Hi and thanks for taking the time to read about my problems, as I mentioned before I am new to the Corvette world, just bought a 1991 base Corvette, looks good but am now trying to maintain it since it was long neglected by previous owner.

So my problem is I noticed ever since I bought it (2weeks ago) idle was too high like 1500 in park 1000 in drive. checked tps that was good, then when checking timing I did not see the timing mark. Stopped motor then I spun engine by slightly cranking with key so I could see timing mark on damper, marked it with whiteout when I finally found it so it would show easily when shooting timing light at it.

Got to use my distributor wrench for the 3rd time ever! So I loosened the distributor bolt just enough to move dist. with some force when engine is running. OK so now I start the car (previously warmed up) and I go under hood to shoot timing light at damper and hope to see timing mark some where on the timing scale but saw nothing, rechecked it several times and still nothing. Please can some one tell me what is up? Car has 88k miles is in relatively good shape, just a bit neglected. I then was running out of time so I adjusted timing according to how car sounded and was running just for the moment. But I have to fix this and am hoping there is some one here who can point me in the right direction.

Curious also to advance timing you move dist clockwise? and to retard counter clockwise??


FYI... yes I disconnected brown wire w/ blk tracer prior to timing and hooked timing light to plug 1.

 

If you are doing everything properly, ( and it sounds like you are) the only thing I can think of that could be wrong is the balancer has slipped.. The balancer has a rubber seal between the 2 discs which can allow the outside ring to slip..This happens sometimes when the balancer gets old and the rubber deteriorates... If you don't see any part of the white timing line then this is probably what has happened....WW

 

Thanks for the reply, I never thought of that? Assuming that is the case, how can I correct this? would I need to replace the damper? How difficult will this be? For now can I just time the motor by ear to get by until I have the time and $$ to take care of this? What should I listen or watch out for? I have noticed I am able to lower the idle by adjusting the timing but not sure this is correct?! I don't want to do more harm than good.

 

The distributor spins clockwise, same as the engine, so to advance the timing, you would turn the cap counterclockwise.



Yup, it'll idle faster as you advance it more.


A bad balancer can cause more damage than you would think. BUT, first I'd verify it was actually bad. Can you see if it looks like the outer shell has moved fore or aft of the inner section? About the only way I can think of other than visually seeing that it is compromised is to bring it up to TDC by looking in the #1 plug hole to see the piston and check the timing mark & scale (may have to turn it over 1 more revolution if on the opposite cycle). Or you could take the belt off (easy), then take the crankshaft pully off and the timing mark on the outside of the balancer should be 10 degrees after the keyway slot in the center section.
I can't remember, but the L98 balancer may have more than 1 groove on the outer shell. May want to check that first to see if there may be another groove on it.




.

 

After thinking about it a bit , there is one other thing that can cause the timing to be off... If the timing chain jumped a tooth this can also cause the timing mark to be off, but the balancer slipping happens way more often then the timing chain...The timing chain jumping would also cause the engine to run pretty bad, usually with missing and backfiring.. ..WW

 

First...Thanks to all for your help!

If there is more than one groove on outer shell how would I know which is correct for timing?

Yesterday as I was cranking the motor slowly to find the mark/groove on the damper I must say the damper looked ok? old, but looked ok to me? I know this means nothing since I have never seen a bad damper?

Other question on timing... after setting by ear yesterday since I had no other alternative, I have noticed motor starts much quicker when I turn the key, previously I would turn the key to crank the motor less than 1 sec. and when I would stop cranking the motor it would start 90% of the time, other times I had to turn key again for less than 1 sec. and motor would turn over. I know this has something to do with timing just not sure which way is better or more wrong?

Motor sounds good and strong when running doesn't hesitate, and I am trying to find a happy spot until I can have this taken care of. Car is only driven 50 miles a week and it will only be during summer months.

 

Yes timing can affect starting.

I had my balancer slip on my '85 and I bought a Dorman balancer from summit for like $34. It's been on there for a few months and people who I've talked to have used them and never had a problem.

The balancer typically will look fine, but usually the if you lay it flat on a table, the inner part of the balancer will have moved outward in relation to the outer part.

 

I thought of the timing chain too, but if that was the case I think the motor would run bad, it is currently running strong and holding idle although a little high 900-1000 when warm. What I was also considering was chain stretch over the years? Not sure?

Also curious what I would expect to pay a shop to change damper and correctly time the car? I would love to do it myself just cant seem to find the time!!

Do you need to remove steering rack to change damper? Can I fit an impact to pull the bolt? again this is a 91 L98

Much thanks again!

 

Balancer is suspect.

#1 plug wire = front cylinder drivers side.

