What is the difference between the Comp 978 Spring and Comp 987 Spring ?

Thanks
Adnan

 

I'd go with 978. The 987 can be used on our applications if installed at correct height and set up correctly. TEA has used 987's on their Stage 1.5's (the very ones on my car have them and they're fine). But, when I need to replace the springs, I'll be putting in 978's. Either of the springs are larger in O.D. than stock springs.

What's the lift of the cam you're going to use them for?

 

i have 987's for sale. short money. i had them, they worked well in my car, but i sold the setup.

 

cam lift is about 632 intake and 646 exhaust. i think i will go with 978

 

That's a bit much for the 978.

 

What is the max lift with 978 ?

 

I am curious as well what the max lift woudl be? Also would like to know if the 978's would use the same seats and retainers. I have 987's but they will not handle enough lift for my future cam. ANY info MUCHOS appreciated.

 

According to the comp book the 978 is 1.850 seat @126lbs and open @ 1.250 with 368lbs- coil bind is 1.195. The 987s are 121@1.800 and 388@1.200- coil bind 1.150.

 

Go with the 977's

 

The 987's aren't being used much any more the way I understand it . I've got the 978's but my lift is only.563. I know AS prefers the 977's, but I'm not sure with the huge lift you're looking at.

 

I thought 977's required Comp R lifters?

 

max recommended lift for the 978 spring is .600". i posted that here for you also. https://ls1tech.com/forums/generation-iii-internal-engine/249301-spring-help.html

 

With the spring rates compared to the 987's you might need them. I'd go with the 978's which would handle the same lift and not require a better lifter.

 

They due require Comp R lifters.....but why not. He has a cam with a ton of lift. In the broad scheme of things...an extra $300-$400 dollars is not a lot to ensure (or almost ensure) durability. The 977's are very strong.. a little noisy..but strong. They have worked well for me with the comp r lifters for the past year. The 987's cause some valve float with cams over .600 lift. Don't risk it. Get 977's!

 

^ I wouldn't use 987's with anything over .600 either.

 

the problem with adding lifters is you have to pull the heads. even more expense in doing that. but again, in his case can't hurt.