Logo

Replaced lifters, adjusted valves, now wil not run - (bent valves?)

bluedog2

Member
I think I may have bent some valves by messing up valve adjustment. Cru RH350, Mark IV. When boat went in water I had a stuck hyd. lifter so I replaced all lifters. Engine restarted with noisy lifters. SO, I adjusted lifters (engine off - 1/2 turn after contact), left covers off so as to do running adjusted later. Tried to restart but when turning engine over heard a very weird sound. Engine was turning over but I have never heard that kind of sound. Like: "mmm, mmm, mmm". No ignition. re- adjusted valves. Checked for other problems - replaced carb, tuned distributor, re-set timing. Now the best I get is barely running, lots of gas, black plugs and hissing back through carb when it quits. Some valves will tick, tick afterwards like lifters are settling down. Push rods do not appear bent and will rotate freely, valves appears to go up and down correctly, but it will not run for a more than 15 sec and then load up. My fear it that I mixed up the adjustment sequence and had the engine 180 degrees out when adjusting the valves and therefore created my problem. Next steps? I am thinking of pulling timing cover and/or heads. Thanks for any input. Tim
 
First, do a compression test--that will tellyou if the valves are bent. If low on a few holes, pull the head(s).

That motor is famous for sucking in water on the exhaust side, which tends to rust the valves and make them hesitant to close. Seeing they are now all going up and down, you might be okay in that respect, but one of them may have stuck a piston while stuck open, bending it.

Good luck!

Jeff
 
I'D be inclined to make sure the valves are adjusted properly before yanking the head...compression test afterwards will tell you if you have them adjusted well (or show a cylinder needed further attention).

You also need to make sure the ignition sytem went back in correctly as a bad connection or crossed wires will yield a poor running engine...
 
It's rather unlikely that a defective cam follower itself would cause a bent valve.


Bring the crankshaft around to #1 TDC on the Compression Stroke...... Must be Comp Stroke.

Recheck the phasing of the distributor. Adjust as needed.

Use the static 8 stop procedure for your initial cam follower adjustment (not the 2 or 3 stop).
Remember that we're not setting or adjusting valves...... we're setting the hydraulic cam follower plunger depth.

Start @ #1, adjust both Intake and Exhaust....... and go right down the firing order while indexing the crankshaft 90* for each cylinder, and in the direction of rotation.
Your info says "Cru RH350"... so if this is a REV RH rotation engine, you'll be indexing the crankshaft CCW (from #1 TDC) when viewed from the front of the engine.

If you get this right.... you will very likley not need to go back through these dynamically.


And again, if this a REV RH engine, your distributor still turns CW same as a standard LH rotation engine.


Do this prior to a compression test.

.
 
Last edited:
If you don't keep careful track of which valves you have adjusted, and which not, you can get in trouble. (Ricardo's "keep is simple" approach is a way to be absolutely sure you have got it right). Once you do your contact and then 1/2 turn that is all that is needed. But if you feel that push rod again later it will have loosened up and will feel like you missed it. A second adjustment could then cause the lifter to bottom out and your valve will remain slightly cracked open. Obviously that will cause bad symptoms.
CaboJohn
 
The GM cam follower plunger has approx .100" of internal travel.
The rocker arm stud thread pitch, X's rocker arm ratio = the fraction of one full turn required to set the plunger @ .0XX" depth.

Just for fun, launch this.

http://www.youtube.com/watch?v=lorANZ1Tptw


This one is good also, and it represents the 8 stop procedure.

http://www.youtube.com/watch?v=89o5rLpbCgI&feature=related

What he fails to mention (not faulting him), are the cam followers prior to oil priming, and wtih the intake manifold not yet installed.
This is a perfect oportunity to view the plunger while the adjustment is being made.... but again, prior to oil priming.

Just as the mildly spring loaded plunger begins to move downward, you will have achieved "zero" lash.
Because this spring pressure is so mild, it can be somewhat deceving as to just when the preload actually begins.

Point being...... for a very accurate initial adjustment, use the 8 stop procedure, and do this prior to the intake manifold being installed, and prior to the oil priming.

I can tell you first hand that I've been using this method for over 45 years..... and it does work. :D



.
 
Last edited:
Thanks for the quick responses. I went down and re-set valves this morning (prior to reading responses) using 2 step w/ 3/4 turn (RH hand sequence). Engine is running but very rough, timing is dead on 8 degrees, (new plugs, wires, pts, cap rtr.). It sounds like it is missing on 3 or so cylinders. Ricardo's method sounds better but I am afraid I am so where in between pumped up and not pumped up lifters as some of them maybe near adjustment and others have worked either full up or down. Can I back off all lash and spin motor to get all of them primed so as to have a common starting point? Thanks again.
 
The 2 or 3 stop will get you close only, IMO.
When this is used, it's best to go back through these dynamically.
If the 8 stop is used, we rarely need to go back through them.

Don't worry if the followers have been oil primed.... or what some call "pumped up".
The concern is that you don't mistake the push rod turning freely, for some plunger setting after the followers have bled off some oil pressure.


.
 
Back
Top