Gear Drives,,,
N/A engine - you dont want them in a N/A car because they transfer too many harmonics to the valve train, basically too sturdy and can cause issues
Blown engine - gear drive is good to use here due to the force they see. the thing that will allow a blown engine to work good with these are the have a large blower belt coming off the crankshaft so this makes a gear drive perfect here
Timing Chains,,,
N/A engine - good for use on any N/A or NOS engine with normal spring pressure for roller cams (600-650max open IMO) or any flat tappet engine. Drag race or circle track
RPM means little to nothing with timing chains until spring pressure goes up. Racers running camshafts that are very aggressive (not something a bracket racer/street guy would run, more like a Super Stock or Comp camshaft) that need say 800 pounds open and are pushing the valve train to the limit will be trying to retard the camshaft the way it wears the camshaft gear teeth so this is when a belt drive comes in to play here
If your not running that sort of aggressive lobe/rocker combo with high spring pressure it really doesnt make a huge difference which one you go with, more so which one you can afford.
You can set thrust easier and degree the cam easier with the belt drive.
If you use a timing chain you need to use the SA Gear Billet with the 2 piece adjustable cam gear (like a belt drive) or the Cloyes 9 key way set or the Cloyes unit with the adjustable cam gear. I would not use a timing chain that is not billet, they seem to allow the chain to fit better
SA Gear the chain fits tighter and stays tighter which are many Comp, Lunati and Erson timing sets.
OK here is my experiance with all three
over the years i have used and seen all three devices
i have put gear drives in engines that were used in dirt track , street and drag and have never had a failure as of yet , i know it happens but it has not happened as of yet with the stuff i have seen i think they work well , if these things can live 5 seasons in a late model dirt car then i assure you they will last in a drag race application
timing chains- have used over the years with equal good luck , but have seen them stretch with very little use in high rpm motors, but yes they have come a long way in the last few years and if you are on a budget then they are the way to go
belt drives - i use a jesel on my stuff as i like the fact i can degree in the cam easier and can adjust for ****y track conditions if i need to and i do believe that they help with harmonics when you start getting into the higher RPM range and the timing seems more stable
but let me add this---why would you put a 70 dollar timing chain on a 10-25 thousand dollar engine just does not seem right but i guess that is just me ,kind of like using a 29 dollar oil pump on a motor you pay big dollars for--will it work, yes but i just can not see the point in doing it
but to each their own
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If it ain't buckin, chirpin & makin all kinds of bad noises, then I ain't happy
Accelerating is optional...........stopping is mandatory. Your car WILL stop one way or another.
I'm swaying toward belt drive right now but i'll need to do more research. Accesability and adjustability make the belt drive desirable. If the belt drives can handle high cylinder pressures and 14:1 compression it may be the better choice.
The Summers Brothers option is pretty interestng also.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
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