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Author Topic: Valve clearances........?  (Read 4348 times)

George A

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Valve clearances........?
« on: August 12, 2015, 03:53:34 PM »
I set my intake and exhaust at .017 and .032, as recommended by George Breckinridge at Utterpower, and my engine seems to fun fine.....however.....

I notice a LOT of "floating free play" in the exhaust push rod as the engine is running. The push rod actually clatters a bit, even after it's been running and thoroughly warmed up. I'm wondering if there's any harm in changing it to say, .020 (or even less) so as to remove some of that slop. It seems to me that I've read of others reducing it without any ill effects and getting a quieter engine in the bargain.

Frankly, I can't remember working on any engine with that much rocker arm clearance, however I'm not sure if doing this would affect the cam/valve timing in some fashion.
« Last Edit: August 12, 2015, 03:55:33 PM by George A »
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dieselgman

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Re: Valve clearances........?
« Reply #1 on: August 12, 2015, 04:46:01 PM »
Take a look at the threads by 38ac regarding valve timing... Yes, valve clearance has a significant and important effect on valve timing and engine performance. Unfortunately with the Indian product, the cam lobe placement as well as lobe profile seems to be all over the place and no rule-of-thumb solution can apply to every engine. The best answer to this issue has been clarified and well explained by 38ac and is worth considering in your case for certain.

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Tom

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Re: Valve clearances........?
« Reply #2 on: August 12, 2015, 05:43:56 PM »
I've run mine at .010 for years without issue. That said the thread referenced by Gary may reduce fuel consumption a bit.
Tom
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George A

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Re: Valve clearances........?
« Reply #3 on: August 13, 2015, 02:54:42 AM »
Sorry to be so late getting back to the party............our wonderful state highway department managed to take out the only fiber optic cable that supplies internet, phone and some cell service for our town.  Been out since about ten this morning and just got service back a few minutes ago.

I'll research that article before I decide, but at this point I think I'll just reduce the clearance to somewhat "normal" specs. If the engine acts normally and doesn't hold the valve open too long or something, I'll just leave it set and keep an eye on it.

Thanks guys! :)
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38ac

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Re: Valve clearances........?
« Reply #4 on: August 13, 2015, 12:46:52 PM »
Lister found need to drastically narrow up the tappet clearance  on the 8/1 which uses the same cam lobes, rockers etc. Why? I have always assumed to change valve timing for 800 RPM vs 650. Cold it be that the large clearances were bothersome at the higher revs?  ??? Possible I have never seen any documentation. My  work in the shop shows that valve timing changes a lot from the 6/1 settings to the 8/1 settings. With a 'roid you never know how close you are to correct timing anyway unless you put a degree wheel on it and check things out. Be aware that valve to piston  clearances are tight and reducing the clearance could very well put things in contact with each other. The 8/1 valve clearances are OK when used at 8/1 bump clearance, possibly not at 6/1 bump. Checking clearance is much easier and cheaper than replacing bent parts.
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George A

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Re: Valve clearances........?
« Reply #5 on: August 13, 2015, 04:55:19 PM »
Glad you chimed in 38c. I think maybe I'll hold off on doing any adjustments for now......I can put up with the noise! :)
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