408 Not putting down the power
TECH Junkie
Joined: Dec 2001
Posts: 3,242
Likes: 0
From: Lakeland, FL
I also had problems with the Comp R's and have seen my graph look like yours as well, swapped back to stock lifters is what helped me, we even tried adjusting the preload but it did not seem to help, I did have the yella terra rockers though so maybe that was part of the problem, seems like comp r's and yt's don't get along too well.
I switched to YTs with my Comp Rs and the problem went away. Heres a before graph with Comp Shaft mounts and Comp R lifters: http://forums.scfba.net/album_page.php?pic_id=109
I switched to Yella Terra rockers and tightened up the preload a bit and this is what I got: http://forums.scfba.net/album_page.php?pic_id=144
I switched to Yella Terra rockers and tightened up the preload a bit and this is what I got: http://forums.scfba.net/album_page.php?pic_id=144
Thread Starter
Staging Lane
Joined: Dec 2003
Posts: 63
Likes: 0
On the dyno again Well...we put the car on the dyno again and nothing changed. We set the preload right between 1/2 turn and 3/4 turn (previously had 1/4 turn). Absolutely no change in HP what so ever!!! The same dip around 5200rpm was in the exact same spot. What would you think about the shaft-mount rockers (Comp)? Could they be too heavy? I would think that if they were too heavy once the power dipped it would stay gone rather than come back up? Anybody have any ideas?
Thread Starter
Staging Lane
Joined: Dec 2003
Posts: 63
Likes: 0
Originally Posted by Country Boy
I switched to YTs with my Comp Rs and the problem went away. Heres a before graph with Comp Shaft mounts and Comp R lifters: http://forums.scfba.net/album_page.php?pic_id=109
I switched to Yella Terra rockers and tightened up the preload a bit and this is what I got: http://forums.scfba.net/album_page.php?pic_id=144
I switched to Yella Terra rockers and tightened up the preload a bit and this is what I got: http://forums.scfba.net/album_page.php?pic_id=144
How much is "A BIT"
TECH Fanatic
Joined: Jan 2002
Posts: 1,205
Likes: 0
From: harrisburg, pa
.008-.010 cold is the recommended and I didnt have this problem at all with my Comp Rs. Tightening them up a little from .005 is an easy thing to try. I wouldnt be too sure it isnt a TB problem too if not a header issue but the dip back up points to something mechanical/electrical or tuning. Stock ported TB is problably maxed out but I wouldnt think it would cause a dip. Anyhow you have room for improvement here and thats a good thing.
Just curious about your plugs and gap?
Just curious about your plugs and gap?
I would of put a bigger cam in that thing. Not necessarily any more lift, but more duration. Sounds like you have some valve train harmonics causing that dip. Some kooks 1 7/8 would pick up some power too.
Thread Starter
Staging Lane
Joined: Dec 2003
Posts: 63
Likes: 0
UP DATE
Got the car off the dyno last night and the dip in HP is fixed. we pulled the comp shaft mount rockers and put the stockers on. we are still down about 20hp. we have one full turn of pre load on the comp R lifters and i thank this is to much so we are going to shim them up and try it again. any one besides Taphee6 set comp Rs with a compression tester? I was going to set them like a half a tune and try it.
Got the car off the dyno last night and the dip in HP is fixed. we pulled the comp shaft mount rockers and put the stockers on. we are still down about 20hp. we have one full turn of pre load on the comp R lifters and i thank this is to much so we are going to shim them up and try it again. any one besides Taphee6 set comp Rs with a compression tester? I was going to set them like a half a tune and try it.
Last edited by johns01ta; Oct 21, 2004 at 06:39 PM.
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TECH Resident
Joined: Nov 2001
Posts: 917
Likes: 0
From: Chattanooga,Tn
mine came apart in under 3000 miles. .005 on the intake and .013 on the exhaust. Not to mention several other peoples lifter have also came apart. Just because yours have not came apart yet does not mean they are not going to. The cups will get beat out of the top of them eventually from cold starts. When it does do not say I didn't warn you.
