How Loud are Adjustable Rocker Arms with Hydraulic Cam?

[BSB67]

Drilled holes for adjusters/baffle clearance on two sets of valve covers. First time 40 years ago, second time 30 years ago. Have both sets on each of my cars today. No PVC or oil issue at all. One has full time oiling to the rockers. Personally, I think it works great and would do it again.

 

[coloradodave]

I've done both on 2 sets of Max Wedge stock 4 bolt covers at different times. Currently I'm running Comp Pro Magnum rockers with 2 sets of cork gaskets glued together. I can't use mounting studs because of clearance problems with my crossram manifold, but would if I could. I have clearance and no leaks.
In the past I had Harland Sharp aluminum rockers (taller) and had to drill holes in the baffles over the adjusting nuts. IIRC I double gasketed those as well. The rockers were 1.5 and the lift +-.550"

 

[PRHeads]

The summit valve covers are pretty tall, and iirc the baffles are located higher than how they are on factory covers.
I’d be surprised if they were hitting.

 

[PurpleBeeper]

UPDATE: I pulled on valve cover & there are no rocker arm contact marks & the Summit valve covers clear the Isky rockers just fine with only a single cork gasket.

However, I did notice that one rocker arm's (#8 intake) adjustment screw is maybe a 1/4" higher than all the others (?) These rockers have a screw/ball adjustment stud & a locking nut.
a. There is no "slop" up/down on that valve. I will have to rotate the engine to put the cam on the base circle to verify. I first "thought" I had this one adjusted way too loose, but it doesn't appear to be the case.
b. I pulled out this pushrod & another one to compare length & they appear to be the same. (I had swapped out two pushrods in the past & wanted to verify I hadn't installed replacements that were too long....not the case).

I'm running Comp Cams hydraulic lifters that came with my cam & none of them have ever been swapped out. Off the top of my head, this leaves me only two "long shot" possibilities for why this one rocker arm (#8 intake) is adjusted so differently.
1. The installed height of the spring on that valve is MUCH lower than the springs on that head (I don't think so, but I will look)
2. The #8 intake lifter is "stuck in the pumped up position" making it effectively taller than the other lifters. Is that even possible?

 

[coloradodave]

UPDATE: I pulled on valve cover & there are no rocker arm contact marks & the Summit valve covers clear the Isky rockers just fine with only a single cork gasket.

However, I did notice that one rocker arm's (#8 intake) adjustment screw is maybe a 1/4" higher than all the others (?) These rockers have a screw/ball adjustment stud & a locking nut.
a. There is no "slop" up/down on that valve. I will have to rotate the engine to put the cam on the base circle to verify. I first "thought" I had this one adjusted way too loose, but it doesn't appear to be the case.
b. I pulled out this pushrod & another one to compare length & they appear to be the same. (I had swapped out two pushrods in the past & wanted to verify I hadn't installed replacements that were too long....not the case).

I'm running Comp Cams hydraulic lifters that came with my cam & none of them have ever been swapped out. Off the top of my head, this leaves me only two "long shot" possibilities for why this one rocker arm (#8 intake) is adjusted so differently.
1. The installed height of the spring on that valve is MUCH lower than the springs on that head (I don't think so, but I will look)
2. The #8 intake lifter is "stuck in the pumped up position" making it effectively taller than the other lifters. Is that even possible?

Not 1/4". Time to pull the rocker arm assembly and put a straight edge against the valve stem tips to make sure they're even. Also check the adjusting screw lengths to make sure you don't have one weird one. You can also manually put #8 on TDC compression stroke and set two equal length pushrods in those lifters to check that they are the same height. You'll find the problem. Hope it's an easy fix...

 

[Dennis H]

X2

XE 275HL

383/432 Stroker that I built

Love the Charger. Thanks for posting the sound clip. Other than the dancing dipstick, it looks/sounds a lot like mine. Cleaner though. Calms me down. I thought it had too much rolling mass sound unlike some BB Chevies I have heard.

 

[PurpleBeeper]

FINAL UPDATE: I double-checked the rocker shaft bolt torque (ok) & re-adjusted the valve lash, this time zero + 1/2 turn in (hydraulic cam). I very carefully cleaned all the threads. The engine is now running smooth & just a "typewriter" sound to the valve gear which is very even.

I believe my last valve lash adjustment was thrown off by "smutz" on the threads & having some lifters bled down & others still pumped up. I don't think I was getting the "right feel" on the pushrods and/or I just got my adjustment order off (?).

Someone at moparts said, "the rocker adjustment is determined by the valve height", which makes sense. About 4 of the adjuster screws are "oddballs" and I don't believe the valve spring heights were "dialed in" when the heads were rebuilt....so, some of the screws look a touch further in/out than others (maybe 1/8" MAX). The Summit valve covers & baffles definitely clear the Isky ductile iron rocker arms with a single set of cork gaskets.

 

[ms2420]

X2

XE 275HL

383/432 Stroker that I built

I have the same cam in my .040 over 440 sixpack set up. Just curious, how much vacuum are you pulling? Power brakes work okay? Still tuning mine but 11mmHg is about the best I've gotten out of it so far. Also going to readjust rockers as mine is slightly more noisy than yours. It does quiet when warm.

 

[Bee1971]

Zero issues with Power Brakes

Idles about 700 Rpms

13"-14" Vacuum

 

[ms2420]

I have some work to do!

Zero issues with Power Brakes

Idles about 700 Rpms

13"-14" Vacuum