PAC 1518's or Duals??
 

OK I am hearing conflicting advice so I need some input. Also tell me "why" not just say "duals" or "PAC's". That is no help...:eyes:

Freshening up springs soon and really like the advantages beehives offer especially the reduced mass. Hell even with steel retainers they weigh CONSIDERABLY less than duals with Ti. Duals good to .650 on it now. Cam is on pretty agressive XFI/X-ER lobes. Springs will be set up properly

I want to lighten the VT some and run the PAC's but have been advised by some that my lobes are too intense for a beehive EVEN THOUGH THEY ARE RATED AT .650. They say I need a good dual.

Thoughts gentlemen............

I think you would be fine with the PACs. XFI lobes were designed with beehive springs in mind. Even though they have more lift they are a little slower off and on the seat than an XER lobe.

I don't have any real experiences with a lot of the beehives as far as longevity, but I've seen a few write ups with theory on oviate wire (aka beehive) springs. The beehive springs have variable damping all in one spring thus reducing the seat pressure needed. In a nutshell, they are supposed to make the engine more efficient and free up horsepower. I'll post the article from one of the magazines if I find it. It was worth something like 10 horsepower (I assume crank hp) with just a spring change.

Thanks guys I have been reading some stuff like this>>> http://www.performanceproductreview....06/Beehive.pdf and this>>>http://www.compcams.com/Community/Ar...p?ID=590414251 and this>>>http://www.ovaltracking.com/tech/200...beehive-1.html

I would love to hear from a shop or somebody who has run them with XFI or X-ER lobes

I do not know what lobes are on my cam but it is fairly agressive. The PAC 1518 beehive springs are some of the best springs you can buy when used with the correct cam shaft lobes. XFI lobes are designed to be used with single beehives. It is not recommended with XER lobes. I have over 10k miles on my setup and I will be pulling a spring here soon to check it. I wrote down the installed height spring pressure and closed. I will see how they are holding up. I'm more afraid of running assosiate dual springs than I am of running a single beehive setup.

I think the duals will hold up longer,and might be cheaper.

I have no experience with single springs. I have always run duals and i have never had an issue.

Thanks N383.... I am in a quandry because that is basically what I am being told. I run run X-ER lobes on the exhaust side so I dunno. The exhaust has the lighter valves so maybe it would be fine????? I think I will try to call PAC and talk with somebody Monday... Hopefully their phone service is better than Comps:eyes:

What about contacting PAC and getting their opinion? This could shed some light.

That is what I will try to do and will post up what I find out.....

In the meantime if Tony, TSP, Shane, Shawn, Damien etc...come across this I hope they will share their opinon......

you can still make a ton of power on duals...why risk it?

Heres one consideration, the PAC1518 spring is indeed good to .650 lift, it coil binds at 1.050 IIRC

however factory hat style valve seal and factory retainer will touch at .639" lift

In that combination you would want to stick to .600" overall lift.

If you were to change the spring base and valve seal combination, PAC1518 are fine over .600 lift, however, speaking for Chris and Al at PAC they will tell you to use a dual spring if you're sufficiently over .600" lift.

Which PAC makes quite a few Dual springs as well.

Thanks AES. That's the kind of information I have been looking for:D My lift is .612 on the intake and .598 on the exhaust side it sounds like I would be pushing it. I'll prolly do 1521's then but I still plan to call PAC Monday....

sounds like 230/234 ish cam

BINGO:D

Damn near your cam just a little more on the exhaust side:angel:

PAC has a new valve spring for 2010, part number 1205 i'd consider using those. Cost wise its $100 less then the 1521 spring set. The spring pressure/rate looks more in line for cam only/stock heads/rockers builds.

Thanks Fraser! I will look into it:D

As stated in this thread, if you're .600 or below than a single spring is the way to go. Less weight on the valvetrain is a good thing. I've actually seen a 9rwhp loss on a small cam using a heavy duty double spring, so you if you can get away with singles then use them.

I have been running xfi lobes all along, they make good power on L92 heads.

I have been using Patriot extremes set at 1.8 height, A buddy runs PAC 1518 which I recommended for his 230-236 112 and he has travelled 35000kms on them with over .600" lift at 1.8 install height. My duals have 25000kms on them both vehicles driven hard.

My duals are fading badly and lost pressure at the seat.. great when new but not so good now. The 1518s have only lost 5 pound at the seat and no sign of fade. The nitrided ovate wire sure is something!!

I have ordered them for mine. The horror stories of 918s scared ppl from beehives the 1218s work good, the 1518s even better and less pressure on valve train compenents and lighter weight retainers.

I'm a PAC man too:D used 1518's on my 232/234 comp with just under .600 lift. As hymey ststed the comp single spring issue has scared people a bit remember PAC made the original comp spring with great results.