After the timing issue is resolved if you still have high idle: Look at the throttle linkage stop it is a screw that is accessed from the rear of the mount boss. From the factory there is a small plug inserted in the rear of the adjustment hole to eliminate adjustment. Often the plug is removed & the throttle stop adjusted without following the correct procedure. If the plug is still in place the idle air control valve is suspect. If the plug has been removed there is a procedure to set the base idle. The procedure is on this forum somewhere & should come up using the search feature, in the meantime I'll look for the link for you in my files.

 

Now I am wondering, #1 plug is 1st plug on drivers side?!?! If so I think I hooked timing lead to wrong plug wire for #1 I realy hope so! I was using 1st plug on passenger side of motor. If this was the case it would make sense right? light was firing on wrong plug/cyl. WOW I really hope this is it, kinda wana take off work to go see!

Thanks so much all!!!

 

I recently had to find TDC on my 91 after some engine mods. The damper was very dirty and I could not see the groove/timing mark. I cleaned it off well and felt around to find it so I could mark it with some yellow paint. There is only one groove.
Yes - the #1 plug is the farthest forward on the driver's side. Good luck!

 

thanks for firing order/pic. I hope so much that is my problem! It makes sense that if I was using the wrong plug I will not see the timing mark correct.

 

Sounds like you found your problem.....You mentioned in your first post that you hooked the timing light wire to plug wire #1, this is why we didn't question your findings.......If this is infact what you did, please come back and post it so we can all "Razz" you for screwing up..We really enjoy Razzing.........WW

 

Here are some things you need to know:
1. Purchase a Field Service Manual (FSM)
2. Educate yourself by reading the stickies at the beginning of this section of the Forum - especially the DIY ones.
3. Keep an eye on the parts for sale/wanted section of the C4 Forum for used parts.
3. You can also find used parts on eBay, Craigslist and Corvette salvage yards (I like www.vette2vette.com).
4. For new parts I like www.corvettecentral.com but other folks have their own favorites such as Mid America, Zip Products, Corvette America etc. Ecklers sells parts too but has a horrible customer service reputation.
It is a good idea to drain all of the car's fluids and replace with new synthetic products. Check your rubber brake hoses and replace with new if needed.
Clean your weatherstripping and treat with a light coat of dialectric grease to keep it supple.
Replace your tires if more than 10 years old. Sites such as www.tirerack.com will show how to check the dates.
Be sure to wave at other Corvettes when you meet them on the road!
http://www.ebay.com/itm/1991-91-CORVETTE-L98-LT5-FACTORY-GM-REPAIR-SERVICE-SHOP-MANUAL-SET-/331192763263?pt=Motors_Manuals_Literature&hash=item4d1ca0837f&vxp=mtr

 

Yeah, we enjoy razzing, I'll start:
Just to clarify in the event you have not noticed it is not an old F**D motor
The cyls are not numbered RS,1234 LS,5678
BTW, firing order is also different

 

I will let all know what I find when I get home tonight, I did say I hooked to #1 cyl, I thought I did. Problem is I was wrong on which that was, I thought it was forward most cyl on passenger side. I really hope I am correct on this. Doesn't the dist. cap have a #1 to indicate plug no. 1? Either way I will trace plug wire on the forward most cyl on drivers side.

Also let me check ebay for a fsm, Previous owner gave me a Hayes manual and from time to time I have checked it and I must say that manual is 100% useless!!!! To some extent I have always preferred Chilton's manuals. The FSM should be best.

 

T H A N K Y O U A L L!!

I am an IDIOT! I should know to double check my setup if something is not right.

Yesterday when I got home, prior to even changing I went right to the vette, opened the hood looked at the wires coming from the distributor and realized right away I was on the wrong wire the day before when I was having trouble timing it. I felt so relieved when I hooked up the light , loosened the dist. started the already warmed up motor, pulled parking brake up put gear selector in drive then checked timing and had to rotate it back almost 1/8 turn to see the timing was dead on ***** accurate on 6*. Shut down the motor, tightened dist. then re-started to double check and all GOOOD. After I put every thing away I realized I should have set timing to 8* but oh well next time!

THANKS AGAIN ALL

 

NO NO NO!! You NEVER admit you were wrong. You need to make something up like you figured out the prior owner had #1 & 3's plug wires switched or something...

Glad you got it figured out and nothing needs repaired.

 

No mention of the EST disconnect then reconnect after timing is set???

 

I have to admit I was wrong , it doesn't happen often but I will always admit when it does.

EST Disconnect then reconnect?? you mean how long it took me?

I would say having to wait for car to warm up took about 20 min, once car was warmed up I would say the whole process took me no more than 5 min?