Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: jerrett on July 07, 2016, 04:43:48 pm

Title: Adjusting valves on 99 cummins ISM
Post by: jerrett on July 07, 2016, 04:43:48 pm
Just finishes adjusting my valves and everything went well.  I have about 110k on her and all the exhaust valves were perfect at.027 so noadjustment was needed.  However, all the intakes were set at .007 and hence all required adjusting to .014.  My concern is why were they all at .007?  It states on the engine plate that .014 and .027 are the correct settings.  If only one or two were off i would not be concerned but with all being .007 I wonder if I am missing something.  I did not mess with the injector settings.
 
Any suggestions or support would be helpful.

Thanks for your help
Jason
Title: Re: Adjusting valves on 99 cummins ISM
Post by: John44 on July 07, 2016, 06:54:18 pm
Should run/sound a little better,wonder when it was adusted last and by who.
Title: Re: Adjusting valves on 99 cummins ISM
Post by: craneman on July 07, 2016, 07:26:18 pm
Probably get a lot of disagreement on this but, I don't see any performance gain technically a slight loss. The Valve lash settings are mainly to transfer heat from the valve to the head. The intake valves don't get near as hot as the exhaust valves. The .007 less valve lash on the intake actually increased your lift and duration on the intake side of the cam. Valve lashes are played with on performance engines in race cars while on the dyno. 
Just my opinion.
Title: Re: Adjusting valves on 99 cummins ISM
Post by: John44 on July 07, 2016, 07:49:44 pm
Not disagreeing but they are also set by the composition of the valves and metal around them,these were 50% off.

Was the engine completely cold?
Title: Re: Adjusting valves on 99 cummins ISM
Post by: craneman on July 07, 2016, 09:06:59 pm
I wasn't recommending, just commenting that he wouldn't feel any difference. When I set mine they will be .014 and .027 and 120 deg. on the injectors. Factory specs.
Title: Re: Adjusting valves on 99 cummins ISM
Post by: Dennis Davis on July 09, 2016, 09:10:32 pm
I worked on import autos professionally from 1970 until three years ago. They were, for the most part, required to check the  adjustment every so many miles. I would say if the factory spec on those intakes were .014 cold, and when you checked them they were all on .007, you might say they definitely needed adjusted. As far as why were they all at .007? I'm with you about those valves all changing by .007. Its very unlikely. Just be glad you checked them. And now I wonder if I should check mine.......... by the way the sticker on the engine should supersede  any previous data on valve lash.

Dennis Davis
99 270


Title: Re: Adjusting valves on 99 cummins ISM
Post by: Hans&Marjet on July 09, 2016, 09:48:18 pm
Probably get a lot of disagreement on this but, I don't see any performance gain technically a slight loss. The Valve lash settings are mainly to transfer heat from the valve to the head. The intake valves don't get near as hot as the exhaust valves. The .007 less valve lash on the intake actually increased your lift and duration on the intake side of the cam. Valve lashes are played with on performance engines in race cars while on the dyno. 
Just my opinion.
I always run my exhaust on the loose side...intake dead on..
Title: Re: Adjusting valves on 99 cummins ISM
Post by: Dennis Davis on July 09, 2016, 11:48:47 pm
You can't go wrong doing that.
Title: Re: Adjusting valves on 99 cummins ISM
Post by: John44 on July 10, 2016, 12:06:53 am
Get ready for some import car questions.