I'm not sure at what point the open pressure starts to become a concern with compressing hydraulic lifter and loosing valve lift, but it may be worth finding out if you plan on using these springs.

 

Good point. I had some rough #'s on this before from a thread on Speedtalk and I need to find it again. The high rpm, low leakdown lifters help dramatically there. I'm using the high rpm low leakdown Johnson lifters partially for this reason. I can also control the bleed down rate with oil weight per Joe Sherman and Chris Straub.

(Mike Jones has one more hydraulic roller lobe that's even one step more aggressive than this one, if you can believe it; some people run my lobe with 1.7 RRs.)



Adam

 

Found it!

Here's the thread: http://www.speedtalk.com/forum/viewt...47549&start=15


Mike Jones (CamKing on ST) replied:

A std OEM hydr lifter has a Leak-down rate of about 20-80 seconds.
A "variable duration" hyd lifter (AdamEdit: Rhodes) has a Leak-down rate of about 8-20 seconds. This will make the cam act smaller at low RPM's(when the oil pressure is low),
then act normal in mid RPM's(as the oil pressure increases), then act small again, as the pressures working against the lifter, overpower the oil pressure.
A "High RPM" hydr lifter has a Leak-Down rate of about 90-120 seconds. This will make the cam act a little larger at low RPM's, but will not bleed down as much at higher RPM's, and can handle more spring pressure.


With a minimum of 2x the leak down rate (and a best-case of 6x), I'm hoping that I'm in a dramatically better situation vs. an oem hydraulic lifter. Mike sells his own slow leakdown hydraulic lifters that work with his hydraulic lobes but I'm pretty sure they're just rebranded Morels and I don't really want to buy $900 lifters at this point. I got mine new-in-box off of CL for $325 so I'm definitely going to try them first and up the oil weight up to 50 weight if they start bleeding down.

My Johnson (now technically Scorpion) lifters are rated to 7,000 RPM although I'm sure that's with less aggressive lobes and probably lightweight valve train components; I'm hoping that the lower beehive spring pressures, lighter weight retainers, and 700RPM less than their rating will make them work for my combo. I'll probably just run em and set my rev limiter below where they start bleeding down and just be happy as long as they hit 5,800 RPM. (My HP peak is supposed to be 5,850, anyway; my 19.25" intake runners (plenum to valve) won't make power much above that anyway.)


Correction: The PAC spring's open pressure should be 349.5 lbs @ 1.2" (height at my max valve lift); it's rated for 358 open @ 1.175 and using the new maths skills you guys taught me, I plugged in the 340lb spring rate and worked backwards to 349.5 lbs open @ 1.200". (This is fun!)

Adam

 

do you have digital calipers? Just extend the central flat rod to the top of the bottom shim and the body to the base of the retainer. The reading is the same as the jaw opening.

http://www.compcams.com/Base/pdf/ValveSpringChart.pdf

Look for installed height row and then seat pounds. spring# 914 could work 147# closed and 367#@ .600 lift. the diameter might require the matching retainer.

Then you have to jump up to 1.900 installed height for more spring choices. Which is doable with +.100 retainers.

this is just comp cams list. Other vendors have other choices. It has been my advice on ordering heads for years is to get +.100 valve stems and start off with 1.900 - 2.000 installed height possible when ever you are using roller cams with .600 You can always shim springs that have lots of space to coil bind. spring degrade and you can pop them off and add a shim in relatively low rpm motors (sub 6500)

About destroyed my AFR 210 head. When I floated and broke off a 2.08 Manley Raceflow valve years ago in my 427 Motown SBC

 

Update: I called PAC (very knowledgeable and helpful) and Comp (had to ask a lot of questions and then go away and come back later to provide me recommendations and essentially said that their recommendation was borderline and maybe I should call PAC to find springs.


In order to switch to Beehive or Conical springs I need different spring locators (I guess because the inside diameter of the spring is a different diameter), this means removing the blue rubber-ish looking valve seals (Viton?) they look like this picture: http://www.jegs.com/images/photos/20...249-518-16.jpg




I've been told that it MIGHT be possible to remove the valve seals carefully with vice grips and put them on again without messing them up but it's probably not worth the risk. I have no idea what spec valve seals to order nor how to actually remove / replace the valve seals.

-Is it simply a matter of grabbing the old ones with vice grips and pulling them straight up and out and pushing new ones on in their place? (after removing the locators (there were locators installed on one head; just not the other))


When I measure my spring installed height I should be measuring it with the locators already installed, right?


-I'm also not clear on whether I have square valve locks or radiused valve locks- when I look at them they are both squarish and roundish.... I can post pictures...



Adam

 

Vice grips? No. Use two flat blade screw drivers and carefully pry up from under the seal.
To install use a socket that spans the center seal section and rest on the perimeter of the seal then tap them on with something not too heavy. Ie NOT a 16oz hammer.
The seals can be cut when removing the valves. If you want to pull the valves and reuse the seals then use a split straw or some such device to put around the end of the valve stem where the locks engage so as to not cut the seal while removing.
This is not a concern while putting the valves in through the seals.

 

<$15 on Amazon for the correct tool.



Do you really want to risk burning oil and having to take the entire top of your head apart to save ~$25? Get new valve seals.

The process is very easy if you have the head off of the block.

 

<$15 on Amazon for the correct tool.



Do you really want to risk burning oil and having to take the entire top of your head apart to save ~$25? Get new valve seals.

The process is very easy if you have the head off of the block.[/QUOTE]

Update: PainfullySlow, thanks for this recommendation. I didn't know this tool existed, and $15 is super cheap. I removed all of the valve seals yesterday and the seats / ID locators and 0.015" shims that were under them. I'm 95% certain I'll be able to reuse the valve seals and reinstall them with no issues.


I then took the opportunity to double-check my spring install height using my new Proform spring micrometer: if I'm reading it right: 1.807" (I assume I'm supposed to crank the thing as hard as I can.)

[QUOTE=PainfullySlow;1596397589]


I think I have enough info to call PAC Springs when they open again on Monday and order springs, retainers, keepers, and locators.


Adam

 

Follow-on Question:

My new springs, retainers, keepers, & seats showed up from PAC springs.

I took the time to measure the installed height after adding a shim under each seat (needed), and my installed heights now vary between 1.802" and 1.819" --Is this an "ok" variation from valve to valve or do I need to shim the 1.819" valve with another 0.015" shim (I don't currently have any more).


Adam