Pac1218
01-25-2021, 08:35 PM
#21
TECH Resident
350
No offense taken...although I have never heard of the Lunati failures for the springs we are talking about. Comp 918's fail and I am a member of the 2 piece 918 club. IMHO the majority of spring fail is operator/installer error other than the Comp 918 debacle when they switched spring manufacturing offshore
OP
your cam should have come with a "cam card" which details its specs, including recommended valve spring. If you can't find the card than contact Comp for one. Unfortunately because its a comp cam it would recommend 26918 or the lighter 26915 springs which I would never put in a lawn mower let alone a SBC
Lloyd Elliott has forgotten more than any of us will ever know about cams, valve train components. He advised the Lunati kit for me after my 918 broke. I do have a different cam, Comp 466 XFI though but it is the same spring spec as the Comp 918
If you can set the Lunati up at 1.800 installed height the open & seat pressure would be fine although at 1/75 IMHO they would be fine with the 503 cam. They are a direct replacement spring for a Gen 2 LT1 motor
If you use a bee hive spring, you should check them minimally every 10k mi...which means pulling it and doing a pressure test and closely look for any cracks. IMHO very tedious maintenance for a street car. a single spring breaks and engine damage typically is massive vs a double spring where the valve won't drop if just one of the springs breaks
No offense taken...although I have never heard of the Lunati failures for the springs we are talking about. Comp 918's fail and I am a member of the 2 piece 918 club. IMHO the majority of spring fail is operator/installer error other than the Comp 918 debacle when they switched spring manufacturing offshore
OP
your cam should have come with a "cam card" which details its specs, including recommended valve spring. If you can't find the card than contact Comp for one. Unfortunately because its a comp cam it would recommend 26918 or the lighter 26915 springs which I would never put in a lawn mower let alone a SBC
Lloyd Elliott has forgotten more than any of us will ever know about cams, valve train components. He advised the Lunati kit for me after my 918 broke. I do have a different cam, Comp 466 XFI though but it is the same spring spec as the Comp 918
If you can set the Lunati up at 1.800 installed height the open & seat pressure would be fine although at 1/75 IMHO they would be fine with the 503 cam. They are a direct replacement spring for a Gen 2 LT1 motor
If you use a bee hive spring, you should check them minimally every 10k mi...which means pulling it and doing a pressure test and closely look for any cracks. IMHO very tedious maintenance for a street car. a single spring breaks and engine damage typically is massive vs a double spring where the valve won't drop if just one of the springs breaks
Had a beehive break in my 4.7L Dakota. Valve kissed the piston and it broke the head casting. Engine only had about 50K on those performance beehive springs and it had Crane 218/224 reground HO Jeep cams in it.
Last edited by Fast355; 01-25-2021 at 08:41 PM.
01-25-2021, 09:47 PM
#22
Yep again personal preference. Sorry about your luck with springs.
I will only use PAC springs, proven badass company.
Beehives for mild cams and possibly double valve springs for a more aggressive lobe profile. Double springs are "some" added insurance but a good amount of ppl use heavy double springs on mild cams that don't need them and end up loosing as much as 9 rwhp over single springs , of course dyno #'s are funky so I take that with some salt.
I will only use PAC springs, proven badass company.
Beehives for mild cams and possibly double valve springs for a more aggressive lobe profile. Double springs are "some" added insurance but a good amount of ppl use heavy double springs on mild cams that don't need them and end up loosing as much as 9 rwhp over single springs , of course dyno #'s are funky so I take that with some salt.
01-26-2021, 11:03 AM
#23
TECH Resident
Yep again personal preference. Sorry about your luck with springs.
I will only use PAC springs, proven badass company.
Beehives for mild cams and possibly double valve springs for a more aggressive lobe profile. Double springs are "some" added insurance but a good amount of ppl use heavy double springs on mild cams that don't need them and end up loosing as much as 9 rwhp over single springs , of course dyno #'s are funky so I take that with some salt.
I will only use PAC springs, proven badass company.
Beehives for mild cams and possibly double valve springs for a more aggressive lobe profile. Double springs are "some" added insurance but a good amount of ppl use heavy double springs on mild cams that don't need them and end up loosing as much as 9 rwhp over single springs , of course dyno #'s are funky so I take that with some salt.
