I was wondering if anyone had a suggestion on what valve springs to use with a Hot Cam. I was thinking Comps 987's

Specifications:
* Outside diameter: 1.430 in. two spring
* Inside diameter: .697 in.
* Seat load: 121 lbs. at 1.800 in.
* Open load: 388 lbs. at 1.200 in.
* Coil bind: 1.150 in.
* Rate: 344 lbs.

Anyone know if these will work or have another suggestion other than GM?

 

Those would be fine. Far better than the GM ones.

The 986 might be a better choice though, since you don't need the extra lift capability of the 987; but would benefit from the higher seat pressure of the 986.

Don't forget, either of those will require head machining, if the heads have the stock 1.25" spring pockets.

 

Thanks. I was aware that the heads would have to be machined. They are actually at the machine shop now getting the stud bosses milled and tapped for screw in studs. They were waiting for me to choose a spring so the pockets could be cut.

 

I have AFR 190's, set up for 1.5rr's and I am also considering using this cam. do I need to have any work done to the heads since I am using the 1.5rr's?

Todd, also, I read that you had to tap the dowel pin inward .030. What do you know of this? I spoke to one guy who did not tap the dowel in and had no problems, however, I read this from http://www.sdpc2000.com.

Note : The LT4 camshaft P/N 24502586 was designed to be used in a number of different engines. Therefore, the following change may need to be made to allow for correct assembly of the engine: For LT1 and L98 engines 1995 and before, the dowel pin in the end of the camshaft must be pushed in so extension from end of cam is .30 +/- .01" , the same as the production part. For 1996 LT1 and LT4 engines, the dowel pin is in the correct position, extending .620" from end of camshaft. This camshaft has a fuel pump lobe.

 

Other than possibly having to machine the spring pocket I wouldn't think you would have to do anything. What size is the spring pocket on AFR's?

I also don't know anything about tapping the dowel pin in. No one has mentioned it to me. A friend of mine has one in a 92 Vette, I'll ask him if he had to make any modifications to the cam and let you know.

 

I have the HOT cam and when I put it in I was worried about this too, but I soon found out that it won't hit the timing chain cover. It sticks out this far cause of the water pump gear that it used on LT1/4's. Just put your cam sprocket over the dowel pin and you will see that the chain sticks out further than the dowel pin does, if you have a double roller.

 

Some timing covers have shapes pressed into them that it will hit. But if it doesn't hit, then ... it doesn't hit. That's all that matters.

 

I"m using 1.5 rockers and my springs are rated up to .550 so I have no worries there. How about you todd? were you aware of teh dowel needing to be tapped in .030?

actually, I was looking at this cam which is similar to the compucam 2032 @ http://www.sdpc2000.com/ ;

part no. 12370845
@ .050 241/224 on 112 lca .488/.509 lift.

I like the profile of the second cam since it is very similar to the compu cam 2032, but one thing concerns me. at the end of the description of part no.12370845 it says this; . Contains eccentric for mechanical fuel pump. Off-road use only, not CARB approved for street use. Not designed for use with computer controlled engines.

Has anyone used this cam? The only difference is that the lift is more than the 2032? I have the slp runners with the tpi stuff and think the hot cam may be a bit much for my intake system, plus, my supercharger redlines @ 5500rpm's (engine speed)

 

I will be using 1.6 rockers for the full .525 lift. No, I didn't know anything about the dowel, but if it needs to be tapped in so be it. I doubt it will though since the cam is used and came from a 95 LT1. It should already have been done.

 

Just FYI... You have to know more than max lift rating to choose a set of springs, especially with a roller cam like any of the LT1/LT4 hot cam-ish variants. The increase ramp angles will bring the valve and spring closed much faster and can actually bounce the valve off of the seat if the springs have to low of closed seat pressure.

 

Well, since I'm @ .492 lift, I have plenty of variance there. If I were using the 1.6rr's, then I definately change springs. But TY for the info!