Quadrajet 'tick'?

[Jeff Rosansky CLC #28373]

Good morning.
As some of you may recall, I had an engine rebuild a year or so ago and it did not go as well as I had hoped. I have had what sounds like a valve tick for a while now that I have not been able to nail it down. I have had the valve covers off with no obvious sign of a problem. Oil level is good and I have 30ish psi when warm at idle. The tick increases as the engine gets warmer.
Have been working on it this morning. Installed a cheapie oil pressure gauge and confirmed previous readings. Sounded like the tick was in the middle of the engine but could not nail it down.  Woke my kid up (he loved that) because his ears are younger than mine. Same thought, mid rear of the engine. Got stethescope (I am sure that isn't spelled right) and the tick is most pronounced at the left rear of the carb by the throttle linkage. It is fairly consistant with engine speed.
I had the carb rebuilt by a local guy when the engine was done but I am not impressed. Engine runs strong bit idles like crap.
Is there anything in a carb that would tick?
Jeff

[Caddyholic]

Is there an exhaust leak in the cross over on the intake manifold? that can sound like a tick.

[Jon S]

Jeff -

Do you have ZDDP added to your oil?  "Sounds like" a flat tappet tick.

[TJ Hopland]

What year are we talking about?   

If its on top I too was thinking maybe an exhaust leak in the intake.    I'm thinking 69 ish there was an open exhaust port under the carb that took the proper gasket to seal up.   This being open would usually cause other running issues so seems unlikely in this case.   Pre 75 has the external choke and a pressed in 'well' that the coil sits in.   The well is in the exhaust passage so a leak there could make a noise.  73+ has the EGR so another place to leak.

What did you do with the rocker arms?   IF they were the same used ones maybe you have one that was worn?  The 472-500 I have had apart all seemed to have one rocker that was worn for some reason.   The other 15 barely have a polished area on em but one will almost be worn through. 

Did you put your stethoscope down around the exhaust manifold?  Does this car have the EFE (heat riser flapper valve)?   Those are good places to get a slight leak.   

[Jeff Rosansky CLC #28373]

Well I guess telling everyone about the engine would have helped....... 70 DeVille with a 472.
I did listen around the manifolds and the sound was not there. Sound was around the carb. All new rockers.
Please describe the exhaust crossover gasket. Now that I think of it, the paint has flaked off over the channel dead center of the intake from the head to the carb. It does have the choke that sits in a well.
Thanks
Jeff

[TJ Hopland]

There is a small exhaust port in the intake side of each head.   The intake then has a passage between the two heads that usually passes directly under the carb in this era.    The choke well is also in this passage.   

The idea was that the heat riser (later called the Early Fuel Evaporation) valve usually at the outlet of the right exhaust manifold would close when the engine was cold thus forcing most of the exhaust to go through the crossover thus heating the carb and choke on its way through the other head and finally out.    As the engine warmed the valve would open and let the exhaust flow normally with minimal extra heat through the intake.

Some of those late 60's that passage was actually open under the carb and took a specific gasket design and material to keep it sealed to the carb.   This passage was in the center of the intake plenum so if it was not sealed you kinda had a uncontrolled EGR system that usually caused all sorts of drivabilty issues.    Later years this passage was not open and then it was finally used for the EGR valves exhaust source when they added EGRs in 73?

[Scot Minesinger]

Jeff,

The exhaust passage in the intake manifold is normal to get hot and cause paint to burn off.  There is nothing in your carb that will make it tic. 

I think you have inspected the valve train on both sides by removing valve covers and all looked good, no holes in rocker arms, nothing out of order, and etc.  Please confirm.

That tic is usually lifters, and maybe one that was replaced is no good.  When this happens the cam pays the price.  Next oil change cut open the filter and look for metal flakes.  Hope you do not have any.  If you do it is time to consider the lifters as a potential problem.

As written by others exhaust leaks sound like a tic too, and check the torque on the exhaust manifolds, plus manifold to Y pipe connections (those can loosen if replaced with course threads on manifold in lieu of fine as per factory).

It may be time to go back to the shop that rebuilt it, I know they did not make you happy, but it is a resource.

[Bobby B]

Jeff,
Hi. Agree with a lot of the above comments, but would be more likely to believe that it's in your valve train, most likely a lifter/lobe. If you're running a new flat tappet cam, break-in is SUPER CRITICAL. It takes but a few minutes to wipe a lobe out if procedures are not adhered to. I've been trying to stick with using roller cams from here on in. Tired of having 5K plus into a motor and having it all come down to that final moment of truth. Sweating it out during initial start-up of a rebuilt engine is not nearly as fun as it used to be. Air/Fuel, Timing, Oil pressure, Checking for leaks, Overheating, etc., (all possible scenarios during Cam break-in) is just a crapshoot all the time with a flat tappet cam and today's oil. I hope they used some form of break-in oil, like Joe Gibbs, etc., and followed all manufacturers guidelines for breaking in their cam. Upper valve train won't last long if it wasn't broken-in properly.
                                                                                                                  Bobby

[Scot Minesinger]

Jeff,

Bobby makes a good point.  When I replaced the lifters (20k mileage on a new cam/new rebuilt engine) because I thought they were bad, but they were not, and replaced anyway (turns out it was the #7 intake valve), break in is required.  Used a special break in oil and at VERY FIRST start had to run car at 2,200 rpm for half an hour.  Believe it or not car is not designed to be in park at that engine speed and to be sure would not overheat, ran box fan with hood open watching rpm and temp gage. 

