Engine Build#2:Camshaft Dial-In

S3700153

if you have never done this, or never even heard of this, it’s called camshaft dial-in. although not as many people do it as should, it is something i had to learn to do by force cause of this damn oldsmobile habit i have. unlike the aftermarket for chevy, olds performance products ore usually not right. i have only had two timing sets ever be spot on to there advertised markings. believe it or not the most consistent timing chains i have bought in recent years are the summit racing brand timing chains!

in a nutshell, your engine is a rotating assembly. your camshaft is designed to orchestrate your valve motion in relation to the rotational position of the crankshaft. by dialing in your camshaft, you are verifying that your camshaft and timing chain are going to fire off your valves at the right time and the proper lift to what you want. like i mentioned, there are numerous timing chains and camshafts out there, and they may or may not be made correctly. hell even my edelbrock cam was a bit off on the exhaust valve duration. a lot of your factory cams and bad replacements are ground retarded from the get go- and some of these multi position timing sets that actually sit 4 deg retarded at the 4 degree advanced markings!

Now, i could sit here and write out exactly how to do a cam dial in, but a quick google search will reveal some spot on articles on how to do it, as well as video’s you can watch on the web. you can buy complete kits to do this as well through summit or jegs. what i will do is point out a few things that i do whi;le going through the procedure.

there are a few ways of doing dial in, i use the intake centerline method with a dial indicator at the lifter. this eliminates all loss of lift through the valvetrain. yes, you can lose quite a bit of advertised lift through a poor valvetrain(like the olds). i use the large moroso degree wheel, a home-made pointer i made out of a bolt, and a piston stop i made from a piece of angle iron and a few bolts. i have a hydraulic lifter that has been welded solid with a plug so it does not collapse and throw off the measure of the dial indicator.

once i center my degree wheel to TDC #1, i position my dialS3700154 indicator directly on the lifter of either intake or exhaust # 1. you then zero the indicator and crank the engine around to .050″ lift at the indicator. look at your wheel and see how it corresponds with your cam card specs. if it is not spot on, note the degree’s of difference. this is the first sign of your cam timing being way off. i go through the process for both intake and exhaust lift. if all readings are off by about the same # of degree’s, adjust your timing chain…or in some extreme cases if it is off by 8 degree’s or more from the card on both intake and exhaust, shit can your timing chain.

as a rule of thumb, advancing your timing chain will usually help your bottom end power-retarding it pushed the power band up the rpm scale. for the most part, you should achieve correct cam timing with the timing set installed in standard position. if the cam is way retarded or advanced from the cam card while the timing set is installed straight up- call the manufacturer cause there is probably a reason for it, like valve clearance to the pistons for radical lift . do not plan on buying a cam and changing it at the timing chain from the get go. although it can be a neat way to save money- just save yourself a headache and buy the camshaft you want. use the timing set adjustments for fine tuning not overhauling the cam timing.

i quit buying used camshafts or anything without a timing card simply because you really don’t know what the hell you have. you can use this process to read an unknown cam or a camshaft you have ran for a few years to check for wear.

once i have my cam timing set, i wheel the engine to TDC#1 and remove the wheel. slide your dampener on(sometimes part way) and see where your ignition timing mark is located in relation to the true TDC location between your indicator and the groove on the dampener. you’re checking to see if the outer weight outer weight of the dampener has spun on the rubber and moved the mark. if this has happened, then you need to shit can your dampener. on the SBC chevy’s there were a few different balancers and timing covers so you can really mess up where you set your timing.

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