I am curious about those of you who run 150-155lbs (360-365lbs open) of valve seat spring pressure on a hydraulic flat tappet cam. Have you had any issues with hydraulic lifters on a street car with these spring pressures.

I made a rocker arm swap (stock stamped to 1.65) last Winter in my 340 and at that time I had a vendor specify that I needed to use their 120lbs/310lbs springs. So I installed them and drove the car this year and I noticed that the engine would not run any higher than 5600rpms after this rocker swap. (let me clarify. If would, but the power died off quickly past this rpm. Before the swap it would rev cleanly to 57/5800rpms with smaller springs and 1.5 stock rockers.) I discussed this with two different Mopar engine builders, and two different spring manufacturers and they all told me that I needed more spring pressure due to the 1.65 rocker ratio and 2.02" valves. They all suggested an average of 150-156lbs on the seat and 350-375lbs open.

(Note: my original cam card showed 135/300 with 1.5 rockers. But I was not asked and I did not even think about checking what the cam card suggested "at the time" that these springs were specified).

I just finished with my spring swap and all the installed heights came out to show 153lbs average (1.810"-1.824" IH) on the seat and 361/362lbs average open pressure (per the spring chart) at .540" lift. I plan on keeping the WOT shift points at about 5800-6k rpms.

I may not get a chance to drive the car again this year due to the weather, but I just wanted to make sure that there is nothing else that I should be looking at before Spring.

Notes: My cam designer (S.B) said that the cam core will handle these spring pressure with no problems. Comp says that my hydraulic lifters (High Energy) max out at apx. 360lbs but they should be fine. My rocker arms are Yella Terra 1.65's that are rated for 600lbs. My push rods are Manton Series 5 (5/16" x .118" wall, 275,000psi), and I use Brad Penn Green Oil.

I know that I am right on the edge with this current setup, but can I stick with the existing Comp High Energy lifters or should I try a set of the variable timing lifters with this new spring setup?

Thanks

Many old time mechanics and automotive repair shops do not keep current on cams, components designs and improvements.
Most manufactures will suggest a safe limit below what the actual component will live up to such as valve spring pressures, did you verify all the valve springs pressures at the actual installed heights and did you verify that you had at least .060 on each spring clearances from coil bind at max lift? If not do that now before running the motor
As far as those pressures on a broken in cam your good in my opinion, I've used those type pressures for years on both hydraulic and solid lifter flat tappet cams and lifters
Also did you check the actual lift at the retainers with the new rocker arms to verify the true ratios? If not check at least two or more at the retainers, both left and right hand rockers
Mr. Murphy lurks waiting to pounce on unsuspecting hot rodders and racers

Cab,
I measured/shimmed each spring to the installed heights mentioned above. I do not have a pressure gage so the 153lb average is per the spring chart. (1.800"=160lbs, 1.825"=150lbs)
My coil bind clearances are .078"/.088" pending lobe design. My seal to retainer clearances are +.100" minimum. I did "try" to check rocker ratio last Winter when I installed the rockers, but I was having trouble with the hydraulic lifters bleeding off on my final setup. If I remember correctly, I was within .015" of the actual theoretical lift when the lifters were giving. So they are close. Plus I have the B3R geometry kit which helps gain a lot of the lift back too.

Thanks Cab!!

I normally use a solid lifter and pushrod with zero lash to check the rocker arm ratio with either the spring that will be used on the motor after getting the cam degreed in and or a soft checking spring for dialing in the cam timing and checking piston to valve clearances. I've seen around .012 to .020 lift loss at the retainers from the soft spring to big pressure roller cam springs
My next engine build will be checked with both 3/8x.125 wall thickness Manton pushrods and 7/16x.145 wall thickness to see exactly how much lift differences there are between the two at the retainers The search for knowledge on racing parts is never ending
BTW, you can use a drill motor and priming rod to check the actual lift at the retainers while priming the motor, caution it can get messy also

I have an acquaintance that I might be able to borrow a spring gauge from. I swapped out some +.075" retainers for a set of +.150" retainers to be able to get the new installed heights.
Thanks guys.

The rocker arms themselves may have been the cause of the lowered rpm for valve float.

For all their apparent weaknesses, the Mopar stamped rockers have a very small moment of inertia around the shaft centerline. Other rockers have higher moments of inertia and require more spring to make up for it.

Article by Dulcich or Freiburger years ago on a smallblock where they switched from stock to roller rockers and promptly lost 200 - 300 rpm.

R.

x2^^

Another factor may be lifter to bore clearance. That can also affect stability at higher rpm.

On top of the added weight/inertia of the rocker itself, you have the added inertia of the valve/spring/retainer having to travel farther from the increased ratio.
All else being equal, I've seen an increase in rocker ratio show signs of valvetrain instability from one hundred up to a few hundred rpm lower than the lesser ratio did.

If the hydraulic lifter is starting to give it up, the higher spring pressure could make it worse. A lot of speculation, you'll just need to go out and drop the hammer to see if the springs helped out or not. IMO, you made a logical choice in increased spring pressure. I don't know how it will turn out, but you will learn something.

I am learning by reading all of the replies. Thank you all!

"If" the existing High Energy lifters do not like the new spring pressures, is there another hydraulic lifter option?
Thanks again!

Fast lobes, hyd lifters and increased rocker ratio. That's a combo that's hard to make happy.

Solid lifters .006" lash.

Can a hydraulic cam work with a solid lifter? Can solid lifters be bought with the same seat heights?

Solid lifters on a hyd lobe is not a problem. You may need new push rods,but not in every case.

Exactly.

I like the way you put that.

I'm going to use that one in the future!!

http://www.compcams.com/Products/CC-'Hydraulic%20Lifters'-0.aspx

It was suggested to me to try the Comp Cams Pro Magnum lifters (Per CC: 370lbs rating) instead of the existing High Energy lifters (360lbs rating, if I have any issues). I was told to set the preload to .00"-.004" and this would give me more rpms.

Have you guys tried this style of lifter?

How do you set .002"-.004" preload? Do you guess with the adjustment? I have 3/8-24 adjusters. I could get .003" if I found zero preload/lash and rotated the adjuster 1/12 of a turn.

They have a .040" lower seat height, but minus my existing 3/4 turn preload (.03"), so the adjusters might be an extra .01" farther out which is a wash. I could keep my existing push rods if I went this route.

Thanks again.

IMO, this is the best path for you to take at this point.

I don't feel running solid lifters on a hyd cam in a street car is the right move.
If you want to adjust valves, put a real solid cam in it.

If the std lifters don't work out, I would try some hylift-Johnson B-2330S lifters instead.

If those won't get the motor to rpm high enough for you, then you have to decide if you can live with however high it goes, or try a different cam that would allow the motor to reach the rpm level you're after.

Fast,

Thank you for the Hy-Lift part number! I emailed them as soon as I read your response.

Per Hy-Lift Johnson Sales: The B-2330S is no way comparable to Comps lifters. This is the best lifter made for the 340. These lifters can achieve 7000rpms, seat pressure up to 160lbs & open pressure to 450lbs. Pre-load is .030" and the seat height is close to the other brands. He said that this lifter is very popular with you High End Mopar Builders. $224 a set of 16.

If my existing Comps don't workout, then it looks like I have found my next hydraulic lifter!

Thank you for giving me the part number for this lifter!!