dc6902

Have 84 with carbureted 350. Heard ticking noise on engine. Identified cylinder, but could not get rid of noise. Went in and replaced all lifters with new ones, replaced 3 slightly bent pushrods. and replaced all of the nuts on the rocker arms. Now engine won't idle, runs rough, backfires at times.

Could I have finished off camshaft? Original lifters did not appear to be bad.

billschroeder5842

IMO Wiping the cam is pretty extreme.

However, you have A LOT going on right now; fuel, spark and air.

My first thought is (if you put the lifter, push rods and tightened rockers correctly) you have air leaks as the L83 is very prone to those. The back fire is a hint that you have a lean condition caused by excess leaks.

Really, tough to tell unless you can "remove" a few items off the "coudl be F'd up list."

ex-x-fire

Back off the rocker arms nuts one turn.

C409

..... ... Sounds like you have over-adjusted (incorrectly adjusted) the valves ... and , use an oil intended for flat tappet cams and catalytic converters ... what caused the bent push rods ? .....

383vett

New lifters on an old flat tappet cam is usually not a good combination. Cams and lifters will wear together as a pair. Break up the pair and you're looking at a new cam pretty soon. Multiple bent pushrods usually mean someone messed up with the valve adjustment or the timing chain slipped a few teeth.

mtwoolford

well you didn't make it any better. It only takes a couple of thousandths of an inch to wear down through the hardening on the cam lobe, and once your into the softer metal, its only a matter of time, sooner rather than later, before significant lobe wear occurs.

if you have the valve cover off, measure the rocker arm movement; all the intakes should be the same and all the exhaust should be the same; if there's an odd ball (or two or three) then you may have found your problem.

Hot Rod Roy

This is a tricky test, because as you turn the engine by hand, and the pushrod is rising, the hydraulic lifter will collapse as the valve spring puts pressure on the lifter. This will give you a changing dial indicator reading, even though the engine (and camshaft) is not moving. You have to wait until the lifter is completely collapsed to get a reading. As you rotate the engine past the cam lobe, the lifter will return to its full extended height. A bit confusing!

gerardvg

Hi

Did you prime the new lifters with oil before installing them?
Note some aftermarket lifters need less than the factory one full turn from zero lash, i found that out with my new engine it would not idle and backfired. Turned out low compression on a few cylinders because the valves were not closing fully. Half a turn was all those lifters needed.

Note the early 84 -85 corvettes had known camshaft lobe wear issues,
my old 85 engine had definite camshaft lobe wear.

The easiest technique to set the lifters is when the particular cylinder piston is at the top of its stroke,
rotate the pushrod with thumb and finger until you cannot turn it that is zero lash.
Then turn the rocker nut 1/2 or one turn clockwise depending on lifter manufacturer,
you will have to start from scratch hopefully the lifters have primed by now.
Undo each rocker a few turns and start again, go via shop manual at what ones you can adjust at crankshaft position or each piston at top of its stroke.

mtwoolford

Thanks for the clarification

Hot Rod Roy

Another thought: I'll bet this problem could be solved by cranking down on the rocker arm adjusting nut before doing the test, until the lifter is collapsed. If the valve doesn't close all the way, the lifter would act like a solid lifter during the test! I haven't tried this technique.

Obviously, you'd need to re-adjust the valves correctly before starting the engine!

ghoastrider1

personaly, I like adjusting while the engine is running. Back off tntill it starts clacking, then down 3/4 turn. If a cam isn't broken in right, its easy to wipe one

Hot Rod Roy

Sorry, Ghost, but this is a confusing post. First, the OP wasn't asking about breaking in a new cam. Second, If you ARE breaking in a new cam, you'd better have the valves adjusted correctly before you start the engine.

Thanks for your many contributions to this forum, though!

dc6902

Update:
Someone suggested checking fuel. Found water in fuel tank. Removed and cleaned tank
Adjusted valves at tdc compression and others 180 degrees out. Put valve covers on . Engine starts. Timed to 10 degrees. Went to fine tune valve adjustment and engine won't run or idle with valve covers off. With valve covers on it is difficult to open oil filler cap. Too much suction. Engine vacuum is 17. What is going on? Plus loud sound from carburetor. Engine runs with valve covers on, just has slight miss. Has Edelbrock intake , no egr, just pcv.

Hot Rod Roy

What does this mean? To me, it sounds like wrong, wrong, wrong!

There's tons of info in this forum on doing it right. Right is much better than wrong! (Unless your explanation has confused me).

dc6902

https://www.google.com/search?q=chev...W_sUegE3ow6tM:

ex-x-fire

Sounds like a massive internal vacuum leak. I bet it uses a lot of oil.

Hot Rod Roy

You invented a creative (and misleading) name for that procedure!

Regarding the crankcase vacuum, check your PCV valve. I'm presuming you haven't had your intake manifold off the car recently?

dc6902

I have had intake off. Removing again tomorrow to check gaskets.

dc6902

Replaced lifters, put sealer only around water ports and front and rear of intake.

Tom400CFI

Sound like you hooked the "breather" side hose from the valve cover to manifold vacuum, rather than the PCV side hose w/the PCV attached to it. OR you hooked the PCV valve hose to manifold vacuum (as it should be) but w/o a PCV valve installed.