Engine tick - ideas

[BigIrish]

The Fairlane I just bought has a rebuilt 289, stock exhaust manifolds. When it gets fully warmed up there is a noticable tick from the engine under load. It sounds like a lifter tick, but only when you give it some gas and only when hot. Let off the gas an coast...no tick. Rev the engine in neutral, no tick.

It seems like the only thing it could be is a exh manifold gasket leak, but I can't see any evidence of it. Maybe cracked manifold? If it was a mechanical tick, then I think it would make the noise regardless of load...right? I checked the lifters (non-adjustable) and they are all tight with no slop.

Any other ideas? Only other thing that crossed my mind is that one cylinder is detonating due to incorrect heat range on a sparkplug or something. [S

 

[kustompower]

sounds like a lifter... How's your oil pressure at idle?
Maybe one is a little loose or sticky and not staying pumped up?

 

[Dr Crankenstein]

I don't think lifter either. Same reasons you don't.

Cracked manifold will do it for sure. Check 'em good for a fine black soot line.

A loose torque converter bolt will do it, too.

Inspect your spark plug wires for condition and proper firing order. #7 and #8 fire one after the other. A common problem is #7 firing #8 because of induction between the wires. If that happens you're firing #8 WAY too early, and severe pinging results under load. Same thing if those two wires are crossed up. (Made that mistake myself a time or two).

 

[rainman]

Could possibly be a cracked flywheel!! I have heard sounds very similar to a lifter come form them.

Shoot looks like the good Dr. already beat me to it!! ha ha

 

[justsomeguy]

I was thinking driveline further down from the motor. It is RPM related and not speed related, right? Check the flywheel bolts first and then it's into the trans. Is it a manual of auto?

 

[T DRIVER]

Try this

Try in a dark room or out at night no lights see if you see any sparks or slite flame around wires or exhaust area check really good !!!!

 

[BigIrish]

Great ideas fellas, thanks. It's definitely coming from the engine and sure sounds like the drivers side. It sounds like its directly in front of me.

It's an auto. I did notice it's missing one of the bellhousing-to-block bolts on the driver's side .

Oil pressure is 40+ psi at idle. The sound is not RPM related, more load related. The noise starts at light throttle, right off the line. If I punch it though, the noise seems to stay the same volume or even decrease. If it was a manifold leak, it should get louder with more gas. [S

Weird. The more I think about it, it sounds like a pre-ignition problem. It's got crappy mis-matched plug wires that are not properly seperated, so I'll start there I think.

T-Driver - dark room thing is a great idea.

 

[hankthebigdog]

had a similar problem and finally pulled the push rods and had one that had a slight bend. Wasn't very noticeable til I rolled it on the welding table. $1.32 fixed me. just a thought.

 

[HOT40ROD]

Does it have the stock exhaust manifolds. If so check the donut between the manifold and the header pipe. It happen a lot on the small block ford. It can drive you nuts to find. Sometime it will only make the ticking noise when the engine is under load.

Or if the manifold were even removed and they did put a gasket in when it put back on the engine. also the manifold can crack.

I would check all of that before I would go internal.

 

[BigIrish]

As usual, I spent the afternoon fixing stuff that wasn't broken (exhaust donut, manifold gasket) only to figure out the problem was a 10 minute fix....too much ignition timing!

I had checked the timing when I first got the car and it was fine, but the engine wasn't warmed up. I checked it again when it was nice and hot and whoa!, way off. I set the timing correctly and no more tick. Lesson learned on that one!

 

[BigIrish]

I thought I had this licked...but no. It's back. Not as bad as before but still can hear it.

Update on oil pressure - its about 45 psi at idle when cold but drops to 20 psi at idle when hot. Is that bad?

It sure sounds like pre-ignition knock on 1 cylinder only. Changed the plugs, no difference. I guess I'll pull one plug wire at a time and try to isolate it. Frustrating.[S

 

[Dr Crankenstein]

Did you change out that crappy set of wires? How do the plugs look? Lean condition?

