They Called Them 180 Motors For The Crank Design.then They Had A Custom Cam Designed For The Crank Design.i Dont Much About Details..i Have Run The 4/7 Cam Didnt See Much Diff,but Id Imagine On The Dyno You Would See Something..
Bear,
My reference to $800 cam was not clear. That cost was not for a 4/7 swap that was for grinding 3 different lobes on 1 cam; 2 intakes and 1 exhaust. This was old PS technology from the late 70's to the early 80's when the GM heads were asymetrical ports. I still do a few of these cams where class rules limit the engine to OEM cylinder heads.
Chris
Bear,
My reference to $800 cam was not clear. That cost was not for a 4/7 swap that was for grinding 3 different lobes on 1 cam; 2 intakes and 1 exhaust. This was old PS technology from the late 70's to the early 80's when the GM heads were asymetrical ports. I still do a few of these cams where class rules limit the engine to OEM cylinder heads.
Chris
Chris, how did they correct for differences between the two different intake ports? Just a lift adjustment, or would the duration change as well? Or just duration?? Seems to me the duration would want to stay the same, since duration has more to do with the rpm range, and that wouldn't change between ports. Are the ports different enough in length to warrant a different duration between the two?
Oh man, I just thought of a ton of questions about this...but I'll settle for those for now.
Chris, how did they correct for differences between the two different intake ports? Just a lift adjustment, or would the duration change as well? Or just duration?? Seems to me the duration would want to stay the same, since duration has more to do with the rpm range, and that wouldn't change between ports. Are the ports different enough in length to warrant a different duration between the two?
Oh man, I just thought of a ton of questions about this...but I'll settle for those for now.
Scott, its all relative. Lift, duration and valve events can all be different. We have computers that now will adjust timing for individual cylinders on say a v-8 engine, so putting different cam timing in each cylinder with a different lobe is no different. In the 80's some PS teams were running cams with multiple lobes. Port length does play a part. When tuning for the intake pulse to find that last bit of HP, yes it plays a part.
Duration yes sustains the power at a given rpm, but the ability of the port to flow A/F to sustain the power is based on how well the port flows. If the port is not good then the cam will have to "crutch" the port. If the port is exceptional, then the cam doesn't have to help as much.
Chris
Makes sense. Thanks.
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