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| 40 Valve Lash??? http://mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=74122 |
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| Author: | dpd [ Tue Aug 20, 2019 8:08 am ] |
| Post subject: | 40 Valve Lash??? |
Just wondering those of you that are running and doing service work on the 40 EFI. Is there a particular valve lash setting that these motors do or don't like?? This is a stock motor question ----no mods Briggs service manual gives .004-.006 on intake and .007-.009 on exhaust The reason I ask is I checked lash on Sunday and they were loose, but the performance on the motor didn't seem to be off. I'm just wondering what yall were going with |
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| Author: | woffman [ Tue Aug 20, 2019 11:28 am ] |
| Post subject: | Re: 40 Valve Lash??? |
MB told me .004 intake and. 006 exhaust on a cold motor. I checked mine for the first time after 12hrs and they were all way out of spec. I want to say they were all over .012. |
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| Author: | dead animal [ Tue Aug 20, 2019 8:40 pm ] |
| Post subject: | Re: 40 Valve Lash??? |
it has been my experience with the 40 briggs that it don't matter where u set the valves, the 40 will do what he wants... then throw pushrods..... then eat cam lobe.... lol, I just set them at .006 and roll out. |
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| Author: | MaXXis85 [ Wed Aug 21, 2019 6:58 am ] |
| Post subject: | Re: 40 Valve Lash??? |
I set at .005" and roll out. people don't understand why there is a specific lash. It is camshaft clearance ramp dependent. These cams have "short" clearance ramps unlike cams in the automotive world. That's why we see .004-.006" vs .015-.020" like older flat tappet motors. If you have too much lash you are opening the valve on the flank of the lobe causing a HARD acceleration which will eventually cause premature valvetrain wear and unwanted noise.. The other purpose of lash is to makes once the engine is heated up there is still sufficient clearance for oiling of the camshaft and valve stem tips. rocker arms. The best way is to set to mfr specs cold.. go run the motor, and do a hot lash check.. You should expect to see the clearance tighten, but still shouls see at least .002". Remember its even less clear on the cams base circle (that's determined by rocker ratio). |
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