Tuning out dips in torque (with a big cam)

[Black02SS]

Part of that dip is due to header design IMO. I have tried several different methods with various cars on the dyno and the only thing that seems to help is header design.

[Gelf VXR]

Interesting, a very smooth / flat spark map produces a nice smooth VE map and 0.005% BEN's, very nice

[Gelf VXR]

My timing table - Note there is no hump at the top of the hill.

Can I ask how you derived this timing table?

[SSpdDmon]

Can I ask how you derived this timing table?

I sent him that timing table and then he pulled a little in the part throttle region as needed. I'd suggest to him that if he pulled timing in those RPM regions, that he carries that reduction all of the way across to the higher grams/cyl. cells.

The idea for this table was based off of the concept of how a distributor works. At low manifold vacuums (high grams/cyl), it ramps up to a flat timing number. As manifold vacuum increases (grams/cyl decrease), timing is advanced. For Kevin, his H/C car will most likely make best power with a timing value of 26~27* @ WOT from 2800rpm on up. Applications that run in higher altitudes may require a different timing figure. This value needs to be determined on a dyno in both scenarios.

[Kevin Doe]

He is right on. I only pulled timing from those low throttle and low load area as needed. I havnt' seen any issues with the higher loads at the same rpms, which is why I havn't pulled any timing there.

Actually, my knock wasn't a function of the load/rpm timing. For some reason it only happened when these criteria was met.
1. Low rpm, low load (~0.2 g/cyl, and 2400 rpms)
2. About 15 mph, but only if I just came from a dead stop.

I pulled a total of 5 degrees from that area in attempt to stop the knocking. No real effect. Some guys actually said they had a similar problem adn it was cured by ADDING timing there. I'm livin with ~1 to ~4 degrees of KR at that low rpm, low load point. No audible knock at all.