QUIKDECISION

I HAVE MY OVAL PORT 781'S AT THE MACHINE SHOP.
I PURCHASED COMP'S BEEHIVE VALVE SPRING pn 26120.
the adversited seat pressure is 155 lbs at 1.880 spring height.
This is using the comp valve spring retainer PN 795-16
Both of these items were purchased from Summit.
Our Machine shop is finding the seat pressure to be 210lbs at a 1.88 height. I had planned on using these springs with the stock hp-500 roller cam.
The Merc and the Crane are one in the same.
Merc#2409-848906A1/ 2409-848491
Crane#169611
284/292
222/230
.576/.598
110* LSA
105*ICL
The folks at the machine shop are also worried with the .598 lift,.... binding and such...
Any ideas on this? Do you think that Summit may have the wrong springs in the right box?
Thank you much for any thoughts you may have on this.

rmbuilder

Doug,
Be sure the machine shop is measuring the spring force with the retainer & spring on the Rimac, but not including the retainer height in the dimension. See the following illustration. The 26120 spring measures 210# force @ 1.730" (.150" less than the rated 1.880" installed ht.) which could quite possibly be the measured dimension less the retainer thickness. Installed height is from both ends of the spring, not from the top of the retainer to the spring seat.

The concerns regarding coil bind are legitimate as the spring set up 155# @ 1.880" with a .598" ex lift will leave you only .052" margin from stack @ full lift. You would have the option of setting the spring @
1.890" @ 151# seat
1.290" @ 373# open
.060" margin stack

1.900" @ 147# seat
1.300" @ 369# open
.070" margin stack

Bob

formula31

I would hope an engine machine shop would know how to measure the spring height properly. If not, you're in much deeper trouble. Coil bind and clearance from the retainer to the seal are issues that need to be checked. You will also need to check valve to piston clearance when the heads and cam are installed.

rmbuilder

Formula31,
Comp does not manufacture a beehive, ovate wire, single spring that rates within 50# of the 210# measured seat force. These springs are easily identifiable which eliminates packaging/shipping problem. It seems the only option would be an error in measurement.

The springs are rated for .590" max lift which works fine on the heavier intake valve and it should not be a problem making up the .008" on the exhaust side.
Bob

QUIKDECISION

I want to thank you both for taking the time to respond.
Bob, once again, you have provided great information.
I have sent you an Email via this forum. Happy Easter to you both.

talon25

RMbuilder,

Have you used these bee hive springs ? what do you think ?
are they the way to go or what ? Thanks

formula31

I repeat. If the shop you have your stuff at cant measure spring height correctly, get your stuff out of there.

Raylar

We only use a conical ovate valve spring on our aluminum heads in our kits and I can tell you we would not use anything else on a mild to moderate hydraulic roller camshaft in any BBC. I have been touting the benefits of these springs for a few years now. Forget big stiff single w/dampner or double valve springs on BBC's with hydraulic roller cams. Keep your valve train as light as possible and eliminate the heat of mutiiple springs and dampners rubbing up against each other. Don't beat your valve train to death in short hours. These type of springs will go long hours without loss of spring pressures and they will keep the lifters, pushrods and rockers from destroying themselves. It's not old school, but it's a technology who's time is definitly overdue!

Ray @ Raylar

BillK

Quick,
I hate to say it as I use Comp Cams stuff almost always but ... lately I have been finding some of thier springs that are nowhere near the advertised pressures Make sure your machine shop puts them in the tester and loads them to coil bind a couple of times before checking them. They usually will lose at least 10-15% the first time you mash them down to coil bind. You might have to send them back and get another set. Personally I agree with your shop that those springs are going to be too close to coil bind for comfort. I like to see at least .100 in any type of endurance application. I have done 2 complete 502's and several sets of heads this spring and have been using a Comp dual spring that sets up at 1.950, can't remember which number right off hand. This is with the Crane 168741 cams ( I think) or whichever of thiers is the same as the Merc 525 cam.

QUIKDECISION

I just returned from the machine shop re: the install the of the beehive valve springs.
I was hoping to use stock length intake and exhaust valves. They are new and the intakes are severe duty and the exhaust are inconnel.
The measured distance from the the bottom of the valve retainer to the top of the spring pocket is 1.73 inches. That will be tough to obtain the recommended spring height of 1.88. The shop is reluctant to machine much out of the spring pocket for fear of hitting water... Does this necessitate longer valves???These are the oval port 781 heads... The valves have already bet cut for the valve job...