Chris Taunton
True Classic
I am thinking to replace the PBS SX-1 cam in my 128 wagon (34* overlap, 110 LCA, 256* duration seat to seat - 220* @ .050"lift, .381" lift). The engine was built by an Xweb guy for a previous owner after he rescued the car from Chris Obert's salvage yard in Santa Cruz, CA. Here is what I've been able to determine based on researching past posts.
1302 cc with 86.4 1500 pistons
Stock valves, ports smoothed but not enlarged, head milled to 9:1 CR (cylinder compression readings are 140 psi on all cylinders on my gauge taken with the engine warm and the throttles open).
It now has a dual 36 DCNF setup
Header from Argentina and free flow exhaust
This seems like an archetypal compression limited 1300. It runs on regular gas with 44 * of total ignition advance.
Using David Vizard's guidelines based on cylinder volume to intake valve diameter ratio and correcting for the low CR, he would say this engine needs:
1) 50* of overlap (seat to seat) for a hot street setup
2) 113* LCA
Those 2 parameters would dictate a duration (seat to seat) of 276 degrees. This is very close to the MWB 236 cam (53* overlap at .015", 112 LCA, 277* duration seat to seat, .392 lift ). All of the other cams I have found seem aimed at 1500+ motors that want more overlap and narower LCA because of higher cylinder volume to valve diameter. This cam is lift limited because it is a regrind. More lift would be nice.
What do all of you think? Let the games begin!
Chris
1302 cc with 86.4 1500 pistons
Stock valves, ports smoothed but not enlarged, head milled to 9:1 CR (cylinder compression readings are 140 psi on all cylinders on my gauge taken with the engine warm and the throttles open).
It now has a dual 36 DCNF setup
Header from Argentina and free flow exhaust
This seems like an archetypal compression limited 1300. It runs on regular gas with 44 * of total ignition advance.
Using David Vizard's guidelines based on cylinder volume to intake valve diameter ratio and correcting for the low CR, he would say this engine needs:
1) 50* of overlap (seat to seat) for a hot street setup
2) 113* LCA
Those 2 parameters would dictate a duration (seat to seat) of 276 degrees. This is very close to the MWB 236 cam (53* overlap at .015", 112 LCA, 277* duration seat to seat, .392 lift ). All of the other cams I have found seem aimed at 1500+ motors that want more overlap and narower LCA because of higher cylinder volume to valve diameter. This cam is lift limited because it is a regrind. More lift would be nice.
What do all of you think? Let the games begin!
Chris
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