on my 91 all the things done are....
PODs
Water Methonol Injection
12cm WG
HTT stage III
Pump Tweaks
Timing bumped so there is less than a fingers thickness to the head

i am running the dyno tomorrow (if wifey doesn't go into labor) i have been putting off adjusting them til i ran the WM for a bit, someone a while back posted that after cleaning a bunch of carbon by effectively "steam cleaning" the engine with water meth that the truck seemed to need it more. wether that is true or not, i waited. the largest load this truck usually sees is a 12ft landscape trialer (fairly lightweight) with about 1000-1500# cargo max. will it hurt to go a little tighter? what does that gain me? i was thinking 18 & 8... but have no real basis for why i was thinking that. i know that spec is 20 & 10. all responces welcome, but remember to get this done be tomorrow i have to get out there by like 2-3pm today, so please respond quickly

 

The common opinion is that the 8 and 18 adjustment gives a little more duration that the stock cam doesnt give. I have read on here in the past about guys going 6 and 16, and running it well for SEVERAL thousand miles. I currently have mine at 8 and 18. I suppose it just allows that much more air in the combustion chambers. Because I couldnt find exact top dead center do to the alignment pin I believe Greg and my self stuck em at a not loose, not tight 8 and 18.

The "steam cleaning" theory is acctually quite interesting. I would like to see before and after pictures of some ones valves and pistons with the water meth install. I can believe it. I dont know just how much carbon could acctually be built up on the back side of the valves as no fuel is sprayed directly on them being direct injection. But still an interesting theory none the less.

 

There was a guy 'round here a few months back said he screwed 'em down to 16/6. Haven't heard from him lately, tho. Probably busy working overtime to pay for the head work and new valves.

 

Mica, I am not a tall certain about this, but I seem to remember a post a while back where they were talking about having the exhaust set to tight causing a piston to melt ???? Something about how much heat/pressure is retained..... might want to search on this.. but again, i am not at all certain I am remembering that correctly.

 

I was that guy that screwed em down to 6 & 16. The truck is still running great, but then I never work it hard either. I have probably put 2500 or so an ti that way.

 

Well I s'pose that's all well and good BUT, ...don't you miss that valve rattle? ...

 

Not really, the combustion rattle from the advanced pump is good enough.

 

Keep us posted to let us know how that's working for you long term. I'll sure be curious to hear how it goes.