taekwondo-kicker

hi, i got a 79 with L82 option, the lifters on the drivers side sounded like they were clinking, so i (we, my dad and i) tightened them up a little and now it is backfiring, do u know what the timing should be set at on it? i read somewhere 12degrees but is that at idle or running speed? or does it even matter? btw, how do you tell if they are hydraulic lifters or standard?

JmpnJckFlsh

tae, the last Corvette engine to have solid lifters was the 72 LT-1; ALL Corvette engines since have had hydraulic lifters.

For the adjustment procedure on hydraulic lifters, see the thread below. The ticking noise in hydraulic lifters in NOT due to clearance, but if the adjustment is backed off too much, you will get a fairly loud rapping knock. Sounds like you may have gone too far in the "tight" direction.
http://www.corvetteforum.cc:88/zerothread?id=127416

I recommend you adjust them once more using the idling engine method. Buy some rocker arm clips and prepare to have a mess. The best way to adjust either solid or hydraulic lifters is to find an old valve cover and cut the top out of it; this tool will cut down on the mess considerably. DO NOT change the rocker arm adjustment more than a quarter of a turn at a time without allowing the engine to restabilize.

If you don't have the chassis service manual for your 79, I highly recommend it...sometimes following the service manual instead of figuring it out for yourself can save you some heartache.

Bob D

Pls, buy a manual. The reason you have backfiring is because an exhast valve or intake valve is over tightened and hanging open or you've knocked loose a plug wire.

Your L82 came stock with a hyd cam & lifters. To adj - first locate a junkyard valve cover, attach a rubber valve cover gasket with gasket seal to the cover and let cure. Cut the top out of the valve cover and bend over the sharp edges leaving the four sides intact. You can adj the Hdy valve lifters while the engine is running. The rockers tend to sling oil, this is why you have modified an extra junkyard valve cover - so you can turn the adjusting nut while the engine is running, but not have the oil sling all over.

Do one side at a time. Start the engine and let it idle with the modified cover on one head. Loosen the rocker adjusting nut slowly using the appropriate socket, extension & ratchet until the rocker starts to clatter or tick. Change the ratchet head to tighten and turn slowly until the rocker just quits clicking, then tighten 1/2 turn more. Do this for all the valves on one side, then the other. If the backfiring continues, there is something else wrong - like a plug wire off or you've burnt one or more valves.

Good luck.

Bob

Paul L

I recommend these manuals. Good investment.
http://www.helminc.com/helm/Result.a...A3HVE05BHPABXC




[Modified by paul79, 1:20 PM 8/6/2001]

taekwondo-kicker

hey thanx for the idea with taking an old rocker arm cover and cutting it out. we just took the old one off and put a rag there to catch the oil. guess what some slipped over the rag and hit the headers. can u say "oil fire"?? lol that was funny sh*& IMHO. :lol: to bad it was my car though. :cry my mom came out to see what was going on and nearly flipped out when she saw the car on fire :mad i used a lot of kerosine and 3 oil flushes to clean that fire extingquisher dust out of it.

do u know what the timing is suppose to be set at? it runs from 6 - 8 degrees before tdc.

no i didn't get anything with my car. i bought it from a junkyard. all i got was the title and car. i used a very bad buying process to buy it: i saw and thought I WANT THAT CAR. and i bought it.

do u know were i can purchase thoughs books locally instead of online?

btw/ thanx for all your help so far.

