GQ-ROD

I don't have this problem but i was curious to know

Are all year C4's affected by this problem?

I have an 84 model should i be aware of this for future reference?

Thanks

lkl2005

I had the same problem with my low miles 86. With the helpful advice of some of the veterans here on the forum. Put a torque wrench on that puppy and tighten it to 60 ft lbs. My belt was squeaking. I have gone back to make sure it is tight 3 or 4 times and it seems to be holding now . I intend to check it on regular basis

65Z01

Hmmm, harmonic balancer should NOT wobble, IMO. I think that means either the balancer elastomere has separated or the front main is worn; I'd lean toward replacing the balancer.

GQ-ROD

I don't have this problem but have read so many vettes do so i wasn't sure what to expect.

I'll be doing a full tune up tomorrow and wanted to check the timing to ensure the marks line up where they should i'll be checking tdc against the harmonic balancer marks so we'll see what i get.

It has a backfiring at wide open throttle and a miss so i'm going through everything.

GQ-ROD

Thanks good advice will check and tighten tomorrow!

Muffin

The harmonic balancer is an almost press fit, need a puller to get it on and off. The nut 2005 refers to is more insurance and to hold the pulley on. If you are seeing a wobble I strongly suspect your damper has/is going south. If the outer ring has moved or can be moved you will never get correct timing. See 65Z01's post again.

GQ-ROD

Thank you, when i check the timing i'll know if it's out of time checking with piston TDC and see how far off the timing marks are.

vetteoz

Typical find

GQ-ROD

Wow thanks for the pic that looks bad!

leesvet

I've had one completely separate...the outter ring came off the rubber liner. When the engine ran it turned...making some noise and a mild vibration. The hard part was the dingging that went on for 20 seconds AFTER shut down ! That took me a day or two to figure out...until I saw the outter ring still spinning on the balancer hub with the motor off.

If you see cracked rubber like the pic, plan on doing the work immediately. Its gonna be any day...

Cliff Harris

The harmonic balancers of old did not have a bolt to hold them in place. Strictly a press fit. I think the bolts were added around 1980 (just a guess -- my '78 Corvette did not have a bolt, my '86 does). [EDIT] I remembered that my '78 Corvette DID have a harmonic balancer bolt. I know that because I messed up the threads in the crank with the balancer puller. [/EDIT]

The outer ring on both the '78 and the '86 came loose from the hub. I found the problem on the '78 when I tried to set the timing and the engine wouldn't even run when I lined up the mark. The '86 balancer ring moved inward until it hit the timing chain cover and ground a hole in it. I found that when oil started pouring out. I filled the hole with J.B. Weld about 10 years ago because I didn't want to go through the hassle of replacing the timing chain cover. Still holding so far...

Matatk

What a coincidence, we have the same garage floor coating



That balancer was on my 89 with about 90,000 miles when I changed it. I had no noticeable vibration, I only found out about it when I tried to set the timing.

Matthew

vetteoz

The good pics get saved for posterity

GQ-ROD

Couldn't see the timing marks today on the balancer so will have to get a piston stop to check the timing and find true top dead center.

Managed to get the old plugs out WOW i'm never surprised by what i find.

All the plugs were tan which was great though number 1 was full of tan crud looked like clay.

All the plugs were very worn and all had different gaps ranging from 45 to 60.

So I gapped to 45 ( per emissions label on hood ) the new ones acdelco #2 performance platinum ( napa did not have the r45ts in stock ) before realizing they sold me the wrong distributer cap.

Even on their website they show the wrong one!

Mine has the bolts with an L shape on the bottom to attach to the distributer the one they gave me and on the website does not show this!

So gotta go back tomorrow and get a new one before i can finish the tune up!

Once i get the piston stop i'll check the timing and post back!

vetteoz

Maybe that is what style your engine came with
All later Vette HEI's have a cap with hold down screws , not the L style locks you have

65Z01

When I did RRs I used a large screw driver blade as a piston stop.

GQ-ROD

I thought about that but my distributer does not have tabs that the cap would screw into, i also checked napa's site and it shows the same one for an 86 vette. So not sure what's up with their system.

When i check autozone's website they DO indeed show a cap with screws that have that L shape at the bottom to lock the cap down to the distributer for an 84 vette.

I'll see what napa says tomorrow ironicly the old cap that's there seems to be a napa gold cap has brass terminals not the galvanized looking terminals the one i bought has.

Weird.

GQ-ROD

I was actually going to use a simple bolt with the proper thread pitch since no one stocks a piston stop locally that i could find.

I thought about the screwdriver but wasn't sure how accurate it would be.

Saw a youtube video of a guy doing this with a homemade piston stop and it was great to see how easy and accurate it was.

Cliff Harris

I have a theory that the timing mark should line up with the groove for the crankshaft key. Can anybody verify (or refute) that?

[EDIT] Since I just took my harmonic balancer off, I did verify that the groove for the crankshaft key does NOT line up with the timing mark. It actually aligns with the edge of one of the spokes in the harmonic balancer. I read somewhere that GM changed the mark to 8° advanced back around 1970. The problem is that you can't see the key groove without taking off the serpentine belt pulley. Here's my harmonic balancer with a rule to show the alignment:

[/EDIT]

GQ-ROD

That's a good point i'm not sure!