I put my 355 together about 2 years ago now. Had it on a chassis dyno last month was very disappointed. Something just didnt seem right. My 355 with 461's, 262xe, 1 5/8s headers, flowmaster dual exh, edle performer, unilite/msd/jacobs ignition, and a 600 holley only put down 196hp to the rear wheels. Much less then a milder 327 build i tested last year. What was even more disturbing was my tq and hp peaks were at very low rpms. TQ peaked at 311@2100rpm, hp @ 4400. The 327 with just a little 256xe peaked at 5250. So something wasnt adding up.

Just got done installing a set of ported L98 heads and comp 1.6 roller tip rockers. Because of the low rpm peaks I wondered if the cam was too far advanced, so I bought a degree wheel and borrowed a dial indicator to check the cam timing while I had the motor apart. I set the dial indicator to read directly off the lip of lifter. Then took read the degrees at 0.050 lift in both directions. Came up with 215* and 3*. Comp instructions say to add together and divide by 2.. so thats 109. 7 degrees advanced instead of the recommended 4*. Maybe part of the problem. But 215-3* should be the intake duration at 0.050 right? thats 212* The 262 cam is supposed to be 218*, the 256 cam is 212*. Now what i'm thinking is that I probably got a 256 cam in a 262 box.

How often does that happen? Does all this sound reasonable or have I made a mistake somewhere? I've never degreed my cam's before, but I think I will from now on. If only to catch mistakes like this.

And btw, graemlins/thumbsup.gif to the new heads and rockers. Sounds better, runs smoother and actually has some top end now. And with the higher v/cover rail on the centerbolts maybe it wont leak as much too!

Was there a stamped description or grind # on the end of the cam?

Rod

Where was the 3° at, BTDC or ATDC? If it was 3° ATDC, you have 212° at .050. If it was 3° BTDC. ;you have 218° at .050......
If it is 3° BTDC, the cam should be on 106° ICL, unless I am very, very, tired....
If 3° ATDC, it is at 112° ICL.

UDHarold

Thanks Harold!! Just lookin at my degree wheel now to figure which way it was. I remember the 3* was to the right of zero. Which would be BTDC. Means my cam is correct then. So still no idea why this thing peaked so early. The 1.6s and heads seem to have changed that though. Don't know by how much. Was thinking that I at least had found my reason.

How much will the 3 xtra degrees of advance affect this setup? Shall I take the front apart to swap? or will it be worth it?


Too bad I can't blame Comp, but hey I tried ;) While I'm at it, might as well ask for a cam recommendation. See just how far off what I have is from optimum. It's in a 4200 c10 with 3.08's. Mainly used for a daily driver and to have fun. See's tow duty maybe 2X a year. (2 horse trailer). This current cam has lots of tq but peters out pretty quickly.. or at least it did before this weekend. More driving will tell.


Edit: forgot to say its a th350 too, unknown stall but probably close to stock. So i've got several things against goin too wild.

Dont feel bad about trying to blame Comp Cams, they had the wrong cam in the right box when I bought my K-kit. It was a small block cam, thank god,if it was another bbc cam I might not have cought it!

7 degrees advanced, eh? Petering out early, eh? Dial it back to +2. Or even 0. With the new heads your inlet flow velocities have to be high anyway, it shouldn't slow them down that much. Might not notice too much bottom end loss at all.

Anyway, it sounds like putting the cam back 4 degrees ( to be only slightly advanced, 2-3 degrees) might be indicated. Timing gear already have a bushing in it?

No bushing in the timing gears. But it is a 3 keyway set and its in the center position now. I was thinking the same as you 427L88(Dean?) and putting it in the 4* back slot so that it only has 3* advance. That would be alot closer to what the spec is anyway. Loving the new combo at the moment, much crisper,revs much quicker, and doesnt peter out quite so early. So probably won't change cams completely, just try retiming this one. Thanks for the help!