Airbornec507

I have the following items that I measured at 1.730" installed hight for my new beehive springs on my heads without shims: the 795-16 10* retainers, 611-16 10* locks and 4705-16 locator seats.

I may have found out why I have valve float in the upper rpms with my current set up (triple valve springs) is due to the installed hight of 1.740" that the guy who built my heads installed the springs at.

Overall I don't know what the seat pressure is for the beehives at 1.730" but I'm shooting to get them installed at 1.750". Is there any other way to get the installed hight to 1.750" without having to remove the heads and getting them worked(that would suck)?

Thanks!

The Engineer

Which beehieve are they; Comp 918s, PAC-1518s or whatever? Also, what is your lift at the valve? You may be able to get away with that installed height, if you don't have too much lift. Just do the math, you don't have enough info in your post for me to figure it out.

WD

Airbornec507

I have the PAC-1218 Beehive valve springs. My CC306 cams intake max lift with 1.6 RR is .544". I'll check to see where coil bind is on these springs with that installed height too.

Coil bind of those springs are 1.140". Installed hight of 1.730" - .544" = 1.186 should be safe. However that's still pretty close to coil bind..........?

94CamaroZ28

The performance porting shop I used to work for felt that .060 clear was needed before coil bind to be safe. Others say it should be as much as .100. I think installed height should be a minimum of 1.744 (1.684 plus .060 free). 1.730 gives you only .046 free; that's a bit too tight for my taste...

You could use offset locks to get more installed height, but then you need to worry if the rockers will clear the retainers with the reduced tip.

Airbornec507

Based on my exhaust lift numbers of .576" and according to your numbers I need to shoot for an installed hight of no less than 1.775". So the question is what sort of lock do I need to go from 1.730" with the CCA-611-16 to 1.775"?

rskrause

How in the world did you decide on that installed height if you don't know what you want the seat pressure to be? You are going about this backwards. If you have float with a triple spring, why do think the beehives will be better?

Here is something I wrote for our shop's website:

Valve Lift and Spring Length Selection
Once you have determined the pressures you need, you can select a valve spring with the appropriate length by taking into account the amount of valve lift in you setup. Start with the installed height needed to get the required seat pressure. Subtract the maximum valve lift plus at least 0.050-60" for coil clearance. If the installed height minus the sum of the valve lift plus 0.050" is more than the coil bind height, the spring has enough lift. Of course, you will still need to check for interference between the retainer and the valve guide, the rocker and the retainer, etc. If the numbers indicate the spring is too short, you will need to pick one with a similar rate but a higher installed height. Special valve retainers or longer stemmed valve may be needed to accommodate higher lift. Some engine builders prefer to keep coil clearance at a minimum. This tends to have a dampening effect on the coils, potentially preventing harmful harmonic vibration. If this approach is chosen, each spring must be carefully checked for adequate clearance.


Rich

rich152

Either way the math is not to hard. Look up the seat pressure at there recomended installed height. Then find out what the pressure per compressed inch is. The amount gained divided by the compression per inch will tell you your seat pressure. But short and skinny you can order a + or - retainer to move your height up and down as long as you have room between the rocker body and retainer. I hope that makes sense. If not I will put it up in equation form. But like Rich said how do you think that going to a lighter spring is going to fix your float problem unless they have a higher compressed pressure and faster rebound rate?

Airbornec507

Once I talked to Lloyd about the cam I have he recommended these springs and locks,retainers, etc. without knowing the specs on the valve stem hight or the extent of the milling done to the valve shelf/seats. He recommended an installed height of 1.750" with the CC306. I have not been able to find what comp recomends as the recommended seat presure and compressed pressure for the cc306. However due to coil bind etc. I would like to shoot for a 1.775" installed hight. I just checked my clearances with the 1.6 Comp Pro Mag rockers and my locks/retainers. The retainer I have (CC-795-16 retainers) seem to be pressing the spring down a lot compared to the somwhat flat retainers that where installed on my previous set up. If I could find a retainer/lock combo that would give me +.045" more hight from the current set I have(CC-795-16 and CC-611-16) that would put me in the sweet spot.

Also as far as the triple springs, etc. I like the fact that the beehive springs have a lot less mass to control. Also many folks have had great results with going from double/triple valve springs to the beehives and settled valve float issues. I don't know what the seat pressure was with the triple springs I had on there but triple springs with an installed hight of 1.740" has to be bad for a hydraulic cams longevity.

Seat pressure with these springs are:

1.8" = 130
1.2" = 330

truedualws6

If you use the 614-16 super locks (they are +.050") you will end up with
a 1.78" installed height.

mdacton

lift on that 306 cam you posted is w/1.5 rockers......redo you math holmes.

also how are you getting shorter than stock instll ht.? what valves are in the heads? exactly how are you measuring? and with what.....

rskrause

Comp calls for the #986 spring:
132 @ 1.750" 293 @ 1.250" coil bind: 1.150" rate: 322#/in
They list #26986 (a beehive) as an alternative:
123 @ 1.750 284 @ 1.175 1.040 280

Rich

Airbornec507

The numbers are with 1.6RR holmes. Do the reverse math for 1.5rr based on my numbers then check out the CC306 stats.

I have aftermarket springs installed. The only thing stock about these heads are the castings. I had a shop port them and put a completely different set up on the heads. They didn't tell me exactly what they put on the heads. I asked them to use the CC986 springs as comp recommends but these springs are obviously different.

Thanks guys for all your help. I will be using the beehive 1218 springs I have with the 614-16 locks to set me around 1.780 installed hight in case I want to go to a bigger cam later on.

mdacton

your right, I was thinking exaust side was 540 with a 1.5

marshall93z

With the advertised coil bind of the 1218s, my GM847 with .595 on the exhaust has a LOT of clearance between the coils!

I have them set up at 1.750" which allows for .610", so you'd think ithey would be close, but they aren't.

speed_demon24

Coilbind on the 1218's and 1518's is 1.08" not 1.14".