Comp Cams 8959 Lifters Noisy

[ThumperNZ]

I am writing this because CC have not answered a tech query and i can't wait forever.
I have built a full roller 348 W block Chevrolet engine, forged pistons etc. The CC 8959 roller hydraulic lifters are noisy at idle with 3/4 turn preload. I've used Howards Cams springs #98437 because CC don't offer a spring at the low 1.68" installed height that the 348 requires. The seat pressure is 135lb, spring rate is 455lb per in. Coil bind is @ 1.055". The cam has 0.499" lift.
Full spring specs are:
Outer OD 1.435"
Outer ID 1.035"
Inner OD 0.937"
Inner ID 0.697"
Installed height 1.68" 135lb
Rate at 1.19" 390lb
Rate per in. 455lb.
Coil bind 1.055"
Free clearance at full lift 0.126"
I'm running CC roller rockers #1820.
Pushrod lengths have been checked for ideal geometry.
What I'm asking is this, is the lifter noise a characteristic of these lifters?
Is the fact that I'm running a stock oil pump a factor? It's running 30 psi at idle.
The engine also exhibits an imbalance feel from idle which disappears as it increases rpm, I'm putting that down to uneven valve opening at idle.
It has good vacuum 18-19 ins so I don't think it has a vacuum leak.

[F-BIRD'88]

The more spring pressure the faster the hyd lifter bleed down at idle.
So use a thicker viscosity oil to reduce idle bleed rate.
Set the rocker preload adj for whats needed. If it needs 1-1/4 turn so be it.

All combined clearances in the hyd lifter oil feed path wil effect the real oil pressure at the lifter. (oversize lifter bores/undersize lifter body. Cam bearing clearances etc etc. The thicker oil will help.
Wrong distibutor body diameter makes a big difference too.
Effects oil leakage in the cam oil galleries.

[DaveMcLain]

Roller rocker arms will tend to make more noise than non roller ones. Also the cam profile used can be a BIG factor when it comes to valvetrain noise.

[ThumperNZ]

The more spring pressure the faster the hyd lifter bleed down at idle.
So use a thicker viscosity oil to reduce idle bleed rate.
Set the rocker preload adj for whats needed. If it needs 1-1/4 turn so be it.

All combined clearances in the hyd lifter oil feed path wil effect the real oil pressure at the lifter. (oversize lifter bores/undersize lifter body. Cam bearing clearances etc etc. The thicker oil will help.
Wrong distibutor body diameter makes a big difference too.
Effects oil leakage in the cam oil galleries.

So, taking into account spring pressure, will there be anything to gain to lower the seat pressure?
I have some +0.05" valve locks which will take off 23 lb from the seat.
I'm using 15W40 Mineral Oil at the moment, I don't usually use oil thicker than that, in fact I was considering whether the oil was too thick already. I usually use 10W40, we live in a moderate climate so 10W30 not needed.
The other post re Roller Rockers, I've used these CC rockers many times without noise, so doubt it's that.

[F-BIRD'88]

Reducing the spring pressure may help. A different oil may help.

More rocker preload sdj may help.

[RevTheory]

Didn't I read on here years ago that the fix for noisy hyd/rollers was a ~.020 hole at the forward lifter galley plugs?

[CGT]

Didn't I read on here years ago that the fix for noisy hyd/rollers was a ~.020 hole at the forward lifter galley plugs?

I've done that on BBC''s with varying success. But I don't think I've heard of anyone trying it on a W engine.

[Walter R. Malik]

Except for the race / short travel hydraulic roller lifters from Competition Cams, their regular hydraulic roller lifters are trash. They have excessive leak down and the hydraulics won't hold adjustment like they should. They need to be adjusted near the bottom of the plunger travel in order to work even half way decent.

[PackardV8]

What heads? What rocker covers?

I've noticed some cam/lifter/spring combinations which are tolerable with iron heads and stamped steel rocker covers become noticeably noisy when used with aluminum heads and rocker covers.

[Newold1]

Here is a quick checking fix determiner. I suppose you are using the stock type metal valve covers? Those covers with roller rockers from comp are real acoustic bongo drums.
Try putting in the original or stock rocker arms and check the clatter noise before and after. I suspect the roller rockers are the drum sticks.
If it turns out that's your problem get a good set of cast aluminum valve covers and install some metal sandwich sound deadener on the inside top of the valve cover. Check clearance and fasten so it won't come loose and drop down on your rockers and such. Done this on BBC's and it works like a champ. Alternate course of action- "Live with IT!

[ThumperNZ]

What heads? What rocker covers?

I've noticed some cam/lifter/spring combinations which are tolerable with iron heads and stamped steel rocker covers become noticeably noisy when used with aluminum heads and rocker covers.

Stock heads and covers. The owner wants the stock appearance, to go with the '61 Bubbletop.
I might try another 1/2 turn preload.
I noticed on another thread, discussion about oil viscosity, so I may try varying that as well.

[Walter R. Malik]

What heads? What rocker covers?

I've noticed some cam/lifter/spring combinations which are tolerable with iron heads and stamped steel rocker covers become noticeably noisy when used with aluminum heads and rocker covers.

Stock heads and covers. The owner wants the stock appearance, to go with the '61 Bubbletop.
I might try another 1/2 turn preload.
I noticed on another thread, discussion about oil viscosity, so I may try varying that as well.

Get a .100" longer pushrod than what you have and turn them down at least a whole turn and a half from "0".

[Geoff2]

I would not go lower than the current 135lb seat pressure; it invites valve bounce. Also higher rocker ratios cause greater bleed down due to mechanical leverage, so if 1.5s might help slightly if you are using higher than this.
Also, in NZ, you should be able to get Penrite oil. Many P' oils are non Friction Modified & it is written on the container. FM is code 'for making the oil thinner when it gets hot'. I find about a 10 + psi increase in idle oil pressure using a non-FM oil compared to a FM oil. I think our American friends are stuck with FMed oils because of stricter govt regulations governing oil, but we are a bit more liberal.

[GOSFAST]

We've used/sold a bunch of Comps retro-lifters over time, haven't had a single issue with many that have been in service for over 10 years now. Have some in the 15 year area!

The 348"/409" lifters should be the same as the 854's for the BBC's but with a link bar length of the Ford?

We run the spring pressures at 150#/160# closed on the hyd-roller platform but with a slightly lower spring rate than yours! Would not use 135# (and definitely NOT lower) closed, 135# is a BBC flat-tappet closed number, not a hyd-roller.

Thanks, Gary in N.Y.

P.S. Just curious, what did you do to the heads to use the 7/16" stud-mount rockers on that "W" platform? Just finished some 409" heads recently, screw-in-studs/guide plates!

[ThumperNZ]

We've used/sold a bunch of Comps retro-lifters over time, haven't had a single issue with many that have been in service for over 10 years now. Have some in the 15 year area!

The 348"/409" lifters should be the same as the 854's for the BBC's but with a link bar length of the Ford?

We run the spring pressures at 150#/160# closed on the hyd-roller platform but with a slightly lower spring rate than yours! Would not use 135# (and definitely NOT lower) closed, 135# is a BBC flat-tappet closed number, not a hyd-roller.

Thanks, Gary in N.Y.

P.S. Just curious, what did you do to the heads to use the 7/16" stud-mount rockers on that "W" platform? Just finished some 409" heads recently, screw-in-studs/guide plates!

The head rocker bosses were milled, I forget how much, but I used the std top height to measure down for the 7/16" rocker stud, added the thickness of the ShowCars guide plate which only mounts on the bottom studs. Also milled the top row, all adjust with equal engagement.