Why is it neccesary??

 

No machinging necessary. However you will need new spring seat/cups to match those springs and some shims to set the spring height. The 986's fit in my stock heads and the 987's are the same except for the inner spring.

But of course you going to want to test fit them to make sure the spring pockets are cut to a large enough diameter.

I think the spring seats you need to use are comp cams 4771-16. And if you need to cut the spring pockets to a larger diameter seat cutter 4719 will get the job done.

 

What I do know is I needed new retainers and locks.

 

If the spring seat is not cut to a larger diameter; what happens when you run the car?? I noticed the springs fit right inside the pocket, but very tightly..

 

They should just slide in. Do the spring seats fit down into the head?? If they don't fit then your going to need to cut the seats a little larger. The tools from Comp Cams are the cutter 4719 and the arbor 4732. Don't cut the pocket any deeper unless you need to increase the distance between the seat the the retainer for proper spring height.

 

I believe you need to cut for the seats. Email Lloyd Elliott and he'll tell you. I ran the same spring setup and I believe he said he machined the seat area.

 

Yes you do have to machine the spring seats to fit them in. If I remember correctly, the 4771 locators are 1.50 or 1.55" in diameter. You can not install them without machining. Do it right and dont half-*** it

 

I didn't cut for the springs You should have seen the other springs that came with the lloyd heads I bought...Every damper was destroyed!!! I knew something was wrong when all I heard was CLACK CLACK CLACK CLACK when the car was running and I lost a crapload of power. Pics will be coming soon of my handywork.. I brought it to a shop for them to put the springs in cause I did not want to do it myself and the guy doing it keeps breaking pushrods so I wonder if by not machining the pocket it is getting coil bound But he was using the 1.6 rollers and when I contacted CompCams they told me if I go with their 1.6 rollers and the "R" lifters plus the 987-16 springs, I would have to buy longer pushrods to correct the geometry. But he also said if I run the 1.5 stockers I can use the 7.195 stock rods without going to the 7.200 or higher ones. He said nothing about machining the pocket, all he said was make sure to use the retainers and 10 degree super locks with the springs as to not have any problems..

 

There is no machining that needs to be done.The only thing you have to do is remove a few ridges where the seat sitsSo that they sit flat.A little scrape with a wood chisel.Not a big deal at all.

 

They definitely sit flat in the pocket from what I see at least, I will be going there in about an hour to drop off the new pushrods and I will take my camcorder and snap a few pics for all to see. It seems to me that with these newer style motors everything that needs to be done to make it quicker costs you your first born!!! Give me an older motor with a freakin carb ANYDAY also with the old fashioned distributor setup and I am in heaven.

On a side note I think my loss of torque was due to the crappy LT4 springs that were in there in the first place!!

 

The springs will sit in the pocket some what, but I am talking about the spring seat/locator that you NEED to put on underneath the spring. This protects the head from the repeated opening and closing of the spring. Also, you HAVE to check spring height too. If you dont have the correct spring height, then you wont have the correct spring pressure.

If you ask any shop that does alot of LT1 heads, they will say that the 987s require machining since they are 1.43" DIA. And the spring seat/locator is 1.5X" DIA also. Where as a stock spring is 1.25" DIA. The 987's are NOT a drop in spring and go.

 

Just brought it home from the shop....no problems except there is still a HUGE ticking noise only under acceleration and at idle...but no loss in oil pressure at all. I'm following Comp's instructions and keeping the revs under 2000 for the next 100 miles then I'm back to the dyno to see if I got my torque back. I think it's time for a 396 anyways so I'm going to drive this thing into the ground.

 

How much torque do you expect to get? 360rwtq is about right. You could make a little more, but how much were you hoping for? Look at my setup for example (I didnt have a dyno tune though), but i made 383rwhp/353rwtq. It seems with these bigger cams, LT1's are about 25-30rwhp more than rwtq.

 

That's true..I just want maybe 5-10LBs more to "even" the score so to say..

 

Watch you hp go up to then You'll never even the score so to speak between the hp/tq. Did you get a dyno tune before or was it a mailorder tune?