Welcome to the Corvette Forums at the Corvette Action Center!

Weird Motor


Well-known member
Jun 17, 2001
Timmins, Ontario, Canada
77 black coupe
Hi yall,

I have recently rebuild my engine in my 77 vette it has a L-48.

Anyways one day i was driving and decided to check my timing, the timing mark was way below the zero mark and no matter how far i turn the distributor i can not get it to lign up with the 8 btc.

Do you think that my timing chain (which is brand new) skipped already or streched.

Any reply would be great.

Thank you very much.
I could be wrong but i thought you had to set the timing with the vacuum advance disconected ?
Sounds like the distributor is one notch off on the drive gear.


Tell us exactly how you are checking the timing and what kind of timing light you have.

I have a light with an adjustable meter. I can read total advance, etc.

Usually I get the car warmed up. Then I pull the vacuum off the distributor and plug the hose. I hook the timing light to the #1 plug wire which is the driver side extreme front cylinder. I make sure my timing light adjustable meter is on ZERO, then I shoot the mark on the balancer.

If you are on #3 instead of #1, etc. your mark will be a mile off.

Your balancer can also slip over time causing you to get a weird reading. This may also cause some vibrations.
Harmonic Balancer's toast

Your harmonic balancer's outer ring (where timing mark is) may have slipped ... either because the rubber in between outer ring & inner hub has deteriorated ... or the the HB's outer ring was unduly pried/yanked upon ... or both. Slipping outer ring is very common cause of timing issues such as yours ... in general HB's aren't repairable. If yours has slipped, buy a NEW harmonic balancer ... and carefully press it into position.
If the car's running....

And you turn the distrib.. does the timing mark move in relation to the turning of the distrib?

If the cars running, and it has it's normal power
an L-48 is 165 hp. and idles smooth, I would agree with the timimg mark on the Harmonic balancer has moved by either they forgot to put the woodruf key on the crank when they installed it -OR- the rubber has died and it slipped..let me pull an old post..

Harmonic Balancer

Pull ALL the plugs.
Disconnect the distrib power ( wire on side of cap labeled BATT on CAP) Remove the distrib cap.

Have somebody bump the car with the key to where the TDC marker on the crank harmonic balancer line up with the pointer on the timing cover ( Just get it close for now)

Is the piston almost all the way up? Use a LONG coathanger down the plug hole to check this if the piston is down..pull the hanger out and bump the engine over again.

Once you get it close get a socket on the harmonic balancer center bolt and turn it EXACTLY so "O" is on the pointer.

put the coat hanger in the hole.. and turn the crank by hand with the wrench... does the piston go UP MORE ( try both directions) get the piston to TDC ( top of travel ) and does the marker line up?

If it dosen't...your harmonic balencer is screwed!

( the rest of the post)

Now locate the #1 plug on the distributor cap
and see if the rotor's pointing in that direction
it should be very close.

If not.....

When the mechanic pulled the distrib, it rotates the oil pump drive by a few degrees so you need a long LONG flatblade screwdriver to turn the OIL
pump drive back into position to realign the distrib to the correct position ( which is pointing to the #1 plug hole)

Make sure your wires are in the correct order
1-8-4-3-6-5-7-2 firing order.

Just a thought on this one as it can be a difficult problem to diagnose without seeing. Is the small timing tab in the right place when it was bolted back on to the timing cover ???

On my car as you look to the front of the engine the tab is down to the right side below the water pump. The balancer on mine only has one groove at the 12 o`clock position and when the engine is at TDC, the mark on the balancer is nowhere near the timing tab, the tab was probably put in that position for easier veiwing when setting up the timing with a light rather than trying to see it at TDC under the water pump. If this is the problem the easy thing to do is buy a timing tape, set the engine up at TDC as per the previous comments and then stick the tape on the balancer making sure the tape O degree mark lines up with the O degree position on the tab. After that you should have no problem checking the timing.

On my car I just painted a white line on the balancer and then used a timing light like 69`s that you can dial in the amount of advance you want. If the distributor was a tooth out or the cam sprocket had jumped on the chain your car probably wouldn`t go or at least be running so rough you`d know something was amiss.

You can quickly check this by pulling a valve cover and bumping the engine over till the mark on the balancer it at the 12 o`clock postion, both valves on #1 cylinder should be fully closed and the rotor should be at the #1 post on the distributor cap then you can quickly verify if the tab is in the right position. It might be that some balancers have the groove marked to accomodate the tab being in this offset position depending on the application but mine isn`t.

A quick way to get the engine at TDC if you are lucky enough to have a four speed without going to all the hassle of removing the plugs and having someone bump the engine is to get the car on a flat surface and put it in fourth gear and push the car forword until you get the mark on the balancer at the 12 o`clock position.

When i check the timing i remove the vacuume to the distributor.

I just have a basic timing light, i do not have one that i can set the advance

I think it propably is the harmonic balancer that is worn out or something because i do hear a strange rubbing/grinding kind of noise coming from the crank or around the harmonic balancer.

Oh and when i turn the distributor the mark does move up towards the 0 mark but i cant turn it anymore to get it pass it.

All of your help is awsome thanks alot guys you guys rock, this summer i will be riding once again.
wipeout and/or wipeout48

Are wipeout and wipeout48 one in the same person? Pardon my ignorance ... but If so, how does that work?
Yes we are the same person's i had prob with my last name so i made a new one. sometimes i show up as wipeout48 or wipeout.

Hope i didnt confuse you.

Strange noise

Havin more thoughts ( Ohhhhh OWWWWW!)

Do you have a chrome timing cover on it?

The pointer might be wrong!

" I think it propably is the harmonic balancer that is worn out or something because i do hear a strange rubbing/grinding kind of noise coming from the crank or around the harmonic balancer."

Are your pulleys tight? Is the balancer scraping the timing indicator? Is it out of round? This a bad thing you need to have fixed NOW!

"Oh and when i turn the distributor the mark does move up towards the 0 mark but i cant turn it anymore to get it pass it."

Why.. are the plugs still in? Is it binding?


Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom