I'm working on an 8BA with an Isky Max 1 camshaft and had a question about camshaft end play. With a .015" timing cover gasket installed, I'm measuring approximately .010" cam end play. Should I be trying to reduce that closer to the minimum specification? What issues can occur if the camshaft end play is on the high side? Is .010" acceptable, or is it worth tightening up?
8BA Camshaft End Play
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glennpm
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As responded to in your previous thread of the same subject
"Bored&Stroked
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Default Re: 52 8BA – Cam Walking Forward & Exhaust Lifter Contacting Center Journal
How thick is the timing cover gasket and who did you buy it from? The original gaskets are very thin (about .008 or so), while some of the aftermarket ones are quite thick (about .016 or so). If you're running a thick gasket, then it allows a lot more cam thrust movement than the original. I always check the end-play on the cam and if I need to make adjustments, then I do it with the gasket (making my own at times). I like to have the thrust on the low-side of the spec (closer to .006) - as this results in more consistent ignition timing."
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Default Re: 52 8BA – Cam Walking Forward & Exhaust Lifter Contacting Center Journal
How thick is the timing cover gasket and who did you buy it from? The original gaskets are very thin (about .008 or so), while some of the aftermarket ones are quite thick (about .016 or so). If you're running a thick gasket, then it allows a lot more cam thrust movement than the original. I always check the end-play on the cam and if I need to make adjustments, then I do it with the gasket (making my own at times). I like to have the thrust on the low-side of the spec (closer to .006) - as this results in more consistent ignition timing."
How much will ignition timing be affected if the camshaft end play is about .004" greater than the minimum spec? The engine is being built as a weekend cruiser, so I'm trying to determine whether it's worth spending additional time chasing a few thousandths of clearance for what may be minimal real-world benefit.
Thank you, that helps. I just wanted to be sure before making a custom gasket.
Yes, I fixed the issue. I removed the camshaft and cleaned up the front faces of the center and rear journals in the lathe. There was quite a bit of rough casting, and the fillet radius between the journal face and diameter was large enough to catch the edge of the lifter. After machining, I now have 0.050" of clearance before the camshaft contacts the side of the lifter without the front cover installed.
Bored&Stroked
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Hey, still wondering where you purchased your timing cover gasket? Was it in a kit from Speedway?
glennpm
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B&S, I'm curious about your mention of timing changes, "I like to have the thrust on the low-side of the spec (closer to .006) - as this results in more consistent ignition timing."
I thought that the Ford flatheads were all flat lobes, parallel to the cam longitudinal centerline. The lifters have a slight radius. Why would the timing change?
I thought that the Ford flatheads were all flat lobes, parallel to the cam longitudinal centerline. The lifters have a slight radius. Why would the timing change?
glennpm
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Thank you!
Bored&Stroked
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Both the cam and the ignition timing change as the cam moves back and forth. The helical gears on a 49-53 thrust the cam towards the timing cover and on 32-48 engines the helical direction is opposite (they thrust towards the block). When you have too much endplay, you can put a timing light on the engine and you'll see the timing "jump around a bit" as you throttle up and down. This is also very true for OHV engines - especially with roller cams.
It came in a Best Gasket Engine Rebuilding Set. The Timing Cover Set alone is part number GS8086.
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Bored&Stroked
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Hmmmmm . . . I thought they had the right thickness gasket, guess not. Last time I had the issue I bought some .008 gasket material and made my own timing cover gasket. But, I'm a picky *******! LOL
Assuming the camshaft can float 0.010". Which I doubt. 0.010" on a 20 degree tooth will equate to 0.004" on the circumference. 0.004" on a 20" circumference is less than 75% of one tenth of one degree at the camshaft. So less than one and a half tenths of one degree of the crankshaft.
Just saying...
One thing a lot of people don't address is the end float on the distributor shaft. Because the drive gear is trying to force the shaft upward, and gravity is pushing it down, it would have the ability to float.
Just saying...
One thing a lot of people don't address is the end float on the distributor shaft. Because the drive gear is trying to force the shaft upward, and gravity is pushing it down, it would have the ability to float.
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