TS-239XR 239/248 duration, .577"/.600", 115lsa?

 

Why in God's name do you need that much lift on the exhaust side?

Well, either way, you'll be at the very outer limits of the 987's as I believe the max lift on their specs is .600".

I thought that was a Crane Cams part number? I can't find it on their website. I'm running the 10308 set, and it has the 893's in it.....at least according to their site....

 

The best source for spring info is the cam grinder. Answering your question would be easier, and hence more likely to get responses, if you posted more details of the setup and what the springs specs are, rather than just a pn.

Rich

 

Bryan: they are a comp spring.

The specs on the springs are: 1.430 2 spring, .697 I.D., seat load 121@1.800, open load 388@ 1.200, 1.150 coil bind, rate lbs./in. 344

 

You should look for something in the 130+ range on the set or what ever the person selling you the cam says.

 

Do you mean 130+ lbs on the seat?

 

yes,

You need a little more spring when your are FI..Get the matching spring for the cam, where ever you buy a cam,

 

Ok, I thought the 388lbs open pressure was what was more important.

I'm probably going to get a .560/.577 lift cam and these are the springs they recommend @ combination motorsports.

 

cool,

good call

 

I was just curious if I decided to go with a larger cam if I could use these springs or not.

 

Ask them, and with FI eng you don't need very large cams to make big power, just put a smaller pulley on, intercooler, or what ever to make more power,

 

I know your right about not needing a really big cam to make big power. I was wrong the open pressure is 328lbs

 

Why do they need to be 130+ lbs on the seat in a FI car?

 

The back side of the intake valve has ~3sq.in of area. With 15psi that's an additional ~45lbs the spring has to overcome to close the valve.

Rich

 

Oh, thanks rich I've been looking at comps website for a long time now and I can't find a spring that has both the seat and open pressures I'm looking for. I'm looking for a spring with at least 130lbs seat pressure and 350lbs open pressure. This is pretty difficult.

The 977part number specs out to 155lbs seat press. @ 1.850, 419lbs open pressure @ 1.250, a coil bind 1.195. This spring will support up to a .595 lift cam. The outside diameter is a little larger than the 987 so I don't know if it'll fit in the head seat with out some machineing.

Comp said that the lifters couldn't really take the 419 open pressure. I've come to not put a lot of faith in their word over the phone. Do you think I'd have lifter promlems with using these springs?