Hot Cams and T Buckets

Generally speaking, hot cams are needed for heavier high performance vehicles and vehicles which are not typically used for street driving. While these cams really sound fantastic, they have some bad-natured habits.

First of all the manifold vacuum is really low (around 5 to 10 inches) making power brakes useless and vacuum modulated transmissions hold the shift points. It will also have a tremendous effect on your carb tune. These can be overcome reasonably easy.

Second, hot cams tend to stress the valve train components. This too can be easily remedied.

Third, your power band is moved and increased in the upper RPM range. And your idle has very little horsepower. Not to mention you typically have to idle around 1000 RPM (or more) just to keep your engine running.

OK, now it's time to dis-spell a myth about why a hot cam "lopes". I'm sure you've heard all kinds of explanations... and most likely it's wrong! Exhaust timing is what causes "loping"... that's it, all the other things you've heard add to the effect but do not CAUSE the "loping". The loping is a direct effect of the exhaust valve opening before bottom dead center! Because the exhaust opens early, part of the combustion takes place in the exhaust manifold (headers). This causes an un-even popping which is readily noticeable as "loping". So forget about valve overlap, lift, duration, and all those "things" you've heard! My source of information came directly from the industry leaders engineering department of Competition Cams, Inc. Those guys know CAMS!

Here's a CompCams tutorial for you!

http://www.compcams.com/Information/Tutorials/

Back to business at hand. There are countless cam manufacturers and hundreds of grinds available for virtually every engine made. You also have cam types to contend with...IE Roller, Solid, and Hydraulic. And then there are cams for computer controlled fuel injection, nitrous, blowers, and a host of other configurations. Because T Buckets are light weight and usually over powered anyway, (and most likely a cruised vehicle instead of raced) milder grinds would be more than enough cam for this application. Even OEM hi-performance cams would be suitable. Some OEM cams even have the   "loping" that you may be looking for with out sacrificing too much bottom end..

OK, let's say you bought a T Bucket that has a "radical" hydraulic cam in it. You  find it very picky to drive around the streets and beats you half to dead while sitting at a light. You have to rev it up to get it moving, and you can't cruise at low speeds. But you just love the "sound" and that wicked midrange and topend! Now you think you're stuck with this, NOT SO! There is a way to tame a "radical" cam to make it behave at lower RPM's! And the bonus is.. you can boost your bottomend horsepower and raise your vacuum as well. HOW? By using variable hydraulic lifters! Under 1500 RPM varaible lifters bleed off and cut your effective lift, duration, overlap, and timing. However, when your engine hits 1500 RPM, the lifters give you 100% effective cam! This bleed off increases your bottom horsepower substantially as well as boost your manifold vacuum 3 to 5 points. Rhodes & Crower make these lifters. The Crower are a bit quieter than the Rhodes, but both will serve you well! Yes, you will still get some "lope" but not as much, and your idle will be considerably more manageable.

If you have a solid lifter cam, I would suggest replacing it with either a hydraulic or roller type. Solid lifter cams are very rough on your engine especially for street use.

Let's talk cam specifications for a minute.. You have to watch out here! Some mfg.'s use their OWN spec's and will not necessarily conform to another mfgs' specs! You need to know this before you start shopping around! One mfgs' duration of 242 can be another mfgs' 310! And one mfgs' lift of .498 can be anothers .510! (depending on rocker ratio) You need to be very aware of this long before you purchase that cam! A lot of factors need to be considered when selecting a cam. The wrong choice here can make your T Bucket run terrible, and possibly damage your engine to boot. I had experienced a valve to piston clearance problem with a hot cam. Ultimately an intake valve broke and completly destroyed a brand new engine! Do not guess about valve to piston clearance! "As a general rule, a total lift of less than .500" is safe on stock pistons". That's what I thought, and that's what I had, and it cost me dearly! The valve reliefs on stock pistons are cast into the tops and vary dramatically in depth!    Do not take chances. 

                     Think about your driving, think about your engine setup, and consider what effect a cam is going to have on your T Bucket!

http://www.compcams.com

http://www.iskycams.com

  A final note (from experience): Hot or "radical" cams are not designed or intended for cruising. They make tune-ups difficult, and are rough on valve train components. Your gas mileage will suffer, and you won't like the lack of power while leaping from traffic light to traffic light.  And, if you have a stock torque converter you will have to put your tranny in neutral EVERY time you want to stop your vehicle (especially T Buckets).