| Slant Six Forum https://www.slantsix.org/forum/ |
|
| Setting Valve Lash https://www.slantsix.org/forum/viewtopic.php?t=52815 |
Page 2 of 4 |
| Author: | jhdeval [ Tue Jul 23, 2013 1:00 pm ] |
| Post subject: | |
My cam is not as aggressive as your 230 @ .050 and but I can't idle below about 470-480. When I first tried though I was at like 1300 as I recall that was near impossible. |
|
| Author: | Doc [ Tue Jul 23, 2013 1:03 pm ] |
| Post subject: | |
The real "decision maker" is the cam in the engine that is getting the lash adjustment. Stock stuff (mild cam with low lift & light spring pressures) I do running. Just turn the idle down and do all the intakes first, then all the exhausts. (more warm-up time for the exhaust valves) Listen for the cylinder to "drop-out" as you insert the thickness gauge... you hear a slight miss-fire if the lash is "right"... and you can hear all the cylinders mis-fire about the same "amount", when you have done the job well. With aggressive cams, I tend to adjust those static. I roll the engine around and watch the valves open & close... in pairs. I adjust the exhaust's lash, when it's "mate" intake is starting to close. I adjust the intake's lash when that cylinder's exhaust valve is starting to open. Use chalk to make the ones I have adjusted. Call it done when all 12 are marked. DD |
|
| Author: | jhdeval [ Tue Jul 23, 2013 1:08 pm ] |
| Post subject: | |
Doc do you warm the engine first or do it cold? Thats kind of where my first question came in. If I set it cold should I adjust the valve more to the tight side so when warm they are right? |
|
| Author: | Doc [ Tue Jul 23, 2013 1:21 pm ] |
| Post subject: | |
I start adjusting when the engine is warm... enough so the choke comes off. I start with the intakes first... then do the exhausts. DD |
|
| Author: | DusterIdiot [ Tue Jul 23, 2013 1:29 pm ] |
| Post subject: | Bzzt... |
Quote: my motor wont idle that low with the 246 @ .050 cam
It's your engineering...My OCG 549 Mill at 250/250 @,050 can get down that low for setting lash, but reset it back up to 900-1000 rpm for idle...of course my setup is a little different than yours...  -D.Idiot |
|
| Author: | jhdeval [ Tue Jul 23, 2013 2:15 pm ] |
| Post subject: | |
Silly question. How much variation should I expect when setting the idle at 1000 rpm in park versus in driver? What I am finding is I am loosing between 400-500 rpm. I feel like that is an unusually large number. |
|
| Author: | wjajr [ Wed Jul 24, 2013 6:07 am ] |
| Post subject: | |
With automatic transmission set parking brake and chock all wheels, and shift into D or R to settle down idle speed. Or back off timing enough to lower rpm. I have a cam that idles at 1000 + rpm in park, 550 to 600 rpm in gear loping & rocking away on its mounts. Lope makes it hard to hear any change in idle sound quality during lash adjustment, and it is almost imposable to adjust lash at 1000 rpm guaranteeing an oily mess as it will be slung all over under hood and on to floor. As Doc suggested, set lash warm with engine off & plugs removed, this a cleaner more accurate method I now use on this engine. I have also used compression readings to fine tune individual cylinder pressures to even out all six cylinders. I found once all six cylinder pressures are within five psi the idle and vacuum smooth out, lope is diminished, and vacuum signal to carburetor is better allowing better A/F idle adjustment. |
|
| Author: | Doc [ Wed Jul 24, 2013 8:50 am ] |
| Post subject: | |
Quote: Silly question. How much variation should I expect when setting the idle at 1000 rpm in park versus in driver? What I am finding is I am loosing between 400-500 rpm. I feel like that is an unusually large number.
Check your distributor's vacuum & mechanical advance curves to see if you are loosing timing advance, in that RPM range.Said another way... If you have 16 drgrees of advance at 1000 RPMs and that drops to say 6 degrees at 600 RPMs, you do get more RPM drop, as the idle speed decreases. |
|
| Author: | roadrunnerh [ Wed Jul 24, 2013 8:59 pm ] |
| Post subject: | |
I did it for the first time this year. I followed the procedure on this site and I didn't think it was that hard. Yeah, you end up inhaling some motor oil and get some hot oil drops on your arms, but all in all it's easy once you get used to everything moving. |
|
| Author: | Danarchy [ Thu Jul 25, 2013 11:59 am ] |
| Post subject: | |
Quote: I start with the intakes first... then do the exhausts.
This brings up a question. 1st time I set the lash I worked back & forth (intake then exhaust) per cylinder, 2nd and 3rd time I did all the intakes, then all the exhausts. I have yet to get it back to how it was originally(1st time)...yeah I know I shouldn't have messed with it to begin with!, but I thought I could smooth it out alittle more.(I still know I can)DD QUESTION: Why would doing all intakes then all exhausts be the preferred method over alternating? P.S. Always adjusted after warming up and running. |
|
| Author: | jhdeval [ Thu Jul 25, 2013 12:33 pm ] |
| Post subject: | |
My personal guess would be that you are not going back and forth between 2 difference gauges so you are more familiar with how it should feel. |
|
| Author: | Danarchy [ Thu Jul 25, 2013 12:45 pm ] |
| Post subject: | |
thats why I did it!... just didn't know if there was a real (important) reason. |
|
| Author: | jhdeval [ Thu Jul 25, 2013 1:04 pm ] |
| Post subject: | |
I went back and forth intake/exhaust. I am a different person though. |
|
| Author: | Doc [ Thu Jul 25, 2013 2:14 pm ] |
| Post subject: | |
Quote: ... QUESTION: Why would doing all intakes then all exhausts be the preferred method over alternating? ...
I do the Intakes first to allow more warm-up time. (I usually start with a cool / cold engine... because I do not like pulling the valve cover off a "hot" engine) This is a non-issue if you already have the engine hot.I like to do all of the same valve type, at one time. This allow me to get a better "feel" and hopefully, better consistancy, valve-to-valve. This also reduces my own "klutz factor" seeing that I am constantly looking to see if I have the correct feeler gauge and / or spending time getting the needed gauge back out of the "stack"... seeing that I just pushed it back into the group, while working with the other size. (Industrial "Ergonomic" engineers call this "lost motion"... I call it Murphy's law)   It's just the way I do it... works for me. DD |
|
| Author: | wjajr [ Fri Jul 26, 2013 5:38 am ] |
| Post subject: | |
Doc: Quote: This also reduces my own "klutz factor" seeing that I am constantly looking to see if I have the correct feeler gauge and / or spending time getting the needed gauge back out of the "stack"...
Yup, nothing like a warm oil soaked clip of feeler gages stuck together, and trying to dig out the next size adjusting intake to exhaust and back to intake, etc. No matter how carefully one is to keep the other gage sticking out from the stack it somehow manages to migrate back into the crowd. Each tic of the engine and clock meters out more oil to clean up when job is completed. |
|
| Page 2 of 4 | All times are UTC-08:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|