edbux
Well-Known Member
I had a smart idea and changed the cam. Went from an Edelbrock Performer cam the previous owner had installed to Comp Cams 270H-10. Rest of the 360 consists of 8.5 compression, LD-340, Mopar performance ignition with orange box (soon upgrading to FBO system), Rhodes lifters, stock 360 heads and a holley 1850 in a 67 Dart with a stock convertor and 727. I'll be getting a 2400 stall installed as soon as the concrete floor in the garage warms up a little.
With the old cam, I could smoke the tires easily and for a long time, 3.23 open rear, have 3.23 sure grip pumpking waiting to be put in. I installed the comp cam on a 106 center line per the instructions. I know my compression is a bit below the recomended minimum, but I am planning to eventually swap over to magnum heads.
Anyways, the problem is a severe hesitation on a wide open launch, runs fine part throttle to full. I bumped the discharge nozzles from .031 to .035 and not much help. Vacuum readings are 15 at idle in neutral, 11 in gear and it drops down to around 3 when I nail the throttle when launching (many odd looks cause of the long black hose across the hood). Advancing the initial timing helps very little. I know my jetting is somewhat lean from reading the plugs. I plan on ordering a jet kit. What I am trying to understand is the power valve. All that I have read say use on that is rated 2hg below your idle vacuum in drive. Currently it has a 6.5, if I understand it correctly I should be using an 8.5? Is the vacuum dropping to 3hg indicative of another problem? Also, at the timed port, I get around 2.5hg at idle, should I get anything there?
Sorry for the long winded post. Here in Idaho, no one knows of a Holley guru and it's mail order for parts. I'd like to get everything I need in one trip to summit's home page.
Thanks
With the old cam, I could smoke the tires easily and for a long time, 3.23 open rear, have 3.23 sure grip pumpking waiting to be put in. I installed the comp cam on a 106 center line per the instructions. I know my compression is a bit below the recomended minimum, but I am planning to eventually swap over to magnum heads.
Anyways, the problem is a severe hesitation on a wide open launch, runs fine part throttle to full. I bumped the discharge nozzles from .031 to .035 and not much help. Vacuum readings are 15 at idle in neutral, 11 in gear and it drops down to around 3 when I nail the throttle when launching (many odd looks cause of the long black hose across the hood). Advancing the initial timing helps very little. I know my jetting is somewhat lean from reading the plugs. I plan on ordering a jet kit. What I am trying to understand is the power valve. All that I have read say use on that is rated 2hg below your idle vacuum in drive. Currently it has a 6.5, if I understand it correctly I should be using an 8.5? Is the vacuum dropping to 3hg indicative of another problem? Also, at the timed port, I get around 2.5hg at idle, should I get anything there?
Sorry for the long winded post. Here in Idaho, no one knows of a Holley guru and it's mail order for parts. I'd like to get everything I need in one trip to summit's home page.
Thanks
