MGB & GT Forum
camshaft endfloat questions
Posted by locortjody
locortjody
JL Fonseca
Corralitos, CA, USA
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Topic Creator (OP)
Sep 29, 2016 12:05 PM
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I am assembling a 3 main 1800 for my TVR, and I have some questions and some wonderings about camshaft endfloat, I would appreciate some input from some experienced builders, as I have done a few MG engines, but my real experience lies elsewhere.
The last MGB engines I assembled, I checked the camshaft endfloat with the cam sprocket and cam assembly assembled and in the block. I check this value with a dial indicator. I got .005, and referring to the shop manual that spec'd 003-007, figured that was right in the middle, so I was OK.
Then I got to wondering. First off, it didn't pass the clunk test. That is, when you pull the cam all the way forward, then hit the sprocket with the open palm of your hand, you get a nasty, "clunk" sound. Laugh if you will, but it's been my experience that when an endfloat is good, you will get a soft, almost inaudible "tick" when it's just right. Then, I noticed that the old thrust plate, as well as the thrust plate from the previous engine I did, were significantly buggered on the thrust side. I did not check endfloats before I took those engines apart, but if you told me the endfloat was .015 or even .020, I wouldn't doubt you.
Then I consulted the Burgess book. PB recommends .001 or as close to .000 as you can get. Joe Huffaker's book cites a max. tolerance of .003, if I recall.
So, my concerns/questions are this:
Endfloats, in my experience work this way, if too loose, the pieces hammer back and forth, and after awhile, the .005 ends up being .010, .020 to who knows how much. (witnessed by the thrustplate wear on the old plate) If assembled at a smaller value, say .002 or .003, the pieces may not ever start hammering in the first place, and be happy forever.
Where do we reach the point of diminishing returns? Is it .003? (I already have it down to a skinny .003) Or should I be shooting for the zero? The past couple engines I've taken apart have indicated by the amount of wear on the thrustplate, that the cam was walking around quite a bit. This cannot be good on an engine that is not terribly generous to its cam lobes and lifters in the first place, to have the cam on walkabout. What seems to be the optimum endfloat value? Are there shims available? I've already invested a lot of time with a glass plate and 600# wetordry to get 2 thou off the sprocket, a shim would be nice
Jose-Luis Fonseca
The last MGB engines I assembled, I checked the camshaft endfloat with the cam sprocket and cam assembly assembled and in the block. I check this value with a dial indicator. I got .005, and referring to the shop manual that spec'd 003-007, figured that was right in the middle, so I was OK.
Then I got to wondering. First off, it didn't pass the clunk test. That is, when you pull the cam all the way forward, then hit the sprocket with the open palm of your hand, you get a nasty, "clunk" sound. Laugh if you will, but it's been my experience that when an endfloat is good, you will get a soft, almost inaudible "tick" when it's just right. Then, I noticed that the old thrust plate, as well as the thrust plate from the previous engine I did, were significantly buggered on the thrust side. I did not check endfloats before I took those engines apart, but if you told me the endfloat was .015 or even .020, I wouldn't doubt you.
Then I consulted the Burgess book. PB recommends .001 or as close to .000 as you can get. Joe Huffaker's book cites a max. tolerance of .003, if I recall.
So, my concerns/questions are this:
Endfloats, in my experience work this way, if too loose, the pieces hammer back and forth, and after awhile, the .005 ends up being .010, .020 to who knows how much. (witnessed by the thrustplate wear on the old plate) If assembled at a smaller value, say .002 or .003, the pieces may not ever start hammering in the first place, and be happy forever.
Where do we reach the point of diminishing returns? Is it .003? (I already have it down to a skinny .003) Or should I be shooting for the zero? The past couple engines I've taken apart have indicated by the amount of wear on the thrustplate, that the cam was walking around quite a bit. This cannot be good on an engine that is not terribly generous to its cam lobes and lifters in the first place, to have the cam on walkabout. What seems to be the optimum endfloat value? Are there shims available? I've already invested a lot of time with a glass plate and 600# wetordry to get 2 thou off the sprocket, a shim would be nice
Jose-Luis Fonseca
dickmoritz
Dick Moritz
Philly 'burbs, PA, USA
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Sep 29, 2016 12:14 PM
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Jose-Luis,
Buenos dias.... Two questions: When measuring camshaft endplay, are you doing so with the timing chain and timing chain tensioner installed? And are you using stock-type timing chain sprockets or an aftermarket vernier-type setup?
Dick
Errabundi Saepe, Semper Certi
(Often wrong, but always certain)
Buenos dias.... Two questions: When measuring camshaft endplay, are you doing so with the timing chain and timing chain tensioner installed? And are you using stock-type timing chain sprockets or an aftermarket vernier-type setup?
Dick
Errabundi Saepe, Semper Certi
(Often wrong, but always certain)
locortjody
JL Fonseca
Corralitos, CA, USA
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Sep 29, 2016 12:40 PM
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dickmoritz
Dick Moritz
Philly 'burbs, PA, USA
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Sep 29, 2016 01:00 PM
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If you have a real 0.003, you're fine. Note that your "clunk" test is largely a function of how snugly the camshaft bearing journals fit into their bearings. If they're a snug fit, then you'll have less of a clunk and more of a tap. The endplay as measured with a dial indicator or feeler gauge is the procedure that determines whether your endplay is within specs, and it certainly sounds like you have it within specs. Furthermore, once the chain is installed, it will dampen fore/aft movement of the camshaft and its sprocket, so it sounds like you're just fine just the way you are...
Dick
Errabundi Saepe, Semper Certi
(Often wrong, but always certain)
Dick
Errabundi Saepe, Semper Certi
(Often wrong, but always certain)
Sep 29, 2016 02:42 PM
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I agree with Dick. Basically, the clearance can be minimal so long as it "feels" alright - no binding or drag. I seem to recall that when I built my engine I was a little under 2 thousandths.
Terry Ingoldsby
terry.ingoldsby@DCExperts.com
Terry Ingoldsby
terry.ingoldsby@DCExperts.com
Speedracer
Hap Waldrop
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Sep 29, 2016 05:01 PM
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.005" is fine, that's the target we use on race engine.
Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com
Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com
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about 6 years and 9 months later...
Jul 16, 2023 03:44 PM
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I realize this is an old thread, but here it goes. Freshly rebuilt 1800 GB K block, I’m installing a new, stock cam, tensioner and gears. Do I need to check end float on the camshaft? If so, what the procedure on that? Is there a link to a video or explanation? TIA
riley1489 thanked seattle76 for this post
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