Heard the same argument against running a standard volume, high pressure big block oil pump. I run an amsoil bypass oil filter and lifters with oiling grooves so I wanted a little more oil volume to compensate. Found actual testing that the big block pump sacrificed less than 1/2 hp to a small block pump while delivering a more consistant oil pressure reading. The amsoil filter keeps the oil clean for 15K or more and the lifter grooves oil the rollers at idle because I often let the thing idle for long periods of time. I have seen lifter roller failures on even stock roller cam engines that run long periods of time under 2,000 rpm.
01-27-2021, 09:26 AM
#25
Stock to mild cam motors that don't see 5+k RPM use much should be "OK"....but many of us have performance builds with more aggressive cams and some initially drank the single spring bee hive kool aide only to find very exspensive engine damage as a result in under 20k mi of use. Guys like Lloyd know this and also some of us who have gone through bee hive failure. Like the song says....once bitten, twice shy.
Yeah the lighter weight mass of a single spring "pencils" out for a better valve train but unfortunately real life use in 6k+RPM use proves they are short lived with larger than stock cams. Yeah under those use conditions changing them every 10-15k mi is part of operational expense but that gets old on a street/strip car. PAC has a better reputation than the Comp bee hive by miles but the spring design itself is the issue with non stock cams. This is why guys like Lloyd won't use them and IMHO that position should be noted vs internet chatter and what I adhere to. YMMV
Yeah the lighter weight mass of a single spring "pencils" out for a better valve train but unfortunately real life use in 6k+RPM use proves they are short lived with larger than stock cams. Yeah under those use conditions changing them every 10-15k mi is part of operational expense but that gets old on a street/strip car. PAC has a better reputation than the Comp bee hive by miles but the spring design itself is the issue with non stock cams. This is why guys like Lloyd won't use them and IMHO that position should be noted vs internet chatter and what I adhere to. YMMV
01-27-2021, 05:58 PM
#26
My PAC 1218s have seen 6300 rpm every week for 4 yrs and 30k miles.
Granted its a .533 lift cam from lloyd so it's on the mild side. Lloyd told me these springs would be fine for this cam he spec'd me and he was right.
Plenty of other highly experienced builders use beehives on much more aggressive cams than mine and do fine. It sucks you got a hold of the bad batch of comp beehives , that's what drew me to PAC springs.
Im gonna put in new PAC 1218s in February since they have 30k miles just for piece of mind.
And just because you have double valve springs doesn't mean you don't have to test them every so many miles, they too wear and need changed esp on aggressive lobes.
I'm in the process of building my forged 383 and will be using a little more aggressive cam in this build. So, I will be looking into PAC double valve springs myself for this build. I still believe PAC singles are perfectly fine for mild cams like the cc502, cc503.
And like you were saying most spring breakage is from install error or mismatched springs vs cam used.
Granted its a .533 lift cam from lloyd so it's on the mild side. Lloyd told me these springs would be fine for this cam he spec'd me and he was right.
Plenty of other highly experienced builders use beehives on much more aggressive cams than mine and do fine. It sucks you got a hold of the bad batch of comp beehives , that's what drew me to PAC springs.
Im gonna put in new PAC 1218s in February since they have 30k miles just for piece of mind.
And just because you have double valve springs doesn't mean you don't have to test them every so many miles, they too wear and need changed esp on aggressive lobes.
I'm in the process of building my forged 383 and will be using a little more aggressive cam in this build. So, I will be looking into PAC double valve springs myself for this build. I still believe PAC singles are perfectly fine for mild cams like the cc502, cc503.
And like you were saying most spring breakage is from install error or mismatched springs vs cam used.
01-28-2021, 01:54 PM
#27
valve springs are a wear item. stock cam with stock valve springs are fine for a few hundred K miles..."if" the motor really never sees rpm use consistently over 5k rpm. Once you start to run motors 5-6k alot on stock springs you find the motor "noses over" as it just stops making power and valves will start to float as the springs just can't keep up
motors with aggressive cams (high lift & fast ramps) are tough on valve springs so be it checking every 10-15k mi to confirm their spring pressure is still on spec, let alone if any are broken or cracked, is recommended
We all, including Lloyd, got "bee hive" springs for our builds and initially they worked well for all the reasons by design a beehive spring offers when they came out (LS motor use). But for many failures became more common especially during the Comp 26918 bad batches.