Can you confirm that the engine was broken in correctly.  You can cut open the oil filter to see if it has small metal flakes in it.  If so, you may have flattened out the cam. 

[savemy67]

Hello Jeff,

All the previous posts offer good advice.  Where should you begin?  Buying the stethoscope was a good start.  Since the stethoscope indicates the noise is more pronounced at the middle of the engine, what is the simplest action to address the symptom?  Since exhaust leaks and valve train noise can sound alike, it is relatively simple to first check that the carb mounting bolts, and the intake manifold bolts are correctly torqued.  Your post said the car idles like crap, so check all the idle adjustments, and then check for intake leaks using a volatile aerosol sprayed at the carb/manifold and manifold/cylinder head mounting flanges (BE CAREFUL).

If you rule out intake/exhaust leaks, how can you check the valve train?  You can remove the spark plugs and valve covers and valve pedestals, and rotate the engine by hand while observing the pushrods.  If a cam lobe is wiped out, you should be able to notice a lack of lift at the respective pushrod even though the lifters aren't fully pressurized.  This task is very tedious, but not difficult.  Last, you could cut the top off a spare valve cover so you can observe the valve train while the engine is running, and use the stethoscope to find the source of the noise (BE CAREFUL).

Sound travels in a solid much better than in a liquid or a gas.  A bad lobe/lifter will propagate sound more easily through the length of the cam than through a pushrod because the oil (liquid) in the lifter isolates the sound to a certain degree.  I am hoping your symptom is nothing more than a bad gasket at the carb.  Good luck.

Christopher Winter

[Jeff Rosansky CLC #28373]

Yes. I broke it in myself. 2200 for 30 min. The shop that repaired the timing gear bolts did not tighten the hose clamps and the bottom rad hose blew off.
Held up on adjuati g the carb because I was still being careful of the cam and didn't want to let it idle much while I adjusted it.
Fast forward to now..... Runs very strong but doesn't idle well. Ran water spray and then just about a whole can of cleaner all around the intake and carb and all vac lines looking for a leak and did not find one. Oil pressure seems fkne at hot idle. Idle and tick gets worse when hot.
I guess I was just hoping it was a metering rod or something in the carb. Grasping at straws I suppose. i just don't want to go in there...... Let alone tell my wife.
I will just let it rest for now.
Jeff

[chrisntam]

Have you put a vacuum gauge on it?  That really helps diagnose engine issues, or at least it will help steer you in one direction or another.

[Bobby B]

Jeff,
Hi. Retarded Timing, Lean burn, and Vacuum leaks are all symptoms of a glowing manifold......Get out your Vacuum gauge like Chris said.
               Bobby

[Jon S]

I'm still convinced it's a tappet/lifter noise.  I would add some ZDDP to the oil in 1/4 container increments.

Once the noise is corrected, we can focus on the rough idle.

[chrisntam]

Yabbut that glowing exhaust manifold ain't right.

[Jon S]

Yabbut that glowing exhaust manifold ain't right.

Didn't see that till now!

[Jeff Rosansky CLC #28373]

No no no...... That glowing manifold was during the break in. Scot was saying how they run hot when breaking them in and I just posted that to show I broke it in.
Vac gauge had 19 but did have a little wiggle.
Jeff

["Cadillac Kid" Greg Surfas 15364]

Jeff,
Just to eliminate the carb being the source of the noise, check to be sure the secondary air valve and the throttle butterflys are secure and not rattling.  If that exhaust manifold is really glowing you definately have an issue with lean mixture and/or leaking valves.
Greg Surfas

[Bobby B]

No no no...... That glowing manifold was during the break in. Scot was saying how they run hot when breaking them in and I just posted that to show I broke it in.
Vac gauge had 19 but did have a little wiggle.
Jeff

Jeff, That indication is loose or worn valve guides, which could very well be your problem.
                                                                                                                  Bobby

[Scot Minesinger]

Jeff,

Presuming you received a valve job when the engine was rebuilt, if not that probably should have been done if it was not.

The most common mistake I see is not correctly sealing the intake manifold that causes rough idle.  To seal it properly the corners where the rubber seals go (four places) need generous RTV sealing.  Most people just rtv the 8 intake manifold ports, and the entire bead needs to be sealed because vacuum communicated with entire manifold.

When I replaced my lifters (turned out to be bad # 7 intake valve) of course had to replace intake manifold gasket and reseal.  It was done incorrectly by others before.  Once I did it correctly idle smoothed right out.  I get 21 vacuum, 19 seems low.  Check the timing, if mark flutters you need to reseal your intake manifold.