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| Typical engine noise. https://slantsix.org/forum/viewtopic.php?t=64521 |
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| Author: | brybry4 [ Thu Feb 20, 2020 2:59 am ] |
| Post subject: | Typical engine noise. |
Hey guys and gals, is this motor typically a bit noisey in general? I am getting a lot of noise from the rockers in the motor but they don't really seem to have a lot of wear to be replaced. Any thoughts? I did mill my head one hundred thousands and has the push rods cut down the same length if that may have anything to do with it. |
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| Author: | Dart270 [ Thu Feb 20, 2020 4:18 am ] |
| Post subject: | Re: Typical engine noise. |
In a solid lifter engine like the Slant 6, the rockers always make some noise. If they are really quiet, they are too tigth and it will not run right and will usually make more wear on the valves. Lou |
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| Author: | DadTruck [ Thu Feb 20, 2020 7:00 am ] |
| Post subject: | Re: Typical engine noise. |
It may be correct, but I don’t know that there is a 1:1 relationship between what is cut off the head and the distance that the pushrod length would need to be adjusted. Certainly if you changed the cam the diameter of the cam base circle would need to be part of the equation. |
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| Author: | brybry4 [ Thu Feb 20, 2020 8:27 am ] |
| Post subject: | Re: Typical engine noise. |
Quote: It may be correct, but I don’t know that there is a 1:1 relationship between what is cut off the head and the distance that the pushrod length would need to be adjusted. Certainly if you changed the cam the diameter of the cam base circle would need to be part of the equation.
I did, I just put in the hughes engines cam, it requires a .004 intake hot valve lash and a .006 exhaust hot valve lash. This is the cam I installed and also has the cam specs card on this page. https://hughesengines.secure.nharmony.c ... rtid=34730 |
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| Author: | Doctor Dodge [ Thu Feb 20, 2020 8:56 am ] |
| Post subject: | Re: Typical engine noise. |
Did you do the lash adjustment with the engine hot and running? The tight lash settings make these cams harder to adjust seeing that there is a lot less room for error. See the thread on the newly released Hughes SL6 cams. DD http://slantsix.org/forum/viewtopic.php?f=19&t=64264 |
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| Author: | DadTruck [ Thu Feb 20, 2020 9:02 am ] |
| Post subject: | Re: Typical engine noise. |
There was quite a bit of discussion over those tight lash cams here at .org a couple of months ago. Let us know how you like it for performance. Concerning the engine noise that you mentioned, can you post a you tube video of the engine at idle, that would help this discussion. Also, 1) with the valve lash set to the cam card, is the push rods thread adjustment at about the center of the available threads, or is it really biased to one end or the other? 2) have you checked the travel of the rocker arm across the valve tip? As the rocker arm pushes the valve down, the rocker arm tip will travel slightly across the top of the valve stem. It is advantageous to have the motion area centered on the valve tip and as small as possible. If the valve train geometry gets way out of the norm, the motion will be out on the end of the valve tip. You can check the motion area by removing the rocker shaft / arms. Painting the tip of a few valve stems black with a Sharpie, re install the rocker shaft / rockers, tighten it properly, spin the motor over a few times with out starting it, remove the rocker shaft and view the motion area. |
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| Author: | Rick Covalt [ Thu Feb 20, 2020 10:10 am ] |
| Post subject: | Re: Typical engine noise. |
If lash is really .004 & .006 there should not be much valve noise. |
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| Author: | volaredon [ Thu Feb 20, 2020 10:32 am ] |
| Post subject: | Re: Typical engine noise. |
When set to factory settings of 0.010 I and 0.020" E, there is minimal valvetrain noise on a stock engine. So to make the clearance even tighter, minimal should move towards "none". |
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| Author: | Dart270 [ Thu Feb 20, 2020 11:43 am ] |
| Post subject: | Re: Typical engine noise. |
I personally would doubt you could run a Slant 6 cam at that tight lash. I don't care who made it or what kind it is. Every aftermarket cam I have run was happier (smoother hot idle, more low end response) with more lash than what the cam grinder said. Just my 2 cents... Lou |
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| Author: | DadTruck [ Thu Feb 20, 2020 12:01 pm ] |
| Post subject: | Re: Typical engine noise. |
Quote: more lash than what the cam grinder said.
adding lash has the effect of reducing duration. The valves opened to the lift that was ground into the cam, they just opened a few degrees later.
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| Author: | brybry4 [ Thu Feb 20, 2020 6:41 pm ] |
| Post subject: | Re: Typical engine noise. |
Quote: There was quite a bit of discussion over those tight lash cams here at .org a couple of months ago.
I do have the hot valve lash set to where the cam card requires. I do love the performance of this Hughes Engines cam compared to the comp cam I had in it before (the comp cam gear chewed up my plastic distributor gear and completely chewed up my oil pump gear.) I'm at the end of the thread adjustment. I probably have about a half a turn clock wise until I'm at the end of the screw. I'm not following you though on the geometry, doesn't the slant have a fixed geometry on the rockers because of it's adjustment screws being on the same inline end as the push rods? I'm not sure if the later slants are different in the head then the laters but mine's 67.
Let us know how you like it for performance. Concerning the engine noise that you mentioned, can you post a you tube video of the engine at idle, that would help this discussion. Also, 1) with the valve lash set to the cam card, is the push rods thread adjustment at about the center of the available threads, or is it really biased to one end or the other? 2) have you checked the travel of the rocker arm across the valve tip? As the rocker arm pushes the valve down, the rocker arm tip will travel slightly across the top of the valve stem. It is advantageous to have the motion area centered on the valve tip and as small as possible. If the valve train geometry gets way out of the norm, the motion will be out on the end of the valve tip. You can check the motion area by removing the rocker shaft / arms. Painting the tip of a few valve stems black with a Sharpie, re install the rocker shaft / rockers, tighten it properly, spin the motor over a few times with out starting it, remove the rocker shaft and view the motion area. |
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| Author: | DadTruck [ Thu Feb 20, 2020 7:14 pm ] |
| Post subject: | Re: Typical engine noise. |
Quote: about a half a turn clock wise until I'm at the end of the screw.
I don't know if you are 1/2 turn from the adjustor being all the way in or all the way out, but in either case you have the rocker starting from a position that is either tipped up or down.Certainly the starting point of the rocker shoe is off center of the valve tip. You really should use and adjustable push rod to determine what length of push rod is needed to get the adjustor back to a nominal position. A lot of folks on this forum have used Smith Brothers push rods. https://www.pushrods.net/ your thought that you can use the adjuster screw to totally make up the difference of an incorrect length push rod would be true if the interface of the push rod end to the adjustor screw was always totally linear and flat, it is not, that is why there is a cup and ball arrangement at the interface. By the way did you also change valves and if so are the valves different from the stock length? |
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