Modifications for Adjustable Lifters

J

JP31

Member
What changes to the block need to happen to change to adjustable valve lifters? Does it require machining?
 
Adjustable lifters do not need a block modification if you use the single lock lifters. If you use the poorly made double lock lifters (base is too small), they are very hard to adjust due to the two nuts on them. I got rid of my double lock lifters and bought the single lock type. They adjust fine.
Rusty Nelson
 
To make valve adjustment easier when using the single lock lifters, you can machine down the top of the lifter guide casting in the valve chamber. This allows you to get both of the needed wrenches on the lifter and make the clearance adjustment all in one step. Without this modification, you have to cycle the lifter to fully open, make the clearance adjustment (because the lifter has to be up to enable you to get both wrenches on it) then cycle the lifter to the fully closed position to measure the clearance. I didn't do that machining when I built my engine, so valve adjustment for me is VERY time consuming. And remember, you're bent over the left front fender when making these adjustments. And like I said, it's VERY time consuming, because it's not something you do everyday.
 
Please do not machine down the lifter bosses. The more oil in the valve chamber is a good thing. The higher the oil level the more oil pressure to the mains. plus going up a steep hill might reduce oil to front main. Some my said it does not make that much difference, I say leave it the way we know it works. Plus if you mill the lifter bores down it can cause the lifter to rock because of lack of support. They did not spend the time and money to make them longer than needed.

To adjust the valves easy. Take a old cam nut and weld a handle on it. Then use that to turn the cam to adjust the valves before you put the cam gear on. It work's great and you do not have to mess up another good block.
 
It is not pretty but does the job. I think you could make one faster than milling the guides.
 

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Only cut the bosses down to the height of the first forward dam and it has no effect on the oil level in the valve chamber. It certainly makes it easier to adjust the valves. I also suggest you use the better quality lifters, not the double nut type.
By the way, most of the oil pumped into the valve chamber is dumped forward into the cam gear housing and exists to the dip tray for lubing the rods, wrist pins, and rings.

Ron
 
For general info, Dan MacEachern lists in his online catalog, modified Chrysler lifters to fit a model A. Drop in. No mods required. These have double locks and the large face that should work with any cam.
I have used Chrysler lifters in model A race engines and they work fine.

The common model A double lock lifters with the one inch face should only be used with cams ground for use with a one inch dia. lifter.
 
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