351-C Heads

The reason I am dissatisfied is that at 5000rpm the valves start to float and there doesn't seem to be any torque from the line. Are there other options available?
Thanks,
Al

Al, It depends on the combination of camshaft, carburation, ignition, etc. Not just the heads. The 351C is well known for making horsepower at high rpm, not for making low end torque. Port plates for the huge ports will help some or the Australian 2V heads will be even better if you want torque. Floating the valves at 5,000 rpm could be the camshaft, carb , ignition combo you have. I would call some of the people who are in the pantera business. Do you belong to Pantera International? If not, you should join. It has helped me for 17 years. I hope this helps

Al,

there are other heads out there that will bolt on, but no stock type iron head nor most aftermarket aluminum heads flow more than your 4V heads. In fact the newest iron SVO head, the N351 that is all the rage is not as good. You'll have to go to a very pricey aluminum head to increase the flow or performance of your stock 4V heads. they are very good heads. It sounds like you have them poorly set up or the wrong cam. I've been running clevelands since 1980, and have never found a real short coming with them. use gears to make up for the torque, and let those big heads breathe!!! Tell me what you like to do, and I'd be happy to steer you towards a cam. Dan

Al -
To add to what has already been posted, I have the 4V heads on my 71 and it runs plenty strong for the street. I had my ignition set per the engine compartment data plate and it ran like a dog. I believe the data plate says 6 to 8 degrees advance, change it to about 12 to 13 degrees advance. You may have weak valve springs and a worn timing chain also. I also have a mechanical roller cam with the matching springs and it will easily rev to 7000 rpm. You might want to spend your money on a new cam, lifters, springs etc.

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Thanks guys for all of your advice. I think I may need new valve springs as per one of our members' suggestion. I would like to run a full roller valvetrain; does anyone have some suggestions for a hydraulic roller valvetrain? Thanks in advance.

One word----Crane

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Originally posted by Al:
Thanks guys for all of your advice. I think I may need new valve springs as per one of our members' suggestion. I would like to run a full roller valvetrain; does anyone have some suggestions for a hydraulic roller valvetrain? Thanks in advance.

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Adding a roller cam causes a few potential problems to consider. First, you cannot run a hydraulic roller unless you use a special-cut smaller base-circle cam, because the roller wheels protrude into the main oil galley on a std cam, causing a catastrophic drop in pressure. There is one roller lifter made with smaller rollers so there is no clearance notch, but I can't recall the mfgr. And roller cams are steel which means you need to either have the steel cam specially constructed to use a stock cam's cast iron distributor drive gear, or run a bronze gear on your distributor and change it yearly due to rapid wear. Finally, there are still some 351C cams out there that have the integral drive gears cut to the wrong angle and will fail any distributor gear within a few miles. They are difficult to inspect out of the engine- be very sure you get a guarantee that covers engine damage since the wear will spread steel particles throughout your engine. Hydraulic roller cams also require stronger valve springs and shorter hardened pushrods with guide plates.