Ad Radar
Car Craft
Click here to find out more!

Valve train chatter...unadjustable

Car Craft
Item Posts    Sort Order

Valve train chatter...unadjustable

drxheel drxheel
New User | Posts: 5 | Joined: 10/13
Posted: 10/06/13
05:02 PM

Help!  I have a '69 400 Chevrolet block (377) .030 over, '72 350 crank, lingenfelter .485 custom grind cam, and mid '70's corvette heads that have been completely re-worked with new springs.  Motor has a weiand tunnel ram with two Holley 450's, '69 camaro small cap dist with pertonix kit.  I got the motor form a friend after he grenaded it at the strip when it was too lean with tune port on top with aluminum heads...he blew number one piston into two pieces.  The only difference in my set up, and his, was the use of aluminum heads and tune port on his set up.  The motor runs like a scalded ape in my rat rod. Motor had less than 5000 miles on it and was his daily driver/weekend strip car.  After my first fire up with new pistons, oil pump etc...I went to adjust the was totally unadjustable.  No bog down even at bottomed out rocker arms...which are stamped steel, not roller.  The valve train noise is terrible...sounds like a Mazda b2000 or Plymouth volare.  So i changed the lifters...still the same, but I can at least bog the motor down.  Where is this noise coming from?  Do I need a longer pushrod? I'm running stock 7.8's as did he, but he had Harland sharp rollers. I replaced the lifters with sealed powers from napa.  I have had all my fellow Chevrolet racing builders to look and adjust running and off...we are all stumped!  I hate driving it because the chatter is terrible at 2000 rpms and criusing in 4th gear.  The reason I went with a fairly low compression head is because the thing weights 2000 pounds with me in it and makes plenty of power to make trash out of the 600-16 bias plies.  Do I need diff heads?  I had the steam holes drilled into these to run them on a the stud height different on a corvette head?  I have adjusted running with a cut out valve cover, oils very well, backed nut off until chatter then tighten til stop and and extra half turn...any ideas out there?  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 10/07/13
12:16 AM

are you getting oil out of the push rods when you have the valve cover off???

perhaps the rear cam bearing is out of place... or a piece of oil filter element has clogged the passage..

did somebody set this engine up with restrictors to the oil galleys for solid lifters..

did the front galley plugs get properly installed..

there might not be enough volume to build enough pressure to pump up the lifters

Sbcoilpassagesrearanglepassage Zpsa2408c1a

Sbcoilingdiagramclear Zps0c7eade2

Rearcambearingsbcoiling Zps45a8d337

Sbcoilingdiagramsideview Zps52219491

there is an interesting thing that can also be done...

pull the intake.. drop the oil pump drive priming tool in.. or build you own out of a distributor.. could the lifter bores be Oversize??? so there is too much oil leak..

many engine builders have a run in test fixture..  that bolts up to the oil filter area.. and bolts to the crank.. a big motor spins the engine with the engine oil pan off to see how much the engine is leaking oil from..   verifies oil pressure.. verified compression on long blocks..

i am waiting for a friend with a machine shop to end up with a junk SBC block so i can do some cutaways on the rear oil passages..  pictures are better than drawings i think..  

drxheel drxheel
New User | Posts: 5 | Joined: 10/13
Posted: 10/07/13
05:51 AM

yes...the oil is squirting out the pushrods...I have to place a shop rag over the cut out valve cover or it will squirt you in the face and fly three feet across my garage!
No restrictions in the oil galley that I ever saw...
I had thought about the front galley plugs like you mentioned...but it's making decent oil pressure...about 25-30psi at idle and 40-50 on the street...
Brand spanking new motor except for cam which is probably just getting broken in
heads were decked .020...
Is there any kind of difference between a truck and car rocker arm and pivot ball?
I did prime the motor at the oil pump after replacing the lifters... Good oiling happening...lifters seemed to slip into the galley nice and snug
I did drain a quart of oil out last night and replace with a quart of Lucas...made no difference...I am running 10-30 valvoline...too thin?  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 10/08/13
08:53 PM

could you need LONG SLOT ROCKER arms???

i preset all my valves with hydraulic lifers with the engine off..

either by pulling the distributor cap and turning the crank one quarter turn at a time.. looking at the way the rotor is pointing.. adjust that valve pair..

or mark the damper like this...

Untitled16 Zps6bd4b651

if you don't have long slot rockers and you are hitting the end of the slots.. you can feel it in the rocker arm.. instead of just pivoting.. it will jump up and down as its levered against the end of the slot..  

drxheel drxheel
New User | Posts: 5 | Joined: 10/13
Posted: 10/09/13
05:41 AM

Thanks long slot? How are they longer? What should I look for on my current rockers as far as wear marks?  Also, I am running an electric oil press's not moving when I increase in rpms...gonna put the mech gauge on it... Could be an oiling prob, or the elect rear cam bearing cocked...oil press seems stuck at meter electric this a common prob with 400 sbc?  If I had an oiling problem, would I still get apparently good oiling through through pushrod/rocker arm like I am?  

drxheel drxheel
New User | Posts: 5 | Joined: 10/13
Posted: 10/23/13
07:23 AM

Dropped a valve...heads were decked...cracked a forged piston on #2... Antifreeze in all 8 cylinders...problem solved!lol! Witness marks on all pistons which are dished with valve relief...did napa deck my heads too much?  Since right head is ruined, I have a new set of heads with guide plates and 1.6 roller rockers....same set up that was originally on the motor when my friend had I need to clay the pistons to be sure?  Never dreamed I would've needed to do it last time based upon these dished pistons  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 10/23/13
08:17 AM

too much lift..

too much duration...

incorrect cam degree in...

the valves can open faster than the piston can move down off TDC...

must check with a mock up build and clay.. or other... even one of the video scope cameras from harbor freight thru the spark plug hole. but that gets kinda iffy.

there are articles on piston valve clearance in most of the magazines..

HR.. CC... SC, CHP. Circle track..

this is a well written article to start your clearance needs...

i have had this issue myself..   had to notch the pistons in my big block chevy..  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 10/23/13
08:21 AM


please use a sharpie  to mark them..

check the other pistons.. for marking..

any valve that might have struck the piston..

please DEFACE the stem at the keepers so it cannot be reused by anybody...

please... depending on the bore size.. you will also want to have the block and crank checked for cracks...

save this set of main bearings and rod bearings to use a a set up set..

so you can mostly assemble the pistons and rods in the block.. without the piston rings to check the piston valve elarance..  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 10/23/13
08:34 AM

there are a LOT better heads than mid 70s 624's or 882 castings anyway...  

dond1965 dond1965
User | Posts: 72 | Joined: 11/13
Posted: 11/28/13
04:43 PM

you said the motor had a broken piston when you got it. the head gasket must have been too thin for the piston deck hight used by both of you, if the pistons touched the heads. or as the others said not deep enough valve notches in the pistons.