Inliners International Forums General Discussion Engines Integral intake Ford sixes..cam info

I'm in the process of collecting parts to build a 200 Ford six for my '65 Falcon Ranchero. I've built a couple of these engines in the distant past, but I don't remember this happening:

A fellow told me today that, I will have to use the adjustable rocker arms, from a solid-lifter engine, if I have install a cam that has any grind other than stock. He said the cam lobe base will be ground down, giving the hydraulic lifters too much "slop"...because of the longer stroke. He says they will rattle like crazy!

For the life of me, I can't remember what cam I used, when I built a 200, back in '71. All I know is, it had a mild street grind............because, at idle, it had very little lope and good low-end vacuum.

Anyway, does anyone have experience with lifters being too strung out and not able to run quiet, because of the extra length of stroke it'll have with a slightly more aggressive cam?

I really don't want the expense of aluminum adjustable rocker arms and doubt if I could find a good set of original adjustable rockers.

Any advice, information would be greatly appreciated.

If the base circle is undercut .060", both to add some lift and get a bigger lobe silhouette, the preferred cure is a pushrod longer than the original by 1/2 of the reduction, in this case .030".
On the other end, let's assume that the lift is increased by .060" (can't be more than .090": .060" × 1.5:1? rocker arm). This needs the rocker to tilt up on the closed valve to keep the same geometry by 1/2 of the lift increase, or .030". Divide this by your rocker ratio to get the amount subtracted from the pushrod length, e.g., 1.5:1 ratio means .020" off the pushrod.
These changes work in opposite directions, but may not cancel each other out. If the cam was reground to stock lift, the pushrod would be longer by the math above with no geometric correction.
Using these numbers, +.030" and -.020" = +.010". Your net pushrod change is only .010", too small to worry about.
The cam grinder may give you the new base circle diameter, or you can compare it with stock to get the reduction.
Don't ask Clifford's receptionist, who has no idea what this means - she's tell you "it's stock", because that's #3 on the list of universal answers.

This all assumes no head mill, block decking, gasket thickness, valve seat recession, or other dimensional changes.

Thanks a lot, Panic!