For those, including me, that experienced failures and head builders like Lloyd who had to deal with a avalanche of bee hive spring failures the choice was simple to return to a double, better than stock, spring. This issue was for non stock motors with higher lift more aggressive lobe cams.
Lloyd advised to check the Lunati springs in 50k mi with my XFI cam. I don't regularly campaign my car as I did a few years ago at the track but so far the Lunati kit has worked very well under 6400 rpm shifts without blinking. YMMV
motors with aggressive cams (high lift & fast ramps) are tough on valve springs so be it checking every 10-15k mi to confirm their spring pressure is still on spec, let alone if any are broken or cracked, is recommended
We all, including Lloyd, got "bee hive" springs for our builds and initially they worked well for all the reasons by design a beehive spring offers when they came out (LS motor use). But for many failures became more common especially during the Comp 26918 bad batches.
For those, including me, that experienced failures and head builders like Lloyd who had to deal with a avalanche of bee hive spring failures the choice was simple to return to a double, better than stock, spring. This issue was for non stock motors with higher lift more aggressive lobe cams.
Lloyd advised to check the Lunati springs in 50k mi with my XFI cam. I don't regularly campaign my car as I did a few years ago at the track but so far the Lunati kit has worked very well under 6400 rpm shifts without blinking. YMMV
01-29-2021, 11:53 PM
#28
Im excited to see how my beehives have held up from a .533 lift cam over 30k miles. Like I said they have seen well over 6000 rpm every week I drove it and the car has trapped 110 mph with bone stock heads with these springs and this small 215/224 cam, zero hiccups, pulls hard to 6300 rpm.
Will be curious if they lost much lbs of pressure at all.
Will be curious if they lost much lbs of pressure at all.
05-19-2024, 06:00 PM
#29
From my understanding, PAC used to make the comp beehive spring. They switched to a different company and that's what gave the comp beehive a bad name as they started breaking springs left and right after they moved away from PAC.
My email thread to/from PAC in 2019 on a 1518 replacement......
Good morning. We have 1218, 1218x, 1219 and 1219x. All the springs would work great.
I think the 1218x would be your best choice and near the same spec rates. They bump up slightly with the X. But the X will provide better performance over a longer period. All your hardware will work with this spring as well. I hope this helps.
Kind regards,
Danny Hester
Technical Sales Representative
From: Eric Rorrer
PAC,
I bought a set of PAC-1518 springs around 10 years ago and am looking to replace them after around 30K miles as a preventive measure.
I dont see the 1518s for sale anymore.....but the PAC-1218X/19X caught my eye as the closest thing to the 1518 series. Are both a drop in replacement for the 1518s? Im looking to reuse my existing retainers and locks if possible.
For reference, my retainer hardware is as follows(car is a 96 Z28...LT1, CC503 cam)....
CCA-4705-16 locator
CCA-795-16 retainer 10*
CCA-614-16 valve lock 10*
My cam lift with 1.6 rockers is 0.536/0.544, so the reduction to 0.600 or 0.625 max lift should not be an issue for me....I think the 1518s were good for around 0.650 if I remember right.
Thanks,
Eric R.
My email thread to/from PAC in 2019 on a 1518 replacement......
Good morning. We have 1218, 1218x, 1219 and 1219x. All the springs would work great.
I think the 1218x would be your best choice and near the same spec rates. They bump up slightly with the X. But the X will provide better performance over a longer period. All your hardware will work with this spring as well. I hope this helps.
Kind regards,
Danny Hester
Technical Sales Representative
From: Eric Rorrer
PAC,
I bought a set of PAC-1518 springs around 10 years ago and am looking to replace them after around 30K miles as a preventive measure.
I dont see the 1518s for sale anymore.....but the PAC-1218X/19X caught my eye as the closest thing to the 1518 series. Are both a drop in replacement for the 1518s? Im looking to reuse my existing retainers and locks if possible.
For reference, my retainer hardware is as follows(car is a 96 Z28...LT1, CC503 cam)....
CCA-4705-16 locator
CCA-795-16 retainer 10*
CCA-614-16 valve lock 10*
My cam lift with 1.6 rockers is 0.536/0.544, so the reduction to 0.600 or 0.625 max lift should not be an issue for me....I think the 1518s were good for around 0.650 if I remember right.
Thanks,
Eric R.
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