Thread: Roller Rockers for Ford 300 Carborated
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Old 12-30-2010, 01:47 PM
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Originally Posted by craighurst
So how i figure out if my geometry is good with bbc rockers? How did you install them on your 300? Also is there any real difference between sbc and bbc rockers?
Dude, what did I just write? Yes, there is a difference! But buy whatever you like.

Install them just like your oem rockers, put each piston at tdc and tighen to zero lash, then tighten allen nut, and tighten big nut a quarter turn. Do int/exh. on each cylinder, and go to the next at tdc.

When you install the first one, mark top of valve with a felt pen, then torque down the rocker at zero lash, then turn engine by hand 360 degrees, until that piston is at tdc on compression stroke again. Remove the rocker and look at the felt pen mark. It will show you where the roller rolled on the valve tip. It should start at the 1/3 point on the distributor side of engine, and roll across the center, and finish at the 1/3 point at the exhaust side of engine. If it shows the roller is too far one way or the other, then the geometry is off, and you have to get longer/shorter p.rods.

Let's assume you check several rockers and all your pushrods are too short. The best way to establish the proper length is to use an adjustable checking pushrod. Crane, Isky, and others offer adjustable pushrods, but the slickest tool is made by Comp Cams. This tool screws apart just like the others, but rather than having to measure the actual length of the pushrod, the Comp Cams tool reads out the length on the side of the pushrod just like a micrometer. Comp sells individual checking pushrods, or you can purchase an entire set intended for those who build many different types of pushrod engines. With this tool, you merely adjust the length of the pushrod until the witness mark is on the inboard third of the valve-stem tip. Then count the number of turns the pushrod is lengthened and you have the proper pushrod length, since each turn is worth 0.050 inch. It's best to wait until you've mocked up the engine for the last time to check for pushrod length. This way, a change to installed height or a cam change won't require a pushrod change.

Do a search. Google it. Read. Learn.

Good luck.
 
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