New valve springs

[chriss4655]

Going to be installing some new valve springs ( comp 980 ) It been suggested to not install the stock cup that the spring sits in ! Does not installing the cup cause any problems ?

 

[mathew]

No, have at it.

 

[Buick Mark]

No problems

 

[bison]

Going to be installing some new valve springs ( comp 980 ) It been suggested to not install the stock cup that the spring sits in ! Does not installing the cup cause any problems ?

What was suggested to be used instead of the cup?

 

[scojack_2001]

Going to be installing some new valve springs ( comp 980 ) It been suggested to not install the stock cup that the spring sits in ! Does not installing the cup cause any problems ?

Ran my Comp 980s for years without the cups and no problems.

 

[chriss4655]

Thanks for the replys , just didn't want to cause any negative results not using the spring cups !

 

[bison]

Thanks for the replys , just didn't want to cause any negative results not using the spring cups !

You could have a negative result if you didn't shim the springs.

 

[chriss4655]

1.70 installed height is what I'am shooting for .

 

[earlbrown]

If you want the spring at 1.700 I believe you need to keep the cups as the factory installed height is 1.727. If you've cut the seats and/or ground the valves it'll be taller than that. It seems like the cups are .025"~.030" thick.

I'd worry more about the spring poundage than the actual installed height.

 

[chriss4655]

On the box 1.70 with give you about 90lbs close seat pressure which is a bit above stock . Hopefully it will give me a bit more top end .

 

[earlbrown]

Based on my personal experience the box is never accurate.

 

[chriss4655]

What kind of seat pressure I'am I looking for ? If I know I can find out at what installed height the correct seat pressure is achieved . Stock cam , just 25 year old springs !!

 

[bison]

What kind of seat pressure I'am I looking for ? If I know I can find out at what installed height the correct seat pressure is achieved . Stock cam , just 25 year old springs !!

I'll say this. 980's out of the box without shims/no external damper on un-machined heads are about the same as a new set of stock springs. I'd want 80-85 on the seat for 5000rpm/25psi with a stock cam. Youd be fine with 75-80 for 4800rpm. Again you may get away with a little less but keep in mind the springs might lose a few percent after you run them. Results will vary if you run less and tye variation wont be to the good. Ive replaced many sets of valve springs over the years. A lot that were re-dos from improper install. Probably the biggest overlooked item on the engine.

 

[chriss4655]

Thanks , I will take them to the machine shop and see at what height it get 80 to 85 lbs and shim them to that. Thanks for the advise

 

[earlbrown]

Just for kicks take an old spring with you. The last set of factory's I pulled averaged 54#s on the seat with the cups. No matter how far off you are on the new install, you're going to be light years ahead of the factory springs.

 

[Fast4Ward]

i think i would watch out for thos 980's mine were in for about 60 miles and they weakened to 50 lbs and same with a friend who pulled his with little mileage and they too showed about the same...i went with Sealed Power VS739R..cheaper and thicker spring rated at 104 lbs and they measured 90 lbs at 1.7 or 8 when the shop installed them....i am using Edelbrock 204/214 cam. Maybe it is a quality control issue with comp cams but perhaps 981 a step higher would be better...just what i've discovered on rebuilding a motor twice in 12 months..DOH! it overheated and creamed..GULP.

 

[earlbrown]

I think comp springs went to crap at once a several years ago. Seems like it happened at the exact same time they moved the springs to mexico. Can't go wrong with PAC springs from my experience.

 

[larrym]

Chris you will need more spring with that roller cam.......

 

[chriss4655]

New springs are on and heat cycled a few times, went for a ride and my high rpm stumble at the top of thrid is gone Have not had a chance to check the pressure on the old ones yet! No cups and no shims , the heads have never been off so no machine work has been preformed on them. Installed at 1.7@ 88lbs closed seat pressure go figure I rounded up a boat load of shims and didn't need a one !!!

 

[bison]

New springs are on and heat cycled a few times, went for a ride and my high rpm stumble at the top of thrid is gone Have not had a chance to check the pressure on the old ones yet! No cups and no shims , the heads have never been off so no machine work has been preformed on them. Installed at 1.7@ 88lbs closed seat pressure go figure I rounded up a boat load of shims and didn't need a one !!!

What was your installed height with the stock springs?