So I was setting valve lash last night. As I am hand cranking the motor it sounds as if the valves are binding a bit, I am getting a bit of a pop sound as the springs compress.

Here is the info.

I am running the stock '72 LT-1 cam, springs are rated for .550 lift, and I am running some stamped roller tip 1.6 rockers. I am using the stock guide plates, studs, and bought some stock length moly push rods. Also running stock solid lifters. Valve job was touched up, and new stock length valves were used.

I checked coil bind at full lift and intake is like 80 plus and exhaust mid spring I was getting 70thou clearance between coils..

I was showing cam lift is .3057 / .3234ex. so with 1.6's I should be around .489 / .517... Correct?

Could it just be the inner dampner spring on the inside making the sounds? Need a lil direction to start looking cause when cranking by hand everything looks fine but it is not all quiet like a hydro setup.

Thanks, Jason

 

Also I set the lash cold out of car at .022 and .028. Manual says to set at .024 / .030, done some reading and most said to set it a touch tighter.

 

Just realised that I am running non self alligning rockers... hummm I thought the guide plates would keep things inline...

Could this be my issue? They dont seem to be binding anywhere or rubbing. sound is more like to be comming from springs.

 

Whats the reason for the stamped rockers

 

If you trying to run 1.6:1 rockers on a stock head the noise your hearing is the pushrods rubbing on the cylinder heads as they bind up in their holes. You need to drill the heads out for better clearance or use a die grinder to open those holes.

 

Compcams has a drill bit alignment tool to slot the pushrod holes.

Pushrod Slot Elongating Louis Tool
PART #4710
DESCRIPTION:
When switching factory Small Block Chevrolet heads over to 1.6 ratio rockers, the pushrod will rub on the bottom of the pushrod slot in the head. Long time cylinder head man Louis *** designed this tool to simplify the modification needed in the situation.
• Tool allows use of hand drill and 5/16" drill bit to elongate the pushrod slot in the precise location and size necessary
• Tool is designed to wear so a new one should be purchased for each set of heads

 

That tool won't work on a set of heads set-up for guide plates, only on normal heads. Die grinder time!

 

I used the rockers cause I knew they would fit under the valve covers. Full rollers I was afraid would not work with the alum. valve covers.

Thanks Eric! What sucks is the heads are torqued on the motor so now I need to see about sealing up the motor and try to grind the clearance. If I pull a push rod I should see some rubbing correct?

 

If I buy a set of stamped 1.5 rockers should I get self alligning or non? I was thinking the guide plates would keep the rocker on track. Am I wrong?

I have the factory rockers, but after the valves all got bent was not sure about using them, figured there was a chance they could have been tweaked when the valves crashed.

I was thinking since I was gonna have to replace them I would get the 1.6's and might as well get roller tips as there was not much price difference. Should have done a bit more research I guess.

 

Put on stock rockers and the noise is not as noticeable. Was looking at old springs and looks like the inner dampner rubs a bit on the inner part of the spring landing. So makes me wonder if the new springs are just rubbing a bit and making the light pop noise I was hearing...

 

I do know that when I tried to swap a set of 1.6 intakes on my wife's LT-1 a few years back that the pushrods bound up in the holes of the cylinder heads and would have caused parts failures if I hadn't caught the problem before running the motor (1970 LT-1 with #186 casting heads.)

The higher lift of the 1.6 rockers could cause additional noise from the springs if that is the only source of noise. I would look carefully at those push rods if I were doing the motor. Maybe all your hearing is spring dampner noise or spring binding from too much lift, many 1.25" diameter spings are only good for around 0.490-0.500" lift, the 1.6 rockers could be taking them past their operating range, you should be able to determine if they have enough clearance with a paperclip and see if it will fit between the coils and flat dampner at full lift. The current trend in racing motors is to run springs down to with-in 0.060-0.040" of coil bind to dampen harmonics but, in regular street motor with normal springs/parts your living dangerously if you try this "trick".

Don't think your alone in being frustrated, I just fired off a new LT-1 over the weekend and it looks like I have some water leaks out of the rocker studs (yes I used Permatex teflon sealant!) and 2 valves are 0.004-5" looser than they were set on the build-up, either stuff is seating in or I have a cam going flat with some pretty light valve springs (115lbs on the seat, 290lbs over the nose.)

Task for the coming week, pull the intake manifold/valvetrain and look everything over then reassemble and test it again. I used Joe Gibbs Racing break-in oil on this motor, now I will see if this stuff is worth the $8Qt it runs. Good thing this motor wasn't in the car but run in on a test stand or I would be really upset right now.

 

simply having guide plates does not ensure rockers align w/ valve tips.

To obtain proper alignment, usually some or all guide plates will need to be shifted/adjusted. Loosen the rocker studs just enough to pry/shift plate.

add- and stock rocker with No roller tip is very forgiving / allows a wide range of alignment.

 

what kind of spring is rated for .550 lift and uses a dampner? Were the spring seats machined for these springs? I use a light pair of springs in #1 cylinder to rotate and check with dial indicator by lightly pushing down on valve to see valve clearence. You can also try the 1.5 rockers without guide plates to see if popping goes away, if it does You will have to grind pushrod gap in head. But then you will be able to use the 1.6 rockers. Just My 2 cents worth.

 

Elgin p/n RV1943X
quite popular, drops-in stock chevy spring pocket, +0.100 height, coil bind at about 1.16". Melling & others market same spring.

 

Thats interesting we never had them back in the Day. I actually went out and bought a spring seat cutter for home use even though I worked in engine machine shops back then. I like when someone makes something simple to help from spending big bucks to get things done.

 

If you haven't run the engine yet, the pops could be the damper sticking against the spring - did you squirt oil on the springs and dampers?

 

Also the valve seal will creek if they are dry.

If your running pushrod guides and the heads have guides built into them this may cause interference on the pushrod. I would take the guides off and see if that helps before grinding on the head cast in guides.IMHO

 

I am back to stock besides springs and I am using Elgin Spring kit. I am using the stock rockers and still getting a bit of pop'n. Starting to wonder if it is not just the damper sticking to the spring like mentioned above. Like mentioned above looks like even on the stock springs the damper was rub'n a bit on the inside. Just wonder if the new springs are just rub'n the same area....

I cranked the motor over several times and didnt see any marks on the pushrods. The guide plates are the stock plates.


Below is what i am using. Stock cam, guide plates and stock length moly pushrods.

8 Stainless Steel 2.02" Intake Valves from Elgin Industries
8 Stainless Steel 1.500" Exhaust Valves from Elgin Industries
16 RV943X .550 lift valve springs from Elgin Industries
16 Hardened steel spring retainers from Elgin Industries
16 Pair hardened 7° valve locks from Elgin Industries

Part # Spring Type O.D. I.D. Seat Pressure Open Pressure Coil Bind
RV943X Single w/damper 1.260" .880" 110# @1.700"
90# @1.750" 325# @1.200" 1.150"

 

If installed height is approx 1.700", I would Not recommend elgin RV943X spring with .550" VL ... I'd nix anything over .490" VL w/ 1.700" IH.
... your description of your valvetrain looks like a fleabay ad ... verbatim? Perhaps those retainers/locks provide more installed height than nominal 1.700" ? If they do ... the valve tip may be sitting so low that underside of rocker may be hitting retainer? Or it may just be normal operating noise.