quote:Originally posted by T.Solo:
I'm interested in replacing the cam since I'm this far into it. should I consider going hydraulic roller? Does this require machining? Is there any oiling modification required or that I should be considering with the top off the engine?
Steve
Roller cams are more expensive, that's their biggest drawback. They tend to float the valves earlier, but we can make compensations for that aspect by selecting the right parts. The cams are more expensive, the lifters are more expensive, the springs are more expensive. The distributor drive gear must be replaced with a gear costing $70.
I would warn you to resist the temptation for what is called "job creep". The goal is to repair the leaking heads.
The valves in the OEM 4V heads need replacement. I think that should be done now. That is job creep too, but I believe it can be justified, due to the risk of re-using the factory valves. I assumed your preference is 2V heads, indicated by your plans to use the Ed heads at a future date. So the Australian 302C heads make sense, as a means to accomplish 6 things at once: (1) fix the leaking gaskets (2) spend as little money as possible (3) convert the motor to 2V heads without having to machine the block for alloy heads & MLS gaskets (4) replace the factory valves (5) raise the compression (6) utilize the 2V intake manifold you have on hand. The iron 302C heads will alloy you to re-use the factory rocker arms, another cost savings. I have no problem with using the factory rocker arms. The 302C heads are compatible with any 2V or 4V headers.
Raising the compression to 10:1 will boost the motor's output by about 20 horsepower. But the increase in compression will improve the "pep" of the motor, it will "feel" more like a 50 horsepower increase. I doubt there is significant power difference between using the 2V heads and 4V heads with a camshaft like the factory Cobra Jet cam (theoretical lift = 0.481"/0.490"); especially if the 2V heads are given a nice 3 angle valve job as they are put together. The real difference between 2V and 4V heads shall be the power band. The motor's power band will be skewed towards lower rpm by the 2V heads, something many people prefer. And the motor's high rpm "pull" will be blunted by the 2V heads, something I would personally miss.
Assuming the pistons in your Pantera's motor have 8cc dished domes, here's the compression you can expect using the various iron quench chamber heads:
1971 4V, D1AE casting, 66cc chambers = 9.3:1
1970 4V, D0AE casting, 63cc chambers = 9.6:1
302C, ARD1AE casting, 58cc chambers = 10.1:1
The 4V heads can be milled to 58cc, but then the chambers would be too small if the motor was updated with flat top pistons further down the road. You could also elect to just keep the 8cc dished pistons. You can see the dishes are so shallow they are virtually flat tops anyway.
On top of the 302C heads, you could install a multi-key-way camshaft timing set, and use it to advance the factory cam by 4 degrees (assuming the motor is still equipped with a factory cam!). Re-calibrate the ignition for 20 degrees centrifugal advance and 16 to 18 degrees initial advance. I'm not sure what carburetor the motor is currently equipped with. If its equipped with the Motorcraft 4300D spread bore, then the motor will need a new Holley bolt pattern carburetor, so this will be an opportunity to install a nice 650cfm to 750 cfm four barrel street-performance carburetor. If the motor is still equipped with a 40 year old factory crankshaft damper replace it with a Romac #0203 damper. These few changes will make the motor feel like a whole new motor.
There's an abundance of info on related topics in sticky #3
-G