LT1capriceclassic

Well the caprice just doesnt feel as quick as it used to be. Will changing the stock valve springs help me out very much? i figured it couldnt hurt to do it, i have 130k on the car right now.

dhdenney

iTrader: (53)

You're running 1.6's on stock valvesprings?

WhyHelloOfficer

iTrader: (5)

If that's the case, then I'd definitely suggest replacing the valve springs with something that can handle the little-extra bit of lift.

Atleast look into the LT4 Valve Springs -- the part number for the set of 16 is GM# 12495494

LT1capriceclassic

thanks. ive been running the stock springs on the 1.6 for years

96capricemgr

iTrader: (1)

The LT4 springs wont reliably fit the pockets in the iron heads.

I do however agree that you need to replace the springs. Selection is pretty limited due to lack of room for a damper and tha lack of a damper means several of the options you have, have been known to break.

Not the cheapest option but I would look into the beehive 915s, the beehive design means no need for a damper and they fit the iron heads just fine. Are fine for most cams you woukld run on as cast iron heads too.

FAD2BLK93

I have been running the lt4 rockers on mine for a year...with no issues, what is a suitable replacement for the aluminium heads? I plan on going to the CC503 soon.

speed_demon24

iTrader: (6)

I'de personally go with the pac's over the comp springs since they changed manufactures. SDPC is running a gp on the 1218's for $120 which are the same as 918's.

96capricemgr

iTrader: (1)

And I would hesitate to use that much pressure on the pressed studs in the iron heads.

The iron heads have no shims, no seats or anything with which to adjust height, meaning you will be installing near 1.70 where the beehives are spec'd for 1.800. 915 will be much more pressure than necessary. While I can't say for sure 918s would be too much for safety I can say they are FAR FAR more then needed.
I have over 10K on Comp 918s, no problem sofar. IMO people were pushing them too hard and that is a big part of the problem people have had. Specs call for a max of .600 lift and I know guys were going beyond that and then blaming the spring for the failure.

A friend with a cammed 9C1 has had the 915s in for a solid year now as well, again reasonable lift and lobes and all is good.

Imnotfast

iTrader: (1)

The Hot springs fint the iron heads and are not crazy pressure for press in studs.
Other wise go to patroit Golds or Xtreams.

BlackScreaminMachine

iTrader: (17)

The retainers are known to fail, just a FYI, the biggest cam would be the hotcam, I would do either 915's or 918's but with pressed in studs, thats not good for keeping the flex down.

speed_demon24

iTrader: (6)

I had no idea iron heads were like that, a 1.70" installed height would have ~160 lbs on the seat And comp is admitting there is a problem with them and they supposidly fixed it but who knows these days, you would think they woulda learned something after the problem they had with them 4-5 years ago.

96capricemgr

iTrader: (1)

I said the LT4 springs will not RELIABLY fit because guys have found some heads they fit and some they don't.


Not a lot of guys have had problems with the pressed studs but some guys have and I prefer to error on the side of caution with such things as the results of pushing things a little too far can be quite bad. I like to consider age too, have to figure it has been a solid decade since GM made those heads, how many years of abuse have those studs been though? Whwen new I might not flinch at a little exessive pressure but with 10 years of flexing and heat cycling to consider I feel differently.

Sort of like the fuel pump thing, the stocker is great IF it is new and has a good electrical supply and ground, yet I still recommend a new Walbro and wiring upgrade to almost anyone modding the engine because these cars are old and parts are getting worn. Feel the same way on the oilpump, I think at mod time a "white" spring is a good idea, not because the stocker is a problem in any way but because the spring can get weak with age and heat cycles.

Back when I had a ZZ4 cam in my Caprice with stock iron heads I used Combination Motorsports springs with 110lbs. on the seat they worked just fine but do not think they are available anymore. They were a spring meant for a different application with the damper removed, I had no problems but others did have some problems.

zlover129

iTrader: (10)

Can someone explain to me the differences between the 915's and 918's? Aren't they both rated to the same lift? I just installed a set of 915's and 1.6's for my car since my old springs had broken dampeners in just about every single spring, tore up my valve seals too. Just wondering, either way i would definitely go with the new beehives if you can

BlackScreaminMachine

iTrader: (17)

Recently had a friend with a 88 Formula 305 TBI and some of his pressed in studs walked and he has headers and a cat back with LOW miles on the motor. So i personally worry.

WhyHelloOfficer

iTrader: (5)

Thanks Dwayne, I didn't know about the iron heads. I appreciate you clearing that up

Skidd

iTrader: (2)

What is the base diameter of the stock springs and spring pocket in the iron heads?

Yeahdoug

PAC has a version of the 915 too... PAC-1215 which is the original Comp 915.

96capricemgr

iTrader: (1)

The pressures are different.

The pocket is I believe 1.250 maybe a little bigger and the base diameter about .865, I really don't have the right tools to measure well. With the seats cut into the heads though you are left at the mercy of dimensional tolerances which is I think why some guys find LT4 springs to fit and some not too.

I do agree that the LT4 springs if they fit the head are a great choice for stock cam with 1.6s.

96capricemgr

iTrader: (1)

Lots of f-body specific stuff I don't know.

Yeahdoug

The difference is in load... both 918 (PAC-1218) and 915 (PAC-1215) have a 1.290 OD and .885 ID. The 918 has 130 lbs @1.800" and the 915 has 105 lbs at 1.800". At 1.200 the 918 has 318 lbs and the 915 has 293 lbs. The stock sprinsg are 1.250 OD, but 1.290 springs should fit.