement at the crank.

 

[Don Jacks]

Believe it or not but Grumpy actually preferred the plastic coated gears in his race engines at one time.Yes thankfully they are gone from the automotive scene.

 

[boxerdog]

It's extremely unlikely anything happened to the timing chain, it's much more likely to be some kind of ignition issue. I'd try to verify that the timing mark is somewhere close to where it should be after finding true TDC. If not, then you need to address that. Then determine where the timing really is. I've also seen weather related coil and/or condenser failures happen abruptly. It does sound like a cap/rotor issue but I guess that is ruled out.

 

[Moparboss]

Only if the cam timing [timing chain and or gears] failed would the valves get bent.An ignition failure will not cause bent valves.Go over the ignition including checking the color of the spark.Check voltage at the coil while you're there.Recheck the ign.timing,if it's way low and that dist.hasn't moved then I'd look at thec chain.Do a compression test.If it's normal[150-160 on a stocker],then the cam timing and therefore the valves are good.If it's really low [120 or less]then you've got bigger issue.Was he engine running when you slamned the hood and it went to crap?

It was running. Running smoothly. I slammed the hood and with 10 seconds idle dropped and ran like crap. Then I gave it the gas a little starting popping out of the exhaust.

 

[Jerry B]

Many years ago I had a small block that just suddenly started running very poorly. Timing was jumping around all over the place. Replaced distributor and that solved the problem.

 

[409gang]

I don't think those plastic gears were used back when 348 and 409's were made and I never seen one from a parts store for a replacement gear. The only place I have ever seen them was on cars made around the mid to late 60's and beyond. Also I have never seen an engine with steel timing gears jump time, those gears would have to be pretty worn for that to happen. They would be so worn that the engine would have never ran right in the first place. I would pull your distributor and check it out including the roll pin that holds the gear on the shaft.

 

[409gang]

Many years ago I had a small block that just suddenly started running very poorly. Timing was jumping around all over the place. Replaced distributor and that solved the problem.

I had the same thing happen to me years back, I was traveling through NC in a 1972 Suburban and my engine started running so bad I could hardly keep any speed up. It was late at night and stopped at a auto parts store and camped out till morning when I could look at it. It wound up being a bad (worn out) distributor, got a rebuilt one from the auto parts store and was back on the road again running like a top.