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Discussion Starter #1
Hello. On a stock 1970 351C-4V, what is about the most lift & [email protected] you can safely go without having to change other parts in the system(heads, rockers, springs etc.)or have to worry about clearances? Thanks.
 

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Anytime a perf cam is installed you have to check clearances anyway.

I built a 2V headed Cleveland with a comp 280 (230 net duration/.530 lift) and TRW flattops and had no piston/valve clearance probs.
 

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When you get to the level of sharkmouth's cam, all your valvetrain parameters bear scrutiny....geometry, coil clearance, VP clearance, seat pressure, etc...

What's the application and current engine build state? You said stock...is it in fact stone stock OEM? If so, how many miles on the engine since new or rebuilt?

Tell us what kind of valvetrain you have and I can suggest ways of simulating the larger camshaft for checking purposes prior to purchase...is your valvetrain adjustable or non-adjustable?

Get back to us...
 
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I just bought the car (70 Cougar Eliminator) last August and haven't been inside the engine, only had the valve covers off. It was suppose to have 7500 miles on a rebuild, which I don't believe because it's a little ticky when warm. It has stock manifolds(intake & exhaust) on it with a 750 vacuum secondary Holley, 2 1/2 inch free-flow exhaust. It's hooked to a wide ratio 4-speed and 3.50 traction-lok. It has the stock rocker set-up (non-adjustable). It runs good, doesn't burn oil and sounds to be a stock cam in it. I hope this is what you were looking for Camachinist. Thanks again.
 
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I know, I know. I have an Autolite 600 CFM to go back on it.
 

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Since you have a non-adjustable rocker setup, you can insert 3/16" spacers between the rocker and valve tip, tighten the rockers back down until the fulcrum bottoms and turn the engine by hand through 2 revolutions, carefully checking for interference between the valves and piston, valve spring coils and retainer to guide...That should roughly approximate the camshaft you wish to use (overlap is hard to mimic but I feel this would be close)...you can always do the same thing,except with .100" spacer or feeler guages once you have the new cam installed..

Since the 4V engine had a healthy CR, you should be able to run a cam with fair duration and overlap without compromising the bottom end power too much...with a 4 speed and 3.50's, things are much more flexible.

Good luck!
 
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