Paul L

Timing on the 1979 L-82 is 12 degrees BTDC. I do not know a source of the manuals other than on-line :(.

taekwondo-kicker

hey were did u find that little sheet of paper on your car? thanx for it though.. guess i got to get my rpm gauge fixed before i can adjust the timing then.. that sucks. oh well another blissful thing i will enjoy doing. peace guys.

taekwondo-kicker

oh yeah one other thing. i dont have air filter on car right now (not street legal yet either) the old one rusted out and i through it out, got to go buy a new one. will not having an air filter on when i set the timing mess up my rpm when i do put one back on? thanx.

taekwondo-kicker

stupid me i posted that all up thinking i had hydraulic lifters :confused: i got solid lifters. anybody knowhow to adjust those? any sugestions? comments? i really need em. thankx

tsw71

You will need the lash specs from the cam card for this. If it specifies .022" lash, then you will use a .022" feeler gauge to set the lash.With engine warm and off, you will do one at a time when the opposite valve for each cylinder is open or at least most of the way open. For example, when the intake valve for #1 cylinder is at least most of the way open, you will set the exhaust valve(it will be closed) for that cylinder using a feeler gauge between the valve stem and rocker arm. Tighten rocker arm nut until the feeler gauge becomes a little snug(you should still be able to pull it out easily). Make note of the ones that have been set as you go so you don't end up doing them twice. When you have done all of the ones that you are able to do, then crank the engine around more as needed to do the ones that have not yet been set. You can crank the engine by hand by using a breaker bar and socket to turn the harmonic balancer bolt. This is better than cranking it over with the starter so you can turn is only as much as needed. A good chevrolet manual will tell you which ones should be set at each particular point in the crank rotation.

Another alternative is to do it while the engine is running. It will make a bit of a mess, but is a lot faster than the previous method. Personaly, I prefer to do it with the engine off as I get a much better feel of the lash with the feeler gauge. Try it both way and you will see what I mean.

Good luck,Tom

dath

Are you SURE you have solid lifters? The 79 L82 didn't have solid lifters from the factory. You should at least buy the Haynes and/or Chiltons books for the C3s. I don't know the proceedure for the solid lifters right off the top of my head, but the books will should tell you. Solid lifters are adjusted with the car off. You take the valve pans off, position the number one cylinder at top dead center on the compression stroke and then adjust the #1 cylinder using a feeler gauge between the rocker and valve to the correct tolerance. Then move the engine (take the plugs out to do this by the way) on to the next cylinder in the firing order and do the same thing. Keep going until all cylinders are done. I just don't know what the tolerance you need would be for sure.

-dath

taekwondo-kicker

am I certain i have solid lifters no. i turn 16 in 2 days, and i know only enough to know when i need help, i am using my dad to help me. he says i have solid lifters in the engine. the last person who owned it ripped em out and put in solids.

thank you for your help, hope that clears up why i have solid lifters. (lest i think i have em, dont worry though, i really dont got a clue what i got :D , thats why im asking u guys for questions and comments and suggestions, i need em)


[Modified by taekwondo-kicker, 12:56 AM 8/8/2001]

SteveG75

If someone put solid lifters on a cam designed for hydraulics, you have some major work to do. They are NOT compatible. Expect to change cam and lifters. Also, the only way to tell what kind of lifters you have is to pull the intake manifold off and check them visually. I would bet you have hydraulic lifters.

Here is the adjustment procedure I used for my cam swap with hydraulic lifters.
1. Pull both valve covers. Loosen all rocker arm nuts.
2. Turn harmonic balancer so timing mark is lined up with tab and distributor rotor is pointing at the #1 plug wire (pull cap off to confirm).
3. Engine is now set to fire #1 cylinder so we will adjust that one first.
4. Tighten rocker arm nut while trying to move the pushrod. When you fell resistance in the pushrod when twirling it or there is no up/down slack, STOP. This is the zero lash position. Now turn the nut 1/2 turn more. This is a fgood preload for a hydraulic cam.
5. Do this for both valves on that cylinder (#1).
6. Rotate engine 90 degrees clockwise when viewed from the front. (Direction it normally turns).
7. Repeat procedure for next valve in firing order. (Can't remember off the top of my head)
8. Do all 8 cylinders this way.
9. Replace valve covers and fire her up.

As for the noise, make sure it is coming from a lifter. Use a mechanic's stethoscope or a long screwdriver to try to pinpoint the noise. I thought I had a bad lifter but it was just my distributor.

Good luck.

BTW, aircleaner will not affect RPM that much.