Make sure the distributor is locked down tight, and hasn't "walked".

Check the timing chain for excessive wear. I know you said it's rebuilt, but a cheapie chain could be on it's way out already.

Is it still doing this only under load? Could be you have too much total timing for today's garbage gasoline. Try some premium gas or octane booster. If that takes care of it, you could modify the vacuum advance or buy an adjustable one.

The oil pressure doesn't bother me. As long as it increases with RPM, I wouldn't worry too much. What kind of gauge is it? An electric gauge is a poor device, and could be way off.

 

[rainman]

B-I one other thing you can check! Make sure all the plugs are tight, and that you're not getting leakage around one! This could cause a spitting sound also!

 

[BigIrish]

Yep, still doing it mostly under light load like gentle acceleration or cruising. Give it about 1/2 throttle or more and no tick. I backed the timing off to only 3 degrees BTC and put some 93 octane in it, but still doing it (not as bad)

I cleaned & inspected the plug wires. They were dirty but seemed to be good 7MM silicone ones - will probably change out anyway.

The plugs all had light gray soot, which I think is normal (?) They all looked the same. I was hoping to find one oddball.

Oil pressure guage is mechanical. Pressure is up over 40 almost immediately off idle, so I guess that's fine.

Timing chain - now that might be something. I notice when I check the timing with the light, the mark jumps around a bit. Any tips on checking for excessive wear on that?

Total advance - how do I check that is correct? Even with the vac line disconnected, the timing sure shoots up fast with just a little revs. Makes me wonder if something is wrong with the dizzy....

Rainman - good idea on the plug seating. I will look at that.

 

[Dr Crankenstein]

The mark moving around is a clear indicator of a loose chain.

If you can turn the motor by hand, you should be able to feel slack in the chain. Put a breaker bar on the crank bolt, turn it ahead a few degrees, then back. You could also take the distributor cap off, and watch the rotor while you turn the crank back and forth.

Total timing can be checked with a dial-back timing light. You will still have mechanical advance with the vacuum disconnected, so that's normal.

 

[TiredIronGRB]

Check for a cracked flex plate....oh and thanks for posting in the proper forum [cl

 

[BigIrish]

Well I think I might have figured it out. (fingers, toes crossed).

I disconnected the vac advance and ran it around awhile, no tick. After hooking it back up and trying to adjust it, the only way I could get it to run well is with the vac advance basically adjusted all the way in (no vac advance).

Took apart the dizzy and the vac advance plate is very worn, doesn't rotate smooth at all. I think it's getting hung up in the advanced position. So I'll either replace that plate or just get a new HEI dizzy I want anyway.

Stay tuned, thanks for all the good ideas.

 

[rainman]

You would think if the advance was sticking it would make a big difference in idle speed! Hope you have it though!!

 

[BigIrish]

Agreed! I think it is sticking part-way through it's travel. At idle with the vac port closed (no vacuum) the spring is probably strong enough to pull it closed. The problem happens when you ease on the throttle at about 2000 rpms. The vac advance should be smoothly backing off with more throttle, but it's getting hung up. It's all cruddy with grit and all the slots & pins in the plate are badly worn.

This explains why I set the timing and then checked it later and it was way too advanced - the vac advance was hung up. I had the dizzy bolt cranked down hard, so it shouldn't have moved.

Either way the dizzy is worn out and needs replaced. Got a new one on order - will report back if that's fixes it!

Also, I found this excellent article on mechanical & vac advance. So now I'm an 'expert'

http://www.gofastforless.com/ignition/advance.htm

 

[BigIrish]

Ok, I think I got this one licked too. Got my new Speedway HEI dizzy, new plug wires installed and...still had the tick when set to the 6 degrees BTDC per the manual. But it generally ran much better and was consistent.

Set it back to 3 deg BTDC and now its great. So it's definitely preignition related.

Now, I'm not sure why it can't handle 6 degrees even on 93 octane. Is it possible the timing mark on the crank pulley is off vs. the marker? [S

Thanks for the input everyone!